Malaria is on the upsurge in Central America, with a 150 per cent increase of cases reported in Guatemala during a recent six-month period and lesser rises in Nicaragua and El Salvador.

Guatemala's National Service for the Eradication of Malaria said 6,128 new cases appeared in the six months ending in Feburary, the latest figures available. The country's population is about 5 million. No deaths have been reported.

According to the Pan American Health Organization, the upsurge is part of a trend in Central America. In 1975, Guatemala, Nicaragua and El Salvador reported 40 per cent of the 142,000 malaria cases recorded in the Western Hemisphere.

In 1957, the organization launched an eight-year campaign to climinate malaria by etradicating the disease-carrying mosquito. The malaria sporozoite can complete its life cycle only within the stomach of this particular mosquito.

There is no known way to prevent a person bitten by the diease-carrying mosuito from catching the diease, and the latest figures support the conclusion of many malaria experts - that in this fight between man and mosquito, the insects are holding their own.

Professionals cite a number of causes for the failure to do away with the carrier mosquito, but the most important long-term reason is the insect's ability to develop immunity to the successive waves of toxins that humans have used.

The malaria mosquito thrives in the same humid, low-lying regions in which cotton is cultivated. The Central American Research Institute for Industry has released a study that tied the rising curve of malaria directly to those areas of cotton plantations.

Health Minister Benjamin Sultan has said that Esquintla Province, along Guatemala's Pacific slope and its richest cotton-growing malaria outbreak.

Another expert said recently: "Malaria goes up very fast but comes down very slowly. Even if we employ all possible resources, it will take at least 3 to 10 years to get back to where we in 1975."

The crisis is taxing Guatemala's limited facilities. The malaria service has a permanent staff of 1,000, plus a volunteer force of 5,000. The staff has had to travel constantly to reach the victims. In El Salvador and Nicaragua, with less resources, the problem is even more severe.