To Westerners, malaria may seem like an archaic disease, but every year it affects as many as 500 million people across the globe. A child dies of malaria every 30 seconds. And an estimated 30,000 travelers annually bring this unwelcome souvenir back from a trip abroad.
Malaria is caused by the parasite plasmodium, which is transmitted by infected female Anopheles mosquitoes. After entering the human body, the parasite migrates to the liver, where it usually multiplies for a week or two before invading red blood cells and causing symptoms such as headache, fever, nausea, and vomiting. If left untreated, malaria can turn fatal by disrupting the blood supply to vital organs.
Travelers are often lulled into thinking that malaria isn’t a concern in urban areas. While there’s little risk in Latin American or Southeast Asian cities, malaria is common in cities across sub-Saharan Africa. There’s less danger if you visit an infected area during daylight hours, since mosquitoes feed mostly at night—though some of them may not get that memo.
No drug guarantees protection, and there’s no consensus about an optimal regime. Antimalaria drugs don’t actually prevent infection—they inhibit the parasites from multiplying in either the liver or the bloodstream. “There are five different parasites,” says Stuart Rose, M.D., president of Travel Medicine in Northampton, Massachusetts. “And two of them can set up shop in your liver and hang out there, out of reach of drugs used to halt the spread of malaria in your blood.” Only one drug will eradicate those parasites, and that’s primaquine, which must be taken with whatever antimalarial you used while traveling.
There are four malarial-prevention drugs that are approved in the United States, and most of them came about because governments needed to protect their military forces around the world, says Alan Magill, M.D., director of experimental therapeutics at the Walter Reed Army Institute of Research. The drug of choice used to be mefloquine, which was developed at Walter Reed during the Vietnam War. But it had to be used for two weeks before travel and a month afterward. Even worse, about a third of those who took it reported side effects ranging from stomach problems to bad dreams and suicidal depression. A newer medication called Malarone, which is a combination of the drugs atovaquone and proguanil, is taken for a shorter period—generally a day before travel and one week after—and is tolerated much more easily, but it has to be taken every day.
Most experts advise supplementing any drug regime with precautions for skin and clothing, and the CDC recommends four types of insect repellents. The industry standard is DEET, which was developed by the U.S. army in 1946. A repellent with 35 percent DEET protects for four to six hours, and there’s little added benefit from concentrations above 50 percent. (The American Academy of Pediatrics recommends 30 percent DEET for children down to the age of two months.) Also on the CDC’s list of repellents are the chemicals picaridin and IR3535, a synthetic used in Avon’s Skin So Soft. For those who prefer natural products, lemon eucalyptus oil is also on the list.
Another option is to wear protective clothing sprayed with permethrin, a chemical that paralyzes a mosquito’s nervous system. “When I check into my hotel,” says Magill, “I make sure the window screens are functioning, then shake the curtains and spray them with permethrin before going to dinner. And I wear long pants, socks, and shoes—no shorts or flip-flops.”
You’ll notice “quine” in the name of many antimalarial medications, and you may think of quinine, the main antimalarial from the 17th century to the 1940s. It was discovered by the Quechua Indians of Peru, who ground the bark of cinchona trees and mixed it with sweetened water to offset the bitter taste, thus producing tonic water. In colonial India, the British mixed their medicinal quinine tonic with gin to make it more palatable. But don’t get too excited about staving off malaria with a few stiff cocktails. The quinine content of tonic water is a small fraction of the medical dosages used in treatments. “If you’re lying on your malarial bed,” says Rose, “go ahead and make your last drink a G and T—and make it a double.”
While malaria might seem like a relic of the colonial era, up to half a billion people get infected every year, including some 30,000 travelers.
Quinine is still used to treat malaria, but a gin and tonic won’t do much good, as tonic water contains a medically insignificant amount of the substance.