The Middletown Press (Middletown, CT)
Monkey study suggests greater Zika risk
Miscarriage in people infected with the mosquitoborne Zika virus might be more commonly than previously thought, according a new study funded by the National Institutes of Health.
According to the study, published in Nature Medicine, fetal death in utero occurred in more than one-fourth of monkeys infected in the laboratory with Zika virus in early pregnancy.
Zika virus is most often transmitted to humans via the bite of an infected Aedes aegypti mosquito. It also is transmitted sexually, and can be passed from a pregnant woman to her unborn child.
Many people infected with Zika virus will not have symptoms; others may have fever, rash, headache, joint pain, red eyes, and muscle pain. In pregnant women, Zika infection can carry serious consequences in the fetus, including a range of birth defects collectively known as congenital Zika syndrome.
Although Zika virus was first discovered in 1947, Zika-related birth defects were not reported until 2015, during a large outbreak of Zika in the Americas.
During that outbreak, more than 5,000 people in the United States were infected, including roughly 100 in Connecticut. None of those who tested positive for Zika in Connecticut — which included 10 pregnant women — acquired the illness locally. In addition, another 63 people — including 49 pregnant women — tested positive for flavivirus, a larger class of viruses that includes Zika as well as West Nile virus and other illnesses.
According to a release from the National Institutes of Health, a team of experts aggregated data on Zikainfected macaques from six National Primate Research Centers in the United States for the new analysis.
The study was funded in part by the National Institute of Allergy and Infectious Diseases and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, both components of the National Institutes of Health.
No licensed treatments or vaccines for Zika virus are currently available, but many are in various stages of development.
Research recently published in the New England Journal of Medicine showed a 5.8 percent miscarriage rate and a 1.8 percent stillbirth rate in a group of pregnant women with symptomatic Zika infection in French Guiana, Guadalupe and Martinique. Authors of the new non-human primate analysis note that the NEJM study included only symptomatic pregnant women, whereas many people with Zika infection don’t have symptoms.
For the new analysis, experts combined published and unpublished data from various studies of pregnant macaques infected with Zika virus. Miscarriage or stillbirth occurred in 13 of 50 (26 percent) of the animals studied. Macaques infected early in pregnancy had significantly higher rates of fetal death than those infected after gestation day 55.
The results track with human data showing more severe fetal outcomes in women infected with Zika in their first trimester compared to those infected later in pregnancy.
According to the study authors, the rates of fetal death in macaques underscore the need for careful monitoring of fetal loss and stillbirth in Zika-affected human pregnancies.