You need to discuss this with a travel med or tropical med doc.

JE is not a common disease; it is carried by a small minority of the mosquitos in JE areas (rural farming areas with ducks and pigs in close proximity). The chances one might get bitten by a mosquito that carries JE goes up the longer you are in a risk area. In making public health recommendations, the risks of disease must be weighted against the risks of the vaccine. The cdc, which is pretty conservative, only recommends it for adults who will be in a risk area for 6 weeks or more. Personally, I would follow the cdc recommendations unless there is some specific risk the child has (e.g., chronic disease, immune dysfunction) that would change the risk/benefit ration.

The important ways reduce mosquito bites include the use of a good, deet-containing repellant. The best are the micro-encapsulated types, such as those made by Sawyers. Get one in the 20-30% deet range; use insectiside-impregnated bednets; wear long sleeves and long pants outside in the dawn/dusk times.

If your friend doesn't feel that those precautions are enough for her son, I'd suggest she re-consider whether to take him along. There is no way to eliminate risk.

mdtravelhealth.com correct JEVax info seasonally in a few areas it is indicated mostly though ususally not. istm.org
good travel MD cutteradvanced.com and insect preventon works
best in most areas for most kids risksare season and low.

The risk of Japanese encephalitis for most travelers appears to be very small. From 1992 to 2008, only four cases were reported in U.S. residents. All were Asian immigrants or family members who traveled to Asia to live or to visit friends or relatives and who had not been vaccinated against the disease (see MMWR). From 1973 to 1992, only 11 cases of Japanese encephalitis were reported in U.S. residents, only five of whom were civilians

Sorry, but as a parent, I strongly feel that this is the not the place to do medical research. Please tell your friend to seek advice from her pediatrician and travel doc, not from strangers on the internet.

When I asked my doctor why the risk is greater over time (after all, one bite on your first day is all it takes) he said part of the equeation is that if you are there for a short time, you are more likely to be careful about applying your repellant.

to clarify -- my friend did check with her doctor, i'm not doing medical research here. i mainly was interested in whether people had experience with getting the vax in Thailand which was suggested by her doctor. i worded my original post in such a way that that was not clear.

As "qwovadis" points out, most "travelers" don't have much of a risk. So, most on travel boards won't have much personal insight. As you pointed out, you're not doing the typical "travel" experience. Your mileage can definitely vary!

Assuming you are entering Thailand through Bangkok, you could easily stop by Bumrungrad, BNH or Sametivej, and get their input into the boy's situation.

Thanks Curt.

Leslie, Sorry for the misunderstanding. Decisions like these are complicated and I'm just a firm believer that parents should to speak to medical people they trust, then weigh the pros and cons for themselves. You've probably seen this, but here is a current CDC statement, which includes info about why they continued the JE pediatric vaccine in the U.S., number of cases in U.S. kids, statistics about side effects and options for getting the vaccine in Asia: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6020a6.htm