As the global community races to better understand the Zika virus, the World Health Organization (WHO) has called on Cornell nutritional sciences professors Julia Finkelstein and Saurabh Mehta to lead an international team of experts to quickly review the risk of transmitting Zika virus through breastfeeding. There is currently no effective vaccine or treatment for Zika virus infection and only limited diagnostics.

The WHO will use the team’s findings, as well as other studies and resources, to inform its forthcoming emergency guidelines on feeding infants during a Zika virus outbreak.

In the meantime, the researchers have found no evidence to suggest that the risks of a mother potentially transmitting the virus to her child via breastfeeding outweigh the benefits of breastfeeding. Their findings were posted May 2 in the Bulletin of the World Health Organization.

But Finkelstein and Mehta caution that knowledge about the links between Zika virus infection and health outcomes are at a nascent stage and more studies and continued surveillance of breastfeeding practices among infected mothers are needed.

“It’s only been a few weeks since research has established that a Zika virus infection in a mother can cause microcephaly. Since the mother most often doesn’t show any symptoms, the potential numbers for how many mothers are really infected could be much greater,” said Finkelstein, the Follett Sesquicentennial Faculty Fellow and assistant professor of epidemiology and nutrition in the Division of Nutritional Sciences.

“We anticipate that people are going to start actively looking at Zika virus infection and breastfeeding transmission as better diagnostics become available and as knowledge about it is increasing around the world,” said Mehta, assistant professor of global health, epidemiology and nutrition and the senior and corresponding author of the study. The first author of the study is Susannah Colt, one of Mehta’s doctoral students in the field of nutritional sciences.

The research team conducted a systematic review of studies and surveillance reports in several international databases involving breastfeeding women infected with Zika virus. While the virus was detected in the breast milk of these mothers, the data were not sufficient to conclude that Zika virus is transmitted via breastfeeding. As with HIV, the virus could potentially be transmitted during pregnancy, labor or breastfeeding, Mehta said.

Zika virus is an emerging mosquito-borne infection linked to an increase in central nervous system malformations and microcephaly in newborns in which the brain does not develop properly, resulting in a smaller than normal head. Often people with microcephaly have an intellectual disability, poor motor function and speech, abnormal facial features, seizures and unusually short stature.

While it is estimated that only 1 in 100 cases in which the mother is infected with Zika virus result in the baby having microcephaly, other complications such as congenital abnormalities and brain malformations may be much more common, in 1 in 5 cases, Finkelstein said.

The Cornell researchers are seen as go-to experts on this major public health issue thanks to their ongoing work in two areas: HIV in pregnancy and breastfeeding, and research on similar viruses including dengue virus. And Cornell’s Division of Nutritional Sciences is a WHO/Pan American Health Organization Collaborating Centre for Nutrition, establishing it as a research and training partner in WHO’s public health and nutrition policies.

Finkelstein, an epidemiologist, is leading efforts in collaboration with the Centers for Disease Control and Prevention on large surveillance programs in southern India and coastal Ecuador to understand the risk factors for birth defects among women of reproductive age.

Mehta, a physician and an expert in infectious diseases, nutrition and epidemiology, has published studies on nutrition and HIV transmission during breastfeeding among HIV-infected women. Since joining Cornell, he has expanded his geographical scope from sub-Saharan Africa to include South Asia and Latin America. He also served as an expert on the WHO emergency guidelines committee formed in response to the Zika virus.

Targeting mosquito-borne infections like Zika virus is complicated, because the mosquito that carries the virus (Aedes aegypti) bites primarily during the day. As a result, established public health interventions to avoid mosquito bites, such as insecticide-treated bed nets, by themselves don’t work, Finkelstein said.

“We urgently need a holistic approach at every level, including better diagnostics, surveillance, prevention and public health interventions that include vaccines, vector control and effective treatment,” she said.