A Peruvian scientist has developed a biological method that prevents the spread of malaria.

By Zoraida Portillo

September 1999

Lima: A simple biological control technique using coconuts, a fruit that is both cheap and abundant in tropical zones, could become a new treatment for malaria.

The disease is endemic in those parts of the world with a humid, tropical climate that provides an abundance of stagnant water where the malaria-carrying mosquitoes breed. Its victims are mostly the inhabitants of the poorest countries, which generally lack basic sanitation services.

Malaria kills three million people annually, nearly double the present number of victims succumbing to AIDS (Acquired Immune Deficiency Syndrome), according to the World Health Organisation (WHO). In Africa alone, it kills one million children each year while in Latin America, 1% of the population of Peru is infected with malaria.

The disease is transmitted by the Anopheles mosquito, which can live at altitudes of up to 3,000 metres and whose bite injects the plasmodium parasite into the human body. It can cause death within 72 hours if treatment is not provided in time.

'The majority of people in malaria zones have the parasite in their bodies, that is, they live with the parasite almost continuously. They go to health centres when they become feverish to receive medicine but, when they feel better, they stop taking it,' says Luis Valdez, a specialist in infectious diseases.

As a consequence, the malaria parasite becomes drug-resistant, allowing pregnant women to transmit the parasite to their foetuses. In addition, even if a person completes the quinine-based treatment course, they can then be bitten again by a mosquito and re-infected, adds the expert.

For these reasons, the best way to attack the disease is through prevention. One of the traditional methods is to spray the marshes where the mosquitoes breed with insecticide, but the chemicals are expensive and generally toxic to both humans and the environment.

Now, the Peruvian microbiologist Palmira Ventosilla, of the Institute of Tropical Medicine of the private Cayetano Heredia University of Lima, has developed a biological control method that uses coconuts to grow a microorganism which in turn kills the anopheles larvae, but does not harm other living things or the environment.

This microorganism is produced commercially in industrialised countries, but its importation is too expensive for poor countries afflicted by the disease.

For a long time, Ventosilla searched for a simple method to naturally develop this bacillus, known by its scientific name of Bti, and finally found what she was looking for in coconuts, a fruit that grows abundantly in tropical zones.

'A small quantity of Bti is introduced into the coconut through a hole that is then plugged with cotton and sealed with candle wax. The hard shell of the coconut protects the incubating bacillus, and the milk inside contains amino acids and carbohydrates necessary for its reproduction,' Ventosilla explains.

After two or three days of fermentation, the coconuts are taken to the swamps where the mosquitoes live, the plugs are removed and the coconuts are thrown into the stagnant pools of water. Two or three coconuts are enough to cover a typical pond.

Experiments have demonstrated that this quantity kills all the larvae contained in the marshy pond, and keeps working for 45 days.

'In reality, the reproduction of Bti is not a problem. The harder job is to win over the local people to accept this technique as one that is viable and effective,' says Ventosilla.

She began her experiments in Salitral, a semi-tropical zone on the northern Peruvian coast where marshes abound, as does the mosquito that transmits the disease.

Its population consists mostly of peasants with a minimal level of education and it was very difficult to convince them to abandon the use of insecticides and adopt the 'coconut treatment'.

It was also easy for the locals to wait for the periodic inoculations provided by the Ministry of Health and to simply go to health centres every time they ran a high fever, and experienced intense chills and sweating.

Now, three years after the treatment's effectiveness was put to the test during the El Nino phenomenon - which had prompted authorities to fear a major outbreak of the disease across the whole northern Peruvian coast - the population is enthusiastically participating in training sessions.

'They bring their own knives and candle wax and seem very interested in learning the right way to soak the cotton with Bti, to insert into the coconut,' says one of the instructors on Ventosilla's multi-disciplinary team, composed of biologists, entomologists, sociologists and anthropologists.

A fundamental factor in the acceptance of this alternative technique was the children.

Jorge Velez, one of the team members, devised a way to teach them about the life-cycle of the mosquito and how to make Bti using coconuts. The children then became the biggest advocates of biological control to their parents.

With assistance from the International Centre on Research and Development (ICRD) of Canada, Ventosilla's team is ready to start a second round in villages of the department of Madre de Dios, in the southern Peruvian Amazon.

The goal is to prove the hypothesis that overhead vegetation and algae protect the Bti bacillus from damage caused by the sun's ultraviolet rays, a factor that could be important for the future refinement and expansion of the malaria-control programme. - Third World Network Features/IPS

About the writer: Zoraida Portillo is a correspondent for Inter Press Service, with whose permission the above article has been reprinted.