Widespread spraying to eliminate mosquitoes has failed to significantly stop the spread of dengue fever and it may be the same case for the Zika virus linked to neurological disorders, the World Health Organization (WHO) said on Wednesday.
The emphasis should be put on enlisting families and communities to protect themselves and eliminate from their homes the mosquitoes that carry the disease, which has spread rapidly in Brazil and Latin America, it said.
Releasing genetically modified mosquitoes or irradiating insects also needed to be studied, but evaluation of such novel methods should be done with “extreme rigor”, the WHO warned.
A three-day meeting of experts set two other top priorities for research: speeding development of tools to diagnose Zika infections and of vaccines to prevent the disease. But they said vaccine trials may come too late for the current outbreak.
WHO Assistant Director General Marie-Paule Kieny said experts had told the meeting that there was no evidence that traditional mosquito control methods had had any significant impact on transmission of dengue, a virus close to Zika.
“This is important because we must be sure that we invest in interventions that work,” Kieny told a news briefing.
“Certainly it is worth continuing to try to use this method for the lack of other interventions.”
She said the Aedes aegyptii species of mosquito that carries Zika is the “cockroach of mosquitoes” because it stays mainly indoors and is hard to eradicate. Efforts to control it needed to be much more targeted to communities and households.
“Then we will see whether it works or not,” she said.
On Tuesday, the WHO advised pregnant women not to travel to areas with outbreaks of Zika virus due to the potential risk of birth defects, a condition known as microcephaly.
Zika has been linked to Guillain-Barre syndrome, another neurological disorder, but neither link has been yet proven.
The most advanced candidate vaccines for Zika are still a few months away from entering early human clinical trials, Kieny said.
“It is therefore possible that vaccines may come late for the current Latin American outbreak, but the development of a vaccine remains an imperative, in particular vaccines suitable for pregnant women and women of child-bearing age,” she said.
(Reporting by Tom Miles and Stephanie Nebehay; Editing by Dominic Evans)