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Japanese Encephalitis Compiled By : Assoc.Prof. Chukiat Sirivichayakul
Assist.Prof. Achara Asavanich Produced By : Information leaflet committee, Faculty of Tropical Medicine,
Mahidol University and Department of Disease Control, Ministry of Public Health  Japanese encephalitis (JE) virus. Transmission to man is mainly by the mosquito Culex tritaeniorrhynchus, which breeds in rice fields.
Transmission
Pigs are amplifying hosts of this virus. The JE virus multiplies rapidly, resulting in viremia, but the pig remains asymptomatic. When the mosquito vector feeds on an infected pig, the virus multiplies in the mosquito and is transmitted to man or other animals, such as horse, cattle, sheep and bird, through mosquito bite. Endemic areas
This disease was first recognized in Japan. Currently, it is found widely in East Asia, Southeast Asia and South Asia. In Thailand, high incidence is found where rice and pig farms coexist, especially in Mae Hong Son, Mukdahan, Kamphaeng Phet, Samut Sakhon and Nan provinces. Symptoms
Approximately 1 in 300 JE virus infected persons become ill. The incubation period is 5-15 days. The illness starts with high fever, vomitting, headache and weakness. One to seven days later (usually 2-3 days), neurological signs and symptoms, such as stiff neck, drowsiness, delirium, convulsions, unconsciousness, tremor and paralysis may occur for 3-6 days. Those with severe conditions may die at this stage (the mortality rate is 15-30%). Finally, the fever gradually subsides, followed by improved neurological conditions. However, about half of the survivors have severe sequelae, such as spasms, paralysis, convulsions, mental retardation, speech disorders and emotional disturbances. Diagnosis
The disease can be diagnosed by physical examination along with the history of living in or entering endemic areas. Detection of antigens and antibodies to JE virus from serum and spinal fluid are considered the most accurate. Treatment
There is no specific anti-JE drug currently available. Only symptomatic and supportive treatments are provided to prevent the complications that may occur. Prevention
After vaccination was applied in Japan, China and Korea, the number of patients in these countries was reduced dramatically. JE virus vaccine is now available in Thailand. Three subcutaneous injections are recommended. The first and second adminstrations are one week apart, and the third dose is a year later. Self-protection and reduction of man-mosquito contact by application of repellent or the use of a bed-net are advisable. Control of mosquito vectors in rice fields and pig-farming areas may require a major effort, since Thailand is considered an agricultural country. A person who has never received vaccination and plans to enter an endemic area should be vaccinated at least two doses two weeks before entry. Note: Now new JE vaccine (CD-JE vax, SA14-14-2) is available in Thailand. |
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Filariasis Compiled By : Assist. Prof. Narumon Komalamisra
Filariasis Cause and endemic areas Clinical features of bancroftian filariasis are the enlargement of scrotum, arms, or legs. It is prevalent in Western Thailand near the Thai-Myanmar border,ie. Amphoe Sangkhla Buri, Amphoe Thong Pha Phum, Kanchanaburi Province; Amphoe Mae Ramat, Tak Province; Amphoe La-un, Amphoe Mueng, Ranong Province. The mosquito vectors of bancroftian filariasis are the Aedes niveus group, whose breeding places are tree holes and bamboo stumps. At present, another strain of bancroftian filariasis, found in immigrant workers from Myanmar, has been reported in Thailand. This strain can be transmitted by several kinds of mosquito vectors, including Culex sp., which are generally found around houses all over the country.
Symptoms Diagnosis Prevention and control Controlling and reducing mosquito populations either by Those who live in endemic areas should take chemoprophylaxis, such as diethylcarbamazine (DEC) which can be requested from local health offices of the Ministry of Public Health. FAQ (Frequently Asked Questions) About Travelers' diarrhea Complied by: Dr. Watcharapong Piyaphanee
What’s Travelers’ diarrhea? Travelers' diarrhea is the most common illness affecting travelers. Every countries is at risk for travelers' diarrhea. But most cases occur in developing countries of Latin America, Africa, the Middle East, and Asia. In Thailand, prevalence of travelers' diarrhea is much lower nowadays, due to better sanitary conditions.
What causes travelers’ diarrhea? Germ in the unclean food or drink can cause travelers' diarrhea.The most common causative agent is enterotoxigenic Escherichia coli (ETEC). Other pathogens can cause travelers' diarrhea such as campylobacter, salmonella, shigella, vibrio spp., and many kinds of intestinal parasites.
The onset of travelers' diarrhea usually occurs within the first week of travel, but it may occur at any time while traveling. It also can occur shortly after you get home.
Even without treatment, travelers' diarrhea usually subsides with in 2-5 days. Most cases are mind. Some cases may having dehydration, fatique, and high grade fever, mayrequired hospitalization. Whenever possible, you should have your stool checked to find the causative pathogen. Most travelers' diarrhea is treated with appropriate antibiotics and supportive treatment. Oral rehydration is recommended to replace the lost fluid and electrolytes. Hospitalized cases usually require intravenous fluid rehydration.
What about the antimotility drug? Antimotility agents (e.g. loperamide) can reduce diarrhea by slowing the bowel movement. Since diarrhea is the body’s defense mechanism to get rid of the pathogen from the gastrointertinal tract, therefore antimotility agents may reduce the clearance of the pathogen and lead to systemic toxicity in the patient. However, these agents may be useful in reducing diarrhea while traveling. Never use these drug in the patients with fever or mucous-bloody stool. Medical consultation is needed.
Is there any drug can be used to prevent travelers’ diarrhea? Taking antibiotics to prevent diarrhea is not recommended. Routine antimicrobial prophylaxis increases the risk for adverse reactions to the travelers and may increase resistance to the organism.
Where can I seek for medical care if I have diarrhea? All hospital in Thailand can take care travelers' diarrhea. Most patients can be treated as outpatients but some patients may need hospitalization. In our clinic, all patients will be requested to collect their stool to check for the pathogen. You may collect your stool before attending our clinic. Use small plastic container collecting device.
How can I prevent travelers' diarrhea? Travelers' diarrhea is caused by a pathogen in unclean food or drink. Here are some useful tips. - Avoid eating food or drinking beverage from uncertain origin. - Avoid eating raw or undercooked meat and seafood. - Avoid unpasteurized dairy products. - Don't drink tap water. - Bottled water is probably safe, but be sure the cap and seal are not broken. - Bottled carbonated beverages and canned drinks are normally safe. FAQ (Frequently Asked Questions) About Malaria Complied by: Dr. Watcharapong Piyaphanee
This information only applies to Thailand and other Southeast Asian countries, since malaria in different parts of the world may have some specific characteristics. What is malaria? Malaria is an infection caused by protozoa and can be fatal. Four kind of malaria parasites infect human: Plasmodium falciparun, P. vivax, P.ovalae and P.malariae. Recently, malaria in monkey (P. knowlesi) has been reported in human also. Is malaria a common disease? And is there any malaria in Thailand? Yes, WHO estimates 300-500 million cases of malaria occur and more than 1 million die each year. Most case occur in Africa. How is malaria transmitted? Usually, people get malaria from infected female Anopheles mosquito bites. Only specific species of mosquito can transmit malaria. When the infected mosquito bites, it releases the infective stage (sporozoite) into the human bloodstream. It take some time for the parasite to develop and multiply. After that, the person will have the signs and symptoms of malaria Because the malaria is found in human blood, it can also be transmitted by blood transfusion, organ transplantation, sharing needles / syringes contaminated with infected blood. Malaria is not transmitted from person to person like a cold or flu. You cannot get malaria from casual contact with malaria-infected person. What are the signs and symptoms of malaria? The symptoms of malaria include fever, chills, headache, muscle pain, loss of appetite. Nausea, vomiting and diarrhea may also occur. Malaria may cause pallor and jaundice (yellow coloring of the eyes and skin). Infection with P. falciparum, if not promptly treated, may cause kidney failure, seizure, coma and leading to death. How soon will a person feel sick after being bitten by an infected mosquito? For most people, symptoms begin 7 days to 8 weeks after infection. Two kinds of malaria i.e. P.vivax and P.ovalae can remain dormant in the liver for several months up to 4 years.
How do I know if I have malaria? If you become ill with a fever with chill, headache, malaise, nausea and vomiting during or after traveling in malaria risk area, you should seek medical care. You should tell your healthcare provider that you have been traveling in the malaria risk area. The common diagnostic test is blood exam for malaria parasite. What is the treatment of malaria? Malaria is a treatable disease treatment should be done early. The type of drugs and length of treatment depend on which kind of malaria is diagnosed, how severe it is and other factors in each patient. How to protect yourself ? If you are traveling into the malaria risk area, the best prevention method is to protect yourself against mosquito bite. Here are some useful tips: - Always sleep under a bed net (preferably a permethrin - impregnated one )
- Use mosquito repellents, ask for “ Yah tah gahn young “ (ยากันยุง ) which is Thai for “ mosquito repellent ”.
- Repellents are available as chemical such as DEET, or natural products e.g. Tropmed herbal Repellent cream, which is DEET – free repellent.
What is the recommended antimalarial prophylactic drug in Thailand? Chemoprophylaxis is NOT recommended in Thailand. Where malaria is multi – drug resistant. No anti – malaria drugs can fully protect you against malaria. Moreover, you may have unpleasant side effect from the drug. Counseling with a qualified medical doctor is highly recommended . Dengue Hemorrhagic Fever Compiled By : Assoc.Prof. Chukiat Sirivichayakul Produced By : Information leaflet committee, Faculty of Tropical Medicine,
The causative agent of denfue hemorrhagic fever (DHF) is dengue virus, of which there are 4 serotypes. When a person is infected with dengue virus for the first time, clinical signs and symptoms are usually mild. However, if he/she is reinfected with a different type of dengue virus, severe conditions such as bleeding or shock will occur and can be fatal. This disease is usually found in children less than 15 years of age. Transmission
Aedes aegypti is the main mosquito vector that transmits the dengue virus from person to person. When a female A. aegypti feeds on a dengue virus infected person, the viruses multiply in the insect body and remain there for the whole life span of the mosquito, approximately 1-2 months. Viruses are then transferred to another person being bitten by an infected mosquito. A. aegypti can be found both inside and outside houses. They prefer to feed during the day. Their breeding places are containers with clear water, for example, jars, vases, ant traps, dishes, cans, pots, flower pots, tires, etc. The prevalence of DHF increases in the rainy season when the mosquito vectors are abundant and children often stay indoors during the day. However, in big cities such as Bangkok, this disease occurs sporadically all year round. Symptoms
Approximately 80-90% of persons infected with dengue virus for the first time are asymptomatic. Hign fever, headache, muscle and joint pain, and minute bleeding spots under skin may be found in some cases. A second infection with a different type of dengue virus, however, causes more severe conditions, which can be divided into 3 phases : 1. Initial febrile phase - patients suffer continuous high fever, which may cause febrile convulsion in some children. Other symptoms are anorexia, nausea, vomiting and abdominal pain. Facial flush and hemorrhagic spots over the body, arms and legs are common. This phase usually lasts 2-7 days.
2. State of shock - the fever has subsided at this stage; patients feel drowsy with profuse sweating, cold hands and feet, weak but rapid pulse rate, pain at the right coastal margin, reduced urine output, and easy bleeding such as nose-bleed, vomiting of blood and bloody stool. In severe cases, blood pressure drops drastically resulting in shock and can lead to death. This phase lasts 24-48 hours;
3. Recovery phase - patients' conditions are improved as shown by good appetite, normal blood pressure, strong and slow pulse, and normal urine output. Bleeding spots under skin are still present over the body in some cases. .jpg) Diagnosis
Standard criteria of the World Health Organization for the diagnosis of DHF are high fever, easy bleeding (positive tourniquet test, bruises, nose-bleed, gum bleeding, etc.), abdominal pain at the right costal margin because of the enlargement of the liver, shock, decreased platelets, and hemoconcentration. Serological and/or virological investigations may be performed to confirm the diagnosis .jpg) Treatment
There is no specific antiviral treatment. Symptomatic and supportive measures are most important. To lower the temperature during the febrile phase, acetaminophen should be given. Aspirin must not be used since it is known to cause bleeding. An antiemetic can also be given to prevent nausea and vomiting. Juice or oral rehydration solution in small amounts given frequently are helpful. Close observation for early signs of shock is necessary. The critical period is at the transition from the febrile to the afebrile phase. Parents should be advised about the warning signs of shock, such as, reduced urination, restlessness or drowsiness, coldness of extremities, or fainting. If these symptoms occur, the patient should be hospitalized immediately. Prevention 1.Preventing children/adults from being bitten by a mosquito vector; using a bed-net, even during the day, is advisable. 2.Eliminating breeding places of mosquito vectors inside and around houses
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