Malaria

sub-Saharan Africa, the Middle East, the Indian subcontinent, South and Southeast Asia, and Oceania. The CDC reports that while major cities in Asia and South America are almost free from malaria, cities in Africa, India and Pakistan are not. There is usually less risk of malaria at altitudes above 4,900 feet (1,500 meters).

The serious health risk of malaria cannot be overemphasized. Preventive measures are essential and include both the avoidance of mosquito bites and the administration of prophylactic medication. The malaria parasite is a protozoan that is transmitted to humans by the bite of an infected female Anopheles mosquito, usually occurring between dusk and dawn.

Symptoms: Fever and flulike symptoms—including headache, muscle aches, chills, fatigue and possibly nausea, vomiting or diarrhea—usually appear within 10 days to four weeks after infection but can occasionally occur sooner or even up to a year later. If left untreated, the disease can become life-threatening.

Treatment: Despite the most stringent preventive measures, it is still possible to contract malaria. The symptoms may not develop until long after your trip, so continue prophylaxis for four weeks following your return home. If you develop flulike symptoms such as chills, fever and headache during a trip to a malarious area or within several months after your last exposure, immediately seek medical attention. It is essential to mention your possible exposure to malaria. The appropriate treatment, usually an antimalaria drug, will depend on several factors, including the severity of your symptoms and the malaria parasite strain causing your disease.

Prevention: Personal protection is the best way to prevent malaria and other insect-transmitted diseases. Stay in well-screened areas when you are indoors, wear clothes that cover most of your body including the feet and ankles when you are outdoors, and use mosquito nets when you are sleeping. You should also use insecticides and repellents on your clothing, tents and nets as well as personal repellents containing at least 30 percent DEET; concentrations above 30 percent, however, do not add significantly to its protective effect or duration. Standard preparations last about four hours, but longer-acting preparations are available. Picaridin is an effective alternative.

The serious health risk of malaria cannot be overemphasized.

Travelers to malarious areas should also take prophylactic prescription drugs. Dosage recommendations may vary depending on the drug susceptibilities of local malaria strains. Most medications used for prophylaxis are safe and well-tolerated, but some severe side effects and toxic reactions may occasionally occur as with any drug. The severity of malaria, however, justifies any temporary mild side effects.

Considerations for divers: The prophylactic antimalarial drug mefloquine (Lariam) occasionally causes side effects that mimic symptoms of decompression sickness. Some countries prohibit diving by individuals taking mefloquine, so ask your physician about possible drug substitutions.

If a diver traveling to an area with a high risk of malaria cannot take any prophylactic antimalarial medication due to side effects, the trip should be canceled. The risk is too high that the diver may contract malaria and even die because of the lack of appropriate prophylaxis.

OTHER CONDITIONS

Amebiasis: The most common symptom of amebiasis is diarrhea, which may become painful and bloody. Caused by the protozoan Entamoeba histolytica that is found in areas with poor sanitary conditions, the disease is transmitted by personto-person contact through the fecal-oral route or by ingesting contaminated food or water. There is no vaccine, making safe food and water practices key to preventing the disease. Obtain treatment from a specialist in infectious diseases or tropical medicine.

Cholera: A bacterial disease, cholera is transmitted through eating food or drinking water contaminated with Vibrio cholerae. Modern sanitation practices have drastically reduced its incidence in most parts of the world. Some countries still require cholera vaccination, but it is not medically justified because travelers rarely develop cholera, even in endemic areas (there are only two cholera cases for every 1 million travelers to endemic