PREFACE AND ACKNOWLEDGEMENTS

Disease Vector Ecology Profiles (DVEPs) are concise summaries of vector-borne and other militarily 

significant diseases that occur in specific countries. DVEPs focus on vector-borne diseases and emphasize essential 

epidemiology, vector bionomics, behavior, and pesticide resistance. Selected bibliographies of pertinent disease and 

disease vector literature are included.

DVEPs are not meant to serve as scientific documents but rather as synopses of relevant entomological and 

arthropod-borne disease information. They are complied from unclassified scientific literature, and are intended to 

provide a historical profile of arthropod-borne disease epidemiology in the recent past for selected geographical 

areas. The epidemiology of arthropod-borne disease is dynamic, and incidence and prevalence are constantly 

changing. This is especially true for Third World countries which are undergoing rapid development and ecological 

change, and those areas experiencing migrations of large refugee populations as a result of civil strife. These 

documents should be supplemented with recent information on foreign public health status and medical 

developments. Component medical department activities may have updated regional information for their areas of 

responsibility. Current disease risk assessment and additional information on other parasitic and infectious diseases, 

and other aspects of medical intelligence can be obtained from the Armed Forces Medical Intelligence Center, 

(AFMIC) Fort Detrick, Frederick, MD 21701 (301-619-7574, DSN 343-7511). Additional information can be 

obtained form the Navy Preventive Medicine Information System (NAPMIS), which maintains up-to-date Disease 

Risk Assessment Profiles (DISRAPs) and Disease Risk Assessment Profiles (VECTRAPs) on most countries of the 

world. DISRAPs and VECTRAPs can be obtained by contacting the Navy Environmental Health Center (NEHC) 

(804-444-7575 extension 456, DSN 564-7575 ext 456).

DVEPs are designed to complement documents obtained from AFMIC and NEHC. Every effort is made to 

make them as accurate as possible. Individuals possessing additions, corrections, or suggestions are encouraged to 

communicate this information to Chief, DPMAIC, for incorporation into future revisions. In addition to DVEPs, 

DPMAIC can provide bibliographic literature searches of its extensive database on pest management, medical 

entomology, pest identification and pesticide toxicology. DPMIAC can also conduct online computer searches of 

other worldwide biomedical databases. DPMAIC (301-295-7479, DSN 295-7479).

Acknowledgments: Individuals who have made significant contributions to this DVEP include: LTC John B. 

Gingrich (research, writing, formatting), Dr. Richard G. Robbins (editorial review), Dr. Bruce Harrison (technical 

review), MAJ Daniel Strickman (technical review), Mrs. Rampa Rattanarithikul (AFRMIS, checklist of Diptera), 

Mrs. Panita Tanskul (AFRIMS, checklist of Acarina), Mrs. Ola Tilghman (typing) and Ms. Charlene Young 

(production). 
TABLE OF CONTENTS 

Map of Thailand ----------------------------------------------------------------------------------------------------------------------------------- 1

Introduction----------------------------------------------------------------------------------------------------------------------------------------- 2

Disease Summary ---------------------------------------------------------------------------------------------------------------------------------- 4

Militarily Important Diseases ------------------------------------------------------------------------------------------------------------------- 5

Malaria------------------------------------------------------------------------------------------------------------------------------------------ 5

Map of Malaria Distribution -------------------------------------------------------------------------------------------------------------- 7

Dengue ----------------------------------------------------------------------------------------------------------------------------------------- 8

Japanese Encephalitis ---------------------------------------------------------------------------------------------------------------------- 9

Map of Japanese Encephalitis Distribution ------------------------------------------------------------------------------------------- 10

Scrub Typhus--------------------------------------------------------------------------------------------------------------------------------- 11

Map Scrub Typhus Distribution--------------------------------------------------------------------------------------------------------- 12

Other Vector-borne Diseases of Potential Militarily Importance----------------------------------------------------------------------- 13

Appendices

Appendix A. Sand Flies Reported from Thailand------------------------------------------------------------------------------------ 15

Appendix B. Tabanids Reported from Thailand-------------------------------------------------------------------------------------- 15

Appendix C. Culicids Reported from Thailand --------------------------------------------------------------------------------------- 16

Appendix D. Ticks Reported from Thailand------------------------------------------------------------------------------------------- 22

Appendix E. Simuliids Reported from Thailand -------------------------------------------------------------------------------------- 23

Appendix F. Culicoides Reported from Thailand ------------------------------------------------------------------------------------ 23

Appendix G. Fleas Reported from Thailand ------------------------------------------------------------------------------------------- 24

Appendix H. Trombiculids Reported from Thailand -------------------------------------------------------------------------------- 25

Appendix I. Scorpiones Reported from Thailand ------------------------------------------------------------------------------------ 27

Appendix J. Pesticide Resistance-------------------------------------------------------------------------------------------------------- 28

Appendix K. Leeches Reported from Thailand--------------------------------------------------------------------------------------- 29

Appendix L. Venomous Snakes of Thailand ------------------------------------------------------------------------------------------ 29

Snake Bite ------------------------------------------------------------------------------------------------------------------------------------------ 30

First Aid -------------------------------------------------------------------------------------------------------------------------------------------- 31

Appendix M. Poisonous and Venomous Plants ------------------------------------------------------------------------------------- 32

Appendix N. Personal Protective Measures ------------------------------------------------------------------------------------------ 34

Appendix O. Chemical Control of Pests and Vectors ------------------------------------------------------------------------------- 35

References ----------------------------------------------------------------------------------------------------------------------------------------- 36

July 1992
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INTRODUCTION

The Kingdom of Thailand (also known as Siam during the periods 1855-1939 and 1946-1949) is located in the 

heart of Southeast Asia. The country is often described as shaped like an elephant’s head because of the peninsular 

“trunk” which it shares with Burma on its western border. It is this narrow strip of land that forms most of the coast of t 

he Gulf of Thailand and that connects its southern neighbor, Malaysia, to the southeast Asian landmass. Thailand’s 

serpentine eastern border is formed by Laos in the north and Cambodia in the south.

Thailand has an area of 514,000 sq km (198,500 sq. mi.), equivalent in size to California. The Ministry of Health 

typically divides the country into four regions, as follows:

(1) Central Thailand dominates the country in terms of population, economics, and politics. 

Because of the vast Chaophraya River system and the rich alluvial plain, this area is agriculturally important and 

considered a major “rice bowl” of Asia. The capital city of Bangkok and the port of Chonburi are near the mouth of 

the Chaophraya and together have an official population of about 60 million people. Unofficially, the population in the 

metropolitan area may be 2-3 times that that amount 

(2) Northeastern Thailand, or the Korat Plateau, makes up one third of the country. The Mekong

River forms the country’s border here between Thailand and its eastern neighbors, but the land itself is poor and suffers 

from alternating conditions of drought and floods. Because of its climate, topography and position, this portion of the 

country has been plagued by poverty and a flood of refuges who have fled the political excesses and economic 

deprivation of Laos, Cambodia, and Vietnam.

(3) Northern Thailand is an area of mountains and deep river valleys, representing the 

beginnings of the Himalayan foothills. Because of the climate and fertility, this area is a major source of timber, rice, 

and substantial but declining illegal opium production. Chiang Mai, Thailand’s second largest city, is also in the north.

(4) Southern or peninsular Thailand is essentially a 450-mile isthmus which is only 10 miles wide 

at its narrowest point. Once covered with rain forests, today it is mostly covered with rubber, coconut, coffee, and 

pineapple plantations. These products, along with ores, are the major exports of the region.

Thailand has a tropical monsoon climate, high in humidity and temperature. In most areas, there are three 

seasons: rainy (May to October), characterized by drenching rains; dry (November to February), when the monsoon 

pattern reverses; and hot (March to April), when “summer” temperatures may exceed 100° F. rainfall varies but is 

generally heaviest in the south and southeast, where the yearly average is 150 inches, and lightest in the northeast.

Based on a 1987 population estimate of 54 million with an annual growth rate of 1.6%, Thailand’s population is 

estimated to be close to 56 million. The largest population center is the Bangkok – Chonburi urban area where at least 

15% of the country’s citizens are located. Because of a desire for urban employment, education, and more arable and 

available farmland, population shifts occurred in the 1970s which resulted in about 70% of the country’s population 

being concentrated in the central and northeast regions. Except for Bangkok and a few other urban areas, such as 

Chiang Mai in the north and Nakhon Ratchasima (Korat) in the northeast, the Thai people primarily are engaged in 

agriculture. The government, knowing that the country could not withstand the unchecked population growth that 

occurred in the sixties, sponsored a voluntary program of family planning. This program was proved successful, and a 

future goal is to keep the annual growth rate below2%. 

Thailand’s people are relatively homogeneous. More than 85% share a common ancestry, speak a dialect of Thai, 

and consider themselves Theravada Buddhists. The largest minority group is the Chinese (12%), followed by the 

Malay-speaking Muslims in the south, the Khmer, and the Mon. These groups are considered to be assimilated into 

Thai culture and society. Small groups of Vietnamese and hill tribes (e. g. Hmong) also have integrated into the 

mainstream of Thai culture.
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Close relations exist between Thailand, the U. S. and other free-world countries. The country prides itself on 

never having been under European domination and is considered sable among the countries of Southeast Asia. The 

system of government is a constitutional monarchy, with a king as the formal head of state. A freely elected House of 

Representatives and an appointed Senate make up the legislative National Assembly. The government has, until 

recently, been heavily dominated by military interests.

The Ministry of Public Health is responsible for health and sanitation, and through the ministry a close working 

relationship has been maintained between Thailand and organizations such as the World Health Organization (WHO) 

and the U. S. Agency for International Development (AID).
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DISEASE SUMMARY

MALARIA: Malaria is a major threat for deployed personnel in mountainous and wooded areas throughout the 

country, but especially in the eastern, northeastern, northern and western parts of the country. Transmission is yearround in most areas, with peak transmission occurring during post-monsoon, dry and pre-monsoon months (OctoberMay). Plasmodium falciparum dominates over P. vivax in most regions, except central and peninsular Thailand, where 

the two species have similar rates of infection. Multiple drug-resistant strains of falciparum malaria exacerbate the 

problem. The mosquito vectors are all night-biters and are usually found in rural areas.

DENGUE: Dengue also is a major threat for deployed personnel. It occurs in both urban and rural areas, with highest 

risk during the monsoon months of May through November. Large outbreaks occur about every 4 weeks and appear to 

be related to a shift in the dominant serotype. All four dengue serotypes occur, and the hemorrhagic fever form of 

dengue appears to be most prevalent when two or more sequential outbreaks of differing serotypes take place. The 

mosquito vectors are day-biting species which, because of peridomestic habits, can cause intense foci of transmission.

JAPANESE ENCEPHALITIS: Japanese encephalitis is highly endemic in the northern, northeastern, and central 

parts of the country. Like dengue, it peak period of transmission occurs in the monsoon months. Although most 

infections are inapparent, clinical cases are often fatal. It is fairly uncommon except among those who live near pigs, 

which serve as amplifying hosts of the virus. The mosquito vectors are rice-field breeders. The are strong fliers in the 

early evening hours and are capable of flying several miles to find human hosts. Although primarily rural in distribution, 

some cases occurs in suburban areas as well. Personnel deployed for over two weeks in rural areas during the 

transmission season should be protected by vaccination.

SCRUB TYPHUS: Scrub typhus is considered a low to moderate risk for deployed forces and is distributed throughout 

Thailand, with highest endemicity in recent years reported from northern and northeastern provinces. Scrub typhus 

outbreaks tend to be highly focal, in consonance with the distribution of chigger vectors. Most foci occur in disturbed 

forest habitats, associated with second growth forests, rubber plantations, orchards, and tall grassy areas. Seasonally 

cases appear most commonly during rainy months.

CHIKHUNGUNYA: This arbovirus disease occurs in rare, but usually intense, outbreaks, with long interepidemic 

cycles of 10 to 20 years. Although the vectors are the same as for dengue, and the disease is therefore primarily urban, 

it also ahs rural area vectors, leading to occasional rural outbreaks. The risk for deployed forces is considered ver low 

in most years.

OTHER VECTOR-BORNE DISEASES: Filariasis (Malayan and Bancroftian) and schistosomiasis occur in very 

limited areas and are of little risk to deployed forces. Murine typhus, while having a somewhat wider distribution, is 

primarily a threat to lower socioeconomic groups, especially refugee populations. West Nile fever and sindbis, while 

both present, are considered low risks. Plague, which has not been reported for many years in Thailand, is not a risk at 

present.
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MILITARILY IMPORTANT DISEASES

MALARIA

INFECTIOUS AGENTS: Plasmodium vivax and P. falciparum occur in about a 20/80 ratio in the north and a 50/50 ratio 

on the peninsula. Plasmodium malaria occurs at very low frequency. Mixed infections are not uncommon. Some studies in 

Thailand have found that vivax malaria will develop in a third of the patients treated for acute falciparum malaria, although 

less than 1% of these were reported to have a mild infection upon admission.

RESERVOIR: Humans are the only important reservoir of human malaria. 

MODE OF TRANSMISSION: From the bite of an infective female Anopheles mosquito, or from an infectious blood 

transfusion.

CLINICAL FEATURES:

Incubation Period– Usually 12 to 14 days; in some cases P. vivax may have a protracted incubation period of up to

 10 month.

Symptoms – Acute febrile illness characterized by chills, fever, headache, sweating, muscular ache and general

malaise. P. falciparum symptoms may include severe anemia jaundice, renal failure, shock, loss of orientation,

convulsions and coma. Symptoms are most severe in P. falciparum malaria. Case fatality rates among non-immune adults 

and children may approach 10%. Relapses are common with improperly treated P. vivax and may occur irregularly for 

years.

Thailand probably has the worst multiple-drug resistance problem in the world. Some surveys have found nearly 100% of 

the falciparum isolates are resistant to chloroquine. Resistance to Fansidar (sulfadoxine-pyrimethamine) is also 

widespread, and resistance to quinine, proguanil, halofantrine, and mefloquine is common along the eastern and western 

borders. Primaquine-tolerant P. vivax has been reported from southern Thailand.

GEOGRAPHIC DISTRIBUTION: The malaria risk is present year-round in rural areas, especially forested and hilly areas. 

The large urban areas, including Bangkok and Chiang Mai, and most coastal resort areas are considered malaria-free. 

Malaria is particularly common in villages of semi-forested areas. A reduction in the incidence of malaria resulted from 

deforestation for cassava cultivation. However, much of the natural forest habitat of the primary vector Anopheles dirus that 

was destroyed by farming is now being replaced with orchard. This ecological change may reintroduce malaria to a wide 

area. Risk is particularly high close to Thailand’s international borders with Malaysia, Burma, Laos, and Cambodia, where 

malaria is a major cause of morbidity in refugee areas (Fig. 1).

SEASONAL DISTRIBUTION: The seasonality of malaria in Thailand is complex. Peak transmission usually occurs from 

October to December in the north and northeast, November to February in the west and northwest, and February to March in 

the peninsula. Efficient dry season transmission is well documented in eastern and northwestern Thailand. A second 

transmission peak occurs in May or June, especially in eastern and northeastern Thailand.

INCIDENCE/PREVALENCE: Malaria was the leading cause of death in 1947, with a mortality rate of 297 per 100,000, 

but control programs reduced the mortality rate to less than 8 per 100,00 by 1982. However, malaria remains a major public 

health problem in Thailand. In 1991, the annual parasite incidence was 3.96 cases per 1,000, but five primarily border, 

provinces (Trat, Tak, Mae Hong Son, Ranong, and Chantaburi) had an AP exceeding 21 per 1,000 and another 5 provinces 

(Kanchanaburi, Surat, Thani, Krabi, Prajuab, and Chumphon) had an API of 11 to 20 per 1,000.

VECTORS AND VECTOR BIOLOGY

Primary Vector: Anopheles dirus, formerly known as An. balabacensis s.1., now is recognized as a complex of 5 

species, with the exact vector status of all but An. dirus s.s. still under investigation. This is the most important 

vector in most areas, particularly in the provinces along the eastern border with Cambodia. Normally a mosquito 

that inhabits hilly, forested areas, it has adapted well to areas where natural forests have been replaced with 

orchards, tea, and rubber plantations.
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An. dirus breeds in shallow pools of fresh water along forest margins in hilly areas. It does not normally occur in 

rice-growing or urban plains. Heavy concentrations occur where human or animal activity is most intense along forest 

margins. Pools are generally located near streams or rivers that contain some organic debris in relatively clean water. 

Most sites are in areas of deep shade and may include puddles formed by tire tracks, hoof prints, and gem pits. An. dirus is 

a highly efficient, exophilic vector, with a peak biting period from 2100 to 0300 hours. Biting occurs earlier sin the 

evening during cool period of the year. Its flight range is estimated at 1-3 kilometers. Adult rest in trees or other nearby 

vegetation after feeding.

SECONDARY VECTORS: Thailand has many potential vectors of malaria. Those documented as significant vectors 

include: 

An. minimus. This complex of three species (A,B, and C) is found in forested and semi-forested foothill regions, 

where it breed at the edges of clean, clear, slow moving streams. Peak populations in the Pakchong district, Nakhon 

Ratchasima Province, occurred from September to November. Adults feed on man both indoors and outdoors, but prefer 

animals to man and tend to be exophilic. Biting activity occurs during the early part of the night (1800-2200 hours). 

Flight range is estimated to be less than four kilometers.

An. maculatus. This complex of seven species have an uncertain role in the epidemiology of malaria in Thailand. 

Years ago, An. maculatus s.s. was found to be positive for sporozoites in the south of Thailand, and has occasionally been 

ELISA-positive, but without sporozoites, in northern Thailand. Another complex member An. pseudowillmori, has been 

found gland-positive in Tak Province. These species tend to bred in sunlit stream margins, seepages, springs, and rice 

fields with slow running water. Adults feed on man both indoors and outdoors, but prefer cattle and tend to be exophilic. 

Feeding activity peaks between 210 and 2400 hours.

An. sundaicus. This is an important vector along coastal areas, where larvae bred in brackish water, salt marshes, 

lagoons, and salt water fish ponds. This primarily anthropophilic species feeds indoors or outdoors. It has an estimated 

flight range of up to two kilometers.

An. conitus. This species commonly breeds in rice fields, but larvae are also found in lakes, ponds, swamps, and 

various impoundments. Sporozoites have only been reported once in this species, although it is regularly ELISA-positive. 

It is primarily a zoophilic species that also feeds on man. Its flight range is estimated be less than two kilometers.

Other species that reportedly have been found ELISA-positive, but without sporozoites observed in the salivary 

glands, include An. nivipes, An. sinensis, An. barbirostris, An. annularis, An. hyrcanus group, and An. sawadwongpomi.
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DENGUE

INFECTIOUS AGENT: Arbovirus of the family Flaviviridae. Four serotypes have been identified.

RESERVOIR: Human, rarely monkeys.

MODE OF TRANSMISSION: Bite of an infective mosquito, Aedes aegypti or Ae. albopictus. 

CLINICAL FEATURES:

Incubation Period – 4 to 6 days.

Symptoms – Include sudden fever of 3-5 days (rarely more than 7), intense headache, pain behind the eyes, severe 

muscle and joint pain, prostration, gastrointestinal disturbances, and a rash from 3-4 days after the onset of fever. 

Dengue may progress to a severe hemorrhagic form with shock, which can be rapidly fatal. This appears to be 

associated with an enhanced immunological response which follows individuals who have had sequential dengue 

infections, usually with different serotypes. The World Health Organization estimates that during any outbreak, 

between 150-200 cases of mild or silent dengue infections occur for every case of dengue hemorrhagic 

fever/dengue shock syndrome seen in hospitals. Mortality is rare except for the hemorrhagic form which may 

produce a fatality rate of up to 5% . Recovery from infection provides homologous immunity of long duration, but 

protection agaisnt different serotypes of only a few months. Patients are usually infective for mosquitoes from one 

day prior to one day after the end of the febrile period. The mosquito becomes infective 8-30 days after the blood 

meal and remains infective for life.

GEOGRAPHIC DISTRIBUTION: Endemic to hyperendemic throughout the country. Risk is higher in urban areas. 

Although dengue once was thought of as a rural disease, it has been primarily an urban disease since the introduction of 

Ae. aegypti in the early 1900. Surveys have shown most villages, as well as urban areas, are heavily infested with 

dengue vectors.

SEASONAL DISTRIBUTION: The highest densities of the vector usually occur during the rainy seas (May through 

October) with dengue outbreaks frequently following two months later. In areas where rainfall is not markedly 

seasonal (i. e. southern Thailand), cases may occur year-round.

INCIDENCE/PREVALENCE: Dengue hemorrhagic fever (DHF) was first reported in Thailand in 1958 when 2,500 

cases occurred in the Bangkok area. The patter of disease during the next 30 years can be divided into 3 phases. 

During the first period (1958-1967), outbreaks occurred every other year with a median incidence of 10/100,000. DHF 

was prevalent only in Bangkok, Thonburi and a few other large municipalities. During the second period (1968-1977), 

outbreaks occurred in four-year cycles, with two years of high incidence followed by two years of low incidence (the 

median incidence during this period was 23/100,00). DHF had spread to must municipalities of every province. DHF 

continued to spread during the third period (1978-1987), when large outbreaks occurred every three to four years with 

a median incidence of 54/100,000. In 1987, over 175,000 cases of DHF were reported, making it the worst epidemic on 

record. Northeastern Thailand was the hardest hit region. In 1990, another extensive outbreak of nearly 112,00 cases

occurred.

VECTOR: Aedes aegypti, the primary vector of dengue, is perfectly adapted to its role because of its domesticated 

habits and close association with man. This is a synanthropic species that breeds in artificial containers such as tires, 

cans, ran barrels, or cisterns. Eggs are laid on moist surfaces and remain viable for many months after they have dried. 

The eggs hatch when flooded. Adults prefer to feed on humans during the day and will also feed on cats, dogs, or other 

domestic animals. Biting activity is usually highest for 2 hours after sunrise and 2 hours before sunset, although 

patterns may vary by season and locale. The entire life cycle usually takes place near or in human dwellings. The adult 

flight range is frequently no more than 100 meters from the breeding site.

Ae. albopictus is an important secondary vector of dengue. Its behavior and habits are very similar to Ae. aegypti 

except it prefers natural breeding sites such as treeholes, coconut shells and bamboo stumps, as well as manmade waterholding containers. It occurs around habitations, but mostly in more rural areas. Rubber plantations nearly all have 

high densities of this species, and it is notably abundant wherever good larval habitats abound.
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PREVENTION/CONTROL: Vector control includes good sanitation and the elimination of mosquito breeding 

places and/or adulticiding measures. Source reduction is the most efficient means of control. Personal protective 

measures include screening and use of repellents, especially where mosquito control is difficult. However, since the 

vectors are primarily daytime feeders, use of repellents is the most important personal protective measure. 

Permethrin-treated uniforms should be worn in conjunction with repellent application. Proper wearing of the uniform 

(i.e. socks and bloused boots) affords considerable protection to military personnel.

JAPANESE ENCEPHALITIS

INFECTIOUS AGENT: Arbovirus of the family Flaviviridae

RESERVOIR: The natural cycle involves wild aquatic birds, including herons and egrets. Young pigs develop high 

viermias and function as important amplifying hosts. Water buffalos during their first year of life also may serve as 

amplifying hosts. Humans and chickens produce levels of virus in the blood too low to infect mosquitoes. 

Consequently, man, like most domestic animas, is a dead-end host.

CLINICAL FEATURES: 

Incubation period– 5-15 days.

Symptoms – Only about one of every 300 persons infected develops clinical encephalitis, but about 25% of 

clinical cases die, and up to half the survivors are left with permanent neural sequelae. Severe infections are 

marked by acute onset, headache high fever, and meningeal involvement, which may lead to convulsions, coma 

and death.

GEOGRAPHIC DISTRIBUTION: Japanese encephalitis is the most common cause of epidemic encephalitis in the 

Orient. In Thailand, the virus is transmitted throughout the country, but cases of human encephalitis are concentrated 

in northern, central, and eastern provinces. Risk is greatly reduced in coastal areas and southern provinces (Fig. 2). 

PREVALENCE/INCIDENCE: Until 1969 the disease was reported from only a few province and cases were few. 

In that year, however, the first large epidemic occurred during the rainy season I the Chiang Mai Valley and other 

nearby valleys in northern Thailand. The total number of reported cases in 1969 was 655 and 152 deaths. Since then, 

epidemics of encephalitis have been reported every year and have become one of the leading causes of death and/or 

disability due to infectious diseases. An annual average of 1,611 cases and 350 deaths was reported between 1970 and 

1984. Then number of cases has fluctuated since 1984, but a decreasing trend has been observed. Although Japanese 

virus transmission occurs primarily in rural areas, transmission also occurs in suburban areas and in Bangkok.

SEASONAL INCIDENCE: Transmission occurs throughout the year, with epidemics during the rainy season in 

May through August. A high percentage of the cases reported occur in children under the age of 15.

PRIMARY VECTORS: Rice field breeding mosquitoes, particularly Culex tritaeniorhynchus. This species also 

breeds in a wide variety of temporary and semi-permanent ground water habitats, including stagnant marshes, tidal 

marshes of low salinity, and small, stable impoundments of clean water around cultivated fields. It is capable of 

adapting to artificial containers. Adults rest in sheltered areas in uncultivated grassy fields, especially on hillsides or 

bordering marshes, or in spaces of loosely constructed rock fences. It is rarely found indoors. Adults prefer to fed on 

domestic animals, particularly pigs and bovids, with biting activity peaking within three hours after sunset, but 

continuing through the night. It feeds on man during periods of high mosquito abundance. Most breeding occurs from 

May through September, usually peaking in June.

SECONDARY VECTORS: At least fourteen species of mosquitoes have been incriminated as vectors, although 

only four species have been incriminated in Thailand. Most of these species breed in rice fields or other ground pools. 

Culex spp. feed primarily at night. The three other vector species incriminated in Thailand are Cx. gelidus (suburban 

to rural areas), Cx. vishnui (rural areas), and Cx fuscacephala (rural areas).
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PREVENTION/CONTROL MEASURES: The most important prevention is the use of a newly marketed vaccine. 

Adulticiding with residual aerosols using ground or aerial equipment may be useful in stopping emergency situations. 

Other measures include killing adult mosquitoes by space and residual spray of human habitations. Screening of 

sleeping quarters and use of bed netting can be effective adjuncts. Avoidance of exposure to vectors by use of 

repellents during peak biting hours is almost important.

SCRUB TYPHUS

SYNONYMS: Tsutsugamushi disease, mite-borne typhus fever, tropical typhus, Japanese river fever, chigger-borne 

rickettsiosis.

INFECTIOUS AGENT: Rickettsia tsutsugamushi.

RESERVOIR: Chigger mites of the genus Leptotrombidium, and possibly other trombiculid genera, act as both 

vector and reservoir through long-term transovarial transmission. Only larval stages of the chigger feed on 

vertebrates, indicating that those infective to man or other hosts have received the pathogen transovarially from the 

female parent. The role of rodents and other commonly infected mammals in the ecology of the disease is uncertain.

MODE OF TRANSMISSION: By the bite of infective larval chigger mite of the genus Leptotrombidium (Family: 

Trombiculidae). Other genera, e. g. Blankaartia and Aschoschoengastia, harbor the pathogen and also bite humans, 

and should be considered potential vectors. 

CLINICAL FEATURES: 

Incubation period– 6 to 21 days, usually 10 to 12 days.

Symptoms – This disease is characterized by a primary skin ulcer or eschar (non-painful sore with black, 

necrotic center) at the site of attachment of an infected mite followed within days by an acute fever, headache, 

profuse sweating and swelling of the lymph glands. Late in the first week of fever maculopapular rash usually (but 

not always) appears on the trunk and extends to the extremities. Mortality rates vary from 1 to 60% depending on the 

strain of pathogen and previous exposure to the disease. Treatment usually results in full recovery, but relapses are 

common if treatment occurs very early in the course of the disease. 

GEOGRAPHIC DISTRIBUTION: Scrub typhus cases have been diagnosed for over 30 years. The disease 

appears nearly countrywide, with highest estimated transmission in northeaster and southern provinces (Fig. 3). 

However , it has the potential to occur everywhere the essential zoonotic components are present: 1) Vector mites, 2) 

wild rats in the genus Rattus, 3) the pathogen, and 4) disturbed environments with transitional secondary vegetation. 

These constitute the so-called “zoonotic tetrad.” The disease often is highly focal, with sharply delineated miteinfested areas of only a few square meters.

 INCIDENCE/PREVALENCE: Serological surveys and isolation of R. tsutsugamushi from chiggers have 

demonstrated that the disease is widespread. Over 60 percent prevalence of antibody has been recorded in a number of 

villages in northern Thailand. This suggests a higher endemicity than reported by the ministry of Public Health. In 

recent years, scrub typhus cases have been reported at much higher levels (776 cases in 1989), partly because of 

enhanced awareness and diagnostic efforts, but also through the use of newer antibiotics for other infectious diseases 

that do not kill the scrub typhus. Some areas have little apparent disease because of natural immunity still present a 

high risk to non-immune soldiers.

VECTOR BIOLOGY: Eggs are laid singly and loosely on the open ground. About 1-5 eggs are laid daily for 6-12 

weeks. the females than pause for 2-6 months, depending on climate, before resuming egg laying. The egg stages 5-

7 days with the larva developing inside the cracked ovum for another 5-7 days. The 6-legged larva then emerges and 

remains in the immediate area until attaching to the host’s skin. Larvae feed on serum exudate, rarely imbibing 

blood, for 2-3 days. Unlike non-vector 
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13

species, scrub typhus vectors cause little or no irritation to their hosts during feeding. Engorged larvae disengage, drop 

off, and enter a pupa-like stage for 7-10 days. The 8-legged, velvety nymph then emerges and feeds on arthropods and 

their eggs. Within two weeks another quiescent stage occurs lasting 12-15 days. Adults emerge and may live up to 15 

months. Adults also feed on arthropod eggs. Mite populations often form highly localized aggregations (mite “pockets” 

or “islands”) which, in turn, often cause highly focal outbreaks.

PREVENTION/CONTROL MEASURES – Use of repellents (diethyltoluamide, DEET) on the skin and impregnation 

of uniforms with permethrin should reduce risks. Elimination of mites by application of acaricides to ground and/or 

burning vegetation in highly infested and bivouac areas should be a logical precautionary measure. Weekly 

administration doxycycline as a chemoprophylactic drug has been effective in controlled studies, although the work is still 

experimental.

OTHER VECTOR-BORNE DISEASES OF POTENTIAL MILITARY IMPORTANCE

MURINE TYPHUS: This flea-borne disease, caused by Rickettsia typhi, has a rodent reservoir, primarily rats, in 

Thailand, with the oriental rat flea (Xenopsylla cheopis) acting as the primary vector. Rattus norvegicus populations are 

high in Bangkok. Adult flea longevity in nature (1-2 years) permits flea-transmitted pathogens to persist in the absence 

of vertebrate reservoirs. The disease is transmitted through the infected feces of fleas, contaminating the bite site and 

other fresh skin wounds. Murine typhus occurs primarily in overcrowded rural areas (e.g. refugee camps) where 

sanitation is poor, although some case have occurred in urban slums and dock areas in the past. After an incubation 

period of 1 to 2 weeks, there is a sudden onset of headache, chills, prostration, fever and general pain. Macular 

eruptions generally appear on the 5th or 6th day after onset of symptoms. Mortality is low (1% to 5%), less than 2% if 

treated. Infection confers immunity agaisnt future infection. The disease can occur year-round, although current 

incidence outside of refugee camps is very low.

FILARIASIS: Wuchereria bancrofti and Brugia malayi are the causative agents of this disease, which is prevalent 

only in a few areas. In Thailand Wuchereria bancrofti is transmitted primarily by Aedes harinasutai, and Brugia

malayi primarily Mansonia spp. Anopheles minimus is another potential vector for W. bancrofti, although formal 

incrimination is still lacking. The reservoir is human infected with microfilaria. Clinically, an allergic and 

inflammatory manifestation may occur one month after infection, but the microfilariae may not appear in blood for 6 

months to a year. Filariasis is not transmitted person-to-person, but may persist for 5 or more years after the initial 

infection. Chronic signs include gross enlargement of the limbs (elephantiasis), breasts and genitalia due to blockage of 

the lymphatic vessels. The delay in clinical signs, coupled with its low endemicity, make filariasis a disease of low 

military importance. Although some reports indicate a widespread distribution for filariasis, nearly all cases are 

reported from rural areas, with the most intense foci located along the Thai-Burmese border near Kanchanaburi and Tak 

Provinces (W. bancrofti) or the isthmus provinces in southern Thailand (B. malayi). Prevalence generally is considered 

low (1 to 2%), even in the most highly endemic province along the Burmese border.

CHIKUNGUNYA: An Alphavirus, family Togaviridae, is the causative agent, with man and monkeys probably the 

reservoirs. Aedes aegypti is responsible for the large epidemics that occur in urban areas. Chinkungunya may have a 

forest cycle involving monkeys and forest Aedes spp. as vectors. Ae albopictus should be regard as an important 

potential vector in rural areas. After an incubation period of 3-5 days, acute febrile illness (which includes high fever, 

headache, polyarthraiga, weakness, and rash) last 3 to 5 days. Joint pain is the most striking feature and is generally 

more severe in adults. Hemorrhagic manifestations, known elsewhere for this disease, are rare in Thailand. 

Transmission may occur throughout the year and countrywide, although the last epidemic in the early 1960s occurred 

primarily in Bangkok. However, this disease is very cyclic, with long intervals of up to 15-20 years occurring between 

outbreaks. When outbreaks do occur, they infect large proportions of the population in a rapid, sweeping manner.

SCHISTOSOMIASIS: This disease, caused by Schistosoma mekongi in Thailand, has a very limited distribution. 

Tricula aperta is the intermediate snail host for S. mekongi. It habitat is shallow water (depth less than two meters), 

under stones, weed, or branches. Suitable habitats are usually sunlit, highly oxygenated, clear water areas with a high 

pH (8.0 to 9.0). Humans are the principal reservoirs; dogs have been documented as important reservoirs of Khong 
14

Island in Laos, but their role in Thailand is uncertain. Transmission occurs when human skin contacts water infested 

with cercariae. After an incubation period of 2-6 weeks, acute febrile period may occur. Chronic symptoms develop 

later, and may include diarrhea, enlarged tender liver, epigastric distress, pain the back, groin, and/or legs, and urticaria. 

Adult worms have a life span of many years in humans, living in mesenteric veins and producing eggs. These eggs 

cause most of the symptoms, depending on number and location of their deposition. Mortality is unusual but can occur 

in serious infestations in children. Transmission appears to be year-round, but only sporadic cases have been reported 

since 1967 – all near the Laotian frontier along the Mekong River. Up to 9% of Cambodian refugees in camps on the 

Thai border have been positive for S. mekongi. However these case do not appear to have been acquired indigenously, 

and the disease is primarily of academic interest at present.

SINDBIS VIRUS: This disease, caused by an Alphavirus, is uncommon in humans, with only sporadic cases 

suspected. The disease is amplified by ornithopilic Culex spp. mosquitoes, with birds being the main reservoir. 

However, it is likely that the relatively anthropophilic Culex spp. (including some JE vectors), Ae. aegypti, or Ae. 

albopictus transmit the disease to humans. Although the virus is widespread, its symptoms are relatively mild, 

including a trunk and limb rash, fever, malaise, and joint pain. It is a self-limiting disease, and mortality from it is 

unknown.

PLAGUE: Plague, caused by Yersinia pestis, and vectored by fleas (primarily Xenopsylla cheopis), has not been 

reported in the country since 1952, and is unlikely to return. However, since rodent (Rattus spp.) reservoirs are 

plentiful, as are flea vector species, reintroduction cannot be completely discounted. The disease produces severe fever, 

swelling of lymph nodes, and pneumonia, with resulting coma and death in 50% or more of untreated cases. The 

longevity of the zoonotic flea vectors, 1-2 years, would enable the agent to persist in nature even in the absence of 

reservoir hosts.

 
15

APPENDIX A. SAND FLIES REPORTED FROM THAILAND

Phlebotomus Sergentomyia

P. argentipes 1S. anodontis

P. major major 1S. bailyi

P. philippinensis gouldi S. barraudi

P. stantoni S. gemmea

P. teshi S. hodgsoni

S. indica

Nemopalpus S. iyengari

N. vietnamensis S. mahadevani

S. pertubans

S. punjabensis

S. silvatica

1 Potential vectors of leishmaniasis, no indigenous transmission reported

APPENDIX B. TABANIDS REPORTED FROM THAILAND

Tabanus Tabanus

T. aganoscibilis T. aurilineatus

T. anabates T. brunnicolor

T. birmanicus T. ceylonicus

T. brunnipennis T. equinctus

T. caduceus T. euphanes

T. dissimilis T. griseipalpis

T. granti T. hypomacros

T. hybridus T. konis

T. indianus T. leuconematus

T. juncundus T. minimus

T. macdonaldi T. neographicus

T. monilifer T. oknos

T. nigrotectus T .pristinus

T. praematurus T. salvazai

T. rufiscutellatus T. striatus

T. siamensis T. thurmani

T. subhybridus T. unicus

T. tonglai

Chrysops dispar Haematopota abacis

C. fixissimus H. cilipes

H. pachycera

H. splendens

H. vimoli
16

APPENDIX C. CULICIDS REPORTED FROM THAILAND

Anopheles (Anopheles) Anopheles (Cellia)

An. aberrans An. aconitus 2

An. argyropus An. annularis

An. asiaticus An. culicifacies B

An. baezai An. dirus 2

An. baileyi An. dirus B 2

An. barbirostris An. dirus C 2

An. barbumbrosus An. dirus D 2

An. bengalensis An. dravidicus

An. bulkeyi An. hackeri

An. campestris An. indefinitus

An. crawfordi An. introlatus

An. donaldi An jamesii

An. fragilis An. jeyporiensis

An. hodgkini An. karwari

An. insulaeflorum An. kochi

An. interruptus An. leucosphyrus A

An. kyondawensis An. macarthuri

An. letifer An. maculatus2

An. lindesayi cameronensis An. minimus A 2 5

An. montanus An. minimus C 2

An. nigerriums An. nemophilous 2

An. nitidus An. nivipes

An. palmatus An. notanandai

An. paraliae An. pampanai

An. pediataeniatus An. philippinensis

An. pollicaris An. pseudojamesi

An. pursati An. pseudowillmori 2

An. roperi An. pujutensis

An. separatus An. sawadwongpomi 2

An. sinensis An. splendidus

An. sintonoides An. stephensi

An. stricklandi An. subpictus

An. tigertti An. sundaicus 2

An. whartoni An. tessellatus

An. umbrosus An. vagus

An. varuna An. willmori

Aedeomyia catasticta Aedes (Alanstonea)

Aedes treubi

Aedes (Aedimorphus)

Ae. alboscutellatus Aedes (Ayurakitia)

Ae. caecus Ae. grffithi

Ae. culicinus Ae. peytoni

Ae. mediolineatus

Ae. orbitae Aedes (Bothaella)

Ae. pallidostriatus Ae eldridgei

Ae. pampangensis Ae. helenae

Aedes (Aedimorphus) Aedes (Finlaya)

Ae. pipersalatus Ae. shortti

Ae. vexans Ae. simlensis

Ae. vittatus Ae. subniveus

Ae. togoi
17

Aedes (Cancraedes) Ae. unicinctus

Ae. indonesiae

Ae. kohkutensis Aedes (Isoaedes)

Ae. cavaticus

Aedes (Diceromyia) Aedes (Mucidus)

Ae. franciscoi Ae. laniger

Ae. iyengari Ae. quasiferinus

Ae. pseudonummatus

Ae. scanloni Aedes (Ochlerotatus)

Ae. whartoni Ae. vigilax

Aedes (Finlaya) Ae. (Rhinokusea)

Ae. albolateralis Ae. longirostris

Ae. alboniveus

Ae. albotaeniatus Aedes (Christophersiomyia)

Ae. assamensis Ae. annulirostris

Ae. christophersi Ae. ibis

Ae. chrysolineatjus Ae. thomsoni

Ae. dissimilis

Ae. elsiae Aedes (Edwardsaedes)

Ae. feegradei Ae. imprimens

Ae. flavipennis

Ae. formosensis Aedes (Stegomyia)

Ae. ganaathi Ae. aegypti 3 

Ae. greenii Ae. albopictus 3

Ae. harinasutai Ae. annandalei

Ae. harveyi Ae. craggi

Ae. inermis Ae. desmotes

Ae. jugraensis Ae. gardnerii imitator

Ae. khazani Ae. malayensis

Ae. leonis Ae. malikuli

Ae. lophoventralis Ae. novalbopictus

Ae. macfarlanei Ae. patriciae

Ae. mikeokopion Ae. perplexus

Ae. niveoides Ae. pseudabopictus

Ae. novoniveus Ae. seatoi

Ae. pexus Ae. w-albus

Ae. poicilius

Ae. prominens Aedes (Lorrainea)

Ae. pseudoniveus Ae. amesii

Ae. pseudtaeniatus Ae. fumidus

Ae. reinerti

Aedes (Neomelaniconion) Armigeres (Leicesteria)

Ae. lineatopennis Ar. annulipalpis

Ar. balteatus

Aedes (Paraedes) Ar. dentatus

Ae. ostentaitio Ar. digitatus

Ae. thailandensis Ar. dolichocephalus

Ar. flavus

Ar. inchoatus

Aedes (Scutomyia) Ar. longipalpis

Ae. albolineatus Ar. magnus
18

Aedes. (Verrallina) Ar. omissus

Ae. adustus Ar. pectinatus

Ae. andamanensis Ar. vimoli

Ae. atrius

Ae. butleri Heizmannia (Heizmannia)

Ae. clavatus Hz. aureochaeta

Ae. cytolabis Hz. chengi

Ae. dux Hz. communis

Ae. gibbosus Hz. complex

Ae. hispidus Hz. covelli

Ae. incertus Hz. demeilloni

Ae. indecorabilis Hz. macdonaldi

Ae. latipennis Hz. mattinglyi

Ae. lugubris Hz. persimilis

Ae. notabilis Hz. propinqua

Ae. phnomus Hz. proxima

Ae. protuberans Hz. reidi

Ae. pseudodiurnus Hz. scanloni

Ae. sohni Hz. scintillans

Ae. torosus Hz. taiwanensis

Ae. uncus

Ae. vallistris Heizmannia (Mattinglyia)

Ae. yusafi Hz. achaetae

Hz. catesi

Armigeres (Armigeres) Hz. thelmae

Ar. aureolineatus

Ar. bhayungi

Ar. jugraensis

Ar. kesseli

Ar. kuchingensis

Ar. malayi

Ar. maximus

Ar. moultoni

Ar. subalbatus

Ar. theobaldi
19

Udaya argyrurus Culex (Culiciomyia)

Cx. bailyi

Culex (Culex) Cx. barrinus

Cx. alienus Cx. dispectus

Cx. alis Cx. fragilis

Cx. barraudi Cx. harrisoni

Cx. bitaeniorhynchus Cx. lampangensis

Cx. edwardsi Cx. nigropunctatus

Cx. fuscocephala 4 Cx. pallidothorax

Cx. gelidus 4 Cx. papuensis

Cx. hutchinsoni Cx. sasai

Cx. infula Cx. scanloni

Cx. jacksoni Cx. spathifurca

Cx. longicornis Cx. spiculothorx

Cx. mimeticus Cx. termi

Cx. mimulus Cx. thumanorum

Cx. murrelli Cx. viridiventer

Cx. perplexus

Cx. pseudosinensis Culex (Eumelanomyia)

Cx. pseudovishnui Cx. brevipalpis

Cx. quinquefasciatus Cx. foliatus

Cx. sinensis Cx. hinglungensis

Cx. sitiens Cx. kiriensis

Cx. tritaeniorhynchus4 Cx. malayi

Cx. vishnui4 Cx. oresbius

Cx. whitei Cx. otachati

Cx. whitmorei Cx. phangnage

Cx. richei

Culex (Lophoceraomyia) Cx. tenuipalpis

Cx. aculeatus

Cx. alphus Culex (Lutzia)

Cx. bengalensis Cx. fuscanus

Cx. bicornutus Cx. halifaxii

Cx. cincetllus

Cx. curtipalpis Ficalbia minima

Cx. demissus

Cx. eukrines Mimomyia (Etorleptiomyia)

Cx. ganapathi Mi. elegans

Cx. gracicornis Mi. luzonensis

Cx. hirtipalpis

Cx. incomptus Mimomyia (Ingramia)

Cx. infantulus Mi. fusca

Cx. lucaris

Cx. macdonaldi Mimomyia (Mimomyia)

Cx. mammilifer Mi. aurea

Cx. minor Mi. chamberlaini

Cx. minutissimus Mi. chamberlaini metallica

Cx. pairoji Mi. hybrida

Cx. peytoni

Cx. pholeter
20

Cx. pilifemoralis Hodgesia

Cx. quadripalpis Ho. lampangensis

Cx. reidi Ho. malayi

Cx. rubithoracis

Cx. spiculosus Coquillettidia (Coquillettidia)

Cx. traubi Cq. crassipes

Cx. tuberis Cq. nigrosignata

Cx. variatus Cq. novochracea

Cx. whartoni Cq. ochracea

Orthopodomyia Mansonia (Mansonoides)

Or. albipes Ma. annulata

Or. Andamanensis Ma. annulifera 5

Or. anopheloide Ma. bonneae

Or. siamensis Ma. dives

Or. wilsoni Ma. indiana 5 

Ma. uniformis 5

Topomyia (Suaymyia) Malaya

To. apsarae Ml. jacobsoni

To. cristata Mi. genurostris

To. houghtoni

To. suchariti Toxorhynchites (Toxorhynchites)

To. vanbarensis Tx. albipes

Tx. bickleyi

Topomyia (Topomyia) Tx. gravelyi

To. aenea Tx. leicesteri

To. angkoris Tx. magnificus

To. inclinata Tx. manopi

To. lindsayi Tx. splendens

To. svastii Tx. sunthorni

Tripteroides (Rachionotomyia) Uranotaenia (Pseudoficalbia)

Tp. affinis Ur. abdita

Tp. aranoides Ur. albipes

Tp. tenax Ur. approximata

Ur. bicolor

Tripteroides (Tripteroides) Ur. bimaculata

Tp. aeneus Ur. demeilloni

Tp. caeruleocephalus Ur. enigmatica

Tp. denticulatus Ur. gouldi

Tp. hybridus Ur. hirsutifemora

Tp. indicus Ur. koli

Tp. powelli Ur. lutescens

Tp. proximus Ur. maxima

Tp. similis Ur. modesta

Tp. tarsalis Ur. nivipleura

Ur. nocticola
21

Uranotaenia (Pseudoficalbia) Uranotaenia (Uranotaenia)

Ur. novobscura Ur. annandalei

Ur. obscura Ur. bimaculiala

Ur. campestris

Zeugnomyia gracelis Ur. diraphati

Ur. edwardsi

Ur. hebes

Ur. longirostris

Ur. macfarlanei

Ur. metatarsata

Ur. orientalis

Ur. prajimi

Ur. rampae

Ur. sombooni

Ur. testacea

Ur. trilineata

2

 Incriminated vector of malaria 

3

 Incriminated vector of dengue

4

 Incriminated vector of Japanese encephalitis

5

 Incriminated or suspected vector of filariasis
22

APPENDIX D. TICKS REPORTED FROM THAILAND

Family Argasidae

Argas (Carios) Haemaphysalis (Haemaphysalis)

A. pusillus H. darjeeling

Argas (Pearsicargas) Amblyomma

A. robertsi Am. cordiferum

Am. cyprium cyprium

Ornithodoros (Alectorobius) Am. geoemydae

O. capensis Am. helvolum

Am. javanense

Ornithodoros (Reticulinasus) Am. supinoi

O. batuensis Am. testudinarium

Family Ixodidae

Haemaphysalis Aponomma

H. traguli A. gervaisi

A. patoni

Haemaphysalis (Kaiseriana) A. varanensis varanensis

H. anomala

H. bispinosa Boophilus

H. hystricis B. microplus

H. lagrangei

H. nadchatrami Dermacentor (Indocentor)

H. obesa D. atrosignauts

H. papuana D. auratus

H. semermis

H. shimoga Ixodes (Afrixodes)

H. wellingtoni I. radfordi

Haemaphysalis (Rhipistoma) Ixodes (Eschatocephalus)

H. asiatica I. vespertilionis

H. canestrinii

H. heinrichi Ixodes (Ixodes)

H. koningsbergeri I. acutitarsus

I. granulatus

Haemaphysalis (Ornithophysalis) I. spinicoxalis

H. bandicota

H. doenitzi Ixodes (Lepidixodes)

H. megalaimae I. kopsteini

H. ornithophila

Ixodes (Partipalpiger)

Haemaphysalis (Aborphysalis) I. ovatus

H. aborensis

H. atherurus

H. capricornis

Haemaphysalis (Garnhamphysalis)

H. calvus
23

APPENDIX E. SIMULIIDS REPORTED FROM THAILAND

Simulium (Eusimulium)

S. aureohirtum

S. sp. A

S. sp. B

Simulium (Himalyum)

S. nigrogilvum

Simulium (Simulium)

S. barnesi

S. chamlongi

S. chiangmaiense

S. digrammicum

S. nekhonense

S. nitidithorax

S. nodosum

S. rufibases

S. sakishimaense

S. sp. D.

S. sp. E

S. thailandicum

APPENDIX F. CULICOIDES REPORTED FROM THAILAND

Subgenus Trithecoides Subgenus (Avaritia)

Culicoides anophelis Cu. actoni

Cu. barnetti Cu. bigeminus

Cu. elbeli Cu. boophagus

Cu. flavescens Cu. brevipalpus

Cu. forade Cu. circumbasalis

Cu. gewertzi Cu. clavipalpus

Cu. macfiei Cu. corti

Cu. palpifer Cu. distinctus

Cu. paraflavescens Cu. dryadeus

Cu. raripalpis Cu. fulvus

Cu. tenuipalpis Cu. geminus

Cu. hewetti

Subgenus (Haemophorctus) Cu. huffi

Cu. calcaratus Cu. imicola

Cu. hoffmanoides Cu. jacobsoni

Cu. nitens Cu. kepongensis

Cu. maculatus

Subgenus (Hoffmania) Cu. nigripes

Cu. andrewsi Cu. niphanae

Cu. bubalus Cu. okinawensis

Cu. indianus Cu. orientalis

Cu. innoxias Cu. oxystoma

Cu. liui Cu. pampangensis

Cu. malayae Cu. peliliouensis
24

Cu. peregrinus Cu. pungens

Cu. recurvus Cu. shermani

Cu. signipennis Cu. shorti

Cu. sumatrae Cu. similis

Cu. tenuifasciatus Cu. yasumatsui

Subgenus (Meijerhelea)

Cu. arakawae

Cu. guttifer

Cu. hegneri

Cu. histrico

Subgenus (Beltranmyia)

Cu. circumscriptus

Cu. halonostictus

Monoculicoides

homotomus

Pontoculicoides

kampupi

APPENDIX G. FLEAS REPORTED FROM THAILAND

Ctenocephalides felis

Lagaropsylla nicula

Maerostylophora hastatus

Stivalius

S. akale

S. aparus

S. klossi

S. new species

Thaumopsylla breviceps orientalis

Thrassis bacchi consimilis

Xenopsylla astia

X. cheopis

X. variabilis
25

APPENDIX H. TROMBICULIDS REPORTED FROM THAILAND

TRIBE: TROMBICULINI

Trombicula Eutrombicula wichmanni

T. calva

T. keechongi Blankaartia acuscutellaris

T. megaderma

T. siamensis Heaslipia gateri

T. taphozous

Neotrombicula scorpionis

Leptotrombidium

L. akamushi Siseca

L. andrei S. rara

L. aramataum S. subrara

L. arvina

L. atractimorphe Myotrombicula vercammeni

L. binbium

L. burmense Miyatrobicula benesnoni

L. deliense

L. dendrium Microtombicula

L. elisbergi M. chamlongi

L. fulleri M. munda

L. gateri M. spicea

L. globosum

L. hanseni Chiroptella

L. harrisoni C. nocticola

L. hastatum C. revelae

L. imbricatum C. sandoshami

L. keukenschrijveri

L. lepismata TRIBE: SCHOENGASTIINI

L. macacus

L. macrosphenum Schoengastia

L. magnum S. kanhaensis

L. manooni S. vieta

L. mastigophorum

L. micula Walchiella

L. monstrosum W. asonluca

L. nakatae W. hanseni

L. oreophilum W. harinastai

L. paniculatum W. lacanosa

L. panitae W. oudemansi

L. peniculatum W. traubi

L. pilosum

L. rapmundi Aschoschoengastia

L. santasiri A. audyi

L. scanloni A. canus

L. scutellare A. ctenacarus

L. sibynatum A. globosa

L. striatum A. indica

L. thurmani A. kittii

L. variaculum A. leechi

A. lorius

Toritombicula densipiliatum A. roluis

A. tafia
26

Tecomatlana melvini

Trombigastia harrisoni

t. rousetti

TRIBE: SCHOENGASTIINI TRIBE: GAHRLIEPIINI

Kayella novita Gahrliepia

G. ewingi lupella

Helenicula G. fenestrulata

H. cardigani G. fletcheri

H. kohlsi G. insigne

H. lanius G. isonychia

H. mutabilis G. khuyingi

H. scanloni G. kritochaeta

G. lewthwaitei

Neoschoengastia G. ligula

N. heynemanai G. marshi

N. longipes G. micropelta

N. struthidia G. mirabilis

N. thomasi G. rutila

G. simulata

Doloisia G. starki

D. bachypus G. suvajrai

D. browning G. tenella

D. domrow G. tessellata

D. hooperi G. tylana

D. intermedia

D. jadini Odontacarus audyi

D. manipurensis

Whartonia

Scoutedenichia centralkwangtunga W. brevis

W. carobangnsis

Riedlinia lipoxena W. maai

W. prima

Cheladonta

C. gouldi Babangia permifera

C. neda

C. prachonage Herpetocarus leprochaeta

C. traubi

TRIBE: GAHRLIEPIINI

Gahrliepia

G. alpestris

G. cetrata

G. chinensis

G. cuspidata

G. dismina

G. disparungius disparungius

G. disparungius pingue

G. elbeli
27

APPENDIX I. SCORPIONS REPORTED FROM THAILAND

Buthidae

Lychas

L. feae?

L. mucronatus

L. sanutillis?

L. shoplandi?

Isometrus

I. maculatus

I. vittatus?

Chaerilus birmanicus?

Scorpiopsidae

Scorpiops oligotrichusb

S. atracinus

S. linstroemi?

S. longimanus benghamis?

Ischnuridae

Liocheles

L. australasiae

Scorpionidae

Heterometrus bengatensis

H. laoticus

H. petersii petersii?

H. spinifer spinifer
28

APPENDIX J. PESTICIDE RESISTANCE

SPECIES LOCALITY INSECTICIDE STAGE DATE STATUS

Aedes aegypti

Ae. aegypti

Ae. aegypti

Ae. aegypti

Ae. aegypti

Ae. aegypti

Ae. aegypti

Ae aegypti

Anopheles conitus

An. aconitus

An. aconitus

Xenopsylla cheopis

X. cheopis

X. cheopis

Surat Thani, Koh Samui

Lopburi, Koh Samong

Nakon Sawan, Tah Tako

Chiang Mai, Muang

Chiang Rai, Muang

Bangkok, Soi Aree

Bangkok, Thonburi

Bangkok, Din Daeng

Phayao, Jadee KumV9 

Chiang Rai, Mae Prik V10

Phavao, Jadee Kum

Kanchanaburi Muang

Bangkok, Klong Toey

Surat Thani, Koh Samui

DDT

DDT

DDT

DDT

DDT

DDT

Dieldrin

Lindane

DDT

DDT

DDT

Dieldrin

DDT

Dieldrin

L

L

L

L

L

L

L

L

A

A

A

A

A

A

1967

1968

1968

1968

1969

4/67

3/67

10/67

9/81

10/81

8/82

2/66

5/69

9/69

R

R

R

R

R

R

R

R

R

R

R

R

R

6 Recent test reported by other sources indicate that nearly all major vectors in most areas of Thailand are resistant to 

DDT and related compounds. An. dirus has been shown to have behavioral resistance, attributed to apparent avoidance 

of DDT-treated areas. At last check, resistance to malathion, fenitrothion and permethrin was not reported.
29

APPENDIX K. LEECHES REPORTED FROM THAILAND

Terrestrial and aquatic leeches occur throughout most of Thailand in swamps, ditches, and tropical rain forests. 

Their effect is both physical and psychological. Large numbers of leeches cause extensive blood loss, and the 

attachment sites are susceptible to secondary infection. The psychological effect is perhaps more important, since 

there are numerous exaggerations about leeches invading the nostrils and urethra 

The aquatic leeches (family Hirudidae) may reach up to 6 inches in length and include the genera Hirudo, 

Poecilobella, Limnatis, and Dinobdella. When a person enters an infested ditch or swamp, leeches quickly swim 

toward the source of disturbance, adhere to the skin, and begin exploring the host for a minute or two prior to 

attaching. Once attached, the leech may engorge in a relatively short time (often less than 15 minutes) and drop off 

after reaching several times its normal size. However, the attachment site may continue to bleed for hours because 

of anticoagulant injected in the site. The habits of land leeches of the genus Haemadipsa (family Haemadipisidae) 

are similar except for the host-seeking behavior. Land leeches usually are found in rain forests on the ground or on 

low vegetation, where high humidity prevents them from desiccating. Brushing against vegetation stimulates their 

immediate and frenetic host-seeking action. Because of their need for high humidity, land leeches are usually 

encountered only during rainy season.

Personal protection agaisnt leeches is afforded by proper wearing of the uniform and extended formulation DEET 

repellent, which is particularly effective against land leeches. However, land leeches can penetrate relatively small 

openings, including boot eyelets. DEET has not been effective agaisnt aquatic leeches, probably because it is 

quickly removed by water. Leeches should not be pulled off (their mouthparts are likely to remain attached); 

instead, they should be forced to disengage by dropping iodine, vinegar, or salt on them, or by touching them with 

a hot object. Treatment for wounds involves the use of a styptic pencil to stop bleeding, followed by application of 

an antibiotic solution.

APPENDIX L. VENOMOUS SNAKES OF THAILAND

Colubridae – This family contains rear fanged snakes whose bites produce only local swelling and pain. Species 

present in Thailand are:

Rhabophis chrysargus

R. subminiatus

R. tigrinus

Elapidae – The cobras, kraits and coral snakes are all considered dangerous. Venoms are primarily powerful 

neurotoxin.

Bungarus spp. – Kraits are slender, cylindrical snakes four to seven feet in length with small flattened heads. They 

are smooth scaled and glossy. Most of them have a vivid pattern of cross bands. Kraits are strongly nocturnal but 

become very quite and sluggish during the day. They are responsible for few snake bites, but the fatality rate is 

high. The banded krait (B. fasciatus) is found throughout Thailand. It is quiet, inoffensive snake curls up and 

hides its head beneath its coils when annoyed. The Malayan krait (B. candidus) and red-headed krait (B. flaviceps) 

occur only in southern Thailand. The red-headed krait has very distinctive coloring. The head and tail are bright 

red; the body is black with narrow stripes low on the side and a narrow stripe or rows or dots down the middle of 

the back. It inhabits jungles, usually in or mountainous country.

Calliophis spp . – Oriental coral snakes. These small (usually less than three feet long), brightly colored snakes 

with patterns consisting of complete rings of yellow (or white), black and usually red. The color pattern shows 

marked individual and species variation. They are snakes of forested jungle habitats, ranging well into the 

mountains. They occasionally occur in suburban areas. Oriental coral snakes are considered uncommon, but this 

may reflect their shy and secretive nocturnal nature. They are quite, unaggressive, and reluctant to biter, but their 

venom is deadly. All species should be considered potentially dangerous. C. maculiceps occurs throughout 

Thailand, while C. gracilis and C. maclelandii are found in the south and north, respectively. Maticora coral 

snakes differ from Calliophis spp. in having venom glands that extend throughout the anterior one-third of their 
30

body. They are generally dark brown to blue-black with narrow light stripes. Two species of long-glanded coral 

snakes, M. bivigata and M. intestinalis, occur throughout southern Thailand. They are nocturnal and secretive, but 

their venom is potentially lethal.

Naja spp. (cobras) – Except for the very distinctive king cobra, all central and South Asian populations are 

considered subspecies of Naja naja. There are significant differences in morphology, coloration, behavior and 

venom composition between subspecies. The Asian cobras are found in most types of terrain, except dense rain 

forest. Flat grassy areas and scattered tree groves are preferred habitat, but they also occur in rice fields and other 

agricultural land. Since they prey on rats, they occur commonly in villages and cities, often in crumbling walls, old 

buildings and gardens. Cobras avoid human contact; if cornered, they rear up and spread their hoods. They are 

most dangerous when surprised at close range. Large cobras may have over 500 mg of venom (a lethal dose is 

estimated at 20 mg), but generally inject very little venom when biting defensively. Some populations produce 

venom with strong narcotizing but weak systemic effects. The monocellate cobra (Naja naja kaouthia) occurs 

throughout Thailand and attains a length of eight feet. The king cobra (Ohiophagus hannah) may reach 18 feet or 

more in length and is one of the world’s most dangerous snakes. It is found throughout Thailand in open, hilly 

terrain, especially cultivated areas. King cobras are active during the day and night and may frequent trees or 

water. This species has the unique habit of constructing an elaborate nest of dead leaves and other decaying 

vegetation. Fortunately, it is scarce throughout its range and bites humans infrequently.

Viperidae – Snakes with triangular heads and vertically elliptical pupils.

Russell’s viper (Vipera russelli) – Identified by its distinctive pattern of large, black-ringed ovals on an olive or 

gray background. This viper averages 40-50 inches but may attain a length of over 5 feet. It occurs primarily in 

rural northern Thailand near hilly forests. This species is mainly nocturnal but may be active during cool days. It 

moves slowly but will strike rapidly and aggressively when disturbed. Russell’s viper is a leading cause of snake 

bite, but more fatalities result from kraits and cobras.

Crotalidae – Moccasins and Asian pit vipers. The Malayan pit viper (Agkistrodon rhodostoma) averages 2.5 feet 

in length and likes a climate with well-marked wet and dry seasons. It inhabits forested and cultivated areas at low 

elevations and is common on rubber plantations. It is a bad-tempered snake that is quick to bite despite its 

sedentary habits. It is responsible for many snakebites throughout Southeast Asia but produces few fatalities (less 

than 2% of people bitten).

Trimeresurus spp. – This large genus comprises the Asian lance-headed vipers. All have large, triangular heads, 

loreal pits and vertically elliptical pupils. Bites from these snakes are frequent, although the fatality rate is low. 

Species present in Thailand are:

T. albolabris

T. kranburiensis

T. monticola meridionalis

T. poperoum

T. puniceus

Hydrophidae – This family contains the sea snakes, some species may also be found in estuaries. Although not 

normally aggressive, these snakes are numerous in tropical waters. Most victims are fishermen. Aside from their 

highly toxic venom, these snakes are dangerous because the bite is often painless, more like a pin prick or sting. 

Over a dozen species occur in the coastal areas of the Gulf of Thailand and Bay of Bengal. Sea snakes are 

laterally flattened, having oarlike tails. Most have nostrils opening on the top of the head.

SNAKEBITE

Laboratory experiments show that snake venoms contain a complex mixture of toxic factors, but the primary 

clinical signs of snakebite poisoning in humans are usually distinctive; viper venom is mainly vasculotoxic, elapid 

venom neurotoxic, and sea snake venom myotoxic. Venomous snakes have two types of bite: 1) a bite inflicted 

when the snake is seeking prey, in which a victim dies rapidly following injection of a large quantity of venom, 
31

and 2) a defensive bite, with little or no venom injected, the snake’s object being to escape. Studies of snakebite 

patients in various parts of the tropics confirm that when venomous snakes bite humans, the bites are nearly 

always of the second type. More than half the victims have minimal or no poisoning. Only about a quarter 

experience serious systemic reactions.

The commonest reaction following snakebite, whether or not the snake is poisonous, is fright. Fear, to 

some degree, is present in all snakebite victims and often dominate the clinical picture. Emotional symptoms 

emerge rapidly, within minutes of the injury while symptoms of systemic poisoning rarely appear until a half hour 

or after the bite. The frightened patient may appear semiconscious, with cold, clammy skin, feeble pulse, and 

rapid, shallow breathing. These symptoms resolve quickly after a placebo injection.

Snakebites are grossly underreported in Thailand, but official statistics recorded 2673 cases in 1984 with 7 deaths.

FIRST AID

1. Get the victim away from the snake. Keep victim calm and quiet. Do not handle the snake or put yourself at risk 

of being bitten. Identify the snake if possible. If it has been killed, keep it.

2. Immobilize the site of the bite. If possible, keep the site of the bite below the level of the heart.

3. Do not give the victim anything to eat or drink.

4. If the bite is on one of the upper limbs, remove any rings or jewelry from that side. 

5. Arrange immediate evacuation. If there is no evidence of venom, keep the victim quiet and under observation.

6. If there is evidence of venom (swelling, spreading pain, bruising, symptoms remote from the bite area), and LESS 

than 30 Minutes have passed since the bite, place a band about 4 inches above the bite. Tighten if just to the point 

that you can only get one finger beneath it. Do not remove the band but, if swelling develops, be prepared to adjust, 

it so that it get no tighter.

7. An ice pack can be used immediately to reduce pain. DO NOT pack a limb in ice or immerse it in ice water.

For information on snakebite, including sources of antivenins worldwide, contact the Arizona Poison and Drug 

Information Center, phone number (602) 626-6016. The local source of information and antivenin is the Red Cross 

Society, Queen Saovabha Memorial Institute, Rama 4 Road, Bangkok, Thailand.
32

APPENDIX M. POISONOUS AND VENOMOUS PLANTS

Euphorbiaceae

Aleurites fordii - The tung oil tree, used in furniture finishes, produces seed which can cause a moderate 

gastroenteritis.

Euphorbia spp - A number of species of spurge in the region produce sap which causes gastroenteritis if 

ingested or is blinding if it contacts the eyes.

Manihot esculentus - The cassava, a much-cultivated plant in the region, contains amygadalin and 

hydrocyanic acid in its sap which act together as skin vesicant.

Excoecaria agallocha - This mangrove type of tree (the milky mangrove) produces a poisonous sap that can 

cause blistering and temporary blindness, depending on where the sap is contacted.

Excoecaria oppositifolia - Has poisonous sap with effects similar to previous species.

Ricinus communis - The castor bean contains ricin, an irritant that can cause severe urticaria and 

conjunctivitis on contact or vomiting and apoplexy if ingested. 

Urticaceae

Laportea bulbifera - The tree nettle possesses silicaceous hairs which break off upon contact, leaving behind a 

skin irritant and vesicant which can persist for weeks.

Laportea interrupta - Has a skin irritant and vesicant similar to the previous species.

Palmae

Arenga pinnata - The sugar plum contains stinging crystals in its fruits which cause severe swelling of the

 throat and mouth if ingested.

Calamus spp. - Rattan, most known for its utility in furniture-making, growing thickly in wet jungle areas and 

has thorns that may break off in the skin and cause severe dermatitis and swelling at the contact for several days.

Caryota mitis - The tufted fishtail palm contains crystals in the fruit, pulp and juice that are very irritating to skin.

Araceae

Alocasia spp - The elephant’s ear plant, often seen as a house plant, grows naturally in marshes and swamps. 

The high content of calcium oxalate crystals make contact with it extremely irritating to the skin.

Leguminosae

Erythrina variegata orientalis - The gao-gao (coral bean) is a bean-like bushy plant which produces poisonous 

substances in all its parts. The bark and leaves may produce diarrhea and act as a central nervous system 

depressant, while the pods produce hallucinogenic effects. 

Mucuna pruriens - The pods of this plant contain thousands of brittle, barbed hairs which detach easily upon 

contact, causing intense itching. 

Derris elliptica - This shrub species can be used to prepare an insecticide. Its clinical features indicate that is a 

skin irritant. Contact also causes increased salivation, numbness of the tongue, and loss of speech. 

Derris malaccensis Features similar to previous species. 
33

Gramineae

Bambusa - The bamboo plant possesses red hairs on its young shoots which can cause mechanical injury to the 

gastrointestinal tract. 

Solanaceae

Solanum nigrum - The nightshade has leaves and berries which contain the potent, and sometimes fatal, poison 

solamine. 

Capsicum spp. - Hot pepper plant leaves can cause severe, rather short-lived, inflammation of the eyes if 

contacted either directly or with contaminated hands.

Meliaceae

Anamirta cocculus- This plant produces a fruit used as fish poison. It also causes an eruption on the body and 

arms if applied to the scalp.

Moraceae

Antiaris toxicariae - This mulberry tree, used to feed silkworms, contains a cardioactive glycoside in its sap, 

but must be injected to take effect.

Apocynaceae

Nerium oleander - This dogbane species is poisonous in all its parts, including leaves, wood, and sap.

Cerbera manghas - The latex of this plant causes blindness if it gets into the eyes.

Anacardiaceae

Melanorrhoea usitata - The wood, leaves, and fruit of the Rengas tree are toxic, giving rise to intractable skin 

eruptions on contact. The wood causes irritation of the mouth, nose, and throat in people in closed rooms, even if it is 

the form of old furniture.

Asclepiadaceae

Calotropis gigantea - This giant milkweed has bark. Its stems contain a proteolytic latex which is irritating 

and caustic to the skin and eyes.

Loganiaceae

Buddleya asiatica - This plant is the well-known source of strychnine, a deadly poison if consumed.

Styraceae

Strychnos nux-vomica - This plant also contains the poison strychnine in its seed coats.
34

APPENDIX N. PERSONAL PROTECTIVE MEASURES

Personal protective measures are the first line of defense against arthropod-borne disease and may be the only 

protection for military personnel deployed in the field. Proper wearing of the uniform and appropriate use of 

repellents can provide high levels of protection against blood-sucking arthropods. The uniform fabric provides a 

significant mechanical barrier to mosquitoes, ticks and other blood-sucking insects. The uniform should be worn 

cover as much skin as possible, as weather and physical activity permit.

Protection provided by the properly worn uniform can be greatly increased by the use of two newly developed 

repellents. An aerosol formulation of permethrin (NSN 6840-01-278-1336) can be applied to the uniform but not the 

skin according to label directions. This will provide both repellent and insecticidal properties to the uniform material, 

and will remain effective through several washings. A new extended lotion formulation of diethyl-m-toluamide 

(DEET) (NSN 6840-01-284-3982) has been developed to replace the 2/oz. bottles of 70% DEET in alcohol. The new 

formulation contains less active ingredient and does not have to applied as often as the old formulation. It is less 

irritating to the skin, has less odor and is generally more acceptable to the user. Combined use of extended duration 

DEET lotion on exposed skin and permethrin on uniform items has been demonstrated in laboratory and field studies 

to provide nearly 100% protection against a variety of blood-sucking arthropods. In addition permethrin may be 

applied to bednets, tentage and other field items as needed. Recent field studies in several countries have shown that 

bed nets treated with pyrethroids are highly effective against mosquitoes and a variety of other blood-sucking 

arthropods.

When operating in tick infested areas, the plants should be bloused into the boots to prevent access to the skin 

by ticks and other crawling arthropods, such as chiggers. Check yourself frequently when walking through tickinfested areas, remove all clothing and examine yourself for ticks. Infected ticks usually require several hours of 

feeding before pathogens are transmitted. Therefore, attached ticks should be removed as soon as possible. It ticks 

become attached, the simplest and best method of removal is by a slow, steady pull with a pair of tweezers or forces. 

Do not squeeze the body, but grasp the tick where the mouthparts enter the skin and pull firmly until the tick is 

extracted. Be careful not break off the mouthparts and leave them in the skin. Wipe the bite area with an antiseptic. If 

the have touched the tick during removal, wash them thoroughly with soap and water or an antiseptic, since tick 

secretions may contain pathogens.

The U. S. Army Environmental Hygiene Agency’s Illustrated Technical guide #174, entitled Personal 

Protective Techniques Agaisnt Insects and Other Arthropods of Military Significance, is an invaluable reference 

available from:

U. S. Army Environmental Hygiene Agency

Entomological Science Division

Aberdeen Proving Ground, MD 21010-5422

DSN 584-3613 Commercial (301) 671-3613.
35

APPENDIX O. CHEMICAL CONTROL OF PESTS AND VECTORS

More detailed recommendations for the selection, application and use of pesticides in field situations 

worldwide, during contingency operations or military exercises can be found in the Contingency Pest Management 

Pocket Guide. This guide is a concise reference on: National Stock Number (NSN)-listed pesticides available through 

military supply channels and designated for contingency use by one or more of the Armed Services; their uses, 

dosages, and application methods; pesticide dispersal equipment; information on surveillance, trapping, and safety 

equipment; personal protective equipment agaisnt disease vectors; air-transport of pesticide that do not meet 

transportation requirements; pesticide dilution and dosage formulation; and U. S. Army military points of contact 

overseas who can provide information on vector-borne disease control in their respective areas of the world.

Copies of the Contingency Pest Management Pocket Guide (also known as Technical Information 

Memorandum #24) can be obtained free of charge from DPMIAC. 

 
36

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