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Malaria: Beware the Mosquito

June 10, 2008 - 7:30am
 
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Malaria: Beware the Mosquito

"Malaria can often be prevented by using antimalarial drugs and by using personal protection measures to prevent mosquito bites. However, in spite of all protective measures, travelers may still develop malaria."

United States Centers for Disease Control and Prevention

image Planning to travel overseas? Headed to a warm climate, maybe a developing country? Do it! But remember, with travel come some health risks. Malaria, for example, is a serious and sometimes fatal disease. As the Centers for Disease Control and Prevention (CDC) indicates, there's no one way to guarantee you won't get it, but there are ways to lessen your risk. Learn how to help prevent it before you depart!

Malaria: What Is It and Where Is It Found?

The first thing to know about malaria is that it's serious. Malaria is caused by a tiny parasite, which is transmitted to humans by the female Anopheles mosquito. Her bite sends the parasite into the bloodstream, where it travels to the liver, hides, and grows. Two weeks later, these parasites invade the body's red blood cells. The "human host" becomes feverish, achy, and generally unwell. Red blood cell destruction often leads to severe anemia and life-threatening failure of multiple body organ systems.

Malaria and the Anopheles mosquito are usually found in tropical areas of Africa, Asia, and Latin America. The prevalence of the disease is aggravated by poor socioeconomic conditions.

Don't Let 'Em Bite You!

It's very important to focus on not getting bitten, urges Dr. David Hamer, director of the Traveler's Health Service at Tufts New England Medical Center in Boston. Admittedly, keeping those nasty critters away is a challenge, but it is the best form of prevention against malaria.

Since mosquitoes feed at night, you need to be most careful right before the sun goes down. Here's how to protect your skin from mosquito bites:

  • Wear light colored clothing which covers your arms and legs (even on hot nights!).
  • Travel with a mosquito net to sleep in (one soaked in the insect repellent "permethrin" is advisable)
  • Use mosquito repellents containing DEET. (While over-application of DEET may be harmful, it is safe when applied one to three times per day at concentrations of 8% to 12% for children and 20% to 30% for adults.)

The ABCs Of Antimalarial Medicines

Antimalarial drugs do not prevent you from being infected but rather kill the malaria parasites during their development. This can reduce the risk of becoming ill or dying. Dr. Cliff Sewell from the Travel Clinic of San Francisco, explains "Antimalarial medications are not preventative, but if a person follows a strict drug regimen, malaria will only rarely develop."

As there are different strains of malaria, each risk area requires a different drug. Based on your destination, the doctor will usually prescribe one of the following: atovaquone and proguanil (Malarone®), mefloquine (Lariam®), doxycycline, or chloroquine. Each has its own side effects and costs.

  • Atovaquone and proguanil is a fixed-dose combination of two antimalarial drugs and is the most recent agent approved for the prevention and treatment of malaria. Clinical trials have shown it to be 98% effective for both preventing and treating malaria. Its cost is about four dollars a pill. The recommended dosage is one tablet daily, starting one or two days prior to arriving in a malaria-endemic area, one tablet a day while in the area, and one tablet a day for seven days after return. The most common adverse affects included headache and abdominal pain.
  • Mefloquine is the most commonly prescribed drug for Africa, most of Asia, and Latin America. You begin taking mefloquine once a week one to two weeks before you leave and continuing throughout your trip and for four weeks after returning home. The cost is seven to ten dollars per tablet. Side effects include nausea, diarrhea, dizziness, and difficulty sleeping. If you have a history of epilepsy, severe psychiatric disorders, or certain heart problems, you should consider taking something else.
  • Doxycycline is easier for the body to tolerate. Doxycycline is taken every day, starting one day prior to departure, and is recommended for Myanmar and parts of Thailand. It costs about three dollars a week. Its most common side effect is sun sensitivity of skin.
  • Chloroquine is also taken once a week and costs four to eight dollars per tablet. Once upon a time, it was the drug of choice until most malaria parasites developed a resistance to it. Now it prescribed only for Central America, Mexico, Haiti, the Dominican Republic, and parts of the Middle East. Its main side effects are upset stomach and headaches.

Medication May Not Insure Protection

How effective are these antimalarials? What are their long-term health consequences? Different travelers have different experiences and opinions.

Travel agent Glenn Talken has followed doctor's orders and taken his medicines faithfully. During his yearlong trip to South America, Glenn took mefloquine and had no negative side effects. He also concentrated on not being bitten, explaining, "I'd make sure to put on a lot of repellent, cover up with long sleeves, even cotton gloves."

San Francisco State University geography professor Hans Meihoefer has actually had malaria. He spent many months in Africa over the course of three visits in the early 1970s. Meihoefer took chloroquine yet still contracted malaria. "This does not necessarily mean chloroquine does not work," cautions Dr. Hamer, "but that this may have been one of the first strains of malaria to be resistant to chloroquine, and consequently, the professor may have been in an area where chloroquine was not the best drug to take."

"I was exhausted," Meihoefer remembers. Had he not been taking chloroquine, his symptoms could have been worse. He doesn't take antimalarials anymore. "I've taken the drugs and gotten malaria. Now, I concentrate more on not getting mosquito bites. I'm more careful."

Though Dr. Hamer advocates preventing mosquito bites, he also encourages travelers to use antimalarial medications, pointing out that they are "90% to 95% effective in areas where the strains are not resistant." He adds that the medicines will only work if travelers are rigorous about taking them. Even a single bite—almost impossible to avoid in areas with many mosquitoes—can lead to infection or even death that could have been prevented by proper treatment with antimalarial medications.

What If You Get Malaria?

Get help FAST! If you are feverish and feel like you have the flu and suspect that you may have malaria, go to a clinic immediately and have a blood test. Some kinds of malaria can become life threatening within only a few hours.

If you are headed for an isolated area, be sure to carry some type of antimalarial just in case. Antimalarial tablets themselves can be used for treatment, but they must be different than the ones you're taking. Some doctors might still recommend sulfadoxine and pyrimethamine (Fansidar®). Dr. Sewell advises his travelers headed to remote areas to carry sulfadoxine and pyrimethamine and take it if symptoms arise. If you make a decision to self-treat, it is still important to seek medical advice as soon as possible.

However, sulfadoxine and pyrimethamine is occasionally fatal and some clinics, such as the Overseas Medical Clinic in San Francisco, won't prescribe it. This medication is no longer recommended on the CDC website. Also, resistance to sulfadoxine and pyrimethamine appears to be rising, especially in parts of east Africa and in South America. Sulfadoxine and pyrimethamine are still an effective way to eliminate the malarial parasite except in the Amazon basin of South America, Southeast Asia, and certain countries in eastern and southern Africa (Kenya, Malawi, Mozambique, South Africa, Tanzania, Burundi,and Uganda). While recommendations change rapidly as new resistance patterns emerge, the combination of mefloquine preventive treatment (where appropriate) with malarone carried for treatment (four pills daily in a single dose for three days) may be far safer choice fortravelers unlikely to be able to reach medical help within 24 hours. In many parts of Asia and Africa there is increased use of artemisinin for treatment – almost always given in combination with other drugs. If you develop malaria while traveling in Africa or Southeast Asia and you have a choice of treatment you should probably opt for an artemisinin-based regimen.

Know the Facts!

Knowing the facts and making the best decision based on them is vital. It's your health and your trip, so be aware! Visit your local travel clinic and obtain as much medical advice as possible before travelling. Make sure you and your physician are clear as to what is being prescribed, its side effects, and any known long-term health consequences.

Wondering about your destination? Seek expert advice at your local travel clinic before leaving home. Also, see the CDC's "Geographic Health Recommendations" on their Traveler's Health site. You'll be able to read about your country of choice.

Bon voyage!

RESOURCES:

American Society of Tropical Medicine and Hygiene
www.astmh.org

Health Information for International Travel Booklet
http://www.cdc.gov/travel/yellowbk99.pdf

International Association of Medical Assistance to Travelers
http://www.iamat.org/

World Health Organization
www.who.org

CANADIAN RESOURCES:

International Society of Travel Medicine
www.istm.org

Travel Medicine Program, Public Health Agency of Canada
http://www.phac-aspc.gc.ca/tmp-pmv/index.html



Last reviewed January 2008 by David L. Horn, MD, FACP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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