Mosquito bite
In February, the World Health Organization (WHO) declared the Zika virus outbreak a public health emergency of international concern. Carried by mosquitoes, the disease has been spreading quickly through the Americas. The virus’ outbreak coincided with an abnormally large number of birth defects, and it is feared the two may be connected. In response, the Centers for Disease Control and Prevention (CDC) has issued travel notices for people traveling to regions and certain countries where Zika virus transmission is ongoing.
WHO warned there could be as many as 4 million new infections this year. Director General Dr. Margaret Chan said there was not definitive proof the birth defects and the virus were linked, but she said the level of alarm was high. There have been about 4,000 cases of microcephaly, or babies born with small brains, since October in Brazil.
There is no treatment for the disease. Asked about a timeframe for a vaccine, WHO Deputy Director General Bruce Aylward said, “We could probably have something in a phase one trial in four to six months, and then have something available in a year.”
The most common symptoms of Zika virus disease are fever, rash, joint pain and conjunctivitis. The illness is usually mild, with symptoms lasting from several days to a week. Severe disease requiring hospitalization is uncommon.
Affected areas
Prior to 2015, Zika virus outbreaks have occurred in areas of Africa, Southeast Asia and the Pacific Islands. The first Zika virus infections in Brazil were confirmed in May 2015, and outbreaks are currently occurring in many South and Central American countries.
With the recent outbreaks, the number of Zika cases among travelers visiting or returning to the U.S. has increased, resulting in local spread of the virus in some areas of the U.S. The first locally transmitted Zika case in the continental U.S. was reported in February, and since then at least seven counties in Florida have declared a public health emergency due to the virus’ spread. Those who are at risk of having been exposed to the virus are recommended not to donate blood for at least four weeks after the date of their potential exposure.
Transmission
Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito. These are the same mosquitoes that spread dengue and chikungunya viruses.
Mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites.
Rarely, a mother already infected with Zika virus near the time of delivery can pass on the virus to her newborn around the time of birth. It is also possible Zika virus could be passed from mother to fetus during pregnancy. This mode of transmission is currently being investigated. Finally, spread of the virus through blood transfusion and sexual contact has also been reported.
Prevention
Unfortunately no vaccine exists yet to prevent Zika virus. It is recommended you prevent Zika infection by avoiding mosquito bites, especially during the daytime. When spending time in areas where Zika virus or other viruses spread by mosquitoes are found, take the following precautions:
- Wear long-sleeved shirts and long pants.
- Stay in places with air conditioning or that use window and door screens to keep mosquitoes outside.
- Sleep under a mosquito net if you are overseas or outside and are unable to protect yourself from mosquito bites.
- Use EPA-registered insect repellents. Always follow product label instructions and reapply insect repellent as direct-ed. Do not spray repellent on the skin under clothing.
- Treat clothing and gear with permethrin or purchase permethrin-treated items. If treating items yourself, follow the product instructions carefully. Do not use permethrin products directly on skin; they are intended to treat clothing.
For more information, visit www.cdc.gov/zika or call (800) CDC-INFO [232-4636].
