Malaria

If you are traveling to almost any tropical country these days it is likely you will need to protect yourself against malaria. This is a disease which was supposed to have been eradicated by now but instead is on the increase. Resistant forms of malaria have now spread to most of the developing world.

Malaria is a disease spread by the bite of an anopheles mosquito. These mosquitoes are more common in open, rural areas and usually bite at night. The parasite is injected by the bite and travels within seconds to the liver where it is protected against the body's defense mechanisms (and most drugs.) It goes through some reproductive stages and then emerges to invade the red blood corpuscles. These are soon destroyed by the parasites, leading to anemia and clogging up small blood vessels. Even if the body manages to destroy these parasites a new batch is forming in the liver, soon to be released to start the process all over again. Even weeks after a bout of malaria is successfully treated the parasites which have been hiding in the liver may emerge again. Only the treatment of the liver stages with special drugs or the prolonged taking of prophylactic drugs will forestall this.

There are four types of malaria--Vivax, Ovale, Malariae and Falciparum. The first two are most likely to cause delayed relapses but least apt to be fatal. Falciparum malaria, often known as malignant malaria, is the one that is most apt to be fatal and is rapidly becoming resistant to many forms of drug therapy.

The reason you must wait at least a year after malaria exposure to donate blood is not the medication but the risk of malaria. The medication is out of your system within at most 28 days. But most of the preventive medicines kill only the malaria parasites circulating in your blood, not the rare forms that might be lurking in your liver only to show up later. Depending on which medicine you took and which of the four types of malaria you were potentially exposed to it is possible for malaria to pop up months after you stop taking the medicine. The possibility of this is VERY remote, but the blood banks don't want to take ANY chances of transmitting malaria so most will not accept blood for a year after you have been in a malaria area. A period of three months would probably be reasonable and I believe some donation centers will accept blood after that interval. But most won't.

At this time malaria is most common in moist, tropical countries but as drug resistance increases it is spreading to other, less typical parts of the world. The rise in air travel also is causing the disease to crop up in unlikely locations such as Switzerland, California and Washington, D.C.

The illness of malaria usually begins 7-30 days after exposure. It starts out as a flu-like syndrome with headache, body aches and a general feeling of unwellness. It soon progresses to include abdominal pain, nausea, vomiting and sometimes diarrhea. The classic symptom is a fever, usually accompanied by body-shaking chills and in an increasingly predictable pattern. Untreated, it can rapidly progress to liver and kidney failure, coma, shock and death.

The diagnosis is typically made by special blood stains which should be performed by people specifically trained in what to look for. If the symptoms persist and the blood stains are negative they should be repeated as often as every 12 hours. Other common travel-related diseases which may mimic malaria to some degree are dengue fever, typhoid, hepatitis and brucellosis.

Treatment is typically with chloroquine, mefloquine or a related drug. As drug resistance increases so does the need to use more powerful drugs, often in combinations. These drugs are often difficult to get and have serious side effects and should be administered by someone experienced in their use such as an Infectious Disease or Travel Medicine specialist.