This is another most common question in our Travel Clinic. People who ask this question usually have good knowledge about Japanese encephalitis and its risk. Many of them have already consulted their travel doctor and many of them have done a good research on Internet. Despite that, many of them still doubt and have some questions like; “Do I really need a JE vaccine?” or “Should I get a JE shot?”. Yes, as you know, there is no universal recommendation which could apply to all. Several factors need to be explored and discussed.
Before we go into detail and try to answer the above question; let review some useful facts about JE;
1. Japanese encephalitis is a mosquito borne disease which mainly confine in Asia including some part of East Asia, South Asia and Southeast Asia; as shown in this World Health Organization map:
2. Life cycle of JE virus is associated with pig which is an amplifying host. Transmission occur mainly in the rural area especially in area where flooding irrigation is practiced or near the paddy field.
3. Most JE infections in human will lead to no symptom at all. Small percentage of infection will lead to symptoms; severity will be vary from very mild to very severe. Only a minority of case will turn into encephalitis or brain inflammation. Unfortunately, people who do develop encephalitis with JE will be severe; around 25% will die and many of survivors will have permanent neurological deficit.
4. In Thailand and many others in Asia; we give JE vaccine to all children. So the number of JE cases in our country is very low now.
5. In the past we use inactivated mouse-brain derived vaccine which require 3 shots in a series. Its efficacy is high, but its potential side-effect is generally concerned especially when going to use a low risk travelers.
6. Nowadays, there are two new excellent JE vaccines. One is an inactivated vero-cell JE vaccine (Ixiaro®) which is licensed in North America, Australia and in some European countries. It is very safe and effective. The other kind of JE vaccine is lived SA-14-14-2 vaccine (CD JEVAX), which is commonly used in Asia including in our clinic. It is very safe and very effective even after single shot.
Although newer and safer JE vaccines are now available, we DO NOT recommend all travelers to Asia to get JE vaccine. Several factors should be considered such as type of travelers, duration of stay, main area of stay (rural/urban), activities during travel, etc. We have to assess all of these factors, in order to assess the magnitude of risk in any individual. In very low risk travelers, such as a businessman who will attend 3-days meeting in Bangkok, we will not recommend JE vaccine. On the other hand, we will strongly recommend JE vaccine in backpackers who plan to travel in Southeast Asia for 3 months and will spent most of the time in rural area.
So formal pre-travel consultation with your doctors/nurses is strongly recommended.
Read more in part 2: Should I get JE vaccine for traveling in Southeast Asia (2)?
We will discuss about current WHO, US CDC recommendation regarding the use of JE vaccine in travelers and what is our practice in our travel clinic.