Risk for individual travelers to get malaria in Thailand is not the same. Some individual may carry higher risk than the others. Risk to get malaria depends on many factors such as
1. Destination. You have NO risk if you travel only in Bangkok, Pattaya, Samui island, Phuket and the urban area. You may have some risk if you travel in the forested area or in the border area. Please see malaria map in Thailand below;
2. Duration of stay. This factor is straight-forward. The more you stay in the jungle area, the higher risk you carry.
3. Activity during travel. Mosquito that bring malaria usually active in the night time especially in dusk and dawn. Any travelers who have activity during that time carry higher risk than travelers who do not have the outdoor activity at night.
4. Seasonality. There is a seasonal variation of malaria risk in Thailand. The highest risk is in the rainy season.
5. The use of protective clothing, bed net and insect repellents.
6. Others
So according to the above factors, please keep in mind that risk for any travelers are not universally equal. But why could we say that the risk for someone to get malaria in Thailand is very, very low. And how low is the risk? Here are some information;
1. According to the study in United Kingdom reported in 1996. The risk for UK travelers to get malaria in Thailand was 1:12,254.
2. One study in 2005 published in the Emerging Infectious Diseases estimated the risk for travelers to get malaria in Thailand equal to 1:50,000.
3. Our hospital (Hospital for Tropical Diseases) is the main referral hospital in Thailand that take care many malaria cases per year. We found that in the 6 years period (2000-2005), there were only 21 travelers’ malaria in our hospital. Moreover, only 3/21 cases really acquired malaria in Thailand. So it is rare to find a case of traveler that really get malaria in Thailand.
So we might say that the risk for general travelers to get malaria in Thailand is very low. So this is why we do not recommend the use of antimalarial medication in Thailand.
However if you would like to travel outside Thailand, such as Myanmar, Lao PDR, Cambodia. The risk may be higher in Thailand, you should consult with qualified medical staffs in this issue.
References:
1. Hill DR, et al. The Risk of malaria in travellers to Thailand. Trans R Soc Trop Med Hyg 1996; 90:680-1.
2. Asking HH, et al. Malaria risk in travelers. Emerg Infect Dis 2005; 11:436-441.
3. Piyaphanee W, et al. Travelers’ malaria at the hospital for tropical diseases, Bangkok, Thailand. A 6 Year review (2000-2005). KJP 2006; 44(3): 229-232.
