Infectious diseases in Thailand

The Thai vaccination program includes immunization for Tuberculosis, Hepatitis B, Diphteria-Pertussis-Tetanus, Polio, HiB, Japanese Encephalitis, Mumps-Measles-Rubella, Chickenpox

For travellers, some common vaccines include Rabies, Japanese Encephalitis, Hepatitis.

Read the detail section for each disease to obtain some additional information.

Tentative graphic representation of infectious diseases risk in Thailand

Diseases above the green dotted line might be of concern.

Diseases below have an associated lower risk (either immunization, quite specific transmission or very low prevalence)

Disease in red are a major health risk; Orange is medium, Gold is only a concern if ignored, Yellow is mostly harmless

Tuberculosis

TUBERCULOSIS

Infection risk: Medium to High in some social environments

Symptoms: Lung infection with bloody cough, fever, loss of weight

Transmission: Airborne (very high)

Effects: Very high mortality (50%); permanent breathing issues in recovered cases

Prevention: Wear mask in high-risk areas; TB skin test and/or vaccine

Details:

Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis. 10% of infections (Active TB) affect lungs, causing chronic cough, blood-stained mucus, fever, weight loss, etc. while 90% show no symptoms (latent TB). This latter group is not contagious but tuberculosis could declare itself at anytime.

For individuals with active TB, the mortality rate is high, up to 50% when untreated. The mortality rate remains high for a minority of infections that are drug-resistant. Half of recovered cases will keep a decreased pulmonary function. Active TB individuals are highly contagious through contaminated air via coughs, sneeze, breath, etc.

Prevention:

Wearing a mask in high-risk and/or busy public spaces is recommended. When a possible risk of contamination exist, a skin test is strongly recommended.

Vaccination is available as BCG vaccine and is highly recommended for individuals potentially in frequent contact with people with active TB.

In Thailand:

Tuberculosis remains the most deadly infectious disease in the world (outside the recent COVID-19 pandemic) and Thailand is in the top 20 of most TB-infected countries. It is particularly prevalent in populations with low socio-economic status. BCG vaccine is now routinely given at birth.

JAPANESE ENCEPHALITIS

Infection risk: Medium

Symptoms: Headache, fever, vomiting, confusion, seizure

Transmission: Mosquito bite

Effects: High mortality (20-30%)

Prevention: Mosquito control, vaccination

Details:

Japanese Encephalitis (JE) is an infection caused by a flavivirus; often asymptomatic but will cause encephalitis in 1 case out of 250 infections. The symptoms include fever, headache, vomiting, confusion and seizure. For severe symptomatic cases, the mortality (20-30%) and morbidity (50%) rates are very high (Cheng et al., 2022) with considerable neurological issues for recovered cases.

The virus is transmitted by some species of mosquito (Culex) through bites to humans (as well as cattle and horses). Pigs are hosts that are mostly asymptomatic and greatly contribute to the propagation of the disease as a healthy reservoir.

Prevention:

There is no antiviral treatment for Japanese Encephalitis and care is only supportive. However, there is an effective vaccine given to babies and adults. Other forms of prevention include mosquito control.

In Thailand:

The disease risk is relatively high in rural areas of Thailand where pigs are present. The impact of the disease is particularly high in Laos. JE vaccine is part of the standard immunization program for children born in Thailand (9-12 months). JE vaccination is not particularly recommended for visitors or residents who do not get into contact or live close to swine farms.

Japanese Encephalitis

RABIES

Infection risk: Medium to High

Symptoms: Fever, tingling, nausea, mobility problems, loss of consciousness, death

Transmission: Dogs (also bats, monkeys,...) bite

Effects: Extremely high mortality (~100%)

Prevention: Vaccination, immunoglobulin treatment

Details:

Rabies is caused by the rabies lyssavirus transmitted from infected animals (mostly dogs). Symptoms generally appears after a few months but it can be as short as a few days (depending on location and type of bite). Once symptoms are present, death systematically occurs in the next few days and there is no treatment for it.

Prevention:

Since there is no treatment once this deadly disease is symptomatic and the rabies virus cannot be easily detected early on, it is essential to have preventive treatment against rabies in case of bite. Vaccination is the most obvious choice. It is 100% effective when a booster is administered in the following days after a suspicious bite. Immunoglobulin treatment is the alternative for unvaccinated patients but the cost is at least 10x vaccination.

In Thailand:

Rabid animals are common in Thailand and the number of cases increasing (Thanapongtharm et al., 2021). Dogs are the main source for human infection with unvaccinated non-feral dogs being more a risk due to their proximity to humans. The disease has become relatively rare in the human population of Thailand in the last two decades due to effective dog management, awareness, post-bite treatment and vaccination.

Vaccination is essential to any person working with dogs and wildlife in general. It is strongly recommended for any resident in Thailand.

Rabies

DENGUE FEVER

Infection risk: Medium to High

Symptoms: High fever, headache, vomiting, limb pain, skin issues, spontaneous bleeding

Transmission: Mosquito bite

Effects: Severe dengue has a mortality of ~1%

Prevention: Mosquito control, vaccination in some cases

Details:

Dengue Fever is caused by a flavivirus called the Dengue virus (DENV), transmitted by some species of mosquitoes (Aedes). The infection causes high fever (>40ºC), headache, vomiting, muscle and joint pain, skin rash and for severe cases, a very important drop in platelets, preventing blood clotting and potentially causing spontaneous bleeding (hemorrhagic fever). In these latter cases, the mortality can be up to 2.5% and is affecting more young children.

There is no specific antiviral treatment for the disease and medical support is mostly to alleviate symptoms. For mild cases, home rest with high oral rehydration to keep fluid balance is essential. Paracetamol can be used for fever but not NSAID (ibuprofen, etc.) which could make things worse. For more severe cases, hospitalization is often necessary.

Prevention:

Dengue fever is one of the diseases where mosquito control (repellent, limitation of breeding sites, screens, insecticides, etc.) is essential has there is no effective medical protection against it for most of the population. The recently developed dengue vaccine is not fully effective yet (for a variety of reasons) but shows some protection against individuals that have contracted Dengue fever in the past.

In Thailand:

Dengue fever is particularly common in the northern provinces during the rainy season. Because Aedes aegypti is a mosquito well-adapted to crowded human population, Dengue fever is more common in urban centers than in the countryside.

Dengue Feve

HEPATITIS

Infection risk: High

Symptoms: Fatigue, nausea, vomiting, joint pain, fever, liver-related symptoms

Transmission: Blood, bodily secretion, shared medical equipment, birth

Effects: Mortality is around 0.5%; permanent liver damage, liver cancer

Prevention: Avoid bodily fluids of strangers; vaccinations (Hep A & B)

Details:

Hepatitis is caused by 5 different viruses called A to E. Symptoms often starts with fatigue, nausea, vomtiing, joint pain, fever and eventually progress with liver related issues such as dark urine, yellow eyes, jaundice, enlarged abdomen, etc.

Hepatitis A & E have only acute forms and resolve by themselves after a few months

Hepatitis B starts with an acute phase of symptoms but 15% of patients will not eliminate the virus and the disease become chronic, leading to important health issues later on such as cyrrhosis and hepatocellular carcinoma or liver cancer.

Hepatitis C is mostly chronic and can remain asymptomatic for decades. It becomes particularly an issue when an infection by hepatitis A or B occurs.

Hepatitis D only occurs when Hepatitis B infection is already present

Prevention:

Avoid unnecessary contact with bodily fluids of strangers as the infected status of many individuals might not be known. This include sharing medical equipment, sexual contacts, and although unlikely, sharing drinks and other saliva contaminated items.

Vaccination exists for hepatitis A, B (and D) and E is in development. Hepatitis C has no vaccine available and it is strongly recommended for carriers of hepatitis C to be vaccinated for A and B.

In Thailand:

Hepatitis B (and D) alone is present in ~5% of the Thai population and is a major health issue due to its chronic status and relatively high transmission rate. Hepatitis B vaccine is now part of the immunization program at birth in Thailand (Ngamurulert et al., 2017; Thitipatarakorn et al., 2022).

Hepatitis

OTHER SEXUALLY TRANSMITTED DISEASES

Infection risk: Variable

Symptoms: Variable

Transmission: Sexual contact

Effects: Variable

Prevention: Screening, condom

Details:

Sexually transmitted diseases (STD) includes chlamydia, gonorrhea, syphillis, AIDS, Herpes, trichomoniasis, ...; Hepatitis and Human Papillomavirus are treated separately. These diseases have variable symptoms.

Prevention:

Screening of partners, protection such as condoms, sex abstinence are all methods that limit considerably any infection. Most diseases are routinely part of STD screening to hasten any needed treatment to the patient and potential infected partners.

In Thailand:

While these diseases are present worldwide, Thailand has some socio-economic part of the population where these STD are more prevalent and overall, infection rates are among the highest in the world. Part of the propagation is due partly to the absence of meaningful sexual education in Thailand leaving a large part of the population completely unaware of these diseases and how to be protected.

Syphilis: Number of cases are doubling every few years for the past decade and is particularly high in the north and central-south-east (Chaiyamahapurk & Kittiyaowamarn, 2021)

AIDS: HIV infection level is the highest in South-East Asia and rates are around 1.1% of the population carrying the virus.

Gonorrhea & Chlamydia: These diseases are the most common STD in the country. Gonorrhea is of particular concern due to an increasing number of antibiotic-resistant infections (Somsri et al., 2022).

STD

MALARIA

Infection risk: Very Low

Symptoms: Fever, tiredness, vomiting, headache

Transmission: Mosquito bite

Effects: Mortality between 10 and 50% for severe cases

Prevention: Mosquito control, prophylaxis, vaccination

Details:

Malaria is a parasitic infection caused by Plasmodium parasite, transmitted by some species of mosquitoes (Anopheles). The infection causes fevers, tiredness, vomiting and headaches which can be mild to severe. Severe symptoms are mostly due to Plasmodium falciparum which has a 10 to 50% mortality when untreated. Other Plasmodium species only produce mild fever symptoms.

Prevention:

Preventive medication exists such as mefloquine, doxycycline and Malarone and antimalarial drugs when infected. Those medications have considerable side effects and their use has to be carefully considered. A candidate vaccine, Mosquirix, is becoming available for children in sub-Saharan Africa but is not available elsewhere.

In Thailand:

Luckily, Plasmodium falciparum is dominant in Africa but represents a minority of infection in Thailand. It varies from region to region, from ~5% in the north to 45% in the south. Other infection are related to Plasmodium vivax that produce mostly mild symptoms.

In addition, malaria is relatively rare in Thailand and occurs in dense forests along the Burmese border and is basically absent from urban centers.

Taken into account the distribution of malaria cases in Thailand and the type of parasites present, it is generally not recommended to take any preventive actions against malaria alone (mosquito control remains important for other diseases).

Malaria

ZIKA FEVER

Infection risk: Very Low

Symptoms: Fever, joint pain, red eyes, headache, rash

Transmission: Mosquito bite

Effects: Low direct mortality but causes congenital defects

Prevention: Mosquito control

Details:

Zika fever is caused by a flavivirus called the Zika virus, transmitted by some species of mosquitoes (Aedes). The infection causes symptoms similar to dengue fever, with high fever, rash, conjonctivitis, general pain, headache. The fever is relatively inconsequential for most individuals except pregnant women where it can cause multiple problems to the fetus, most notably microcephaly. One out of two live births will have large scale abnormalities.

Prevention:

There is no antiviral treatment for the disease and medical support is mostly to alleviate symptoms. Aspirin and NSAID are not recommended as they can worsen symptoms and infection. Zika fever is one of the diseases where mosquito control (repellent, limitation of breeding sites, screens, insecticides, etc.) is essential has there is no effective medical protection against it and no vaccine is currently available.

In Thailand:

The virus is endemic to Thailand but has not created its own outbreak locally yet. The cause of the 2016 outbreak (which coincide with the American outbreak) is unclear but was of low incidence. When there is no outbreak, the risk of catching Zika fever is fairly low.

Zika Fever

CHIKUNGUNYA

Infection risk: Very Low

Symptoms: Fever, joint pain, eventually headache, general pain, swelling, rash

Transmission: Mosquito bite

Effects: Mortality between 0.1 and 0.5%

Prevention: Mosquito control

Details:

Chikungunya is an infection caused by a virus called the Chikungunya virus (CHIKV), transmitted by some species of mosquitoes (Aedes). The infection causes a sudden high fever followed by joint and muscle pain. Headaches, back pain, nausea, fatigue and skin rash are common. Occasional neurologic disorders can occur.

Prevention:

There is no antiviral treatment for the disease and medical support is mostly to alleviate symptoms. Aspirin and corticosteroids are not recommended as they can worsen symptoms and infection. Chikungunya is one of the diseases where mosquito control (repellent, limitation of breeding sites, screens, insecticides, etc.) is essential has there is no effective medical protection against it and no vaccine is currently available although some are successful in phase II trials.

In Thailand:

The disease has occasional outbreaks in Thailand (2008-2009, 2013, 2018-2019). Between these outbreaks, the risk is quite low.

Chikungunya

ELEPHANTIASIS

Infection risk: Very Low

Symptoms: Severe swelling of arms, legs, breasts and genitals; thickening of the skin

Transmission: Mosquito bite

Effects: Very low mortality but permanent disability for severe cases

Prevention: Mosquito control, deworming

Details:

Elephantiasis, also known as lymphatic filariasis, is a parasitic infection caused by a worm (Wulchereria bancrofti) in Thailand. The parasite is transmitted by some species of mosquitoes (Mansonia). Most infections are asymptomatic but cases who do show symptoms are affected by a blockage of the lymphatic system, leading to edemas and swelling of the lower limbs in particular, but also arms, breasts and genitals.

Elephantiasis is one of the most common cause of disability worldwide with million of new cases annually. Since there are no animal reservoir, there are hopes to eradicate the disease globally.

Prevention:

Prevention and treatment often include mass deworming with medications such as albendazole and ivermectin or diethylcarbamazine. However, for symptomatic cases, it can take years for the disease to subside as adult worms cannot be eliminated. Prevention without evident infection risk is mostly mosquito control (for elephantiasis and other diseases) since no vaccine has been successfully developed for the disease.

In Thailand:

Once common in Thailand, the disease has been officially eradicated since 2017 with no endemic case known for more than a decade.

Elephantiasis

CHOLERA

Infection risk: Low

Symptoms: Extreme diarrhea, dehydration

Transmission: Contaminated unclean water, uncooked food

Effects: High mortality (50-60%)

Prevention: Clean water & sanitation, vaccination

Details:

Cholera infection is caused by the bacteria Vibirio cholerae, transmitted via unsafe water and food (particularly shellfish), often contaminated by human feces. Symptoms range from none to intense watery diarrhea, with occasional vomiting and muscle cramp. It leads to severe dehydration and electrolyte imbalance. Treatment include the administration of fluids & electrolytes and antibiotics and reduces mortality to <1%.

Prevention:

A decent sanitation system and basic hygiene mostly prevent this disease. Avoid drinking unclean water in obviously unsanitary conditions. A vaccine exists for residents and travelllers in regions where cholera is abundant.

In Thailand:

The disease is relatively uncommon in Thailand and with the exception of a peak in cases between 2007 and 2010, the number of annual cases is generally far below 100. It is considered a non-endemic disease in Thailand (Ali et al., 2015) due to good sanitation and easy access to clean water. No vaccination is required.

Cholera

YELLOW FEVER

Infection risk: None

Symptoms: Initial fever, chill, loss of appetite, nausea, muscle pain, headache

Transmission: Mosquito bite

Effects: High mortality (~50%) for severe cases

Prevention: Mosquito control, vaccination

Details:

Yellow Fever infection is caused by a flavivirus called the Yellow Fever virus (DENV) transmitted by some species of mosquitoes (Aedes). The infection causes fever, headache, chill, back pain, nausea, vomiting, loss of apetite, fatigue that lasts a few days. 15% of infections will enter a second severe phase where fever starts again, with jaundice, a sign of liver damage. The disease changes into an hemorrhagic fever with kidney failure and delirium. In these severe cases, the mortality is around 50%.

Prevention:

There is no antiviral treatment for the disease and medical support is mostly to alleviate symptoms. Vaccination exists and is effective. Proof of vaccination is a requirement to enter high-risk country and enter many countries in Asia and Africa when coming from high-risk countries. Because of the administrative nature of the vaccine certificate, Yellow Fever vaccine can only be provided in specific government-approved medical facilities in Thailand.

In Thailand:

Despite having Aedes mosquito species in Thailand (and Tropical Asia), the disease is absent from the continent and can only be caught in Central Africa and Equatorial America. To prevent the spread of the disease, vaccination is a requirement to enter Thailand IF coming from a high-risk country.

Yellow Feve

TYPHOID FEVER

Infection risk: Low

Symptoms: High fever, abdominal pain, headache, vomiting

Transmission: Infected water or food

Effects: High mortality (~20%)

Prevention: Clean water & sanitation, vaccination

Details:

Typhoid Fever is caused by the bacteria Salmonella enteri typhi transmitted via unsafe water and food, contaminated by human feces. Symptoms include progressively high fever, extreme weakness, various abdominal symptoms. After 3 weeks, symptoms worsen into a variety of complications. Medical treatment reduces the mortality below 1%

Prevention:

Good sanitation system and basic hygiene limit the spread of such disease. However, keep in mind to avoid unclean water and food washed with unclean water. A relatively effective vaccine exists and is elective for travellers in region where typhoid fever is common.

In Thailand:

Typhoid fever is relatively uncommon in Thailand with only a handful of cases per 100000 people. The geographic distribution of the disease is unequal; the northwestern provinces (Mae Hon Song, Chiang Mai, Chiang Rai, Lamphun) are the most affected with 10 to 100x more cases than the national average (Techasaensiri et al., 2018). The disease is also very sensitive to epidemics which are often quite localised but can have a large number of cases.

Typhoid Fever

LEPROSY

Infection risk: Very low

Symptoms: Nerve, skin, eye, respiratory track damages, lack of pain

Transmission: Prolonged contact with infected fluids

Effects: Not deadly but permanent disability and surinfection are common

Prevention: Hygiene, preventive medication and vaccination

Details:

Leprosy (also known as Hansen's Disease) is a long-term infection by the bacteria Mycobacterium leprae or lerpomatosis. Incubation can take several years before the first symptoms appear, which are usually skin colour changes and insensitive to pain and heat. Limb deformation occur due to cartilage loss and nerve damage will affect 30% of individuals, potentially leading to paralyses, generalised numbness and more infections.

Leprosy is treated via multi-drugs therapy but advanced damage is not recoverable.

Prevention:

Lack of hygiene and basic sanitation is directly related to leprosy cases. The disease is not very contagious and requires prolonged contact to eventually be infected. The BCG vaccine used for tuberculosis is effective against leprosy.

In Thailand:

The country only sees a few tens of cases of leprosy per year, similar to most western countries.

Leprosy

TICK-BORNE DISEASES

Infection risk: Low

Symptoms: Variable

Transmission: Tick bites

Effects: Variable

Prevention: Repellent, long sleeves, skin check

Details:

Ticks are blood-sucking parasites that will bite mammals and potentially transfer pathogens into their host. A large number of diseases are known to be transmitted by ticks, often with accessory hosts such as wildlife or pets.

Prevention:

Ticks are typically in contact with human during outdoor activities, by direct contact or through a carrier pet such as a dog. Direct contact can be avoided with some repellent and the use of long sleeves clothes. A post-outdoor activity skin check is also efficient at removing ticks.

In Thailand:

The most common pathogens found in Thailand are bacteria that can cause babesiosis, erlichiosis, hepatozoonosis, bartonellosis and typhus through a screening of a large number of dogs (Eamudomkarn, 2017). However, these pathogens are rarely reported in Thailand as causing diseases even if babesiosis seems quite common. Rickettsia infection, also known as Typhus has a few reported cases every year (see references in Eamudomkarn, 2017). There has never been a reported case of borreliosis (Lyme disease) in Thailand and the bacteria Borrelia burgdorgferi is very uncommon (Sthitmatee et al., 2016).

Tick Diseases

LEPTOSPIROSIS

Infection risk: Variable

Symptoms: Headache, muscle pain, fever and many complications

Transmission: Variable (soil, animals, water)

Effects: Mortality of 5%

Prevention: PPE, housing, sanitiation

Details:

Leptospirosis is a blood infection caused by the bacteria Leptospira. Symptoms are often mild with headaches, fever, muscle pain but severe forms show pulmonary hemorrhage, meningitis, kidney failure. Mortality is up to 70% for severe cases. Bacteria infect humans through water and soil contaminated by animal secretions and require frequent exposure to develop into the disease.

Prevention:

The simple use of protective personal equipment such as adequate shoes, gloves prevents most infection. Good sanitation system and proper housing are also factors that limit the spread of the disease. There is no vaccine with high efficacy for humans. Treatment in case of infection is done through several antibiotics.

In Thailand:

Leptrospirosis is a common disease in Thailand, particularly in the north-east. Rice farmers are particularly exposed to it, more especially during the rainy season when contact with contaminated soil and water is increased. Some recreational activities leading to contact with water (kayaking, canoeing, rafting) are potentially at risk.

Leptospirosis

SCHISTOSOMIASIS

Infection risk: Very Low

Symptoms: Abdominal pain, diarrhea, bloody stool and urine

Transmission: Contaminated water

Effects: Mortality from 0.5 to 10%

Prevention: Snail control, sanitation, hygiene

Details:

Schistosomiasis is a parasitic infection of intestine and urinary tract by flatworms. Symptoms are abdominal pain, diarrhea, blood in stools and urine and chronic infection leads to liver damage, kidney failure, bladder cancer, etc. Transmission of the parasite occurs through contaminated water inhabited by a species of snail acting as an intermediary host. The mortality rate is unclear from 0.1% to 10% for severe chronic forms.

Prevention:

Access to clean water and sanitation helps to prevent contamination. Hygiene and awareness of the disease is also helpful to limit the number of cases. Various treatments are available when infected.

In Thailand:

Schistosoma mekongi is the parasite species present in Thailand but seems to be limited to the border around the Mekong river. The hydrographic system of Thailand possibly limit the presence of Neotriuca aperta, the snail intermediary host. As a consequence, there are no reported endemic cases of schistomiasis in Thailand but it is common in Laos and Cambodia.

Schistosomiasis

FOOD-BORNE PARASITES

Infection risk: Variable

Symptoms: Variable

Transmission: Contaminated food, soil

Effects: Variable

Prevention: Clean food, cooking

Details:

Food-borne parasites are tapeworm infections and includes diseases such as Echinococcosis and Cysticercosis/Taeniasis. The former has various symptoms that will affect liver, lungs and brain while the latter has skin-related symptoms, abdominal pain and can affect the brain. Transmission occurs via infected food such as not properly cooked organs, pork, beef or water, soil and various materials contaminated with the parasite eggs.

Prevention:

Treated and/or properly cooked food can eliminate most of the eggs that will develop into tapeworms. Proper sanitation and hygiene also helps in reducing the abundance of eggs present in contaminated sources.

In Thailand:

Taenia saginata, the beef tapeworm, is the most common cestode parasite. Cysticercosis/Taeniasis is apparently quite common in rural areas of the North and Northeast of Thailand but likely considerably under reported (Waikagul et al., 2005). Echinococcosis is present but is possibly rare and not endemic (Morakote et al., 2007)

Food Disease

Q-FEVER

Infection risk: Very low

Symptoms: Flu-like to atypical pneumonia

Transmission: Cattle, Sheeps, Goats & domestic animals

Effects: Chronic Q-fever is fatal

Prevention: Vaccination

Details:

Q-Fever is an uncommon disease caused by the bacteria Coxella burnetti transfered from infected animals such as cattle, sheeps, goats, dogs, cats, etc. The infection leads to a series of symptoms such as fever, malaise, profuse perspiration, headache, muscle & joint pain, loss of appetite, respiratory problems and some gastrointestinal symptoms. Around 50% of infected people are asymptomatic. The disease can progress to an atypical pneumonia, liver enlargement, jaundice and chronic Q-fever leads to endocarditis which is fatal if untreated.

Prevention:

Q-fever is easily treated with antibiotics. A vaccine also exist for people at risk

In Thailand:

The spread of Q-fever in Thailand (and in Asia) is largely understudied. A study in the Chiang Mai province showed that more than 50% of dairy cattle herds are carrier of Coxella burnetti (Rodtian, 2016) and meat cattle range between 70 and 80% in the North and Isaan (Opaschaithat et al., 2018) while buffalos in southern provinces seemed to have lower numbers (Kidsin et al., 2021). Despite these seemingly high numbers, the reported number of Q-fever in humans in Thailand is relatively low and likely undiagnosed (Suputtamongkol et al., 2003).

Q Fever

LEISHMANIASIS

Infection risk: Very low

Symptoms: skin ulcers, mouth & nose ulcers, anemia, liver & spleen issues

Transmission: Sandflies bite

Effects: Mortality between 1 and 2%, scarring

Prevention: Sandfly control

Details:

Leishmaniasis is a disease caused by the trypanosome parasite Leishmania. It is infected to human via some species of sandflies. The infection often causes skin ulcers, sometimes specifically around the mouth and nose that takes months to recover and leave considerable scarring. A type of infection called black fever can cause mild fever, low red blood cell count and damage to the spleen and liver. This later type is often fatal when untreated.

Prevention:

Prevention is done through insect control. Sandflies are sensitive to DEET-based repellent and many insecticides. The use of nets is also an effective prevention when sleeping. However, sandflies being smaller than mosquitoes, the mesh size should be smaller than 0.6mm.

For the black fever type, a recommended treatment is available but cutaneous types treatments have limited effectiveness, particularly in Asia.

In Thailand:

The disease exists in Thailand through an infection with Leishmania siamensis. However, the number of infection is relatively low (Leelayoova et al., 2017) and is more associated with immuno-compromised patients such as HIV-positive individuals. Keep in mind however that the disease is quite common in some countries in the region such as Laos, Nepal or India.

Leishmaniasis

HANTAVIRUS

Infection risk: Very low

Symptoms: high fever, general ache, nausea, skin bleeding, renal dysfunction

Transmission: Contact with rodents (urine, feces, saliva)

Effects: High mortality 10s%

Prevention: Limit contact with rodents

Details:

Hantavirus infection in Asia is the cause of hemorrhagic fever with renal symptoms (HFRS). The disease starts with high fever, chills, headache, backache, abdominal pain, nausea and vomiting; then skin bleeding, associated with low blood pressure and renal dysfunction and eventually death. The mortality rate is highly variable depending on the type of virus.

Prevention:

The main prevention is to avoid excessive contact with bodily secretions of rodents, particularly for people working in rural areas & rodent carers and adequate hygiene. There is no specific cure for HFRS and treatment consists of renal dialysis. Some medication reduces the duration of the illness and mortality rate.

In Thailand:

The country has given its name to a specific hantavirus, called the Thailand Virus (THAIV) and found in bandicoots (Pattamadilok et al., 2006). Thailand also has the Serang Virus (SERV), carried by common rats. The mortality rate of these virus is mostly unknown (Chandy & Mathai, 2017) which underline that overall, it is not a very common disease.

Hantavirus

INFLUENZA

Infection risk: Variable

Symptoms: Fever, runny nose, cough, sore throat, muscle pain, headache, fatigue Transmission: Airborne

Effects: Variable mortality; high impact in some children and elderly

Prevention: Masks, hand hygiene, isolation, vaccination

Details:

Infection by the Influenza virus, causing fever, runny nose, coughing and sore throat, muscle pain, headache, fatigue, etc. Part of the risk associated with influenza is complications due to other infection leading to pneumonia, meningitis, acute respiratory distress syndrome, encephalitis, etc.

Prevention:

Isolation of infected individuals and wearing mask when in close proximity is strongly recommended. Quadrivalent vaccines are suitable for effective protection, as these vaccines uses antigens from different viral strains to obtain the best immune response to the upcoming influenza epidemics. Flu vaccine is recommended for people at risk of severe effects from influenza infection such as the elderly and people potentially in contact with infected groups (i.e. health & education working environments).

In Thailand:

The flu is a worldwide disease. However, because of Thailand's position in the Asian tropics, there isn't much seasonality in the occurrence of the disease in the intertropical zone. While influenza epidemics move from the northern to southern hemisphere following the onset of winter season in temperate countries, it is in South-East Asia that new strains tend to appear, due to its presence all year long and the high density of population. Yearly quadrivalent vaccines generally provide an adequate protection against Influenza.

CHICKENPOX

Infection risk: Very high

Symptoms: Skin rash with blisters, mild fever, tiredness, headache

Transmission: Airborne

Effects: Low mortality (0.02%) but very contagious

Prevention: Isolation, vaccination

Details:

Varicella (also known as chickenpox) is caused by the Varicella Zoster virus (VZV) via airborne transmission through cough and sneezes of infected persons (chickenpox or shingles). Some symptoms appears in adults and adolescents with nausea, headache, loss of appetite, aching muscles, rash and oral sores and low grade fever. Children do not show such early symptoms and directly have a rash that progress into very itchy blisters and pustules followed by the formation of scabs.

Prevention:

Since the disease is highly contagious, individuals with chickenpox or shingles should be isolated. The virus can easily be neutralized by normal cleaning products.

Because of rare complications, Varicella vaccine is routinely administered in many countries but sometimes restricted only to vulnerable individuals as there is some debate if widespread vaccination is beneficial or not at a public health level. Keeping this virus in circulation helps natural immunization of healthy individuals and reduces the occurence of shingles at adult age.

In Thailand:

Chickenpox is present worldwide and most children get infected by a relatively harmless form of the disease or are vaccinated.

SHINGLES

Infection risk: Variable

Symptoms: Skin rash with tingling and local pain, fever, headache, tiredness

Transmission: Varicella virus reactivation

Effects: Very low mortality but painful long-lasting neuralgia

Prevention: Vaccination

Details:

Shingles is caused by a reactivation of the dormant Varicella Zoster virus (VZV) caught with chickenpox. Symptoms start with headache, fever, malaise and eventually progress in more characteristic symptoms such as burning pain, itching and skin rash. Shingles is caused by viruses hidden in ganglions and reactivated and not suppressed by the immune system for unclear reasons.

Prevention:

Shingles can only be prevented or have a reduced severity with shingles or chickenpox vaccines.

In Thailand:

Worldwide, shingles affects a very large number of individuals at least once over their lifetime.

GASTROENTERITIS

Infection risk: Variable

Symptoms: Vomiting, nausea, watery diarrhea

Transmission: Fomites

Effects: Low mortality but very contagious

Prevention: Children hygiene, Vaccination

Details:

Gastroenteritis is caused by the viral infection of Rotavirus A via surfaces contaminated with feces. Symptoms starts with nausea and vomiting and followed by watery diarrhea causing severe dehydration.

Rotavirus infection is present worldwide and most children will be infected before the age of 5. As children are in regular contact with the virus, a natural immunity is created and by the time the individual reached adulthood, rotavirus infection is then mostly asymptomatic. Only a small percentage of infected individuals require hospitalization. However, because of the very high contagiousness, it still represents a large number of patients which mainly explain the widespread vaccination.

Prevention:

The virus is hardly affected by standard cleaning and disinfecting products and very highly contagious. Vaccination is developed to limit the pressure of rotavirus gastroenteritis on hospital systems.

In Thailand:

Gastroenteritis is a worldwide disease. Rotavirus vaccination is recommended but not compulsory in the Thai vaccine schedule.

PNEUMONIA

Infection risk: Variable

Symptoms: Fever, cough, chest pain and breathing difficulties

Transmission: Airborne, fomites

Effects: Mortality up to 5% with 50% hospitalization

Prevention: Vaccination

Details:

Pneumococcal pneumonia is an infection caused by the bacteria Streptococcus pneumoniae. It is the most common type of pneumonia, suddenly starting with severe chills and fever, cough, shortness of breath, chest pains and eventually nausea, vomiting, headache, fatigue and muscle pain.

Bacterial pneumonia is treated with antibiotics but it is not uncommon for the bacteria to be resistant, leading to worsening symptoms.

Prevention:

Vaccination protects against severe streptococcus pneumonia infections and has been added to the standard immunization schedule in many countries.

In Thailand:

Pneumococcal vaccine is not part of the standard immunization schedule in Thailand. The disease remains a burden on the health system, particularly with increasing antibiotic resistance (Gamil et al., 2021)

MEASLES

Infection risk: Low

Symptoms: High fever, cough, runny nose, red eyes, rash

Transmission: Airborne

Effects: Mortality around 1%

Prevention: Isolation, Vaccination

Details:

Measles is caused by the measles virus via airborne transmission through cough and sneezes of infected persons. Symptoms starts with high fever, cough, runny nose and inflamed eyes, followed by red, flat rash spreading from the face to the rest of the body after a few days. Complications are common including diarrhea, otitis, pneumonia and less commonly seizure, blindness, meningitis, etc.

There is no antiviral treatment for the disease but supportive care and treatment of secondary infection improve recovery.

Prevention:

Measles is a worldwide disease only present in humans and very highly contagious. Control is only possible via widespread vaccination.

In Thailand:

Measles in Thailand was relatively under control due to past effective vaccination cover. However, epidemics occured in some regions recently, particularly the southern provinces and occasionally localised areas in Central provinces (Gonwong et al., 2016).

MUMPS

Infection risk: Low

Symptoms: Fever, headache, malaise, pain, loss of appetite, neck swelling

Transmission: Airborne, contact

Effects: Low mortality of 0.02% but complications such as infertility is possible

Prevention: Isolation, Vaccination

Details:

Mumps is is caused by the mumps virus via airborne transmission through droplets and other secretions of infected persons. Symptoms starts with non-specific characteristics such as low-grade fever, headache, muscle pain, loss of appetite, sore throat and eventually shift to parotitis (neck gland swelling), typical of the disease. Orchitis (testicule infection), meningitis and encephalitis are very common complications as well as a series of other less common infections.

There is no antiviral treatment for the disease so supportive care and prevention of complications are the focus of treatments.

Prevention:

Mumps is a worldwide disease only present in humans and highly contagious. Control is only possible via widespread vaccination and isolation of infected cases.

In Thailand:

Mumps in Thailand has registered a very low number of cases in recent years, thanks to effective vaccination cover (Anugulruengkitt et al., 2022).

RUBELLA

Infection risk: Low

Symptoms: Itchy rash, swollen lymph nodes, slight fever, sore throat and fatigue.

Transmission: Airborne

Effects: Very low mortality except for congenital infection

Prevention: Vaccination, immunity testing for pregnant women

Details:

Rubella (or German measles) is caused by the rubella virus via airborne transmission through coughs of infected persons. Symptoms show a mild but itchy rash, swollen lymph nodes, eventually associated with sore throat, fatigue and fever. Complications such as bleeding, testicular swelling, encephalitis exist but are rare. Infection during pregnancy commonly result to miscarriage or congential defects.

There is no antiviral treatment for the disease so supportive care is the main health management

Prevention:

Rubella is a worldwide disease only present in humans and highly contagious. Control is only possible via widespread vaccination.

In Thailand:

Rubella is more common in Thailand than Europe or the Americas but yearly cases remain quite low.

POLIOMYELITIS

Infection risk: Very low

Symptoms: Mild fever and sore throat, headache, stiffness, skin sensitivity, paralysis

Transmission: Fecal-oral and oral-oral

Effects: Low mortality but debilitatiing post-polio syndrome

Prevention: Vaccination

Details:

Poliomyelitis (or Polio) is caused by the poliovirus mostly via contaminated water and food from either feces or direct oral transmission. The disease is mostly asymptomatic for 70% of the population but for the remaining 30%, it will presents itself as a sore throat and low fever. 1% of infected individuals will however show headache, pain, vomiting, lethargy, irritability that can progress into a paralytic disease where post-polio syndrome is a frequent outcome.

There is no antiviral treatment for the disease itself but treatments of symptoms, helping recovery and preventing complications.

Prevention:

Polio is a worldwide disease only present in humans and highly contagious. Since the use of vaccination (1950) and WHO eradication program (1988), wild polio has disappeared from most countries. Control is only possible via widespread vaccination.

In Thailand:

The last endemic case of poliomyelitis was in 1997 and there is almost no risk of being contaminated. Polio vaccine is routinely administered to babies born in Thailand.

DIPHTERIA

Infection risk: Low

Symptoms: Mild fever and sore throat, swollen neck, barking cough, various complications

Transmission: Airborne, fomites

Effects: Mortality from 5 to 20%

Prevention: Vaccination

Details:

Diphteria is caused by the bacteria Corynebacterium diphteriae via coughs and sneezes and eventually contaminated objects. Often asymptomatic or just mild symptoms limited to mild fever, chills, fatigue, cyanosis, sore throat and cough, problematic swallowing and breathing. The later symptoms caused by dead respiratory tissues can limit swallowing and breathing and causing arythmia, myocarditis and nerve palsies which are common complications.

No antibiotic is effective at treating the disease. Severe cases can require intubation and/or tracheotomy and admission in ICU to manage heart failure and various paralyses.

Antitoxin is available to prevent further damage.

Prevention:

Dipheria is a worldwide disease controlled through widespread vaccination

In Thailand:

Diphteria is relatively rare in Thailand with a handful of cases every year, mostly in areas with low vaccine coveage. Diphteria vaccine is on the national immunization program.

TETANUS

Infection risk: Variable

Symptoms: Muscle spasms, fever, sweating, headache, heart issues

Transmission: Puncture or cut skin with contact with soil, dust, manure

Effects: Mortality from 10 to 20%

Prevention: Vaccination

Details:

Tetanus (also known as lockjaw) is caused by the bacteria Clostridium tetani which enters the body through broken skin in contact with contaminated soil, dust, manure, saliva from animal bites. Mild spams are the first symptom, starting in the jaw and eventually spread to the rest of the body, causing breathing problem and tetany. Fever, headache, restlessness, etc. are associated symptoms.

Tetanus is treated with immunoglobulin, antibiotics and benzodiazipines for mild cases; severe cases require intensive care. Despite treatment, the mortality is around 10%. Prognosis is considerably better for individuals with up-to-date immunization.

Prevention:

Tetanus is prevented through vaccination of a toxoid. Natural immunization does no occur with this disease as the immune response required would be deadly.

In Thailand:

Tetanus is more common in warm, wet climate with soil rich in organic matter as found commonly in Thailand. Thanks to the vaccination cover, the disease remain relatively uncommon in the country.

PERTUSSIS

Infection risk: Low risk

Symptoms: Common cold-like, extremely severe cough and consequences

Transmission: Airborne

Effects: Low mortality, up to 1% for newborns

Prevention: Vaccination

Details:

Pertussis (also known as whooping cough) is caused by the bacteria Bordetella pertussis and infect through droplets from coughs and sneezes of infected individuals. Symptoms starts like a common cold, followed by severe cough, causing gasps, vomiting, tiredness and broken ribs. Symptoms are mild for vaccinated individuals.

Pertussis is treated with various antibiotics and full recovery is common with the exception of newborns where severe pertussis has a 0.5% mortality.

Prevention:

Pertussis is a worldwide disease prevented by widespread vaccination.

In Thailand:

Pertussis is not that rare in Thailand among newborns but the vaccination coverage of the adult population make an infection unlikely.

HAEMOPHILUS INFLUENZAE

Infection risk: variable

Symptoms: Respiratory track infection, eye, blood infection, meningitis

Transmission: unclear

Effects: variable

Prevention: Vaccination

Details:

Not a specific disease in itself, it covers all type of infections caused by the bacteria Haemophilus influenzae. It is not related to influenza (flu). For yound children, it causes blood infection, pneumonia, epiglottitis and meningitis and a few less common infections.

Prevention:

Hib vaccine is a routine immunization in most developed countries

In Thailand:

Hib vaccine is part of the routine immunization in Thailand.

HUMAN PAPILLOMAVIRUS

Infection risk: Variable

Symptoms: Warts and lesions on various part of the body

Transmission: variable

Effects: Benign except some strain leading to various cancers

Prevention: Vaccination, early screening

Details:

Human papillomavirus (HPV) is a very common viral infection which show no symptoms or spontaneous resolution in 90% of cases. A large number of strains exists, causing different symptoms such as common & plantar warts but also warts and precancerous lesions in genital, anal and buccal areas. HPV has numerous strains causing minor diseases but a handfull are strongly associated with cancers. These strains are mostly sexually transmitted infections.

Prevention:

HPV vaccination is a relatively recent immunization to prevent the infection of strains known to produce cancerous cells.

In Thailand:

HPV vaccine is uncommon in Thailand.

COVID-19

Infection risk: High

Symptoms: Fever, cough, tiredness, loss of taste & smell

Transmission: airborne

Effects: Mortality >15% (initially), now below 1%

Prevention: Vaccination, mask, isolation

Details:

COVID-19 is a viral disease caused by SARS-CoV-2 virus. Symptoms are quite variable but often include fever, cough, fatigue, breathing difficulties and loss of taste or smell. Around a third of infected individuals will not show noticeable symptoms. The disease is mild for most symptomatic individuals but 20% will show severe symptoms, a quarter of them being critical. Transmission is mostly through airborne particles from coughs, sneeze and breath.

Some antiviral drugs are now available and reduce the risk of severe illness for sensitive groups. Other treatments are supportive.

Prevention:

COVID-19, following the 2020-2022 pandemic, is a worldwide disease that is in the process of receding to a common respiratory disease. Its original impact is related to the complete absence of immunity in the population. As time goes by, people are more regularly exposed to the virus and/or vaccinated and its impact on public health becomes manageable without additional social measures.

Vaccination is available. Its recommendation are changing as the emergency situation will eventually stabilize itself. For the time being, the vaccine is strongly recommended for individuals with complication or exposure risks (elderly & healthcare workers).

In Thailand:

The prevalence of COVID-19 in Thailand is variable. Very high in Bangkok, but very low (comparetively to the rest of the world) along the Laos and northern Myanmar border. Mortality rate is also around half the world average.

Influenza

Chickenpox

Shingles

Gastroenteritis

Pneumonia

Measles

Mumps

Rubella

Polio

Diphteria

Tetanus

Pertussis

HiB

HPV

COVID19