Malaria Protection Varies by Area to Be Visited

A two-week safari in Kenya has taught a 56-year-old Iowa banker and his wife that important precautions should be taken before traveling to parts of the world where malaria is common.

They now know that sub-Sahara Africa is one place for which effective malaria preventives are essential. They also are aware that having a physician with an understanding of tropical medicine can be life saving for people returning from malaria-infected areas with symptoms that can confuse medical experts.

On the flight home, both travelers were nauseous and had muscle pain. The woman developed a fever two days after returning to Iowa. Their regular doctor treated her for dysentery and her husband for the flu.

Two days later, with a temperature of 104, the woman was admitted unconscious to a hospital where an alert lab technician found her blood contained parasites that cause a potentially lethal form of malaria. It required two days of intensive treatment before she regained consciousness and two weeks before she recovered completely. Her husband, who was not as ill, also had malaria and responded well to treatment.

“Both cases are typical of what is happening to travelers who go to malarious areas, especially sub-Sahara Africa, without effective drug prophylaxis and anti-mosquito protection,” said Dr. Hans Lobel, a malaria expert at the U.S. Centers for Disease Control in Atlanta.

An estimated 7 million Americans each year visit countries where malaria is endemic. Of the roughly 1,000 travelers who develop malaria, several hundred are infected with the species of malaria parasite, called falciparum, which is most commonly associated with serious illness and death. Between 1959 and 1987, 68 American travelers died of falciparum malaria, according to CDC records.

The risk run by tourists varies widely depending on their destination and the extent to which they protect themselves from mosquitoes that carry the parasites. Whether travel includes rural areas or is confined to cities also has a strong influence.

A recent CDC study of 1,534 Americans who had acquired falciparum malaria--the type incurred by the banker and his wife--revealed that 80% had visited sub-Sahara Africa, 7% Asia, 7% the Caribbean and South America, and the remainder other parts of the world where malaria exists. Considering that only about 100,000 Americans visit sub-Sahara Africa each year, versus 900,000 to Asia and South America, the danger is obviously great.

The attack rate for sub-Sahara Africa as a whole is 500 cases per 100,000 travelers, but it reaches 1,700 cases per 100,000 in Ivory Coast, Burkina Faso, Ghana, Togo and Benin, a study by a French agency reported.

Travelers to West Africa are more apt to spend time in rural areas where mosquito controls are less in use than in urban areas, while travelers to Asia and South America spend most of their time in cities or resorts where malaria transmission is uncommon, according to the CDC’s Dr. Eve Lachritz. Those who do journey into the countryside are apt to do so during the day, a safer time since mosquitoes carrying the malaria parasite bite only at night.

Falciparum malaria can kill up to 40% of victims who remain untreated or whose treatment is delayed too long. Symptoms can occur as early as eight days after exposure and as late as several months after returning home. Travelers with malaria often are unaware that symptoms may develop long after returning home. Consequently, proper treatment may be delayed because symptoms can easily be mistaken for other illnesses such as the flu. Many physicians in this country have had little or no experience diagnosing malaria and may not think to order the appropriate blood test.

General advice from the CDC for travelers to any malaria-infected area is to take one of the anti-malaria drugs that are appropriate for the region to be visited (there are several types) and reduce contact with mosquitoes by remaining in screened areas. Sleep under a mosquito net impregnated with repellent, and wear clothes that cover most of the body. It also is a good idea to apply insect repellent to exposed skin while outdoors at night. The most effective repellents contain the ingredient known as DEET (the chemical name is N,N diethylmetaoluamide).

No anti-malarial drug can guarantee complete protection, the CDC says. Therefore, using repellents, impregnated bed netting and even clothes that have been sprayed with repellent is advisable in high-risk areas.

Among the preventives, the anti-malarial drug chloroquine could, at one time, have been used prophylactically for travel anywhere in the world. But because of increasing chloroquine resistance by the malaria parasite, it now is considered effective only in Mexico, Central America north of Panama, Haiti, the Dominican Republic and the Mideast, including Egypt. The Iowa couple had been given chloroquine and consequently were incompletely protected for travel to Africa.

For travelers to malaria-infected areas in Africa, Asia, South America, New Guinea and the Pacific Islands, the recommended choice is now mefloquine, a drug approved by the Food and Drug Administration in 1989.

Either chloroquine or mefloquine should be started one week before entry into a malaria area and continued for four weeks after leaving the area. Chloroquine is said to be safe for pregnant women, but mefloquine is not recommended for pregnant women, children who weigh less than 33 pounds, people taking beta-blocker heart drugs and travelers with a history of psychiatric illness or epilepsy.

Although medical sources say all tourists visiting malaria-infected areas should take preventive drugs and follow other precautions, studies have shown that large percentages do not. One survey of 4,042 U.S. citizens returning on direct flights from Africa and from Haiti revealed that only 64% had been advised to take preventive drugs, 33% by a physician and 26% by a travel agent. Only 80% of those so advised did so.

Another study of malaria deaths found that 77% had taken no anti-malarial drug, 13% took chloroquine and traveled to chloroquine-resistant areas, and 11% took dosages of the proper drug, which did not work.

For more detailed information about malaria and drug prophylaxis, call the CDC 24-hour Malaria Hotline: (404) 332-4555.