Zika virus is spread primarily through the bite of an infected Aedes species of mosquito; it can also be sexually transmitted. The disease became a nationally notifiable condition in the United States in January 2016. One month later, the World Health Organization declared Zika virus a Public Health Emergency of International Concern in response to the clusters of microcephaly, or incomplete brain development, and other neurological disorders. The CDC is also researching whether Zika virus triggers early miscarriages and Guillain-Barre Syndrome. The latter is an uncommon sickness of the nervous system that can cause muscle weakness, nerve damage and possible paralysis or death. There is no vaccine or treatment for Zika virus.
The link of Zika to birth defects is the main impetus behind the CDC awarding nearly $60 million in August to states, cities, and territories to support efforts to protect Americans from Zika virus.As of July 21, 2016, 433 pregnant women have tested positive for Zika virus in the United States and District of Columbia. These women are part of the U.S. Zika Pregnancy Registry, recently formed by the CDC to monitor pregnant women with Zika and their infants.
“We are following women during and after pregnancy, as well as infants who survive,” said Dr. McQuiston. “We don’t know the long-term effects of fetuses who survive the virus. There might be cognitive effects or other developmental delays. We don’t know. Much research is still needed.”
As of July 27, 2016, 1,658 cases of Zika have been reported in the continental United States and Hawaii; none of these have been the result of local spread by mosquitoes, with fewer than 20 believed to be the result of sexual transmission and one as a result of a laboratory exposure. In U.S. territories, however, the numbers tell another story. As of this writing, Puerto Rico has 4,699 cases locally acquired.
“We have teams on the ground around the world as part of our education and prevention efforts,” said Dr. McQuiston. “In Puerto Rico, we are distributing Zika prevention kits containing mosquito repellent and other prevention tools. Ensuring women can prevent pregnancy if desired is also important.” The CDC advises men who travel and are exposed to the virus to use condoms or abstain from sex for six months. The virus can live in semen for months.
Women who are pregnant are warned not to travel to Zika-infected areas. As a precaution, women of child-bearing age are advised to wait eight weeks before trying to get pregnant after traveling to a Zika-infected country.
In 2015, large epidemics of the Zika virus have occurred in Brazil, Central America, some Caribbean islands and South America. As of February 2016, 34 countries and territories have active transmission of Zika virus, which can cause symptoms of fever, body aches and red eyes. Typically, most people do not become ill and may not realize they have been infected.
“We have known about Zika for a long time,” said Dr. McQuiston. “It was first identified in the 1940s in Uganda, but human infections were rarely reported. With the recent epidemic and more cases to study, we now see that devastating birth defects can be a possible outcome of Zika infection during pregnancy.”