Malaria Disease - Symptoms & Treatment

Malaria has been eradicated from North America, Europe and Russia but, despite efforts, continues to flourish in parts of the tropics. Falciparum malaria is the most severe form of the disease. When treated, malaria seldom is fatal; untreated, it's fatal in 10% of victims usually as a result of complications.

Untreated primary attacks last from a week to a month or longer. Relapses are common and can recur sporadically for several years. Susceptibility to the disease is universal.

Causes

Malaria is caused by Plasmodium vivax, P.malariae, P.falciparum, and P.ovale, all of which are transmitted to humans by mosquito vectors.

Malaria is transmitted by the bite of female Anopheles mosquitoes, which abound in humid, swampy areas. When an infected mosquito bites, it injects Plasmodium sporozoites into the wound. The infective sporozoites migrate by blood circulation to parenchymal cells of the liver; there they form cyst like structures that contain thousands of merozoites.

On release, each merozoite invades an erythrocyte and feeds on hemoglobin. The erythrocyte eventually ruptures, releasing heme (malaria pigment), cell debris, and more merozoites that, unless destroyed by phagocytes, enter other erythrocytes. At this point, the infected person becomes a reservoir of malaria who infects any mosquito that feeds on him, thus beginning a new cycle of transmission.

As parasites, P.vivax, P.ovale, and P. malariae may persist for years in the liver and are responsible for the chronic carrier state. Because blood transfusions and street-drug paraphernalia also can spread malaria, drug addicts have a higher incidence of the disease.

Signs and symptoms

Early stages of malaria may be similar to the flu. The following are the most common symptoms of malaria. However, each individual may experience symptoms differently. Symptoms may include:

• fever
• chills
• headache
• muscle ache
• malaise
• nausea
• sometimes vomiting, diarrhea, and coughing

The symptoms of malaria may resemble other medical conditions. Always consult your physician for a diagnosis.

Diagnostic tests 

During a physical examination, the doctor may identify an enlarged liver and an enlarged spleen . Malaria blood smears taken at 6 to 12 hour intervals confirm the diagnosis.

Treatment

Malaria is treated with oral chloroquine in all but chloroquine-resistant P.falciparum infection.

Malaria caused by P.falciparum, which is resistant to chloroquine, requires treatment with oral quinine, given concurrently with pyrimethamine with sulfadoxine and a sulfonamide, such as sulfadiazine. Relapses require the same treatment, or quinine alone, followed by tetracycline. Mefloquine also may be used for chloroquine-resistant malaria.

The only drug effective against the hepatic stage of the disease that is available in the United States is primaquine phosphate, given daily for 14 days. This drug can induce DlC from increased hemolysis of red blood cells (RBCs); consequently, it's contraindicated during an acute attack.

For travelers spending less than 3 weeks in areas where malaria exists, weekly prophylaxis includes oral chloroquine, beginning 2 weeks before and ending 6 weeks after the trip. Chloroquine and pyrimethamine with sulfadoxine may be ordered for those staying longer than 3 weeks, although combination treatment can cause severe adverse reactions. If the traveler isn't sensitive to either component of pyrimethamine with sulfadoxine, he may be given a single dose to take if he has a febrile episode.

Any traveler who develops an acute febrile illness should seek prompt medical attention, regardless of prophylaxis measures taken.

Prevention

Health authorities try to prevent malaria by using mosquito-control programs aimed at killing mosquitoes that carry the disease. If you travel to an area of the world with a high risk for malaria, you can install window screens, use insect repellents, and place mosquito netting over beds. Insecticide-impregnated bed netting has successfully reduced the number of malarial deaths among African children.

Check with your doctor before visiting any tropical or subtropical area at high risk for malaria. Your doctor can give your family anti-malarial drugs to prevent the disease. Several malaria vaccines are currently being developed and tested across the world, but because the malaria parasite has a complicated life cycle, it is a difficult vaccine to develop.