Preventing Turista and Other Travelers' Ailments : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 3)

Physicians may also prescribe other drugs for travelers' diarrhea. These include doxycycline (Vibramycin), diphenoxylate (Lomotil), and the newer quinolone drugs, ciprofloxacin and norfloxacin. However, none of these drugs has been approved by FDA specifically for travelers' diarrhea due to E. coli. Moreover, doxycycline is not approved for children younger than 8, and the two newer quinolone drugs may be dangerous when taken by those under 18.

Perhaps the most widely used anti-diarrheal medications are the over-the-counter drugs bismuth subsalicylate (Pepto Bismol) and loperamide (Imodium). Several scientific studies have been published on the effectiveness of these products in treating travelers' diarrhea. These products are approved for treating diarrhea, and FDA is reviewing their effectiveness for treating travelers' diarrhea as well. Both products treat diarrhea's symptoms rather than killing the bacteria. "This is an infection and you need to get rid of it," Sack says.

Bismuth subsalicylate may take a few hours to work and cannot stop severe diarrhea. Nor should it be used by people taking a lot of aspirin or other blood thinners, pregnant women, or people subject to seizures, says Celia Maxwell, M.D., a medical officer in FDA's anti-infective drug division.

Malaria

If travelers' diarrhea is the disease most likely to strike Americans abroad, malaria is the most serious ailment they are likely to encounter. Once thought to be under control and perhaps even close to eradication, malaria has made a remarkable comeback in the past decade or two, says CDC's Lobel.

Malaria is caused by a single-cell blood parasite called plasmodium. The parasite is usually transmitted to people by the bite of an infected Anopheles mosquito. Symptoms start with a listless feeling, loss of appetite, muscle aches, and a low fever. After a few days, the classic symptoms appear: a fever that can reach 105 degrees Fahrenheit and teeth-rattling chills that can last 20 to 60 minutes. The fever may break and then return again on a 48-to-72-hour cycle, and it may be accompanied by nausea, diarrhea and vomiting.

Worldwide, some 200 million people are estimated to have malaria, Lobel says. Those numbers are guesses, Lobel admits, since reliable figures are hard to come by. In Africa, he says, "most everybody has been infected." In this country, about 1,000 malaria cases a year are reported to CDC, a figure Lobel thinks represents only a third of the true numbers. According to Bruce Burlington, M.D., deputy director of FDA's Office of Drug Evaluation II, people living in Africa come "more or less into equilibrium" with malaria and don't get as sick as travelers who are newly infected.

Malaria is prevalent throughout the tropics, but the traveler's risk of contracting the disease is greatest in Africa and the island of Papua New Guinea in the Pacific near Australia. It is common but less of a risk in India and southeastern Asia, central and northeastern South America, and in Haiti. It is less prevalent in China and the Middle East. Even in high-risk regions, he adds, the chances of getting malaria are much greater in rural areas than in cities.

The reasons for malaria's comeback are a familiar refrain nowadays. The mosquitoes that transmit the disease now resist what had been the most effective pesticides, and many of the parasites themselves now resist what had been the most effective drug used to prevent and treat the disease.

Actually, malaria is four diseases caused by four different species of the plasmodium organism. In particular, the form known as falciparum now widely resists chloroquine (Aralen), the drug developed in the 1940s to prevent and treat malaria. Often called "malignant malaria" or "black-water fever," falciparum is the most serious form of the disease and the one most likely to kill its victims. Resistance began to appear in the 1960s and is widespread in most places falciparum malaria is found today.

Fortunately, malaria can still be prevented and cured in most cases if diagnosed properly, Lobel says. While chloroquine remains an effective anti-malarial drug in nonresistant areas and for the nonfalciparum forms, mefloquine (Lariam), approved by FDA in 1989, is now also recommended.

Travelers going to chloroquine-resistant areas who cannot take mefloquine — people taking beta blocker drugs for heart conditions or who are subject to seizures, FDA's Maxwell says — can use pyrimethamine/sulfadoxine (Fansidar) or doxycycline. Doxycycline is as effective as mefloquine, Lobel says, but cannot be used for as long a time because of its potential side effects. Doxycycline must also be taken daily rather than weekly as with chloroquine and mefloquine. Fansidar can cause an uncommon but potentially fatal rash as a side effect, so it is generally used only when other drugs aren't appropriate.

Several other drugs are sometimes prescribed for malaria by physicians in other countries. One, proguanil (Paludrine), is widely used in Great Britain and Kenya. Others include pyrimethamine (Daraprim) and pyrimethamine-dapsone (Maloprim). None are as broadly effective as mefloquine or chloroquine, some need to be used with other anti-malarial drugs, and a few have serious side effects. Nor have any been approved by FDA for malaria.

As with travelers' diarrhea, the best treatment for malaria is prevention. Americans are advised to avoid the mosquitoes that transmit the disease. Stay inside at dusk and dawn, wear long pants or long-sleeved shirts when in mosquito-infested areas, sleep in well-screened rooms or under mosquito nets, and use an insect repellant such as DEET (N, N-diethyl-m-tolumide) on exposed skin.

Other Diseases

Most other diseases or medical conditions to which American travelers are likely to be exposed are rare and easily avoided. Schistosomiasis, for example, occurs in much of Africa, the Middle East, northeastern South America, and some Caribbean islands. Also called bilharzia or snail fever, it is caused by a freshwater snail-borne parasite. Schistosomiasis can be prevented by staying out of freshwater lakes and streams in infested areas. Salt water and adequately chlorinated swimming pools are okay, though.

Sleeping sickness is a serious illness that is transmitted by the bite of tsetse flies. It is confined to areas of Africa usually not on most American tourists' itineraries. For travelers visiting such areas the best advice for prevention is to wear long pants and long-sleeved shirts when outside. (See accompanying article for drug treatment.)

About the Author

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