Pope Francis said on Saturday that medical science is winning the war against the Zika virus. In the United States, three areas have reported their first locally acquired cases of the virus, which has been blamed for causing microcephaly, an abnormally small head, in children born to women infected while pregnant. But local transmission has not been confirmed in the continental United States. The entire northern and eastern third of the country are considered at little risk for Zika transmission.
Although Zika has been the target of international campaigns to prevent its spread, a report published Monday in the New England Journal of Medicine offers a new look at the virus’ history and its effects in the United States.
The study, led by scientists at the Centers for Disease Control and Prevention, included mice infected with Zika via sex, and found that infection led to a small, but detectable, drop in immune function. They noted that mice infected with the virus through sex showed no effect on immune function when infected only in the reproductive organs. Sex, the researchers wrote, may be a “new pathway” for transmission in humans and that, along with geography, could explain why this doesn’t seem to be happening in some U.S. regions.
The scientists also wrote that the effects of Zika infections in animals can be predicted by gene sequencing and by analyzing DNA across the entire population. And they also wrote that they expect Zika to be a significant threat in coming years. “It remains possible that a combination of the following factors will result in continued high infection rate, and continued spread into more communities in the U.S.,” they wrote. These factors are:
Expansion of mosquito-breeding zones that support the proliferation of mosquitoes capable of transmitting Zika virus
Increased mosquito exposure in Southern and Midwestern regions
Maintaining and improving preparedness for Zika, though improvements are possible
Modifying travel preferences
Reporting sexual transmission on a larger scale in the United States “would have a significant impact on rates of infection in the general population, and could also likely lead to adverse health outcomes.”