Some strains of the parasite are now showing resistance to the drugs used to prevent its development and travellers may not have the protection they think they have.
The parasite lives in the salivary gland of the female mosquito, and, when she bites man, can enter the bloodstream. The parasites move to the liver and begin maturing. This process may take six to 11 days and produces no symptoms.
The high fever associated with malaria is due to the release of parasites into the blood. The fever recurs every second or third day, depending on the type of parasite.
The Spanish Jesuits in Peru, some 400 years ago, noted that the native Indians used an extract from the bark of the cinchona tree to treat the fever of malaria and brought this treatment back to Europe. The extract responsible for this effect is quinine and this drug is still used.
In endemic areas, most children acquire the infection early and are subject to recurrent bouts of illness.
Those who survive seem to develop a partial immunity and come to terms with the chronic infection. Bouts of acute fever then become rare although persistent infection can lead to chronic anaemia, liver damage and enlargement of the spleen.
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