WASHINGTON, D.C. (CNN) – Thirty-three members of the U.S. military have contracted the Zika virus overseas in countries where the virus has been identified, according to the Pentagon.

One of the military servicemembers is pregnant. Under Pentagon health policies, female servicemembers are permitted to move out of countries where Zika exists.

An additional six people who have military personnel in their families have also been infected, according to Maj. Ben Sakrisson, a Pentagon spokesman. He could not say how many are still ill or how many have returned to the United States.
The Pentagon began tracking the number of personnel with Zika earlier this year.

Military personnel are advised to follow the same rules as civilians to protect themselves in mosquito-infested areas, such as wearing appropriate clothing and using insect repellant.

The Army is collaborating with outside partners to develop a Zika virus vaccine, according to the Walter Reed Army Institute of Research. Walter Reed is working with Sanofi Pasteur, a major vaccines developer and manufacturer.