A Cuban company is increasing sales of its mosquito larvicides to fight malaria in Africa, despite cautions by U.N. experts that such products have limited use and are not the most cost-effective method of attacking the disease.

Salesmen for the state-owned company, Labiofam, are allegedly pushing their products by playing on the warm bilateral relations established when Cuba assisted many newly independent African nations in the 1970s.

Labiofam’s Web pages say its larvicide Griselesf is used in anti-malaria programs in Ghana, Angola, Gambia, Tanzania, Nigeria, Burkina Faso, Equatorial Guinea and Zambia. Malaria kills an estimated 600,000 people in the region each year.

Ghana alone signed a $74 million, two-year deal for a single larvicide program, a Labiofam representative in the West African nation, Hafez Adam Taher, was quoted as saying in a British newspaper report earlier this year.

But an April report by the World Health Organization cautioned about the use of larvicides to control malaria in sub-Saharan Africa. Biological or chemical larvicides kill the larvae of mosquitoes that transmit malaria, dengue and many other diseases.

Larvicides should be used “only in areas where the breeding sites are few, fixed and findable” — rare in Africa — and there are more cost-effective ways of fighting malaria, said the report by WHO, which is part of the United Nations.

The most cost-effective ways of fighting malaria in rural Africa are insecticide-treated bed nets, spot sprays, drugs and diagnostics, the report added. Larvicides might be more effective in urban areas, but “more good-quality evidence is needed to support this view.”

The report “is not saying (larvicides) are conclusively inefficient, but that we have not seen strong evidence to support its use,” said Dr. Rainier Escalada, a malaria expert at the Pan American Health Organization, which operates as WHO’s branch in Latin America.

The Pesticide Evaluation Scheme run by WHO has not checked the effectiveness of any larvicide submitted by Cuba, said Dr. Raman Velayudhan, a dengue expert at the WHO headquarters in Geneva, Switzerland.

Malaria experts in Africa prompted WHO to issue its report because of concerns that Cuba’s growing larvicide sales in the region are diverting funds away from better malaria controls, said one U.N. official in Geneva.

Taher argued that larvicides “can become a strategic intervention in the fight against malaria … No single thing can do it. If you want to tackle malaria seriously, you have to go to the roots,” Britain’s respected Financial Times newspaper reported.

The Labiofam’s Web pages claim the bio-larvicides Griselesf and Bactivec are effective against many different kinds of mosquitoes but totally safe for humans, animals and plants.

Bactivec was developed in 1986 to fight dengue fever and uses the Bacillus Thuringiensis Israelensis SH-14, according to the digital pages. The bacteria kill the mosquito larvae that feed on them.

Griselesf appears to be a more recent product that uses the Bacillus Sphaericus stump 2362 (CQ), sometimes used to break down tree stumps, and is “characterized by its effective, long-lasting action, flexible storage conditions and ease of application.”

A one-year test of an unidentified Labiofam larvicide in the Brazilian city of Rio de Janeiro against the mosquitoes that carry dengue cut the infection rate from 9 percent to less than 1 percent, according a 2004 report by Cuba’s Prensa Latina news agency.