Immunization and prevention of infectious disease while traveling in the tropics are of concern to everyone.

In Singapore, the hygiene standards are high, and there is strict surveillance of infectious diseases. However, when traveling to other destinations within Asia, conditions may be less than optimal. Therefore, the following immunizations for travelers are advisable, in addition to routine childhood requirements.

Polio - For persons who have received a complete series of polio vaccine (either inactivate or oral polio vaccine), an additional single dose of inactivated polio vaccine is advisable for travelers to developing countries, especially for persons 18 years of age and older.

Typhoid - Typhoid vaccination is recommended for travelers visiting developing countries. It is available by injection or oral form (tablets).

Yellow fever - An attenuated live-virus vaccine which is given as a single injection. This vaccination is recommended for travel to certain parts of Africa and South America. Some countries in Africa require a certificate of yellow fever vaccination from all entering travelers; other countries in African, South America and Asia require evidence of vaccination from travelers coming from endemic areas. The vaccination is given as a single dose at registered vaccination centers, which will issue a certificate of vaccination. The vaccination and certificate are good for 10 years.

Hepatitis B vaccine - Several recombinant inactivated viral antigen vaccines (Engerix, H-B-Vax II, and recombivax) are available, and are given in a 3-part series over 6 months. Protection for 13 years years, and possible life. New evidence suggest if a series was started earlier, and not completed, it can still be completed at any time. The immediate benefits of vaccination will be protection from hepatitis B infection, plus long-term potential benefits, such as a marked reduction in the risk of liver cancer.

Hepatitis A vaccine - This vaccine is advisable for susceptible travelers going to areas where hygiene is poor, particularly outside the usual tourist routes. Hepatitis A is contracted by contaminated food and water. Inadequately cooked cockles are a frequent source of infection. Vaqta and Havrix are inactivated-virus vaccines available in a 2-dose series, given 6-12 months apart. Evidence supports protection for 10 years and possibly life. Immune serum globulin (ISG of GG) pooled from human serum provides passive short-term protection from hepatitis A. Given in 3-6 month doses, it is reserved for those going to risk areas on very short notice, and children less than 2 years of age.

Japanese B encephalitis - Vaccination against Japanese B encephalitis, a mosquito borne disease that occurs in rural Asia, is advisable for summer travelers who anticipate spending nights in rural rice growing areas where they will be heavily exposed to mosquitoes. Countries where the disease may be a problem include China, Korea, Taiwan, Thailand, Vietnam, India, Nepal, Sri Lanka and the Philippines. For American travelers, 3 injections given about 1 week apart are recommended. The vaccine is available at several Singapore hospitals, but 2-3 days prior notice may be necessary to procure the vaccine.

Meningococcal disease - Meningococcal vaccine is recommended only for tourists traveling to areas where epidemics are occuring. It is given as a single subcutaneous injection, and will provide protection up to 3 years.

Dengue fever and dengue hemorrhagic fever - Vaccines against dengue fever is currently being developed.

Tetanus and diphtheria - Whether traveling or not, everyone should receive a primary series of immunizations against tetanus and diphtheria and a tetanus diphtheria tozoid booster injection every 10 years.

Cholera - Vaccination against cholera offers limited protection, and is not routinely recommended unless it is a requirement for entry into the country of destination, or if a cholera epidemic is in progress.

Other Precautions
In addition to vaccinations, prevention against infectious diseases in unhygienic regions include avoiding raw or inadequately cooked food or drinking unboiled or unprocessed beverages. Care should also be taken to minimize exposure to mosquitoes and other insects.

The above recommendations for immunizations are meant as general guidelines. It is best to consult with your doctor prior to your trip.