The US National Institutes of Health (NIH) and Fundacao Oswaldo Cruz-Fiocruz, a national scientific research organisation connected to the Brazilian Ministry of Health, have started a multi-country study to assess the risks posed by Zika virus on pregnant women.

Conducted in Puerto Rico, the Zika in Infants and Pregnancy (ZIP) study will later also be carried out in several locations in Brazil, Colombia, and other areas affected from active local transmission of the virus.

Transmitted mainly through infected Aedes aegypti mosquitoes bites, the Zika virus can also spread from mother to child or through sexual transmission.

The Zika virus has been linked to microcephaly, a condition under which babies are born with abnormally small heads and possible neurological damage.

Several other problems caused by the virus have also been found in pregnant women, and among fetuses and infants who are infected with Zika virus before birth.

Pregnant women can suffer from stillbirth, miscarriage, absent or poorly developed brain structures, eye defects, hearing loss, and impaired growth.

The study is being funded and conducted by Fiocruz in collaboration with NIH and its different units comprising the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), The National Institute of Allergy and Infectious Diseases (NIAID), and the National Institute of Environmental Health Sciences (NIEHS).

Fiocruz president Paulo Gadelha said: "This study, in partnership with NIH, is essential to elucidating the scientific complexity of the Zika virus.

"It will be fundamental to developing prevention and treatment strategies against the disease."

The researchers intend to compare birth outcomes between mothers who were infected with Zika virus and those who were not.

The study will also compare the risk of pregnancy complications among women who have symptoms of the Zika infection and those who are infected but do not have symptoms.

"This study, in partnership with NIH, is essential to elucidating the scientific complexity of the Zika virus."

Aside from this, the researchers will evaluate how the timing of the infection affects pregnancy outcomes and the role of environmental influences, social determinants and other infections, including dengue virus infection.

Pregnant women participating in the ZIP study will be monitored every month during the duration of their pregnancies and then six weeks after delivery.

They will also be instructed about the signs and symptoms of acute Zika virus infection and will have to notify their clinic immediately if they experience any such symptoms.

Even after delivery, a breast milk sample, if available, will be obtained for testing Zika virus.

Image: Electron micrograph of Zika virus. Photo: courtesy of CDC / Cynthia Goldsmith.