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WHO urges aggressive mosquito control strategies; proposes $56 million plan to combat Zika
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WHO is encouraging countries affected by Zika virus to control the mosquito population through innovative and biological methods, and it is considering the use of genetically modified mosquitoes to further reduce the population, according to a press release.
Current methods used to contain the Zika epidemic are limited, according to WHO. PCR diagnostics can only detect infection during illness when the virus is replicating; however, 80% of infected patients are asymptomatic and are unlikely to undergo testing during this phase. In addition, although several companies are conducting vaccine research and development, it will be at least 18 months before the vaccines are assessed in large-scale trials. WHO, therefore, recommends that vector control is the best way to combat Zika virus.
WHO reviews, recommends interventions for vector control
A potential intervention that may reduce the mosquito population involves a genetically modified mosquito prototype that was recently evaluated by a WHO Vector Control Advisory Group, the release said. Trials assessing these mosquitoes in the Cayman Islands demonstrated significant reductions in mosquito populations, according to WHO. The advisory group recommended that the genetically modified mosquitoes be further assessed in field trials to determine the impact on disease transmission.
Another control technique involves the mass release of male mosquitoes sterilized by low doses of radiation, the release said. The technique was successfully used by the International Atomic Energy Agency and the Food and Agriculture Organization of the United Nations to control agriculturally important insects.
A “promising” biological method to reduce the population releases male mosquitoes that naturally carry Wolbachia bacteria, which are found in 60% of common insects, according to WHO. The bacteria, which can be transmitted from males to females when mating, prevent eggs from hatching. It does not, however, infect humans or other mammals. A particular strain of Wolbachia being investigated reduces mosquitoes’ ability to spread dengue. Mosquitoes carrying the bacteria have been released in Australia, Brazil, Indonesia and Vietnam. Additional, large-scale field trials will be launched soon, the release said.
Other biological methods were already launched in some countries affected by Zika. For example, El Salvador introduced larvae-devouring fish into water storage containers.
“Given the magnitude of the Zika crisis, WHO encourages affected countries and their partners to boost the use of both old and new approaches to mosquito control as the most immediate line of defense,” the release said.
WHO releases international strategic response
To gather additional resources to combat Zika, WHO proposed a strategic response plan that would require the help of 23 partners, including UNICEF, the Pan American Health Organization and the U.N. Development Program, and $56 million in funding. The majority of interventions will be implemented in countries reporting Zika virus infections, microcephaly and Guillain-Barré syndrome (GBS) cases. Conducting laboratory testing, monitoring cases and communicating the public health risk of Zika virus, however, will be implemented worldwide.
Margaret Chan
“The Zika situation is particularly serious because of the potential for further international spread, given the wide geographical distribution of the mosquito vector, the lack of population immunity in newly affected areas, and the absence of vaccines, specific treatments and rapid diagnostic tests,” WHO Director-General Margaret Chan, MD, said in a release. “This Strategic Response and Joint Operations Plan aims to provide support to affected countries, build capacity to prevent further outbreaks and control them when they do occur, and to facilitate research that will help us better understand this virus and its effects.”
According to WHO, to implement the response plan:
- $7.1 million is needed to enhance surveillance of the Aedes aegypti mosquito vector, Zika virus infection, microcephaly and GBS;
- $15.4 million is needed to educate communities about the risk for Zika virus infection and address stigma;
- $6.4 million is needed to increase efforts for vector control and promote personal protection measures, including the use of insect repellent and treated mosquito nets;
- $14.2 million is needed to provide counseling and contraceptive services to women and adolescent girls of childbearing age, offer guidance to high-risk individuals and pregnant women, and expand access to care to people affected by Zika virus;
- $6.4 million is required for research investigating the link between Zika and microcephaly and GBS, as well as research assessing sexual transmission and mother-to-child transmission of Zika virus, and fast-tracking the research and development of new products; and
- $6.1 million is needed to coordinate comprehensive international and national response activities.
Research and development of vaccines and diagnostics
As part of its international response, WHO developed a “R&D Blueprint” that aims to fast-track medical countermeasures and avoid as much harm as possible during epidemics.
“The Ebola outbreak of 2014-15 highlighted the need for a master plan for research and development to both prepare for health emergencies and to be able to mount a fast response in case of need,” Marie-Paule Kieny, PhD, WHO Assistant Director-General for Health Systems and Innovation, wrote in a WHO commentary. “Our relatively poor knowledge of the Zika virus presents a series of challenges for research and development. However, building on experience from the Ebola epidemic, WHO has been able to set in motion a rapid R&D response for Zika.”
WHO already has identified 15 companies and research groups that are investigating a Zika virus vaccine. Two vaccine candidates, a DNA vaccine from the United States and an inactivated vaccine from India, appear to be at an advanced stage of development, Kieny wrote. In addition, WHO identified 10 biotech companies that can provide nucleic acid or serological tests. Although no tests have been approved for regulatory use, it is a matter of weeks or months before a commercial test will be available, according to Kieny.
“Ebola taught the global R&D community many valuable lessons, and proved that when we work together, we can develop new medical products much faster than we thought possible,” she said.
Disclosure: Infectious Disease News was unable to confirm relevant financial disclosures at the time of publication.