The National Institutes of Health (NIH) announced its research priorities for studies to investigate how Zika virus infection affects reproduction, pregnancy and the developing fetus. Zika virus currently is circulating in about 30 countries and territories, notably in Latin America and the Caribbean. The virus has been linked to a spike in cases of microcephaly— an abnormally small head resulting from an underdeveloped and/or damaged brain — among newborn babies.

One of the highest priorities is to establish conclusively what role, if any, Zika virus has played in the marked increase in suspected microcephaly cases. In Brazil, more than 4,000 microcephaly cases have been reported since October 2015, up from 147 known cases in 2014. It is possible that these microcephaly cases could have another cause, or that a contributing factor in addition to Zika virus — another virus, for example — could be leading to the condition.

Given recent reports that Zika virus may be sexually transmitted, studies also are needed to determine if the virus is present in reproductive fluids, such as semen or vaginal secretions, and whether it can cause infection via the reproductive tract. Evidence from such studies might prove important in informing guidance for preventing the spread of Zika virus through intimate contact, particularly for women who are pregnant or likely to become pregnant. Additionally, these studies may indicate whether the virus poses a hazard for in vitro fertilization and other assisted reproductive procedures. Other studies of interest would investigate whether Zika virus infection affects long-term fertility in men and women and poses a risk for future pregnancies.

NIH also aims to modify ongoing studies to incorporate Zika virus research. For example, current studies of pregnant women and infants could be modified to check tissue samples for the virus and to look for potential health effects in those who were exposed.

The notice highlighting these research priorities was issued by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute of Allergy and Infectious Diseases, National Institute of Neurological Disorders and Stroke, and National Institute of Dental and Craniofacial Research. The new notice complements an earlier NIH announcement designed to spur Zika research to conduct basic research to better understand the virus and the disease it causes and to develop diagnostic tools, treatments and vaccines.