Japanese Encephalitis hits Asia hard


Heavy rains poured down upon most of the tropics this past year; we saw numerous hurricanes in the Caribbean while Asia suffered heavy monsoons and cyclones. There has been much human suffering as a result.

During the rainy season, and for many weeks after, standing water serves as the perfect environment for mosquito larvae. As you would expect, this season there has been an explosion in the mosquito population. With increasing numbers of mosquitoes, we typically see increases in many different diseases.

This season has been notable for a surge in the number of cases of Japanese Encephalitis. Japanese encephalitis virus (JEV) is the main cause of brain infection and inflammation in Asia. This disease is normally thought of as a rural disease, as ecologically it needs animals like pigs to serve as reservoirs. However, in Asia the distinction between rural and urban is often blurred and many cities have patches of agriculture and livestock.

This summer a Belgian girl on a 2-week trip with her family to Shanghai contracted the virus and died. She never left the city, which is among the most urbanized and populous metropolitan areas on the planet.

Larger numbers of infected people have been seen not only in East Asia and Southeast Asia (Indochina) but also in India. For the past several months, an epidemic has been burning in the center of India, primarily in the state of Uttar Pradesh. There have been over 4,000 cases, but the numbers of new cases have begun to ease off.

The disease is spread by a night-biting mosquito, but not the same night biter that causes malaria. When the virus makes its way to the central nervous system, it can cause a whole range of symptoms, from headache, memory problems and coordination difficulty to seizures, coma and death in approximately a third of those with clinical illness.

While this is a serious disease, it is remarkably easy to avoid. The two measures which should put any traveler to Asia at ease are immunization and personal protective measures.

The Japanese Encephalitis vaccine has a standard 3-dose regimen given over 21 to 28 days and is very effective in protecting against the disease. If you plan to travel to Asia, ideally you should begin the series at least four weeks before departure and get all three doses for maximal protection.

Personal protective measures are the standard individual methods of preventing mosquito bites. These consist of having appropriate clothing, wearing DEET-based mosquito repellents in a 20%-50% concentration on exposed skin (but never on mucous membranes such as eyes, nostrils or lips), spraying clothing with permethrin (which lasts several weeks after just a single application), sleeping in an air-conditioned room or under a mosquito net at night, not wearing perfumes or colognes, and using mosquito coils as needed.

This outbreak highlights the importance of seeking professional and expert help before travel. A travel medicine specialist will know about any disease outbreaks around the globe plus what precautions to take and which vaccines to recommend, whether you are traveling on business or for pleasure, adventure or study or on a mission. You can find a list of such specialists on the worldwide Web at two places: www.istm.org and www.astmh.org.

With sensible immunizations and proper education, you will be healthier and safer.

Healthy travels!

—Travel & Health is written by Alan M. Spira, M.D., DTM&H, FRSTM