# Infection

A picture of Malaria—a type of infectious disease
**Infection** is the invasion of an organism's body tissues by disease-causing agents. The disease is caused by the invading agents multiplying. As they multiply, they produce toxins and damage host tissues. **Infectious disease**, also known as 'transmissible disease' or 'communicable disease', is illness resulting from an infection.

## Common infectious diseases

### Diseases caused by bacteria

* Tuberculosis - also called *TB*.
* Bubonic plague
* Pertussis - also called *whooping cough*
* leprosy

### Diseases caused by viruses

* AIDS/HIV
* Hepatitis B
* Polio
* Colds
* Influenza - also called the *flu*.
* COVID-19

### Diseases caused by fungus

* Thrush
* Ringworm
* Cryptococcosis
* Candidiadis
* Athlete's foot

### Diseases caused by parasites

* Malaria (carried by mosquitos)
* Schistosomiasis (flat worms)
* Chagas disease

### Diseases caused by proteins

* Prions are proteins which act as infectious diseases.

### Diseases caused by many infectious agents

Some infections are caused by different infectious agents at different times. For example, some diarrhea is caused by bacteria. Some is caused by viruses.

* Diarrhea
* Pneumonia
* Meningitis

This is a very short list. There are many more diseases from infection and other causes: common diseases.

## Getting infectious disease

Some diseases can be passed from one person to another easily. Other infectious diseases are harder to get. If a person kisses or touches another person who is infected with the flu, a cold, measles, or a sore throat, he or she may get their disease. They may also give the person their disease if they cough on them. Other medical conditions such as AIDS, herpes, and hepatitis B, are only passed by closer contact. Having sex with an infected person, blood transfusions, or touching their blood or urine can sometimes pass on these conditions or diseases.

## Stopping infectious disease

People can stop disease by:

* Covering the mouth every time during coughing
* Only drinking clean water
* Only eating very cooked meat
* Using a condom during sex

## Treating infectious disease

Bacteria are usually treated with antibiotic medicines like Tetracycline and Penicillin. Viruses will not be killed by antibiotics. They must be treated with special medicines called antivirals. Medicines to treat HIV/AIDS like zidovudine are antivirals. Antifungals like miconazole and fluconazole treat infections from fungus. Anti-parasitic medicines like Praziquantel and mebendazole.

Some infectious diseases have no treatments that work well. For example, there is no medicine that works well to cure West Nile Virus and Rabies. So it is important to avoid getting these diseases. Some infectious disease goes away on its own. These mild diseases do not need to be treated. For example, colds are caused by viruses and they do not need medicines.

Some diseases can be prevented by immunizations. Immunizations try to make a person have an immune reaction to an infectious agent. This is usually done before the person gets the disease. Examples of diseases prevented by immunizations are: polio, tetanus, and pertussis. In some cases, if all of the disease can be removed from society, we can get rid of the disease completely. An example of this is smallpox. This virus used to kill people, cause blindness, and bad scars. Now there has not been a person who had smallpox in over thirty years.

## Signs and symptoms (relating to infectious diseases)

* *syphilis*
	+ Hutchinson's teeth (picture)
	+ Hutchinson's triad
	+ Westphal's sign
	+ Clutton's joints
	+ Dennie–Marfan syndrome

* *measles*
	+ Koplik's spots

* *African trypanosomiasis*
	+ Winterbottom's sign

* Meningism
* Fever
	+ Liebermeister's rule
	+ Faget sign

## Related pages

* Sexually transmitted disease
* Social distancing
* Vaccine
* Vector (biology)
* Zoonosis

## Other websites

* World Health Organization Report on Infectious Disease - 2002