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Malaria prophylaxis depends on destination.

SAN DIEGO -- A very small insect causes more than 1 million deaths each year, and in some countries, ranks second only to HIV/AIDS in associated mortality rates.

But malaria doesn't just affect people who live in endemic regions, Dr. Loren Miller said. Americans who travel to those countries for business or pleasure are also at risk, and should discuss malaria prophylaxis with their health care providers.

Prophylaxis is generally very safe and extremely effective, but choosing the right agent is key, said Dr. Miller, director of the infection control program at Harbor-UCLA Medical Center, Torrance, Calif. Two of the most common agents--chloroquine and mefloquine -are no longer effective in many parts of Mexico, Central and South America, the Middle East, sub-Saharan Africa, India, and Southeast Asia.

In chloroquine-susceptible regions, the drug is a good choice, but still has limitations. "It has to be started 1-2 weeks before travel, so it's not useful in people who come to the travel clinic and tell you they're leaving in a few days," Dr. Millier said. The drug also has to be continued for a month after travel. It's generally well tolerated, although it can exacerbate psoriasis.

Mefloquine can also be an option in countries of susceptible malaria strains. It too, must be started well in advance of travel [1-3 weeks] and continued for 4 weeks afterward. Adverse effects include the rare possibility of psychiatric symptoms, and exacerbation of seizure disorders and cardiac conduction abnormalities.

The combination of atovaquone/proguanil is another option. "This can be started just 1 day before travel and it has to be continued for 7 days afterward. It's very well tolerated, although contraindicated in those with a creatinine clearance of less than 30 mL/minute."

The drug is very expensive, running about $56 a week and, like all antimalarials, isn't usually covered by insurance.

"The poor man's alternative is doxy-cycline," Dr. Miller said. This must be started 1-2 weeks early and continued 2-4 weeks after travel. "This drug can cause photosensitivity, which you need to talk about because these people are going to tropical areas--and it can cause vaginal candidiasis."

Many experts consider primaquine to be a second-line agent. It's most effective against Plasmodium vivax. A glucose-6-phosphate dehydrogenase deficiency test is necessary for blacks, Asians, and patients of Mediterranean descent, because the drug can cause acute hemolysis in deficient patients. "Since this test takes a while to come back, primaquine is not recommended for patients who want to travel soon," he said.

Dr. Miller divides his vaccination protocol into three parts, according to destination. "If they're going to Central America, the Caribbean, or the mid-East, they get chloroquine. If they're going to the area of the Thai-Burma border, they get atovaquone/proguanil or doxycycline. If they're going anywhere else, they get mefloquine or, if they can't take that, either doxycycline or atovaquone/proguanil."

The Centers for Disease Control and Prevention's Yellow Book notes which antimalarials are effective in any given country. For that resource, go to www.cdc.gov/travel/.

Dr. Miller reported having relationships with Pfizer, Cubist Pharmaceuticals, GlaxoSmithKline, and Merck. He has been a consultant with Theravance.

BY MICHELE G. SULLIVAN

FROM THE ANNUAL MEETING OP THE AMERICAN COLLEGE OF PHYSICIANS
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Title Annotation:INFECTIOUS DISEASES
Author:Sullivan, Michele G.
Publication:Internal Medicine News
Date:May 1, 2011
Words:535
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