This week’s post is an update on Zika virus. Since my initial post there have been more developments leading to a better understanding of the condition although the problem of Zika spread remains to play out. Some new information will be highlighted below:
- Zika virus is spread through the mosquito bites of Aedes Aegyptii (African) and Aedes Albopictus (Asian) species. They prefer warm climates and do not survive at altitudes > 6500 ft. They are both present in the US, primarily along the Gulf coast.
NEW: Zika spread between humans has also been confirmed through unprotected sexual contact (Vaginal, anal). Women are recommended to avoid pregnancy for 8 weeks after returning from areas of disease activity regardless of symptoms. Men returning from endemic areas are recommended to avoid unprotected sexual contact (Vaginal, anal and oral) for 8 weeks if no symptoms and for 6 months if symptoms are experienced. Men returning from endemic areas with symptoms should avoid unprotected sex for the entire term of their partner’s pregnancy.
- Only 1:5 people have symptoms due to infection. Nevertheless a pregnant woman can have fetal effects with an asymptomatic infection.
NEW: The risk of microcephaly due to infection during pregnancy is estimated at 1:100. This data comes from the recent spread of Zika through French Polynesia (Oct. 2013 -Apr 2014). The greatest risk of microcephaly is still thought to be due to infection during the first trimester. This is good news. However there is also some concern raised about the fetal effects of Zika infection during the 2nd or 3rd trimester related to deafness, visual problems, mental retardation and stillbirth. Not such good news.
- What should a pregnant woman do?
As of March 2016 US officials have recommended all pregnant women who visited a Zika endemic area to get blood test for the virus regardless of symptoms. An Ultrasound looking at fetal head size and presence of calcification so is also recommended. (See link -MMWR) Any questions regarding testing during pregnancy should be directed to your OB-GYN or Infectious Disease specialist.
Overall the spread of Zika is a scary proposition, but one that should be approached with sound scientific knowledge and public health measures. Like the hitchhiker’s guide says: ‘Don’t Panic!’ It is likely that this outbreak will continue and even reach mainland US, perhaps as early as this summer. Below is a map of some of the most likely places to be infected first.
Scientists are working on a vaccine and a mouse model of disease has recently been discovered which should help in testing any candidate vaccines.
I am happy to answer any questions regarding Zika that you may have. Questions of testing during pregnancy should be directed to your OB-GYN or Infectious Disease specialist.
The NY Times posted a good article last week if you’d like additional information; nytimes.com – Short Answers to Hard Questions About Zika Virus
In good health!
Paul Miller, MD