DAN Discusses Malaria and Antimalarial Drugs
By Dan Leigh, Managing Editor
The July and August issues of Alert Diver hosted stories about dengue fever. Within the series we also mentioned dengue's better-know sister ailment. Malaria, a serious and sometimes fatal disease is caused, like dengue, by the bite of an infected mosquito.
According to the Centers for Disease Control, four kinds of malaria can infect humans: Plasmodium falciparum (plaz-MO-dee-um fal-SIP-a-rum), P. vivax (VIGH-vacks), P. ovale (o-VAHL-ley), and P. malariae (muh-LAIR-ee-uh).
Where Does Malaria Happen?
Malaria occurs in more 100 countries and territories worldwide. More than 40 percent of the people in the world are at risk of contracting the disease. Large areas of Central and South America, Hispaniola (Haiti and the Dominican Republic), Africa, the Indian subcontinent, Southeast Asia, the Middle East and Oceania are considered malaria-risk areas.
How Common Is It?
The World Health Organization estimates that yearly 300-500 million cases of malaria occur; more than 1 million people die of malaria each year. About 1,200 cases of malaria are diagnosed in the United States annually. Most U.S. cases are in immigrants and travelers returning from malaria-risk areas - mostly from sub-Saharan Africa and the Indian subcontinent.
Which Drug To Take?
Prescription Only. Antimalarials are available only by prescription through a healthcare provider, who typically prescribes such medication based on your travel itinerary and medical history. Some antimalarials are more effective in some parts of the world than others. In fact, certain areas of the world have developed strains of malaria (e.g., in P. falciparum or P. vivax; the "P" in both stands for "Plasmodium") that are resistant to conventional suppression with chloroquine phosphate. Additionally, a medical condition may prevent someone from taking certain drugs. Later in this article, you'll read about some available alternative drugs.
Specific to Diving:
There is no clinical data that establishes any interactions with antimalarial drugs and diving. Most dive medicine professionals do not expect any complications with the antimalaria drugs and diving. However, the use of Mefloquine (Lariam) by divers is not universally accepted by all dive medicine professionals. Please consult the dive operator at your destination for the local opinon regarding Mefloquine (Lariam).
Watch Your Dosage.
Overdosage of antimalarials can be fatal. Keep drugs in childproof containers out of the reach of children. Follow dosage schedule exactly, without missing doses. Buy antimalarials in the United States before traveling overseas. The quality of antimalarials sold outside the United States may not be reliable, and they may be difficult to obtain.
Your healthcare provider will prescribe the antimalarial best suited to you and your destination. If you have any questions about the drug recommended, call your healthcare provider or pharmacist.
Protect yourself from mosquito bites. Wear long-sleeved shirts and long pants, and apply insect repellent to exposed skin. Mosquitoes that transmit malaria bite between dusk and dawn.
Use insect repellents that contain DEET (chemical name N,N-diethyl-meta-toluamide), a colorless oily liquid insect repellent developed in the early 1960s. The concentration of DEET varies among repellents. Those with concentrations of 30-35 percent are quite effective, generally lasting about four hours. Follow label directions and take these precautions:
Travelers who will not be staying in well-screened or air-conditioned rooms should spray a pyrethroid-containing flying-insect spray in living and sleeping areas during evening and nighttime hours. Sleep under mosquito netting, or bed nets sprayed with the insecticide permethrin or a similarly used insecticide, deltamethrin. In the United States, permethrin is available as a spray or liquid to treat clothes and bed nets. Bed nets already treated with permethrin may also be purchased. Adequate prophylaxis against malaria should also include an antimalarial drug, tailored to the sensitivity of the organism according to the geographic location. THIS IS NOT OPTIONAL: IT IS ESSENTIAL. Tourists traveling to places where malaria is endemic without taking appropriate prophylaxis have died of the disease.
Antimalarials & Regions
In this section we'll discuss drugs that are commonly used for malaria prophylaxis. These guidelines and schedules are ones commonly recommended at the time of writing (July, 2002). However, antimalarial drug prophylaxis recommendations frequently change. For updated recommendations check the CDC website (listed below) or with your doctor. Your doctor can recommend dosage schedules and amounts, for both adults and children. The schedules listed in this article apply only for malaria PROPHYLAXIS (PREVENTION). If you contract malaria, treatment of the disease will likely require different dosages, schedules or drugs. If you require malaria prophylaxis and are allergic to any antimalarial drugs, report this to your doctor so that a different drug can be selected.
Travelers to malaria-risk areas in South America, Africa, the Indian subcontinent, Asia and the South Pacific should take one of the following drugs:
Travelers to the borders of Thailand with Burma (Myanmar) and Cambodia, the western provinces of Cambodia, and in the eastern states of Burma should read "Malaria Information for Travelers to Southeast Asia" at www.cdc.gov/travel/malariadrugs.htm. Mefloquine resistance has been reported in these areas and either doxycycline or Malarone are the recommended antimalarial drug.
Travelers to malaria-risk areas in Mexico, Haiti, the Dominican Republic, certain countries in Central America, the Middle East, and Eastern Europe should take chloroquine or hydroxychloroquine sulfate as their antimalarial drug.
Mefloquine (brand name Lariam ®)
Directions for mefloquine use:
Mefloquine side effects and warnings:
Most travelers who take mefloquine have few, if any, side effects. The most commonly reported minor side effects include nausea, dizziness, difficulty sleeping and vivid dreams. Mefloquine has been reported to cause serious side effects, such as seizures, hallucinations and severe anxiety. Minor side effects usually do not require stopping the drug. Travelers who have serious side effects should see a healthcare provider.
Mefloquine should not be taken by people who are allergic to it. A doctor will usually prescribe the drug for people with the following conditions only after careful consideration:
Alternatives for travelers who cannot or choose not to take mefloquine include doxycycline or Malarone™.
Directions for doxycycline use:
Doxycycline side effects and warnings:
Doxycycline is not for children under the age of 8 because it can cause staining of the permanent teeth. Additionally, doxycycline is not to be taken by pregnant women because it can cause staining of the teeth of the unborn child.
A relatively new antimalarial drug in the United States, Malarone combines two drugs (atovaquone and proguanil) and is an effective alternative for travelers who cannot or choose not to take mefloquine or doxycycline.
Directions for Malarone use:
Malarone side effects and warnings:
hloroquine (brand name Aralen®)
Directions for chloroquine use:
Chloroquine side effects and warnings:
Although side effects are rare, nausea and vomiting, headache, dizziness, blurred vision, and itching can occur. Chloroquine may worsen the symptoms of psoriasis.
Hydroxychloroquine sulfate (brand name Plaquenil®)
Directions for hydroxychloroquine use:
Hydroxychloroquine sulfate side effects:
Although side effects are rare, nausea and vomiting, headache, dizziness, blurred vision, and itching have been reported; and hydroxychloroquine sulfate may worsen the symptoms of psoriasis.
Pyrimethamine (brand name Daraprim)
Direction for pyrimethamine use:
Adults and adolescents take pyrimethamine as a single dose. For children, dosage is based on body weight.
Pyrimethamine side effects:
When you are taking pyrimethamine, it is especially important that your health care professional know if you are taking any of the following:
Amphotericin B by injection (e.g., Fungizone);
Antineoplastics (cancer medicine);
Antithyroid agents (medicine for overactive thyroid);
Azathioprine (e.g., Imuran);
Chloramphenicol (e.g., Chloromycetin);
Flucytosine (e.g., Ancobon);
Ganciclovir (e.g., Cytovene);
Interferon (e.g., Intron A, Roferon-A);
Mercaptopurine (e.g., Purinethol);
Methotrexate (e.g., Mexate);
Plicamycin (e.g., Mithracin); or
Zidovudine (e.g., AZT, Retrovir).
Use of these medicines together with pyrimethamine may increase the chance of side effects affecting the blood. Make sure you tell your doctor if you have any other medical problems, especially:
Fansidar (sulfadoxine and pyrimethamine)
Direction for fansidar use:
The first dose of Fansidar should be taken one or two days before departure to an endemic area; administration should be continued during the stay and for four to six weeks after return.
Fansidar side effects / adverse reactions:
Adverse effects of Fansidar include: nausea, vomiting, headache, photosensitivity (increased sensitivity to the sun's rays), dizziness. Rare side effects include convulsions and blood disorders like anemia and low white blood cell or platelet counts. Fansidar should not be taken by people who are allergic to sulfa drugs.
A Final Word
Succinctly: Avoidance is your best bet, but travel is an exhilarating and educational experience as well. Worth the risks? It's up to you, but if you plan your travels with your health in mind, you'll reduce your chances of encountering a life-threatening disease.
© 2002 DAN - Alert Diver, September 2002