Two new studies, conducted throughout ten countries, have found that overall, women are 60-90% more likely to contract the Zika virus than men of the same age – despite both sexes having equal exposure to mosquitoes. In some countries such as Columbia, the numbers spike drastically, showing that women there are 300% more likely to contract the virus than men. Though scientists are not completely certain what contributes to these statistics, the leading cause is thought to be sexual intercourse.
It has long since been known that Zika can be transmitted sexually. However, new data shows that Zika can remain active in men’s semen for several months after contracting the virus – even in men demonstrating the most mild of symptoms. On this flip side, there is no evidence that Zika transfers from female to male. Meaning that an infected women who has sex will not transfer the virus to the man, but an infected man who has sex with a women will almost certainly transfer the virus.
For this reason, it is widely presumed that sex is now one of the leading drivers of Zika among young women in South America. Other medical experts, such as Donald A. Berry, a leading bio-statistician at the University of Texas, call the studies misleading. For example, mass amounts of women in south America live in fear of contracting the virus, therefore regularly get themselves tested. Since men cannot bear children, and the effects of Zika on their bodies are of less consequence than women, rarely, if ever, do men seek out to be tested.
According to Berry, the fact that so many more women get tested than men, could cause an artificial inflation in statistics – such as is seen in the two most recent studies. A second study on bio-statistics recently published in The New England Journal of Medicine seems to back up Mr Berry’s conclusions.
The Center for Disease Control notes how up to 80% of Zika infections are asymptomatic; 50% of pregnant women who have ended up testing positive for Zika in the United States, were completely unaware they had contracted the disease. For these reasons, the CDC concludes that the spread of Zika around the America’s may be more prevalent than the statistics suggest. The CDC advocate for comprehensive randomized testing throughout the America’s in order to reveal the true extent of the epidemic.