Zika could infect up to 1.65 million women of childbearing age in the first wave of the epidemic, a new study suggests.
Researchers refined earlier estimates of who’s at risk to arrive at a figure for people who might realistically become infected. They focused on women of childbearing age because Zika causes birth defects, including microcephaly, in newborns.
Women in South and Central America and the Caribbean are most at risk, according to the study. The largest number of infections is expected to be in Brazil, where athletes and spectators will gather next month for the Olympic Games.
“Projections such as these have an important role to play in the early stages of an epidemic, when planning for surveillance and outbreak response is actively under way both internationally and locally,” the researchers wrote in the journal Nature Microbiology.
Much of the concern about Zika has focused on South and Central America, where most of the children with birth defects have been born. But infections are also occurring in the United States and its territories.
The U.S. Centers for Disease Control and Prevention said at least 400 pregnant women in the United States have shown evidence of Zika infection. In most cases in this country, the virus has spread by sexual contact, but health officials recently reported the first U.S. case of direct transmission by mosquito bite.
The CDC has updated its guidance for preventing sexual transmission of the virus. For more information, visit the CDC site.
Projecting Zika’s spread
For most people other than women of childbearing age, Zika poses low risks. Often an infected person shows mild or no symptoms, and the infection passes within a matter of days.
To plot the potential spread of Zika, scientists from the U.K. and U.S. studied populations in small, local geographical areas. They acknowledge that their estimates are a best guess of how the first wave of the Zika epidemic will play out in the Americas.
"It is difficult to accurately predict how many child-bearing women may be at risk from Zika because a large proportion of cases show no symptoms,” said Andrew Tatem, the director of Flowminder, a foundation at the University of Southampton, in England. “This largely invalidates methods based on case data and presents a formidable challenge for scientists trying to understand the likely impact of the disease on populations."
More on Zika
You can read the researchers’ study here.
The CDC provides current information about:
- Areas where Zika is spreading
- Symptoms, testing and its own response plan
- Tips for those who are traveling to Rio de Janeiro for the Olympics and Paralympics.
The Providence To Your Health blog has kept readers up to date on Zika with these previous posts:
- Women can give Zika to men, health officials say
- As the number of pregnant women with Zika rises, CDC responds
- Two new studies: Zika virus can affect adults
If you plan to travel to Brazil, or have spent time with someone who may have been exposed to Zika, discuss the circumstances with your health care provider. To meet with a Providence provider, visit our directory of care givers and clinics.