Mosquito Control Activities During Local Transmission of Zika Virus, Miami-Dade County, Florida, USA, 2016

Janet C. McAllister; Mario Porcelli; Johana M. Medina; Mark J. Delorey; C. Roxanne Connelly; Marvin S. Godsey; Nicholas A. Panella; Nicole Dzuris; Karen A. Boegler; Joan L. Kenney; Linda Kothera; Lucrecia Vizcaino; Audrey E. Lenhart; John-Paul Mutebi; Chalmers Vasquez

Disclosures

Emerging Infectious Diseases. 2020;26(5):881-890. 

In This Article

Lessons Learned

The purpose of using adulticides in an outbreak is to immediately reduce the number of adult mosquitoes (particularly older ones) that might be capable of transmitting disease. We observed interruption of vectorborne Zika virus transmission in Wynwood and both red zones in Miami Beach after beginning intensive adulticiding. In the United States, adulticide treatments using space-spraying techniques against Ae. aegypti mosquitoes have been shown to quickly knock down adult populations.[11] However, these adult mosquito reductions are transient because not all mosquitoes will be active (and thus exposed) during application; in addition, adulticides do not control larvae and pupae, new adult mosquitoes will quickly repopulate an area. Therefore, repeated adulticide treatments are needed to eliminate newly emerging mosquitoes.

The use of larvicides alone does not immediately control adult mosquito populations, and it is not unusual to see the effect of larvicides until several weeks after their application.[12] Our observation in Wynwood, where mosquito numbers remained suppressed when both adulticide and larvicide applications occurred, compared with the area that received only adulticide treatments, reinforces the necessity of a combination approach to achieve and sustain impact. Observations that aerial adulticiding and combinations of adult and larval mosquito control can successfully interrupt vectorborne disease transmission have been previously reported. Aerial adulticiding in California stopped West Nile virus transmission in an area that received the treatment, whereas cases continued to occur in untreated surrounding areas.[13] Although larvicides are typically not recommended as part of a malaria control program, an example of the effect of both adulticide and larvicide contributing to reduction of disease was documented in Kenya, where transmission of malaria decreased substantially after a combination of larvicide and insecticide-treated nets were used.[14] The combination approach can prolong the recovery of a treated mosquito population because adult mosquitoes are killed, thereby immediately interrupting virus transmission and deposition of new eggs, and emergence of new adults is interrupted by the larvicide, keeping the population from quickly rebounding and thus preventing ongoing virus transmission.

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