At least four babies have been born in New York City with Zika-related brain developmental symptoms since July, the city’s health department said Wednesday, bringing the total number of such births to five.
The numbers were announced in an alert the city’s Department of Health and Mental Hygiene sent to doctors, urging them to remain vigilant and to continue to warn pregnant women and sexually active women of reproductive age who are not using a reliable form of birth control against traveling to places where the virus is spreading.
It was a reminder that while the threat of the virus may have eased in many places around the world, it still poses a danger and its consequences are likely to be felt for some time.
Zika is primarily transmitted by mosquitoes but can also be passed on through sex. In most cases, the virus causes only mild illness, but the danger to women who are pregnant or trying to become pregnant is much greater, because of the impact the disease can have on fetal development.
A small percentage of women with the virus have given birth to infants with a abnormally small heads and stunted brain growth — a condition known as microcephaly.
As of Friday, about 8,000 New Yorkers have been tested for Zika and 962 have tested positive, including 325 pregnant women, according to the health department.
All the cases were associated with travel; six involved sexual transmission by a partner who had been to the areas hit hardest by the Zika epidemic.
In addition to the five babies with brain developmental symptoms, eight other infants have tested positive for Zika virus in New York City but have not shown evidence of what is being called congenital Zika virus syndrome.
Though much of the early focus of public health officials centered on children born with microcephaly, there is concern that the virus could cause a host of other developmental problems, including brain and eye abnormalities, shortened or hardened muscles and tendons, and neurological impairment.
“Today’s news is a reminder that Zika continues to be a threat to pregnant women and their babies,” said the city’s health commissioner, Dr. Mary T. Bassett.
“We are closely following all babies born to mothers who test positive for Zika infection and will connect parents to available services to improve their child’s quality of life,” she added.