Most of the several million Americans who travel to malaria-plagued countries come home healthy thanks to swallowing protective drugs during the trip.
But the number sickened each year because they didn't take those pills has risen by a few hundred since the mid-1990s. Even as tourism in developing countries grows, too many travelers don't know to take anti-malaria medicines — or skip them from worry about side effects, such as rare psychiatric symptoms linked to Lariam, the most-prescribed drug.
Now doctors are looking to a meeting of the world's malaria experts in January to settle just which medication is the best choice for different people heading on vacations, military duty or other trips to malaria-ridden countries.
Don't expect a simple answer.
The malaria parasite has developed resistance to that old standby drug, chloroquine, in most of the world, rendering it largely useless. That leaves most travelers three options: Lariam, a newer and possibly safer drug called Malarone, and the antibiotic doxycycline.
Each has pros and cons that make declaring a No. 1 choice for everybody all but impossible, cautions Dr. Bradley Connor, a New York travel-medicine specialist.
"Your one-week business traveler vs. your teenage backpacker across Africa have very different risks," agreed Dr. Kevin Kain, director of the University of Toronto's Center for Travel and Tropical Medicine.
All three drugs "work well if you take them," Kain said. Customizing the prescription to each patient's health and destination can limit side effects, ensuring travelers don't abandon their pills.
For example, Lariam isn't supposed to be used by anyone with depression, a history of other psychiatric disorders, or epilepsy. Also, it's losing effectiveness in parts of Thailand, Cambodia and Myanmar. On the other hand, Lariam is the only once-a-week pill; the others require remembering a daily dose.
But the backpacker spending three months amid malaria-carrying mosquitoes may want the cheapest option, doxycycline. The busy executive may prefer Malarone because treatment ends one week after returning home; the other two drugs must be taken for a month after returning to kill any still-lurking malaria.
Adding to the complex decision, the Food and Drug Administration recently took two steps that may influence prescriptions:
The FDA strengthened warnings that Lariam may cause psychiatric side effects ranging from anxiety and dreams to hallucinations, depression, occasionally even psychotic behavior. Those risks have long been known, but the updated warnings stress that people with active or recent depression and other risk factors shouldn't take Lariam.
However, the FDA cautions that the drug's alleged link to suicide has not been proven, and calls Lariam an important option. Travel-medicine specialists estimate serious side effects occur in one in 10,000 to one in 15,000 Lariam users.
Separately, the FDA added to competitor Malarone's label results of a new study of 1,000 travelers that favorably compared Malarone to Lariam. The drugs appeared equally effective, but 5 percent of Lariam users had side effects bothersome enough to stop the drug, compared with 1.2 percent of Malarone users, says Kain. The Toronto physician headed the study funded by Malarone maker GlaxoSmithKline. The side effects were bothersome but not serious.
Malarone isn't risk-free — people with serious kidney damage can't use it — and after just two years of sales, it doesn't have Lariam's 17-year track record. Likewise, doxycycline's side effects include nausea, heartburn, sunburn and, for women, yeast infections.
Those advantages and disadvantages are the reason the Centers for Disease Control and Prevention wants to debate the matter at its January meeting, before it updates the government's official health advice for travelers.
Meanwhile, specialists advise people heading for developing countries to consult a travel clinic or other doctor with specific expertise in the destination; a regular doctor might not know they need anti-malaria pills, much less which one. Give the clinic a complete history of medical or psychiatric problems.
"It's not in any of our interests to make people sick with malaria drugs. What we're trying to do is stop people from coming back in body bags from their holiday," Kain said.