A new analysis questions the effectiveness of different methods for controlling the mosquitoes that can transmit Zika and other diseases.
The researchers, from the University of East Anglia in England, reviewed evidence about chemical controls, such as pesticides and larvicides, and biological controls, such as placing mosquito larvae-eating crustaceans or fish in standing water containers.
Biological controls did appear to reduce numbers of disease-carrying mosquitoes more than chemicals, but the quality of evidence was often poor, the research team noted.
Some studies showed that chemical controls slashed mosquito numbers by up to 76 percent, while others found no significant reduction. Also, the overall results of the studies were weak, the researchers added.
They found little evidence that chemical spraying around homes was effective, and any reductions in mosquito numbers weren’t sustained.
“Although chemical measures are widely used and expected to be effective, we consider most of the evidence in favor of chemical spraying to be quite poor,” said study leader Dr. Paul Hunter, a professor of medicine.
“In fact, there is some evidence that spraying may be counterproductive as it generates a false sense of security such that people no longer put effort into removing mosquito breeding sites around the home,” he said in a university news release.
The World Health Organization recommends using more than one type of control method to tackle all life stages of mosquitoes, and says the elimination of mosquito breeding sites is the most effective method of control, the researchers said.
“Although there is limited evidence relating to integrated campaigns combining multiple methods of control, the WHO is correct to reiterate that the most effective intervention is likely to be the elimination of mosquito breeding sites. This requires sustained and ongoing education campaigns,” Hunter said.
The analysis was published Dec. 7 in the journal PLOS Neglected Tropical Diseases.
The World Health Organization has more on Zika.
This Q & A will tell you what you need to know about Zika.
To see the CDC list of sites where Zika virus is active and may pose a threat to pregnant women, click here.