Malaria and the Traveling Diver

Undercurrent has reported before on malaria and problems with Lariam, the most widely used malaria prophylaxis. Most problems concern the drug’s neuropsychiatric side effects, but now Undercurrent reader, Dr. Jose Miguel Duran, has written us with a different Lariam tale.

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Dear Ben,

“My wife and I were diving in Irian Jaya for two weeks last year. Like we have done before in other tropical destinations, we took Lariam (mefloquine) for two weeks before our trip, during the trip, and for four weeks afterwards. We also used lots of one hundred percent DEET.

“Two months after our return I fell ill with 104-105° F fever, severe chills, muscle and joint pains, and severe weakness. After three days I thought it could be malaria (symptoms worsened every forty-eight hours) and, indeed, one of my infectious diseases colleagues confirmed Plasmodium falciparum malaria.

“I took two weeks of quinine and doxycycline and felt well, although quite weak, until, to my surprise, I had another attack three months later. This time I had a different parasite: Plasmodium vivax.

“Double infections are quite rare; either I was bitten by two mosquitoes or a very promiscuous one. For now I am well again, at least until the next time, as my colleague encouragingly puts it. The moral is: by all means use mosquito precautions, repellants, and take a prophylaxis as recommended by the Centers for Disease Control (www.cdc.gov) or your doctor when traveling to a malaria endemic region (the whole world except USA, Canada and Europe, according to the WHO map). Keep a high index of suspicion and have your physician rule out malaria if you come up with an acute febrile illness even months after your return from one of those regions. I know of two other patients with P. vivax malaria (acquired in Kenya and India) who went undiagnosed for seven to eighteen months while they were checked and unsuccessfully treated for everything from Lyme disease to typhus.”

Malaria kills three million people each year, including one child every thirty seconds. The tropical disease is caused by the parasite Plasmodium, spread through the bite of an infected female mosquito. Victims may suffer feverish attacks, flu-like symptoms, fatigue, diarrhea, and/or a whole range of other symptoms that may not appear for many months after the parasite enters one’s blood stream.

Traveling divers need to know where it appears and what to do about it. The U.S. Centers for Disease Control and Prevention (CDC) recommends malariafighting drugs for Americans traveling to all or parts of many diving venues: Belize, Costa Rica, Honduras, Mexico, Venezuela, the Dominican Republic, Papua New Guinea, the Solomon Islands, Vanuatu, Indonesia, Malaysia, the Philippines, and Egypt. CDC’s recommendations are updated frequently, so it’s best to check their Web site (www.cdc.gov) when planning a trip to any tropical destination.

Lariam (mefloquine) is often prescribed for high- risk regions where mosquitoes are resistant to chloroquine, the drug long used as the primary weapon against malarial parasites. It’s been known to produce neuropsychiatric side effects ranging from confusion, dizziness, and problems with vision, to anxiety, insomnia, nightmares, panic attacks, delirium, hallucinations, and even suicidal behavior. Physical side effects can also include peripheral numbness and tingling — mimicking the symptoms of decompression sickness, according to Joel Dovenbarger, vice president of medical services for Divers Alert Network. He points out that no one knows who will have adverse reactions to the drug until they occur.

The Consumers Union has reported the case of an American woman who spent a month in a psychiatric hospital following a bad Lariam trip in Kenya. The U.S. Army is studying the possibility that Lariam may be linked to the recent series of domestic killings and suicides at Fort Bragg, N.C. UPI reports that three of the four soldiers involved in the killings had been given Lariam in Afghanistan. According to the Wall Street Journal, Hoffmann-La Roche, manufacturer of Lariam, is sending notices to health care professionals warning that some people have committed suicide after taking it.

So, divers ought to avoid Lariam and select CDC-recommended alternatives, depending on location. The newest, Malarone, has been found to have fewer adverse effects than Lariam or chloroquine, according to the U.S. Food and Drug Administration.

More help may be on the way. Researchers have had some encouraging results with a vaccine made from the milk of genetically engineered mice, which prevents monkeys from developing malaria. The genetic manipulation technique has allowed goats to produce the malaria vaccine in their milk. Scientists believe that the same vaccine, massproduced in goats’ milk, could protect millions from malaria.

Scientists at North Carolina State University have patented a compound from tomatoes that could be a safer and more effective mosquito repellant than DEET, the chemical in many commercial insect repellents. A product containing the extract will be on the market by the end of the year. Lab experiments at Iowa State University also suggest that the oil in the catnip plant is ten times more effective at repelling mosqui-toes than DEET. Catnip has yet to be tested on humans, but it’s unlikely that it would be harmful in repellent sprays or creams. Researchers also believe it would only work at short range, like DEET, but it still might be unwise to wear it while while hiking in the Belize Jaguar Preserve.

— Ben Davision