A multi-institutional study that included researchers from the University of Washington suggests that the Zika virus may pose a greater threat of miscarriages than previously recognized.
The study, published July 2 in Nature Medicine, found that one in four nonhuman primates infected with Zika early in pregnancy experienced miscarriage or stillbirth, even though the animals showed few signs of infection.
“This research shows that Zika virus must now join the ranks of malaria and syphilis as a preventable infectious cause of stillbirth,” said Dr. Kristina Adams Waldorf, professor of obstetrics and gynecology at the UW School of Medicine. She’s also an adjunct professor in the department of global health, which bridges the University of Washington Schools of Medicine and Public Health.
“Reducing the number of preventable stillbirths in the world will mean that we must prevent Zika virus infections in pregnant women,” she added. “We must continue to send the public health message that women and their sexual partners should avoid travel to areas with local mosquito transmission of Zika virus during pregnancy and prior to conception.”
The study’s lead author was Dr. Dawn Dudley, senior scientist in the department of pathology and laboratory medicine at the University of Wisconsin-Madison. Other collaborators from the University of Washington were Dr. Michael Gale Jr., professor of immunology and adjunct professor of global health, and Dr. Lakshmi Rajagopal, associate professor of pediatrics and adjunct associate professor of global health. Dr. Charlotte Hotchkiss, a veterinarian at the Washington National Primate Research Center, was also a co-author.
The Zika virus is spread primarily through the bite of an infected mosquito, but also from the mother to the fetus during pregnancy, and through sexual contact. Symptoms of infection include rash, conjunctivitis, headache, and joint and muscle pain. These symptoms tend to be mild and, in many cases, the infection causes no symptoms at all. However, thousands of pregnant women who became infected gave birth to children with severe neurological damage, abnormally small heads, eye and limb malformations and other disorders, collectively known as the Congenital Zika Syndrome.
A rapid scientific response to address this global threat led to development of animal models of Zika virus infection to understand the spread of disease and to test vaccines. Scientists noticed an unexpected number of stillbirths after an experimental infection with the Zika virus.
They aggregated data from six National Primate Research Centers across the United States and found that, following Zika virus infection of the mother, the fetus died in 13 of 50 animals studied (26 percent). This was significantly higher than the 4 percent to 11 percent rates of miscarriage and stillbirth among uninfected animals housed in the primate centers.