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.
DISEASES TRANSMITTED BY INSECTS
DISEASES TRANSMITTED THROUGH
FOOD AND WATER
DISEASES TRANSMITTED THROUGH
INTIMATE CONTACT
OTHER DISEASES
SUMMARY OF RECOMMENDATIONS
FOR EAST ASIA
COUNTRIES IN REGION
China, Hong Kong, Japan, Democratic People's Republic of Korea
(North), Republic of Korea (South), Macao, Mongolia, Taiwan.
GENERAL PRECAUTIONS
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.
DISEASES TRANSMITTED BY INSECTS
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.
MALARIA
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.
DENGUE FEVER
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.
JAPANESE ENCEPHALITIS
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
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.
OTHER INSECT DISEASES
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).
PREVENTING INSECT BITES
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.
DISEASES TRANSMITTED THROUGH FOOD AND WATER
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).
TYPHOID FEVER
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.
CHOLERA
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.
HEPATITIS A
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.
PARASITES
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.
DISEASES TRANSMITTED THROUGH INTIMATE CONTACT
AIDS / HIV
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.
HEPATITIS B
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.
OTHER DISEASES
SCHISTOSOMIASIS
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.
RABIES
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