List of parasites of humans
Endoparasites -- Protozoan organisms
Table:
Common name of organism or disease

Latin name (sorted)

Body parts affected

Diagnostic specimen

Prevalence

Source/Transmission (Reservoir/Vector)

Granulomatous amoebic encephalitis and Acanthamoeba keratitis (eye infection)

Acanthamoeba spp.

eye, brain, skin

culture

worldwide

contact lenses cleaned with contaminated tap water

Granulomatous amoebic encephalitis

Balamuthia mandrillaris

brain, skin

culture

worldwide

via inhalation or skin lesion

Babesiosis

Babesia B. divergens, B. bigemina, B. equi, B. microfti, B. duncani

red blood cells

Giemsa-stained thin blood smear

New England (different species have worldwide distribution)

tick bites, e.g. Ixodes scapularis

Balantidiasis

Balantidium coli

intestinal mucosa, may become invasive in some patients

stool (diarrhea=ciliated trophozoite; solid stool=large cyst with horseshoe shaped nucleus)

ingestion of cyst, zoonotic infection acquired from pigs (feces)

Blastocystosis

Blastocystis spp.

intestinal

direct microscopy of stool (PCR, antibody)

• worldwide: one of the most common human parasites[1][2]
• Developing regions: infects 40–100% of the total populations[1][2][3]

eating food contaminated with feces from an infected human or animal

Cryptosporidiosis

Cryptosporidium spp.

intestines

stool

widespread

ingestion of oocyst (sporulated), some species are zoonotic (e.g. bovine fecal contamination)

Cyclosporiasis

Cyclospora cayetanensis

intestines

stool

United States

ingestion of oocyst thru contaminated food

Dientamoebiasis

Dientamoeba fragilis

intestines

stool

up to 10% in industrialized countries

ingesting water or food contaminated with feces

Amoebiasis

Entamoeba histolytica

intestines (mainly colon, but can cause liver failure if not treated)

stool (fresh diarrheic stools have amoeba, solid stool has cyst)

areas with poor sanitation, high population density and tropical regions

fecal-oral transmission of cyst, not amoeba

Giardiasis

Giardia lamblia

lumen of the small intestine

stool

worldwide?

ingestion of water containing deer or beaver feces

Isosporiasis

Isospora belli

epithelial cells of small intestines

stool

worldwide – less common than Toxoplasma or Cryptosporidium

fecal oral route – ingestion of sporulated oocyst

Leishmaniasis

Leishmania spp.

cutaneous, mucocutaneous, or visceral

visual identification of lesion or microscopic stain with Leishman's or Giemsa's stain

visceral leishmaniasis – worldwide; cutaneous leishmaniasis – Old World; mucocutaneous leishmaniasis – New World

Phlebotomus, Lutzomyia – bite of several species of phlebotomine sandflies

Primary amoebic meningoencephalitis (PAM)[4][5]

Naegleria fowleri

brain

culture

unknown, but infection is rare

nasal insufflation of contaminated warm fresh water, poorly chlorinated swimming pools, hot springs, soil

Malaria

Plasmodium falciparum (80% of cases), Plasmodium vivax, Plasmodium ovale curtisi, Plasmodium ovale wallikeri, Plasmodium malariae, Plasmodium knowlesi

red blood cells, liver

blood film

tropical – 250 million cases/year

Anopheles mosquito

Rhinosporidiosis

Rhinosporidium seeberi

nose, nasopharynx

biopsy

India and Sri Lanka

nasal mucosa came into contact with infected material through bathing in common ponds

Sarcocystosis

Sarcocystis bovihominis,Sarcocystis suihominis

intestine, muscle

muscle biopsy

widespread

ingestion of uncooked/undercooked beef/pork with Sarcocystis sarcocysts

Toxoplasmosis (Acute and Latent)

Toxoplasma gondii

eyes, brain, heart, liver

blood and PCR

worldwide: one of the most common human parasites; estimated to infect between 30–50% of the global population.[6][7]

ingestion of uncooked/undercooked pork/lamb/goat with Toxoplasma bradyzoites, ingestion of raw milk with Toxoplasma tachyzoites, ingestion of contaminated water food or soil with oocysts in cat feces that is more than one day old

Trichomoniasis

Trichomonas vaginalis

female urogenital tract (males asymptomatic)

microscopic examination of genital swab

worldwide

sexually transmitted infection – only trophozoite form (no cysts)

Sleeping sickness

Trypanosoma brucei

brain and blood

microscopic examination of chancre fluid, lymph node aspirates, blood, bone marrow

50,000 to 70,000 people; only found in Africa

tsetse fly, day-biting fly of the genus Glossina

Chagas disease

Trypanosoma cruzi

colon, esophagus, heart, nerves, muscle and blood

Giemsa stain – blood

Mexico, Central America, South America – 16–18 million

Triatoma/Reduviidae – "kissing bug" insect vector, feeds at night

Considering the table together with the context snippets below.

Give the answer to the question: Who is the stain named after that is a diagnostic specimen for a species of parasitic euglenoids causing Chagas disease that is prevalent in a country in the southern portion of North America ? Output only the correct answer as {"answer": "YOUR ANSWER"}. Base your answer solely on the given information.

Granulomatous amoebic encephalitis ( GAE ) is a rare , usually fatal , subacute-to-chronic central nervous system disease caused by certain species of free-living amoebae of the genera Acanthamoeba , Balamuthia and Sappinia pedata . The term is most commonly used with Acanthamoeba . In more modern references , the term balamuthia amoebic encephalitis ( BAE ) is commonly used when Balamuthia mandrillaris is the cause .
Acanthamoeba keratitis is a rare disease in which amoebae invade the cornea of the eye , and affects roughly 1.2 to 3 million people each year . Acanthamoeba are protozoa found nearly ubiquitously in soil and water , and can cause infections of the skin , eyes , and central nervous system . Infection of the cornea by Acanthamoeba is difficult to treat with conventional medications , and Acanthamoeba keratitis ( AK ) may cause permanent visual impairment or blindness , due to damage to the clear portion of the front of the eye ( called the cornea ) or through damage to other structures important to vision . Recently , AK has been recognized as an orphan disease and a funded project , orphan diseases Acanthamoeba keratitis ( ODAK ) has tested effects of diverse drugs and biocides in AK .
Acanthamoeba is a genus of amoebae that are commonly recovered from soil , fresh water , and other habitats . Acanthamoeba has two evolutive forms , the metabolically active trophozoite and a dormant , stress-resistant cyst . Trophozoites are small , usually 15 to 25 μm in length and amoeboid in shape . In nature , Acanthamoeba species are free-living bacterivores , but in certain situations , they can cause infections ( acanthamebiasis ) in humans and other animals .
A contact lens , or simply contact , is a thin lens placed directly on the surface of the eye . Contact lenses are ocular prosthetic devices used by over 150 million people worldwide , and they can be worn to correct vision , for cosmetic , or therapeutic reasons . In 2010 , the worldwide market for contact lenses was estimated at $ 6.1 billion , while the US soft lens market was estimated at $ 2.1 billion . Multiple analysts estimated that the global market for contact lenses would reach $ 11.7 billion by 2015 . As of 2010 [ update ] , the average age of contact lens wearers globally was 31 years old , and two-thirds of wearers were female . People choose to wear contact lenses for many reasons . Aesthetics and cosmetics are the main motivating factors for people who want to avoid wearing glasses or to change the appearance of their eyes . Others wear contact lenses for functional or optical reasons . When compared with spectacles , contact lenses typically provide better peripheral vision , and do not collect moisture ( from rain , snow , condensation etc . ) or perspiration . This can make them preferable for sports and other outdoor activities . Contact lens wearers can also wear sunglasses , goggles , or other eyewear of their choice without having to fit them with prescription lenses or worry about compatibility with glasses .
Tap water ( running water , city water , town water , municipal water , sink water , etc . ) is water supplied to a tap ( valve ) . Its uses include drinking , washing , cooking , and the flushing of toilets . Indoor tap water is distributed through indoor plumbing , which has existed since antiquity but was available to very few people until the second half of the 19th century when it began to spread in popularity in what are now developed countries . Tap water became common in many regions during the 20th century , and is now lacking mainly among people in poverty , especially in developing countries . Tap water is often culturally assumed to be drinking water , especially in developed countries . Usually it is potable , although water quality problems are not rare . Household water purification methods such as water filters , boiling , or distillation can be used when tap water 's potability is doubted . The application of technologies ( such as water treatment plants ) involved in providing clean water to homes , businesses , and public buildings is a major subfield of sanitary engineering . Calling a water supply tap water distinguishes it from the other main types of fresh water which may be available ; these include water from rainwater-collecting cisterns , water from village pumps or town pumps , water from wells , or water carried from streams , rivers , or lakes ( whose potability may vary ) .
Balamuthia mandrillaris is a free-living amoeba that is known to cause the deadly but rare neurological condition known as granulomatous amoebic encephalitis ( GAE ) . B. mandrillaris is found in the soil and water and was first discovered in 1986 in the brain of a mandrill that died in the San Diego Wild Animal Park . B. mandrillaris can infect the body through open wounds or by inhalation . Balamuthia has been isolated in nature . It is believed to be distributed throughout the temperate regions of the world . This is supported somewhat by the detection of antibodies to the protist in healthy individuals . The genus name Balamuthia was given by Govinda Visvesvara ( b. September 28 , 1931 ) , in honor of his late mentor , the renowned parasitologist William Balamuth ( 1914-1981 ) for his contributions to the study of amoebae . It was in 1993 when Visvesvara isolated and studied the pathogen for the first time .
Babesiosis is a malaria-like parasitic disease caused by infection with the eukaryotic parasite Babesia , an alveolate in the phylum Apicomplexa . Human babesiosis transmission via tick bite is most common in the Northeastern and Midwestern United States and parts of Europe , and sporadic throughout the rest of the world . It occurs in warm weather . People can get infected with Babesia parasites by the bite of an infected tick , by getting a blood transfusion from an infected donor of blood products , or by congenital transmission ( an infected mother to her baby ) . Ticks transmit the human strain of babesiosis , so it often presents with other tick-borne illnesses such as Lyme disease . After trypanosomes , Babesia is thought to be the second-most common blood parasite of mammals , and they can have a major impact on health of domestic animals in areas without severe winters . In cattle the disease is known as Texas cattle fever , redwater , or piroplasmosis .
Babesia , also called Nuttallia , is an Apicomplexan parasite that infects red blood cells , transmitted by ticks . Originally discovered by the Romanian bacteriologist Victor Babeș , over 100 species of Babesia have since been identified . Babesia comprises more than 100 species of tick-borne parasites that infect erythrocytes in many vertebrate hosts . Babesia species infect livestock worldwide , wild and domestic vertebrate animals and occasionally humans where it causes the disease babesiosis . In the United States , B. microti is the most common strain of the few which have been documented to cause disease in humans .
Giemsa stain ( /ˈɡiːmzə/ ) , named after German chemist and bacteriologist Gustav Giemsa , is used in cytogenetics and for the histopathological diagnosis of malaria and other parasites .
New England is a region composed of six states in the northeastern United States : Maine , Vermont , New Hampshire , Massachusetts , Rhode Island , and Connecticut . It is bordered by the state of New York to the west and by the Canadian provinces of New Brunswick to the northeast and Quebec to the north . The Atlantic Ocean is to the east and southeast , and Long Island Sound is to the southwest . Boston is New England 's largest city , as well as the capital of Massachusetts . Greater Boston is the largest metropolitan area , with nearly a third of New England 's population ; this area includes Worcester , Massachusetts ( the second-largest city in New England ) , Manchester , New Hampshire ( the largest city in New Hampshire ) , and Providence , Rhode Island ( the capital and largest city of Rhode Island ) . In 1620 , Puritan Separatist Pilgrims from England established Plymouth Colony , the second successful English settlement in America , following the Jamestown Settlement in Virginia founded in 1607 . Ten years later , more Puritans established Massachusetts Bay Colony north of Plymouth Colony . Over the next 126 years , people in the region fought in four French and Indian Wars , until the English colonists and their Iroquois allies defeated the French and their Algonquian allies in America . In 1692 , the town of Salem , Massachusetts and surrounding areas experienced the Salem witch trials , one of the most infamous cases of mass hysteria in history . In the late 18th century , political leaders from the New England colonies initiated resistance to Britain 's taxes without the consent of the colonists . Residents of Rhode Island captured and burned a British ship which was enforcing unpopular trade restrictions , and residents of Boston threw British tea into the harbor . Britain responded with a series of punitive laws stripping Massachusetts of self-government which the colonists called the Intolerable Acts .
Tick-borne diseases , which afflict humans and other animals , are caused by infectious agents transmitted by tick bites . They are caused by infection with a variety of pathogens , including rickettsia and other types of bacteria , viruses , and protozoa . Because individual ticks can harbor more than one disease-causing agent , patients can be infected with more than one pathogen at the same time , compounding the difficulty in diagnosis and treatment . 16 tick-borne diseases of humans are known , or which four have been discovered since 2013 . As the incidence of tick-borne illnesses increases and the geographic areas in which they are found expand , health workers increasingly must be able to distinguish the diverse , and often overlapping , clinical presentations of these diseases . Several high-profile deaths have been caused by the tick-human transmission of disease , including the death of former Senator Kay Hagan in the United States in 2019 at the age of 66 .
Ixodes scapularis is commonly known as the deer tick or black-legged tick ( although some people reserve the latter term for Ixodes pacificus , which is found on the west coast of the USA ) , and in some parts of the US as the bear tick . It is a hard-bodied tick ( family Ixodidae ) of the eastern and northern Midwestern United States and southeastern Canada . It is a vector for several diseases of animals , including humans ( Lyme disease , babesiosis , anaplasmosis , Powassan virus disease , etc . ) and is known as the deer tick owing to its habit of parasitizing the white-tailed deer . It is also known to parasitize mice , lizards , migratory birds , etc . especially while the tick is in the larval or nymphal stage .
Balantidiasis is a protozoan infection caused by infection with Balantidium coli .
Balantidium coli is a parasitic species of ciliate alveolates that causes the disease balantidiasis . It is the only member of the ciliate phylum known to be pathogenic to humans .
A mucous membrane or mucosa is a membrane that lines various cavities in the body and covers the surface of internal organs . It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue . It is mostly of endodermal origin and is continuous with the skin at various body openings such as the eyes , ears , inside the nose , inside the mouth , lip , vagina , the urethral opening and the anus . Some mucous membranes secrete mucus , a thick protective fluid . The function of the membrane is to stop pathogens and dirt from entering the body and to prevent bodily tissues from becoming dehydrated .
Blastocystosis refers to a medical condition caused by infection with Blastocystis . Blastocystis is a protozoal , single-celled parasite that inhabits the gastrointestinal tracts of humans and other animals . Many different types of Blastocystis exist , and they can infect humans , farm animals , birds , rodents , amphibians , reptiles , fish , and even cockroaches . Blastocystosis has been found to be a possible risk factor for development of irritable bowel syndrome .
Blastocystis is a genus of single-celled heterokont parasites belonging to a group of organisms that are known as the Stramenopiles ( also called Heterokonts ) that includes algae , diatoms , and water molds . Blastocystis consists of several species , living in the gastrointestinal tracts of species as diverse as humans , farm animals , birds , rodents , reptiles , amphibians , fish , and cockroaches . Blastocystis exhibits low host specificity , and many different species of Blastocystis can infect humans , and by current convention , any of these species would be identified as Blastocystis hominis . Blastocystis is one of the most common human parasites in the world and has a global distribution . It is the most common parasitic infection in the United States , where it infected approximately 23% of the total population during year 2000 . In less developed areas , infection rates as high as 100% have been observed . High rates of infection are found in individuals in developed countries who work with animals . Although the role of Blastocystis hominis in human disease is often referred to as controversial , a systematic survey of research studies conducted by 11 infectious disease specialists from nine countries , found that over 95% of papers published in the 10 years prior identified it as causing illness in immunocompetent individuals . The paper attributed confusion over pathogenicity to the existence of asymptomatic carriers , a phenomenon the study noted is common to all gastrointestinal protozoa . However , Blastocystis has never fulfilled Koch 's postulate that infection of a healthy individual with Blastocystis leads to disease . The fact that Blastocystis ' infection route is oral-anal indicates that carriers have been in contact with faecal contaminated matter which might have included other intestinal pathogens that explain the observed symptoms . A more likely explanation is the presence of virulent and non-virulent strains as there exists and enormous genetic variation between different strains ( or genotypes ) .
Cryptosporidiosis , also known as crypto , is a parasitic disease caused by Cryptosporidium , a genus of protozoan parasites in the phylum Apicomplexa . It affects the distal small intestine and can affect the respiratory tract in both immunocompetent ( i.e. , individuals with a normal functioning immune system ) and immunocompromised ( e.g. , persons with HIV/AIDS or autoimmune disorders ) individuals , resulting in watery diarrhea with or without an unexplained cough . In immunosuppressed individuals , the symptoms are particularly severe and can be fatal . It is primarily spread through the fecal-oral route , often through contaminated water ; recent evidence suggests that it can also be transmitted via fomites in respiratory secretions . Cryptosporidium is commonly isolated in HIV-positive patients presenting with diarrhea . Despite not being identified until 1976 , it is one of the most common waterborne diseases and is found worldwide . The infection begins when a human consumes food or water containing cysts of the Cryptosporidium organism .
Cryptosporidium is a genus of apicomplexan parasitic alveolates that can cause a respiratory and gastrointestinal illness ( cryptosporidiosis ) that primarily involves watery diarrhea ( intestinal cryptosporidiosis ) with or without a persistent cough ( respiratory cryptosporidiosis ) in both immunocompetent and immunodeficient humans . Treatment of gastrointestinal infection in humans involves fluid rehydration , electrolyte replacement , and management of any pain . As of January 2015 [ update ] , nitazoxanide is the only drug approved for the treatment of cryptosporidiosis in immunocompetent hosts . Supplemental zinc may improve symptoms , particularly in recurrent or persistent infections or in others at risk for zinc deficiency . Cryptosporidium oocysts are 4-6 μm in diameter and exhibit partial acid-fast staining . They must be differentiated from other partially acid-fast organisms including Cyclospora cayetanensis .
Cyclosporiasis is a disease caused by infection with Cyclospora cayetanensis , a pathogenic protozoan transmitted by feces or feces-contaminated food and water . Outbreaks have been reported due to contaminated fruits and vegetables . It is not spread from person to person , but can be a hazard for travelers as a cause of diarrhea .
Cyclospora cayetanensis is a parasite that causes diarrheal disease in humans , and , perhaps , in other primates . Originally described in the early 1990s , it was virtually unknown in developed countries until awareness increased due to several outbreaks linked with fecally contaminated imported produce . C. cayetanensis has since emerged as an endemic cause of diarrheal disease in tropical countries and a cause of traveler 's diarrhea and food-borne infections in developed nations . This species was placed in the genus Cyclospora because of the spherical shape of its sporocysts . The specific name refers to the Cayetano Heredia University in Lima , Peru , where early epidemiological and taxonomic work was done .
Dientamoebiasis is a medical condition caused by infection with Dientamoeba fragilis , a single-cell parasite that infects the lower gastrointestinal tract of humans . It is an important cause of traveler 's diarrhea , chronic abdominal pain , chronic fatigue , [ citation needed ] and failure to thrive in children .
Dientamoeba fragilis is a species of single-celled excavates found in the gastrointestinal tract of some humans , pigs and gorillas . It causes gastrointestinal upset in some people , but not in others . It is an important cause of travellers diarrhoea , chronic diarrhoea , fatigue and , in children , failure to thrive . Despite this , its role as a commensal , pathobiont , or pathogen is still debated . D. fragilis is one of the smaller parasites that are able to live in the human intestine . Dientamoeba fragilis cells are able to survive and move in fresh feces but are sensitive to aerobic environments . They dissociate when in contact or placed in saline , tap water or distilled water .
Amoebiasis , also known amoebic dysentery , is an infection caused by any of the amobae of the Entamoeba group . Symptoms are most common during infection by Entamoeba histolytica . Amoebiasis can be present with no , mild , or severe symptoms . Symptoms may include abdominal pain , diarrhea , or bloody diarrhea . Complications can include inflammation and ulceration of the colon with tissue death or perforation , which may result in peritonitis . People affected may develop anemia due to loss of blood . Cysts of Entamoeba can survive for up to a month in soil or for up to 45 minutes under fingernails . Invasion of the intestinal lining results in bloody diarrhea . If the parasite reaches the bloodstream it can spread through the body , most frequently ending up in the liver where it can cause amoebic liver abscesses . Liver abscesses can occur without previous diarrhea . Diagnosis is typical by stool examination using a microscope , but may not reliably exclude infection or separate between specific types . An increased white blood cell count may be present in severe cases .
Entamoeba histolytica is an anaerobic parasitic amoebozoan , part of the genus Entamoeba . Predominantly infecting humans and other primates causing amoebiasis , E. histolytica is estimated to infect about 50 million people worldwide . E. histolytica infection is estimated to kill more than 55,000 people each year . Previously , it was thought that 10% of the world population was infected , but these figures predate the recognition that at least 90% of these infections were due to a second species , E. dispar . Mammals such as dogs and cats can become infected transiently , but are not thought to contribute significantly to transmission . The word histolysis literally means disintegration and dissolution of organic tissues .
Giardiasis , popularly known as beaver fever , is a parasitic disease caused by Giardia duodenalis ( also known as G. lamblia and G. intestinalis ) . About 10% of those infected have no symptoms . When symptoms occur they may include diarrhea , abdominal pain , and weight loss . Vomiting , blood in the stool , and fever are less common . Symptoms usually begin 1 to 3 weeks after exposure and without treatment may last up to six weeks . Giardia usually spreads when Giardia duodenalis cysts within feces contaminate food or water which is then eaten or drunk . It may also spread between people and from other animals . Risk factors include travel in the developing world , changing diapers , eating food without cooking it , and owning a dog . Cysts may survive for nearly three months in cold water . Diagnosis is via stool tests . Prevention is typically by improved hygiene . Those without symptoms do not usually need treatment .
Giardia duodenalis , also known as Giardia intestinalis and Giardia lamblia , is a flagellated parasitic microorganism , that colonizes and reproduces in the small intestine , causing giardiasis . The parasite attaches to the epithelium by a ventral adhesive disc or sucker , and reproduces via binary fission . Giardiasis does not spread via the bloodstream , nor does it spread to other parts of the gastrointestinal tract , but remains confined to the lumen of the small intestine . Giardia trophozoites absorb their nutrients from the lumen of the small intestine , and are anaerobes . If the organism is split and stained , its characteristic pattern resembles the familiar smiley face symbol . Chief pathways of human infection include ingestion of untreated sewage , a phenomenon particularly common in many developing countries ; contamination of natural waters also occurs in watersheds where intensive grazing occurs . Giardia infections occur worldwide , however Giardia lamblia is the most commonly identified intestinal parasite in the United States and Canada among children in day care centers , hikers , family members and immunocompromised adults . Approximately 20,000 cases per year in the United States are reported .
In biology , a lumen ( plural lumina ) is the inside space of a tubular structure , such as an artery or intestine . It comes from Latin lumen , meaning 'an opening ' . It can refer to :
The small intestine or small bowel is an organ in the gastrointestinal tract where most of the end absorption of nutrients and minerals from food takes place . It lies between the stomach and large intestine , and receives bile and pancreatic juice through the pancreatic duct to aid in digestion . The small intestine has three distinct regions - the duodenum , jejunum , and ileum . The duodenum , the shortest , is where preparation for absorption through small finger-like protrusions called villi begins . The jejunum is specialized for the absorption through its lining by enterocytes : small nutrient particles which have been previously digested by enzymes in the duodenum . The main function of the ileum is to absorb vitamin B12 , bile salts , and whatever products of digestion were not absorbed by the jejunum .
Isosporiasis , also known as cystoisosporiasis , is a human intestinal disease caused by the parasite Isospora belli ( now known as Cystoisospora belli ) . It is found worldwide , especially in tropical and subtropical areas . Infection often occurs in immuno-compromised individuals , notably AIDS patients , and outbreaks have been reported in institutionalized groups in the United States . The first documented case was in 1915 . It is usually spread indirectly , normally through contaminated food or water ( CDC.gov ) .
Cystoisospora belli , previously known as Isospora belli , is a parasite that causes an intestinal disease known as cystoisosporiasis . This protozoan parasite is opportunistic in immune suppressed human hosts . It primarily exists in the epithelial cells of the small intestine , and develops in the cell cytoplasm . The distribution of this coccidian parasite is cosmopolitan , but is mainly found in tropical and subtropical areas of the world such as the Caribbean , Central and S. America , India , Africa , and S.E . Asia . In the U.S. , it is usually associated with HIV infection and institutional living .
Epithelium ( /ˌɛpɪˈθiːliəm/ ) is one of the four basic types of animal tissue , along with connective tissue , muscle tissue and nervous tissue . Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body , as well as the inner surfaces of cavities in many internal organs . An example is the epidermis , the outermost layer of the skin . There are three principal shapes of epithelial cell : squamous , columnar , and cuboidal . These can be arranged in a single layer of cells as simple epithelium , either squamous , columnar , or cuboidal , or in layers of two or more cells deep as stratified ( layered ) , either squamous , columnar or cuboidal . In some tissues , a layer of columnar cells may appear to be stratified due to the placement of the nuclei . This sort of tissue is called pseudostratified . All glands are made up of epithelial cells . Functions of epithelial cells include secretion , selective absorption , protection , transcellular transport , and sensing . Epithelial layers contain no blood vessels , so they must receive nourishment via diffusion of substances from the underlying connective tissue , through the basement membrane . Cell junctions are well employed in epithelial tissues .
Leishmaniasis is a disease caused by parasites of the Leishmania type . It is spread by the bite of certain types of sandflies . The disease can present in three main ways : cutaneous , mucocutaneous , or visceral . The cutaneous form presents with skin ulcers , while the mucocutaneous form presents with ulcers of the skin , mouth , and nose , and the visceral form starts with skin ulcers and then later presents with fever , low red blood cells , and enlarged spleen and liver . Infections in humans are caused by more than 20 species of Leishmania . Risk factors include poverty , malnutrition , deforestation , and urbanization . All three types can be diagnosed by seeing the parasites under the microscope . Additionally , visceral disease can be diagnosed by blood tests . Leishmaniasis can be partly prevented by sleeping under nets treated with insecticide . Other measures include spraying insecticides to kill sandflies and treating people with the disease early to prevent further spread . The treatment needed is determined by where the disease is acquired , the species of Leishmania , and the type of infection . Some possible medications used for visceral disease include liposomal amphotericin B , a combination of pentavalent antimonials and paromomycin , and miltefosine .
Leishmania /liːʃˈmeɪniə/ is a genus of trypanosomes that are responsible for the disease leishmaniasis . They are spread by sandflies of the genus Phlebotomus in the Old World , and of the genus Lutzomyia in the New World . At least 93 sandfly species are proven or probable vectors worldwide . Their primary hosts are vertebrates ; Leishmania commonly infects hyraxes , canids , rodents , and humans .
Skin is the soft outer tissue covering of vertebrates with three main functions : protection , regulation , and sensation . Other animal coverings , such as the arthropod exoskeleton , have different developmental origin , structure and chemical composition . The adjective cutaneous means of the skin ( from Latin cutis , skin ) . In mammals , the skin is an organ of the integumentary system made up of multiple layers of ectodermal tissue , and guards the underlying muscles , bones , ligaments and internal organs . Skin of a different nature exists in amphibians , reptiles , and birds . All mammals have some hair on their skin , even marine mammals like whales , dolphins , and porpoises which appear to be hairless . The skin interfaces with the environment and is the first line of defense from external factors . For example , the skin plays a key role in protecting the body against pathogens and excessive water loss . Its other functions are insulation , temperature regulation , sensation , and the production of vitamin D folates . Severely damaged skin may heal by forming scar tissue . This is sometimes discoloured and depigmented . The thickness of skin also varies from location to location on an organism .
A mucocutaneous junction , or mucocutaneous boundary , is a region of the body in which mucosa transitions to skin . Mucocutaneous zones occur in animals , at the body orifices . In humans , mucocutaneous junctions are found at the lips , nostrils , conjunctivae , urethra , vagina ( in females ) , foreskin ( in males ) , and anus . In the nostrils the mucocutaneous junction has a dense microvascular network , and shows a marked similarity to that found in the mouth , between the oral mucosa and the lips . At a mucocutaneous junction , epithelium transitions to epidermis , lamina propria transitions to dermis , and smooth muscle transitions to skeletal muscle . A mucocutaneous junction is often the site of an arterial anastomosis , a watershed area of venous and lymphatic drainage , and sensory ( but not motor ) nerve overlap . Winkelmann ( 1959 ) documented that the mucocutaneous boundary is a specific erogenous zone with rete ridges where the nerve endings rise closer to the surface .
An organ is a group of tissues with similar functions . Plant life and animal life rely on many organs that coexist in organ systems . A given organ 's tissues can be broadly categorized as parenchyma , the tissue peculiar to ( or at least archetypal of ) the organ and that does the organ 's special job , and stroma , the tissues with supportive , structural , connective , or ancillary functions . For example , in a gland , the tissue that makes the hormones is the parenchyma , whereas the stroma includes the nerves that innervate the parenchyma , the blood vessels that oxygenate and nourish it and carry away its metabolic wastes , and the connective tissues that provide a suitable place for it to be situated and anchored . The main tissues that make up an organ tend to have common embryologic origins , such as arising from the same germ layer . Functionally related organs often cooperate to form whole organ systems . Organs exist in most multicellular organisms . In single-celled organisms such as bacteria , the functional analogue of an organ is known as an organelle . In plants , there are three main organs . A hollow organ is an internal organ that forms a hollow tube , or pouch such as the stomach , intestine , or bladder . In the study of anatomy , the term viscus refers to an internal organ . Viscera is the plural form .
Visceral leishmaniasis ( VL ) , also known as kala-azar , is the most severe form of leishmaniasis and , without proper diagnosis and treatment , is associated with high fatality . Leishmaniasis is a disease caused by protozoan parasites of the genus Leishmania . The parasite migrates to the internal organs such as the liver , spleen ( hence visceral ) , and bone marrow , and , if left untreated , will almost always result in the death of the host . Signs and symptoms include fever , weight loss , fatigue , anemia , and substantial swelling of the liver and spleen . Of particular concern , according to the World Health Organization ( WHO ) , is the emerging problem of HIV/VL co-infection . This disease is the second-largest parasitic killer in the world ( after malaria ) , responsible for an estimated 20,000 to 30,000 deaths each year worldwide . R.B . Sir Upendranath Brahmachari ( Bengali : উপেন্দ্রনাথ ব্রহ্মচারী ) ( 19 December 1873 - 6 February 1946 ) was an Indian scientist and a leading medical practitioner of his time . He synthesised Urea Stibamine ( carbostibamide ) in 1922 and determined that it was an effective substitute for the other antimony-containing compounds in the treatment of Kala-azar ( Visceral leishmaniasis ) which is caused by a protozoon , Leishmania donovani .
Cutaneous leishmaniasis is the most common form of leishmaniasis affecting humans . It is a skin infection caused by a single-celled parasite that is transmitted by the bite of a phlebotomine sandfly . There are about twenty species of Leishmania that may cause cutaneous leishmaniasis . This disease is considered to be a zoonosis ( an infectious disease that is naturally transmissible from animals to humans ) , with the exception of Leishmania tropica - which is often an anthroponotic disease ( an infectious disease that is naturally transmissible from humans to vertebrate animals ) .
Phlebotomus is a genus of sand flies in the Diptera family Psychodidae . In the past , they have sometimes been considered to belong in a separate family , Phlebotomidae , but this alternative classification has not gained wide acceptance .
Lutzomyia is a genus of phlebotomine sand flies consisting of nearly 400 species , at least 33 of which have medical importance as vectors of human disease . Species of the genus Lutzomyia are found only in the New World , distributed in southern areas of the Nearctic and throughout the Neotropic zone . Lutzomyia is one of the two genera of the subfamily Phlebotominae to transmit the Leishmania parasite , with the other being Phlebotomus , found only in the Old World . Lutzomyia sand flies also serve as vectors for the bacterial Carrions disease and a number of arboviruses .
Naegleriasis ( also known as primary amoebic meningoencephalitis ; PAM ) is an almost invariably fatal infection of the brain by the free-living unicellular eukaryote Naegleria fowleri . Symptoms are meningitis-like and include headache , fever , nausea , vomiting , a stiff neck , confusion , hallucinations and seizures . Symptoms progress rapidly over around five days , and death usually results within one-to-two weeks of symptoms . N. fowleri is typically found in warm bodies of fresh water , such as ponds , lakes , rivers and hot springs . It is also found in an amoeboid or temporary flagellate stage in soil , poorly maintained municipal water supplies , water heaters , near warm-water discharges of industrial plants and in poorly chlorinated or unchlorinated swimming pools . There is no evidence of it living in salt water . As the disease is rare , it is often not considered during diagnosis . Although infection occurs very rarely , it almost inevitably results in death . Of the 450 or so Naegleriasis cases in the past 60 years , only seven have survived , implying a case fatality rate of 98.5% .
Naegleria fowleri , colloquially known as the brain-eating amoeba , is a species of the genus Naegleria , belonging to the phylum Percolozoa , which is technically not classified as true amoeba , but a shapeshifting amoeboflagellate excavata . It is a free-living , bacteria-eating microorganism that can be pathogenic , causing an extremely rare fulminant ( sudden and severe ) and fatal brain infection called naegleriasis , also known as primary amoebic meningoencephalitis . This microorganism is typically found in bodies of warm freshwater , such as ponds , lakes , rivers , almost exclusively in hot geographic areas , and hot springs . It is also found in the soil near warm-water discharges of industrial plants , and in unchlorinated or minimally-chlorinated ( under 0.5 mcg/ltr residual ) swimming pools . It can be seen in either an amoeboid or temporary flagellate stage .
Insufflation ( Latin : insufflare , lit . 'to blow into ' ) is the act of blowing something ( such as a gas , powder , or vapor ) into a body cavity . Insufflation has many medical uses , most notably as a route of administration for various drugs .
A swimming pool , swimming bath , wading pool , paddling pool , or simply pool is a structure designed to hold water to enable swimming or other leisure activities . Pools can be built into the ground ( in-ground pools ) or built above ground ( as a freestanding construction or as part of a building or other larger structure ) , and are also a common feature aboard ocean-liners and cruise ships . In-ground pools are most commonly constructed from materials such as concrete , natural stone , metal , plastic , or fiberglass , and can be of a custom size and shape or built to a standardized size , the largest of which is the Olympic-size swimming pool . Many health clubs , fitness centers , and private clubs have pools used mostly for exercise or recreation . Many towns and cities provide public pools . Many hotels have pools available for their guests to use at their own leisure . Educational facilities such as high schools and universities sometimes have pools for physical education classes , recreational activities , leisure , and competitive athletics such as swimming teams . Hot tubs and spas are pools filled with hot water , used for relaxation or hydrotherapy . They are common in hotels and health clubs , and can also be found in many private homes . Special swimming pools are also used for diving , specialized water sports , and physical therapy , as well as for the training of lifeguards and astronauts . Swimming pools may be heated or unheated .
A hot spring is a spring produced by the emergence of geothermally heated groundwater that rises from the Earth 's crust . While some of these springs contain water that is a safe temperature for bathing , others are so hot that immersion can result in an injury or death .
Malaria is a mosquito-borne infectious disease that affects humans and other animals . Malaria causes symptoms that typically include fever , tiredness , vomiting , and headaches . In severe cases it can cause yellow skin , seizures , coma , or death . Symptoms usually begin ten to fifteen days after being bitten by an infected mosquito . If not properly treated , people may have recurrences of the disease months later . In those who have recently survived an infection , reinfection usually causes milder symptoms . This partial resistance disappears over months to years if the person has no continuing exposure to malaria . It is caused by single-celled microorganisms of the Plasmodium group . The disease is most commonly spread by an infected female Anopheles mosquito . The mosquito bite introduces the parasites from the mosquito 's saliva into a person 's blood . The parasites travel to the liver where they mature and reproduce . Five species of Plasmodium can infect and be spread by humans .
Plasmodium falciparum is a unicellular protozoan parasite of humans , and the deadliest species of Plasmodium that causes malaria in humans . The parasite is transmitted through the bite of a female Anopheles mosquito and causes the disease 's most dangerous form called falciparum malaria which is responsible for around 50% of all malaria cases . P. falciparum is therefore regarded as the deadliest parasite in humans , causing 405,000 deaths in 2018 . It is also associated with the development of blood cancer ( Burkitt 's lymphoma ) and is classified as Group 2A carcinogen . The species originated from the malarial parasite Laverania found in gorillas , around 10,000 years ago . Alphonse Laveran was the first to identify the parasite in 1880 , and named it Oscillaria malariae . Ronald Ross discovered its transmission by mosquito in 1897 . Giovanni Battista Grassi elucidated the complete transmission from a female anopheline mosquito to humans in 1898 . In 1897 , William H. Welch created the name Plasmodium falciparum , which ICZN formally adopted in 1954 . P. falciparum assumes several different forms during its life cycle . The human-infective stage are sporozoites from the salivary gland of a mosquito . The sporozoites grow and multiply in the liver to become merozoites .
Plasmodium vivax is a protozoal parasite and a human pathogen . This parasite is the most frequent and widely distributed cause of recurring malaria . Although it is less virulent than Plasmodium falciparum , the deadliest of the five human malaria parasites , P. vivax malaria infections can lead to severe disease and death , often due to splenomegaly ( a pathologically enlarged spleen ) . P. vivax is carried by the female Anopheles mosquito ; the males do not bite .
Plasmodium ovale curtisi is a subspecies of parasitic protozoa that causes tertian malaria in humans . The subspecies was described in 2010 when it was established that the two subspecies of Plasmodium ovale , while morphologically identical are genetically distinct .
Plasmodium ovale wallikeri is a subspecies of parasitic protozoa that causes tertian malaria in humans . The subspecies was described in 2010 when it was established that the two subspecies of Plasmodium ovale , while morphologically identical are genetically distinct .
Plasmodium malariae is a parasitic protozoan that causes malaria in humans . It is one of several species of Plasmodium parasites that infect humans , including also Plasmodium falciparum and Plasmodium vivax , responsible for most malarial infection . Found worldwide , it causes a so-called benign malaria , not nearly as dangerous as that produced by P. falciparum or P. vivax . The signs include fevers that recur at approximately three-day intervals - a quartan fever or quartan malaria - longer than the two-day ( tertian ) intervals of the other malarial parasites .
Plasmodium knowlesi is a parasite that causes malaria in humans and other primates . It is found throughout Southeast Asia , and is the most common cause of human malaria in Malaysia . Like other Plasmodium species , P. knowlesi has a life cycle that requires infection of both a mosquito and a warm-blooded host . While the natural warm-blooded hosts of P. knowlesi are likely various Old World monkeys , humans can be infected by P. knowlesi if they are fed upon by infected mosquitoes . P. knowlesi is a eukaryote in the phylum Apicomplexa , genus Plasmodium , and subgenus Plasmodium . It is most closely related to the human parasite Plasmodium vivax as well as other Plasmodium species that infect non-human primates . Humans infected with P. knowlesi can develop uncomplicated or severe malaria similar to that caused by Plasmodium falciparum . Diagnosis of P. knowlesi infection is challenging as P. knowlesi very closely resembles other species that infect humans . Treatment is similar to other types of malaria , with chloroquine or artemisinin combination therapy typically recommended . P. knowlesi malaria is an emerging disease previously thought to be rare in humans , but increasingly recognized as a major health burden in Southeast Asia . P. knowlesi was first described as a distinct species and as a potential cause of human malaria in 1932 . It was briefly used in the early 20th century to cause fever as a treatment for neurosyphilis .
A blood film - or peripheral blood smear - is a thin layer of blood smeared on a glass microscope slide and then stained in such a way as to allow the various blood cells to be examined microscopically . Blood films are examined in the investigation of hematological ( blood ) disorders and are routinely employed to look for blood parasites , such as those of malaria and filariasis .
Anopheles ( /əˈnɒfɪliːz/ ) is a genus of mosquito first described and named by J. W. Meigen in 1818 . About 460 species are recognised ; while over 100 can transmit human malaria , only 30-40 commonly transmit parasites of the genus Plasmodium , which cause malaria in humans in endemic areas . Anopheles gambiae is one of the best known , because of its predominant role in the transmission of the most dangerous malaria parasite species ( to humans ) - Plasmodium falciparum . The name comes from the Ancient Greek word ἀνωφελής anōphelḗs 'useless ' , derived from ἀν- an- , 'not ' , 'un- ' and ὄφελος óphelos 'profit ' . Mosquitoes in other genera ( Aedes , Culex , Culiseta , Haemagogus , and Ochlerotatus ) can also serve as vectors of disease agents , but not human malaria .
Rhinosporidiosis is an infection caused by Rhinosporidium seeberi .
Rhinosporidium seeberi is a eukaryotic pathogen responsible for rhinosporidiosis , a disease which affects humans , horses , dogs , and to a lesser extent cattle , cats , foxes , and birds . It is most commonly found in tropical areas , especially India and Sri Lanka . The pathogen was first identified in 1892 , and was comprehensively described in 1900 by Seeber . Many aspects of the disease and of the pathogen Rhinosporidium seeberi remain problematic and enigmatic . These include the pathogens natural habitat , some aspects of its lifecycle , its immunology , some aspects of the epidemiology of the disease in humans and in animals , the reasons for the delay at in vitro culture , and establishment of disease in experimental animals , hence paucity of information on its sensitivity to drugs , and the immunology of the pathogen . Thankamani isolated an organism believed to be R. seeberi and gave the name UMH.48 . It was originally isolated from the biopsies and nasal swabs of rhinosporidiosis patients . The various developmental stages of UMH.48 showed a strong resemblance with the structures seen in hisopathological sections of rhinosporidiosis in tissue samples . The spores of UMH.48 were found to be viable even after a decade of preservation in the refrigerator without any subculture , resembling the features of Synchytrium endobioticum , a lower aquatic fungus that causes black wart disease in potatoes . However , carefully performed molecular studies showed the definitive identity of the organism . Arseculeratne , Sarath N ; Atapattu , Dhammika N. no-repeat ; background-position : right .1em center } .
The pharynx ( plural : pharynges ) is the part of the throat behind the mouth and nasal cavity , and above the esophagus and larynx - the tubes going down to the stomach and the lungs . It is found in vertebrates and invertebrates , though its structure varies across species . In humans , the pharynx is part of the digestive system and the conducting zone of the respiratory system . ( The conducting zone - which also includes the nostrils of the nose , the larynx , trachea , bronchi , and bronchioles - filters , warms and moistens air and conducts it into the lungs ) . The human pharynx is conventionally divided into three sections : the nasopharynx , oropharynx , and laryngopharynx . It is also important in vocalization . In humans , two sets of pharyngeal muscles form the pharynx and determine the shape of its lumen . They are arranged as an inner layer of longitudinal muscles and an outer circular layer .
The nasal mucosa lines the nasal cavity . It is part of the respiratory mucosa , the mucous membrane lining the respiratory tract . The nasal mucosa is intimately adherent to the periosteum or perichondrium of the nasal conchae . It is continuous with the skin through the nostrils , and with the mucous membrane of the nasal part of the pharynx through the choanae . From the nasal cavity its continuity with the conjunctiva may be traced , through the nasolacrimal and lacrimal ducts ; and with the frontal , ethmoidal , sphenoidal , and maxillary sinuses , through the several openings in the nasal meatuses . The mucous membrane is thickest , and most vascular , over the nasal conchae . It is also thick over the nasal septum where increased numbers of goblet cells produce a greater amount of nasal mucus . It is very thin in the meatuses on the floor of the nasal cavities , and in the various sinuses . It is one of the most commonly infected tissues in adults and children . Inflammation of this tissue may cause significant impairment of daily activities , with symptoms such as stuffy nose , headache , mouth breathing , etc . Owing to the thickness of the greater part of this membrane , the nasal cavities are much narrower , and the middle and inferior nasal conchæ appear larger and more prominent than in the skeleton ; also the various apertures communicating with the meatuses are considerably narrowed .
Sarcocystis is a genus of parasites , the majority of species infecting mammals , and some infecting reptiles and birds . The lifecycle of a typical member of this genus involves two host species , a definitive host and an intermediate host . Often , the definitive host is a predator and the intermediate host is its prey . The parasite reproduces sexually in the gut of the definitive host , is passed with the feces , and ingested by the intermediate host . There , it eventually enters muscle tissue . When the intermediate host is eaten by the definitive host , the cycle is completed . The definitive host usually does not show any symptoms of infection , but the intermediate host does . About 130 recognized species are in this genus . Revision of the taxonomy of the genus is ongoing , and all the currently recognised species may be a much smaller number of species that can infect multiple hosts . The name Sarcocystis is dervived from Greek : sarx = flesh and kystis = bladder .
The gastrointestinal tract ( digestive tract , alimentary canal , digestion tract , GI tract , GIT ) is an organ system within humans and other animals which takes in food , digests it to extract and absorb energy and nutrients , and expels the remaining waste as feces . The mouth , esophagus , stomach and intestines are part of the gastrointestinal tract . Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines . A tract is a collection of related anatomic structures or a series of connected body organs . All bilaterians have a gastrointestinal tract , also called a gut or an alimentary canal . This is a tube that transfers food to the organs of digestion . In large bilaterians , the gastrointestinal tract also has an exit , the anus , by which the animal disposes of feces ( solid wastes ) . Some small bilaterians have no anus and dispose of solid wastes by other means ( for example , through the mouth ) . The human gastrointestinal tract consists of the esophagus , stomach , and intestines , and is divided into the upper and lower gastrointestinal tracts . The GI tract includes all structures between the mouth and the anus , forming a continuous passageway that includes the main organs of digestion , namely , the stomach , small intestine , and large intestine . However , the complete human digestive system is made up of the gastrointestinal tract plus the accessory organs of digestion ( the tongue , salivary glands , pancreas , liver and gallbladder ) . The tract may also be divided into foregut , midgut , and hindgut , reflecting the embryological origin of each segment .
Muscle is a soft tissue found in most animals . Muscle cells contain protein filaments of actin and myosin that slide past one another , producing a contraction that changes both the length and the shape of the cell . Muscles function to produce force and motion . They are primarily responsible for maintaining and changing posture , locomotion , as well as movement of internal organs , such as the contraction of the heart and the movement of food through the digestive system via peristalsis . Muscle tissues are derived from the mesodermal layer of embryonic germ cells in a process known as myogenesis . There are three types of muscle , skeletal or striated , cardiac , and smooth . Muscle action can be classified as being either voluntary or involuntary . Cardiac and smooth muscles contract without conscious thought and are termed involuntary , whereas the skeletal muscles contract upon command . Skeletal muscles in turn can be divided into fast and slow twitch fibers . Muscles are predominantly powered by the oxidation of fats and carbohydrates , but anaerobic chemical reactions are also used , particularly by fast twitch fibers . These chemical reactions produce adenosine triphosphate ( ATP ) molecules that are used to power the movement of the myosin heads . The term muscle is derived from the Latin musculus meaning little mouse perhaps because of the shape of certain muscles or because contracting muscles look like mice moving under the skin .
Toxoplasmosis is a parasitic disease caused by Toxoplasma gondii . Infections with toxoplasmosis usually cause no obvious symptoms in adults . Occasionally , people may have a few weeks or months of mild , flu-like illness such as muscle aches and tender lymph nodes . In a small number of people , eye problems may develop . In those with a weak immune system , severe symptoms such as seizures and poor coordination may occur . If infected during pregnancy , a condition known as congenital toxoplasmosis may affect the child . Toxoplasmosis is usually spread by eating poorly cooked food that contains cysts , exposure to infected cat feces , and from an infected mother to her baby during pregnancy . Rarely , the disease may be spread by blood transfusion . It is not otherwise spread between people . The parasite is known to reproduce sexually only in the cat family . However , it can infect most types of warm-blooded animals , including humans . Diagnosis is typically by testing blood for antibodies or by testing amniotic fluid for the parasite 's DNA .
Toxoplasma gondii ( /ˈtɒksoʊplæzmə ˈɡɒndiaɪ/ ) is an obligate intracellular parasitic one-celled eukaryote ( specifically an apicomplexan ) that causes the infectious disease toxoplasmosis . Found worldwide , T. gondii is capable of infecting virtually all warm-blooded animals , :1 but felids , such as domestic cats , are the only known definitive hosts in which the parasite may undergo sexual reproduction . In humans , T. gondii is one of the most common parasites in developed countries ; serological studies estimate that 30-50% of the global population has been exposed to and may be chronically infected with T. gondii , although infection rates differ significantly from country to country . For example , previous estimates have shown the highest prevalence of persons infected to be in France , at 84% . Although mild , flu-like symptoms occasionally occur during the first few weeks following exposure , infection with T. gondii produces no readily observable symptoms in healthy human adults . :77 This asymptomatic state of infection is referred to as a latent infection and has recently been associated with numerous subtle adverse or pathological behavioral alterations in humans , though it has been shown recently that the association between behavioural changes and infection with T. gondii is weak . In infants , HIV/AIDS patients , and others with weakened immunity , infection may cause a serious and occasionally fatal illness , toxoplasmosis . :77 T. gondii has been shown to alter the behavior of infected rodents in ways that increase the rodents ' chances of being preyed upon by felids . Support for this manipulation hypothesis stems from studies showing T. gondii-infected rats have a decreased aversion to cat urine . Because cats are the only hosts within which T. gondii can sexually reproduce to complete and begin its lifecycle , such behavioral manipulations are thought to be evolutionary adaptations that increase the parasite 's reproductive success . The rats would not shy away from areas where cats live and would also be less able to escape should a cat try to prey on them . The primary mechanisms of T. gondii-induced behavioral changes in rodents is now known to occur through epigenetic remodeling in neurons which govern the associated behaviors ; for example , it modifies epigenetic methylation to cause hypomethylation of arginine vasopressin-related genes in the medial amygdala to greatly decrease predator aversion .
Polymerase chain reaction ( PCR ) is a method widely used in molecular biology to rapidly make millions to billions of copies of a specific DNA sample allowing scientists to take a very small sample of DNA and amplify it to a large enough amount to study in detail . PCR was invented in 1983 by Kary Mullis . It is fundamental to much of genetic testing including analysis of ancient samples of DNA and identification of infectious agents . Using PCR , copies of very small amounts of DNA sequences are exponentially amplified in a series or cycles of temperature changes . PCR is now a common and often indispensable technique used in medical laboratory and clinical laboratory research for a broad variety of applications including biomedical research and criminal forensics . The vast majority of PCR methods rely on thermal cycling . Thermal cycling exposes reactants to repeated cycles of heating and cooling to permit different temperature-dependent reactions - specifically , DNA melting and enzyme-driven DNA replication . PCR employs two main reagents - primers ( which are short single strand DNA fragments known as oligonucleotides that are a complementary sequence to the target DNA region ) and a DNA polymerase . In the first step of PCR , the two strands of the DNA double helix are physically separated at a high temperature in a process called Nucleic acid denaturation . In the second step , the temperature is lowered and the primers bind to the complementary sequences of DNA . The two DNA strands then become templates for DNA polymerase to enzymatically assemble a new DNA strand from free nucleotides , the building blocks of DNA . As PCR progresses , the DNA generated is itself used as a template for replication , setting in motion a chain reaction in which the original DNA template is exponentially amplified .
Apicomplexans , a group of intracellular parasites , have life cycle stages evolved to allow them to survive the wide variety of environments they are exposed to during their complex life cycle . Each stage in the life cycle of an apicomplexan organism is typified by a cellular variety with a distinct morphology and biochemistry . Not all apicomplexa develop all the following cellular varieties and division methods . This presentation is intended as an outline of a hypothetical generalised apicomplexan organism .
Apicomplexans , a group of intracellular parasites , have life cycle stages evolved to allow them to survive the wide variety of environments they are exposed to during their complex life cycle . Each stage in the life cycle of an apicomplexan organism is typified by a cellular variety with a distinct morphology and biochemistry . Not all apicomplexa develop all the following cellular varieties and division methods . This presentation is intended as an outline of a hypothetical generalised apicomplexan organism .
Apicomplexans , a group of intracellular parasites , have life cycle stages evolved to allow them to survive the wide variety of environments they are exposed to during their complex life cycle . Each stage in the life cycle of an apicomplexan organism is typified by a cellular variety with a distinct morphology and biochemistry . Not all apicomplexa develop all the following cellular varieties and division methods . This presentation is intended as an outline of a hypothetical generalised apicomplexan organism .
Trichomoniasis ( trich ) is an infectious disease caused by the parasite Trichomonas vaginalis . About 70% of women and men do not have symptoms when infected . When symptoms do occur they typically begin 5 to 28 days after exposure . Symptoms can include itching in the genital area , a bad smelling thin vaginal discharge , burning with urination , and pain with sex . Having trichomoniasis increases the risk of getting HIV/AIDS . It may also cause complications during pregnancy . Trichomoniasis is a sexually transmitted infection ( STI ) which is most often spread through vaginal , oral , or anal sex . It can also spread through genital touching . People who are infected may spread the disease even when symptoms are not present . Diagnosis is by finding the parasite in the vaginal fluid using a microscope , culturing the vagina or urine , or testing for the parasite 's DNA . If present other STIs should be tested for . Methods of prevention include not having sex , using condoms , not douching , and being tested for STIs before having sex with a new partner .
Trichomonas vaginalis is an anaerobic , flagellated protozoan parasite and the causative agent of trichomoniasis . It is the most common pathogenic protozoan infection of humans in industrialized countries . Infection rates between men and women are similar with women usually being symptomatic , while infections in men are usually asymptomatic . Transmission usually occurs via direct , skin-to-skin contact with an infected individual , most often through vaginal intercourse . The WHO has estimated that 160 million cases of infection are acquired annually worldwide . The estimates for North America alone are between 5 and 8 million new infections each year , with an estimated rate of asymptomatic cases as high as 50% . Usually treatment consists of metronidazole and tinidazole .
African trypanosomiasis , also known as African sleeping sickness or simply sleeping sickness , is an insect-borne parasitic disease of humans and other animals . It is caused by protozoa of the species Trypanosoma brucei . Humans are infected by two types , Trypanosoma brucei gambiense ( TbG ) and Trypanosoma brucei rhodesiense ( TbR ) . TbG causes over 98% of reported cases . Both are usually transmitted by the bite of an infected tsetse fly and are most common in rural areas . Initially , the first stage of the disease is characterized by fevers , headaches , itchiness , and joint pains , beginning one to three weeks after the bite . Weeks to months later the second stage begins with confusion , poor coordination , numbness , and trouble sleeping . Diagnosis is by finding the parasite in a blood smear or in the fluid of a lymph node . A lumbar puncture is often needed to tell the difference between first and second stage disease . Prevention of severe disease involves screening the population at risk with blood tests for TbG . Treatment is easier when the disease is detected early and before neurological symptoms occur . Treatment of the first stage is with the medications pentamidine or suramin .
Trypanosoma brucei is a species of parasitic kinetoplastid belonging to the genus Trypanosoma . The parasite is the cause of a vector-borne disease of vertebrate animals , including humans , carried by genera of tsetse fly in sub-Saharan Africa . In humans T. brucei causes African trypanosomiasis , or sleeping sickness . In animals it causes animal trypanosomiasis , also called nagana in cattle and horses . T. brucei has traditionally been grouped into three subspecies : T. b. brucei , T. b. gambiense and T. b. rhodesiense . The first is a parasite of non-human vertebrates , while the latter two are the known parasites of humans . Only rarely can the T. b. brucei infect a human . T. brucei is transmitted between mammal hosts by an insect vector belonging to different species of tsetse fly ( Glossina ) . Transmission occurs by biting during the insect 's blood meal . The parasites undergo complex morphological changes as they move between insect and mammal over the course of their life cycle . The mammalian bloodstream forms are notable for their cell surface proteins , variant surface glycoproteins , which undergo remarkable antigenic variation , enabling persistent evasion of host adaptive immunity leading to chronic infection . T. brucei is one of only a few pathogens known to cross the blood brain barrier .
A chancre ( /ˈʃæŋkər/ SHANG-kər ) is a painless genital ulcer most commonly formed during the primary stage of syphilis . This infectious lesion forms approximately 21 days after the initial exposure to Treponema pallidum , the gram-negative spirochaete bacterium yielding syphilis . Chancres transmit the sexually transmissible disease of syphilis through direct physical contact . These ulcers usually form on or around the anus , mouth , penis and vagina . Chancres may diminish between four and eight weeks without the application of medication . Chancres , as well as being painless ulcerations formed during the primary stage of syphilis , are associated with the African trypanosomiasis sleeping sickness , surrounding the area of the tsetse fly bite .
Tsetse ( /ˈsiːtsi/ SEET-see , US : /ˈtsiːtsi/ TSEET-see or UK : /ˈtsɛtsi/ TSET-see ) , sometimes spelled tzetze and also known as tik-tik flies , are large biting flies that inhabit much of tropical Africa . Tsetse flies include all the species in the genus Glossina , which are placed in their own family , Glossinidae . The tsetse are obligate parasites that live by feeding on the blood of vertebrate animals . Tsetse have been extensively studied because of their role in transmitting disease . They have a prominent economic impact in sub-Saharan Africa as the biological vectors of trypanosomes , which cause human sleeping sickness and animal trypanosomiasis . Tsetse are multivoltine and long-lived , typically producing about four broods per year , and up to 31 broods over their lifespans . Tsetse can be distinguished from other large flies by two easily observed features . Tsetse fold their wings completely when they are resting so that one wing rests directly on top of the other over their abdomens . Tsetse also have a long proboscis , which extends directly forward and is attached by a distinct bulb to the bottom of their heads . Fossilized tsetse have been recovered from Florissant Fossil Beds in Colorado , laid down some 34 million years ago . Twenty-three extant species of tsetse flies are known from Africa . Tsetse were absent from much of southern and eastern Africa until colonial times .
Tsetse ( /ˈsiːtsi/ SEET-see , US : /ˈtsiːtsi/ TSEET-see or UK : /ˈtsɛtsi/ TSET-see ) , sometimes spelled tzetze and also known as tik-tik flies , are large biting flies that inhabit much of tropical Africa . Tsetse flies include all the species in the genus Glossina , which are placed in their own family , Glossinidae . The tsetse are obligate parasites that live by feeding on the blood of vertebrate animals . Tsetse have been extensively studied because of their role in transmitting disease . They have a prominent economic impact in sub-Saharan Africa as the biological vectors of trypanosomes , which cause human sleeping sickness and animal trypanosomiasis . Tsetse are multivoltine and long-lived , typically producing about four broods per year , and up to 31 broods over their lifespans . Tsetse can be distinguished from other large flies by two easily observed features . Tsetse fold their wings completely when they are resting so that one wing rests directly on top of the other over their abdomens . Tsetse also have a long proboscis , which extends directly forward and is attached by a distinct bulb to the bottom of their heads . Fossilized tsetse have been recovered from Florissant Fossil Beds in Colorado , laid down some 34 million years ago . Twenty-three extant species of tsetse flies are known from Africa . Tsetse were absent from much of southern and eastern Africa until colonial times .
Chagas disease , also known as American trypanosomiasis , is a tropical parasitic disease caused by the protist Trypanosoma cruzi . It is spread mostly by insects known as Triatominae , or kissing bugs . The symptoms change over the course of the infection . In the early stage , symptoms are typically either not present or mild , and may include fever , swollen lymph nodes , headaches , or local swelling at the site of the bite . After 8-12 weeks , individuals enter the chronic phase of disease and in 60-70% it never produces further symptoms . The other 30-40% of people develop further symptoms 10-30 years after the initial infection , including enlargement of the ventricles of the heart in 20-30% , leading to heart failure . An enlarged esophagus or an enlarged colon may also occur in 10% of people . T. cruzi is commonly spread to humans and other mammals by the blood-sucking kissing bugs of the subfamily Triatominae . These insects are known by a number of local names , including : vinchuca in Argentina , Bolivia , Chile and Paraguay , barbeiro ( the barber ) in Brazil , pito in Colombia , chinche in Central America , and chipo in Venezuela . The disease may also be spread through blood transfusion , organ transplantation , eating food contaminated with the parasites , and by vertical transmission ( from a mother to her fetus ) . Diagnosis of early disease is by finding the parasite in the blood using a microscope . Chronic disease is diagnosed by finding antibodies for T. cruzi in the blood .
Trypanosoma cruzi is a species of parasitic euglenoids . Amongst the protozoa , the trypanosomes characteristically bore tissue in another organism and feed on blood ( primarily ) and also lymph . This behaviour causes disease or the likelihood of disease that varies with the organism : for example , trypanosomiasis in humans ( Chagas disease in South America ) , dourine and surra in horses , and a brucellosis-like disease in cattle . Parasites need a host body and the haematophagous insect triatomine ( descriptions assassin bug , cone-nose bug , and kissing bug ) is the major vector in accord with a mechanism of infection . The triatomine likes the nests of vertebrate animals for shelter , where it bites and sucks blood for food . Individual triatomines infected with protozoa from other contact with animals transmit trypanosomes when the triatomine deposits its faeces on the host 's skin surface and then bites . Penetration of the infected faeces is further facilitated by the scratching of the bite area by the human or animal host .
Mexico ( Spanish : México [ ˈmexiko ] ( listen ) ; Nahuatl languages : Mēxihco ) , officially the United Mexican States ( UMS ; Spanish : Estados Unidos Mexicanos , EUM [ esˈtaðos uˈniðoz mexiˈkanos ] ( listen ) , lit . Mexican United States ) , is a country in the southern portion of North America . It is bordered to the north by the United States ; to the south and west by the Pacific Ocean ; to the southeast by Guatemala , Belize , and the Caribbean Sea ; and to the east by the Gulf of Mexico . Covering almost 2,000,000 square kilometers ( 770,000 sq mi ) , the nation is the fifth largest country in the Americas by total area and the 13th largest independent state in the world . With an estimated population of over 129 million people , Mexico is the tenth most populous country and the most populous Spanish-speaking country in the world , while being the second most populous nation in Latin America after Brazil . Mexico is a federation comprising 31 states plus Mexico City ( CDMX ) , which is the capital city and its most populous city . Other metropolises in the country include Guadalajara , Monterrey , Puebla , Toluca , Tijuana , and León . Pre-Columbian Mexico dates to about 8000 BC and is identified as one of six cradles of civilization and was home to many advanced Mesoamerican civilizations such as the Olmec , Toltec , Teotihuacan , Zapotec , Maya , and Aztec before first contact with Europeans . In 1521 , the Spanish Empire conquered and colonized the territory from its politically powerful base in Mexico-Tenochtitlan ( part of Mexico City ) , which was administered as the viceroyalty of New Spain . The Roman Catholic Church played a powerful role in governing the country as millions were converted to the faith , although King Charles III expelled the Jesuits in the 1770s . The territory became a nation state following its recognition in 1821 after the Mexican War of Independence . The post-independence period was tumultuous , characterized by economic inequality and many contrasting political changes .
Triatoma is a genus of assassin bug in the subfamily Triatominae ( kissing bugs ) . The members of Triatoma ( like all members of Triatominae ) are blood-sucking insects that can transmit serious diseases , such as Chagas disease . Their saliva may also trigger allergic reactions in sensitive individuals , up to and including severe anaphylactic shock .
The Reduviidae are a large cosmopolitan family of the order Hemiptera ( true bugs ) . They are unusual among the Hemiptera because almost all are terrestrial ambush predators ( most other predatory Hemiptera are aquatic ) . The main examples of nonpredatory Reduviidae are some blood-sucking ectoparasites in the subfamily Triatominae . Though spectacular exceptions are known , most members of the family are fairly easily recognizable ; they have a relatively narrow neck , sturdy build , and formidable curved proboscis ( sometimes called a rostrum ) . Large specimens should be handled with caution , if at all , because they sometimes defend themselves with a very painful stab from the proboscis .