Disease Risks and Precautions
in East Asia

The material provided below is for informational purposes only.
It may not be current, and it should not be considered definitive.

All travelers should check the Center for Disease Control (CDC) website
for the most current disease risk and disease prevention information.



China, Hong Kong, Japan, Democratic People's Republic of Korea (North), Republic of Korea (South), Macao, Mongolia, Taiwan.


Travelers to theEast Asia may be exposed to potential diseases from a number of sources. The most frequently reported illness is traveler's diarrhea, but there are other diseases which are unique to this area or the tropics. The Indian Subcontinent contains a variety of diseases transmitted by insects, contaminated food and water, or close contact with infected people. Specific diseases are discussed under each of these topical headings.

In order to reduce the risk of infection travelers must (1) protect themselves from insects, (2) ensure the quality of their food and drinking water, and (3) be knowledgeable about potential diseases in the region to be visited. Finally, diseases are not restricted to cleanly defined geographical areas, i.e. mosquitoes can fly over city or country borders, therefore, all travelers should protect themselves by taking the basic preventive precautions.


Many diseases are transmitted through the bite of infected insects such as mosquitoes, flies, fleas, ticks, and lice. In general travelers must protect themselves from insect bites by wearing proper clothing, using bednets, applying an insect repellent to exposed skin and clothing, and if possible, avoiding high risk situations, i.e. outdoor activities during night time hours from dusk to dawn when mosquitoes bite, unscreened living accommodations, etc. If a mosquito net is unlikely to be available, consideration should be given to purchasing a portable mosquito net.


Risk: China: Travelers visiting cities and popular rural sites on usual tourist routes are generally not at risk, and taking drugs to prevent malaria is therefore not recommended. Malaria risk is found in rural areas only, except no risk in provinces bordering Mongolia and in the western provinces of Heilungkiang, Kirin, Ningsia Hui Tibet, and Tsinghai. North of 33oN latitude, transmission occurs between July and November; in the region between 33oN and 25oN latitude, transmission occurs from May to December; in the region south of 25oN latitude, transmission occurs year-round.

In Hong Kong, Japan, North Korea, South Korea, Macao, Mongolia, and Taiwan, there is no risk of malaria.

Prevention: Since malaria transmission in China is largely confined to the rural areas not visited by most travelers, taking drugs to prevent malaria is only recommended for travelers who will have outdoor exposure during evening and nighttime hours in rural areas. Travelers to China at risk of malaria should take one of two drugs to prevent malaria transmission. If traveling to rural areas other than those listed below, travelers should take a weekly CHLOROQUINE tablet. The weekly dosage for an adult is 500 mg once a week. This drug should be taken one week before entering a malarious area, weekly while there, and weekly for 4 weeks after leaving the malarious area.

Travelers to southern China, Hainan Island, and provinces bordering Laos, Myanmar (Burma), and Viet Nam should take MEFLOQUINE to prevent malaria. This drug is marketed in the United States under the name Lariam. The adult dosage is 250 mg (one tablet) once a week. MEFLOQUINE should be taken one week before leaving, weekly while in the malarious area, and weekly for 4 weeks after leaving the malarious area.


Risk: Dengue fever occurs in parts of China and Taiwan. The risk of infection is small for most travelers except during periods of epidemic transmission.

Prevention: There is no vaccine for dengue fever therefore the traveler should avoid mosquito bites. These mosquitoes bite mainly in the daytime.


Risk: Transmission is usually seasonal (associated with the rainy season). There is a risk for travelers to rural areas of East Asian countries, especially China, and Korea. Japanese Encephalitis also may occur with a lower frequency in Hong Kong, Japan, Singapore, and Taiwan. In all areas, Japanese Encephalitis is primarily a rural disease. The chance that a traveler to Asia will develop Japanese Encephalitis is probably very small.

Prevention: Vaccination should be considered for persons who plan long-term residence in rural areas Travelers who visit rural farming areas for 3 weeks or more during the transmission season should consider immunization. Travelers who remain unimmunized should wear mosquito repellents, sleep under bednets, and bring insecticidal sprays to use in their sleeping quarters.


Yellow fever is a viral disease found in parts of Africa and South America. It is transmitted to humans by a mosquito bite. Even though there is no risk of becoming infected while traveling in countries in the Indian Subcontinent, a number of these countries REQUIRE a yellow fever vaccination if a traveler is coming from areas in AFRICA and SOUTH AMERICA where yellow fever is found.

If you are ONLY traveling from the United States to an East Asian country, CDC does not recommend, and you are not required to have a yellow fever vaccination. However, if your travel plans include traveling to or from a country in Africa or South America, you may be required to have a yellow fever vaccination.


Risks: Other diseases spread by mosquitoes, sand flies, black flies, or other insects are prevalent, especially in rural areas. These diseases include: Filariasis(mosquito), leishmaniasis (sandfly), Congo-Crimean Hemorrhagic Fever (tick), typhus (lice), and Plague (fleas).


To reduce mosquito bites travelers should remain in well-screened areas, use mosquito nets, and wear clothes that cover most of the body. Travelers should also take insect repellent with them to use on any exposed areas of the skin. The most effective repellent is DEET (N,N-diethyl meta-toluamide) an ingredient in most insect repellents. Travelers should also purchase a flying insect-killing spray to use in living and sleeping areas during the evening and night. For greater protection clothing and bednets can be soaked in or sprayed with PERMETHRIN, which is an insect repellent licensed for use on clothing. If applied according to the directions, permethrin will repel insects from clothing for several weeks.


Food and waterborne diseases are the number one cause of illness to travelers and are very common in the Indian Subcontinent. Traveler's diarrhea is the most frequent health problem for travelers. It can be caused by viruses, bacteria, or parasites which are found universally throughout the region. Transmission is most often through contaminated food or water. Infections cause diarrhea and vomiting (typhoid fever, cholera, and parasites), liver damage (hepatitis), or muscle paralysis (polio).


Risk: Travelers to East Asia are at risk for typhoid fever, especially when traveling to smaller cities, villages, or rural areas.

Prevention: By drinking only bottled or boiled water and eating only thoroughly cooked food, a traveler lowers the risk of infection. Currently available vaccines have been shown to protect 70- 90% of the recipients. Therefore, even vaccinated travelers should be cautious in selecting their food and water. Two available vaccines provide equivalent protection against typhoid fever -- oral and injectable.

Recommendations: CDC recommends a typhoid vaccination for those travelers who are going off the usual tourist itineraries, traveling to smaller cities and rural areas, or staying long term, that is, a traveler for six weeks or more. Typhoid vaccination is not required for international travel.


Risk: Cholera cases have been reported in some areas of East Asia especially China. The risk of infection to the U. S. traveler is low, especially those that are following the usual tourist itineraries and staying in standard accommodations. Travelers should consider the vaccine if they have stomach ulcers, use anti-acid therapy, or if they will be living in less than sanitary conditions in areas of high cholera activity.

Prevention: Travelers to cholera infected areas should follow the standard food and water precautions of eating only thoroughly cooked food, peeling their own fruit, and drinking either boiled water, bottled carbonated water, or bottled carbonated soft drinks. Persons with severe cases respond well to simple fluid and electrolyte-replacement therapy, but medical attention must be sought quickly when cholera is suspected. The available vaccine is only 50% effective in reducing the illness, and is not recommended routinely for travelers.


Risk: Travelers are at high risk for Hepatitis A (except travelers to Japan), if travel plans include visiting rural areas and extensive travel in the countryside, frequent close contact with local persons, or eating in settings of poor sanitation. A study has shown that many cases of travel-related hepatitis A occur in travelers to developing countries with "standard" itineraries, accommodations, and food consumption behaviors.

Prevention: The virus is inactivated by boiling or cooking to 85 degrees centigrade for one minute, therefore eating thoroughly cooked foods and drinking only treated water serve as general precautions. Havrix, the hepatitis A vaccine currently licensed for use in the U.S., or immune globulin (IG) is recommended before travel for persons 2 years of age or older. Hepatitis A vaccine is preferred for persons who plan to travel repeatedly or reside for long periods of time in intermediate or high risk areas. Immune globulin is recommended for travelers < 2 years of age. Immune globulin is recommended for persons of all ages who desire only short term protection.

Recommendations: CDC recommends hepatitis A vaccine or IG for protection against hepatitis A. For travelers over 18 years of age, hepatitis A vaccine should be given in a two dose series with the second dose administered 6-12 months after the first.
Immune globulin should be used for travelers < 2 years of age. Immune globulin is recommended for persons of all ages who desire only short term protection.


Risk: Travelers to East Asia are at risk of parasitic infections. There are many types of parasites and infection may occur in several ways: by eating undercooked meats infected with parasites or their larva; by eating food or drinking water contaminated with parasites or their eggs; by contact with soil or water infected with parasites; or through insect bites. Several types of parasites can penetrate intact skin and travelers are advised to wear shoes.

Prevention: Travelers should eat only thoroughly cooked food, drink safe water, wear shoes, refrain from swimming in fresh water, and avoid contact with insects, particularly mosquitoes, biting flies, gnats, and midges.



Risk: AIDS is found in some parts of the region. In East Asia, the predominant modes of transmission are not fully defined due to the recent spread of HIV into these areas. The risk to a traveler depends on whether the traveler will be involved in sexual or needle-sharing contact with a person who is infected with HIV. Receipt of unscreened blood for transfusion poses a risk for HIV infection.

Prevention: No effective vaccine has been developed for HIV. Travelers should avoid sexual or needle-sharing contact with a person who is infected with HIV. If a blood transfusion is necessary, screened blood should be from an HIV-negative blood donor.

Recommendations: Travelers should avoid activities known to carry risks for infection with HIV.


Risk: The risk of Hepatitis B virus infection is high for East Asia. All countries in the region except Japan, report high levels of infection. The risk to the individual international traveler is determined by the extent of: (1) direct contact with blood or other body fluids, etc.; (2) intimate sexual contact with an infected person; (3) the duration of travel.

Prevention: The primary prevention consists of either vaccination and/or reducing intimate contact with those suspected of being infected. For those travelers expecting to reside in countries of high risk, as well as all health workers, vaccination is strongly recommended. Vaccination should ideally begin 6 months before travel, in order to complete the full series.

Recommendations: CDC recommends vaccination for any of the following people: any health care worker (medical, dental, or laboratory) whose activities might result in blood exposure; any traveler who may have intimate sexual contact with the local population; any long-term (6 months or more)
traveler, e.g. teachers, who will reside in rural areas or have daily physical contact with the local population; or any traveler who is likely to seek either medical, dental, or other treatment in local facilities during their stay. Hepatitis B vaccination is not required for travel to any country.



Risk: Schistosomiasis infection is found in some parts of China, including many rivers and lakes of southeastern and eastern China along the valley of Chang Jiang (Yangtze) river and its tributaries. The risk is a function of the frequency and degree of contact with contaminated fresh water for
bathing, wading, or swimming.

Prevention: The traveler cannot distinguish between infested and non-infested water. Therefore, swimming in fresh water in rural areas should be avoided. Bath water should either be heated to 50 degrees C (122 degrees F) for five minutes or treated with chlorine or iodine as done for drinking water. If exposed, immediate and vigorous towel drying or application of rubbing alcohol to the exposed areas may reduce the risk of infection. Screening procedures are available for those who suspect infection, and schistosomiasis is treatable with drugs.

Recommendations: Avoid contact with potentially contaminated water.


Risk: For some countries in East Asia, there is a risk of rabies infection particularly in rural areas, or in areas where large numbers of dogs are found. No risk in Japan and Taiwan.

Prevention: Do not handle any animals! Any animal bite should receive prompt attention. When wounds are thoroughly cleaned with large amounts of soap and water, the risk of rabies infection is reduced. Exposed individuals should receive prompt medical attention and advice on
post-exposure preventive treatment.

Recommendations: There are no requirements for vaccination, but pre-exposure vaccination is recommended for:

- travelers visiting, for more than 30 days, foreign areas where rabies is known to exist;
- veterinarians and animal handlers;
- spelunkers; and
- certain laboratory workers.

Pre-exposure vaccination does not nullify the need for post exposure vaccine, but reduces the number of injections.

Summary of Recommendations for EAST ASIA

Travelers should (1) take Mefloquine (or equivalent) for malaria prevention, (2) follow precautions to prevent insect bites, (3) pay attention to the quality of their drinking water and food, (4) have a dose of Immune Globulin (IG) or the Hepatitis A vaccine, and (5) consider booster doses of tetanus (Td) and polio (eIPV) vaccines. (6) Depending on the locations to be visited, planned activities, and health of the traveler, the following vaccines should be considered: Hepatitis B, Japanese Encephalitis, Typhoid, Meningococcal, Rabies (pre-exposure), and Cholera. Details for these recommendations are found in this document. (7) Finally, the normal "childhood" vaccines should be up-to-date: Measles, Mumps, Rubella (MMR Vaccine); Diphtheria,Tetanus, Pertussis (DTP Vaccine) [ < 7 years of age]; and Polio vaccine.

Disease risks and precautions