The Zika outbreak in Latin America may have peaked and could come to an end within three years, according to a predictive model examined in a paper recently published in the journal Science.
For the model, scientists focused on three factors key factors to predict the future arc of the Zika epidemic. The first factor is the speed of virus transmission, which was determined using available infection rates in nations with large-scale local transmission and data on mosquito population density. Second, researchers developed a timeline of the history of the current epidemic and, while assessing for future herd immunity, mapped a model for future waves of Zika transmission. Third, the researchers examined the large-scale connectivity of human populations to determine the spread of the virus.
The model predicts that the Zika virus outbreak in Latin America will likely subside within three years. After that, there will be a reprieve from any sort of Zika endemic for approximately 10 years.
"You can think of it like the forest after a giant fire," Justin Lessler, PhD, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore and one of the paper's authors, told NPR. "All of the extra brush is gone, and it's going to take a while before enough brush — or in the case of a disease, enough susceptible people — can build back up to support another fire."
In the U.S., according to the researcher's estimates, Zika will likely be a threat for a few summers to come, with this summer being the hardest hit. Bryan Lewis, PhD, a disease modeler at Virginia Tech in Blacksburg, told NPR this summer is likely to be the worst for Zika in the U.S. due to the import of travel-associated cases from Latin America. As the outbreak wanes internationally, so too will the amount of travel-related Zika cases in the U.S.
However, the new model has detractors. Michael Osterholm, PhD, director of the Center for Infectious Disease Research and Policy at the University of Minnesota in Minneapolis, pointed to the lack of information obtained by scientists about how Zika spreads as a flaw in the model.
"I think the model is a real overreach of the data we have," Dr. Osterholm told the Los Angeles Times. "I really believe the worst is yet to come with Zika throughout the Americas. It has not peaked."
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