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Mosquito Related Illnesses

Mosquito bites are a nuisance anywhere. Anyone who lives in the tropics, however, should become familiar with mosquito borne diseases that so far have tended to be located in the tropics.

Thailand is not a particularly mosquito infested country, and tends to be pretty average for a tropic country. Mosquito borne illnesses exist here, but are not a common infliction upon ex-pats, especially in urban areas. Decades ago, things were different, and government eradication efforts are mainly to credit for this turnaround. Nonetheless, there are still occasional reports of an ex-pat or traveller getting a mosquito borne illness, especially near the borders with Cambodia and Burma.

Malaria is very rare in the main population centers, but dengue fever is on the rise and I've known a few expats who have gotten dengue.

Minimizing Mosquito Bites

Things you can do to minimize mosquito bites:

Apply anti-mosquito lotions and sprays
Do not apply perfumes and colognes
At restaurants, request mosquito coils and place them upwind
At home, cover any standing water (such as the urns), deal with any places that hold rainwater, and for any ponds with lotus flowers and the like you should add some small fish that eat mosquito larvae
Get a mosquito net for travelling with
Cover your body with clothes, including socks, even if you wear sandals
It's said that mosquitoes are more attracted to dark colors
At home, use electronic mosquito killers and repellers (but these are of very questionable effectiveness, hence listed last here)

Most mosquitoes are most active around sunrise and sunset, which is why you see a peak in activity around these times, but some mosquitoes are active all times of the day and nite. There are several species active in Thailand.

Most mosquitoes travel along the ground and are fairly energy conserving. People are usually aware of seeing only mosquitoes near eye level or on their arms, but most mosquito bites are on exposed lower extremities. I wear sandals almost all the time, and always wear thick socks, usually dark brown or black, but any color that matches my clothes. I have never been bitten thru a thick sock. If only thin socks are available, then I will put on 2 or 3 pairs, but just 1 thick sock is enough. The problem is that thick socks normal in ordinary stores in northern countries are hard to find in Thailand, except at some sporting shops that attend to mountain hikers, so I stock up on socks whenever I travel to a northern country.

I advise a lot of people this way, but most people choose to ignore it, so when they complain about bites or mosquitoes around their legs or keep slapping at them, I just remind them that I can lead a horse to water but I can't make it drink. (Socks also protect your feet and keep them clean against anything else down on the ground.)

Dengue Fever

The disease "dengue fever" is carried by a particular species of mosquito, the Aedes aegypti mosquito. It is on the rise to becoming one of the top public health problems in the tropics.

The mosquito which carries this virus is most common in urban areas around human dwellings, and is most active during the daytime. The Aedes mosquito breeds in clear water.

Symptoms usually start to appear between 5 and 7 days after being bitten. The symptoms include severe headaches, high fever which may fluctuate, bone aches (hence the slang name), joint and muscle pains, nausea and vomiting, and a rash of small red spots a few days after the onset of fever.

Dengue fever is a very serious illness, and you should go to a good doctor immediately for treatment. It can become fatal if the symptoms are allowed to progress over time to DHF (Dengue Hemorrhagic Fever), which is characterized by heavy bleeding, though DHF is thought to affect mainly longterm residents who have picked up more than one strain of the virus. Aspirin should be avoided, because aspirin reduces blood clotting and thus makes hemorrage more likely.

There is no vaccine against dengue fever, and no specific treatment. You'll have to follow the doctor's orders. Dengue fever is often mistaken for malaria, the flu (influenza) or something else. Malaria can be excluded by a blood test, and the indication of dengue can be inferred by a blood test. Recovery will take time, with tiredness sometimes lasting several weeks.

There are actually several types of dengue fever (currently listed as four), and it's also known as breakbone fever. In Thailand, the dengue type has shifted from predominantly "breed one" to majority "breed two" as of early 2008.

Research revealed that the Aedes aegypti mosquito that carries dengue does not travel far from its breeding place, unlike other species of mosquito, which explains why dengue outbreaks tend to occur in localized areas of a few hundred meters radius. It is believed that dengue spread by infected human migrant workers more than migrant mosquitoes. Therefore, when an outbreak can be determined in a particular location, the authorities may come and spray. However, given that urban dwellers tend to travel around the city and symptoms start around 5 to 7 days later, it's not always clear where the infection occured. Nonetheless, if someone living near you gets dengue, and especially if another person living near you also gets dengue, then maybe it's time for a vacation. However, rarely have two people of the same family gotten dengue, so don't impulsively run like it's the plague.

It is projected that in 2008, there will be around 25,000 to 30,000 reported cases in Thailand. If we set it at 35,000 out of a population of 70 million, that would mean about 1 in 2000 people will be infected. (It's fairly similar to HIV / AIDS statistics.)

At these rates, if you live here for 20 years then you run a 1% chance of getting an infection over those 20 years. However, that assumes you are like the vast majority of people in Thailand in that you don't take any precautions. If you want to reduce your chances substantially, then follow the recommendations near the top of this page.

Malaria

The mosquitoes that transmit malaria are found in remote areas, not any of the major cities. These mosquitoes generally bite around sunset and sunrise. Malaria transmitting mosquitoes are usually found near the Cambodian border (especially near the seaside) and the Burma border.

Symptoms of malaria include: sudden high fever and chills, muscle aches and headaches. They usually show up after an incubation time of 7 to 30 days.

To be properly diagnosed with malaria, you must undergo a blood smear examination, which all major hospitals and many clinics can (and of course should) administer. There are drug-resistant strains of malaria, and it's important to tell the doctor where you've been because the particular drug resistance varies by region.

Japanese Encephalitis

Japanese Encephalitis is a very serious disease spread by ticks and mosquitoes, and of concern in northern and central Thailand. It's rare in humans, but known. Though most travel guides don't even mention it (e.g., Lonely Planet), many people recommend that expats living in northern Thailand get the immunization shots for Japanese Encephalitis.

> Health > Mosquito Related, Dengue

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