As Zika continues to grab headlines in the Americas, a new study published in The Lancet medical journal says a stronger link has been found between the virus and microcephaly, particularly for women in the first trimester of pregnancy.
The research is based on data compiled during the Zika outbreak in 2013-14 in French Polynesia, say the authors from the Institut Pasteur in Paris. They estimate that the risk of microcephaly is about one for every 100 women infected with Zika during the first three months of their pregnancy. Microcephaly is a neurological abnormality that results in infants being born with abnormally small heads, often leading to intellectual disability, speech impairment and behavioural issues.
In February, the World Health Organization declared the suspected link between Zika virus and microcephaly to be a public health emergency of international concern. Brazil is the current hot spot and has been the site of spraying campaigns to combat the mosquitoes that carry the virus.
The outbreak in French Polynesia began in October, 2013, and ended in April, 2014, during which more than 31,000 people were believed to have been infected. The study says eight cases of microcephaly were identified – five pregnancies were terminated, and three children were born.
Authors Simon Cauchemez and Arnaud Fontanet said the information from French Polynesia helps quantify the risk of microcephaly during Zika outbreaks, such as the current one in South America, and "may help better inform the broader public health response." They noted that while infection with Zika virus often leads to mild symptoms, "its emergence in the Americas has also coincided with a steep increase in patients developing Guillain-Barré syndrome (an autoimmune disorder that causes acute or sub-acute flaccid paralysis)."
To reduce the risk of microcephaly, pregnant women and those of childbearing age should avoid travel to affected countries.