Controlling the mosquito population is the best method to reduce the spread of the Zika virus in the future, according to a study released Wednesday by a scientific team led by The Scripps Research Institute, based in La Jolla.
The virus came to light last year after babies born to infected mothers had smaller heads than normal, and the disease spread from tropical regions into the U.S., including San Diego County.
The TSRI research team concentrated on Miami, where Zika was introduced by travelers as many as 40 times last year, according to the study detailed in the journal Nature.
They sequenced the Zika genome at several stages of the outbreak, tracing the origin of most of the viruses to the Caribbean region, and tracking their spread into this country.
The researchers said most travel-related infections in Miami didn’t lead to further transmissions in the southern Florida city, and a direct link was discovered between mosquito control efforts and disease prevention.
“We show that if you decrease the mosquito population in an area, the number of Zika infections goes down proportionally,” said Kristian Andersen, director of infectious disease genomics at the Scripps Translational Science Institute.
“This means we can significantly limit the risk of Zika virus by focusing on mosquito control,” Andersen said. “This is not too surprising, but it’s important to show that there is an almost perfect correlation between the number of mosquitoes and the number of human infections.”
San Diego County officials sprayed 10 neighborhoods last year where mosquitoes capable of carrying tropical diseases were located near people sickened with Zika after traveling out of the country.
No one in the San Diego region has been infected with Zika by a mosquito locally, and no mosquitoes in the region have been discovered carrying Zika.
The county Health and Human Services Agency reported 89 San Diegans have been sickened with Zika since 2015, two by sexual transmission and the rest acquired via travel.
Based on data from the Florida outbreak, Andersen said he sees potential in stopping the virus through mosquito control efforts both in the U.S. and in other infected countries, rather than through travel restrictions or other methods.
“Given how many times the introductions happened, trying to restrict traffic or movement of people obviously isn’t a solution,” he said, noting that Miami saw 5.7 million international travelers last year. “Focusing on disease prevention and mosquito control in endemic areas is likely to be a much more successful strategy.”
The scientists also found that the virus didn’t keep neatly into neighborhoods or city blocks, but moved around with the infected people.
They used rapid viral genome sequencing on the virus from 28 of the reported 256 Zika cases in Miami, plus seven mosquito pools, to model last year’s outbreak. The scientists hope that the system and study findings will help provide public health officials with real-time information on any outbreaks this year.
More than 60 researchers from nearly 20 institutions — including study co-leaders at the U.S. Army Medical Research Institute of Infectious Diseases, Florida Gulf Coast University, University of Oxford, Fred Hutchinson Cancer Research Center, Florida Department of Health and the Broad Institute of MIT and Harvard — collaborated in the investigation.
The research was funded by, among others, the National Institutes of Health, the Pew Charitable Trusts, U.S. Centers for Disease Control and Prevention, European Union Seventh Framework Programme, U.S. Agency for International Development Emerging Pandemic Threats Program and the Defense Advanced Research Projects Agency.
–City News Service