What is Zika fever?

Zika fever, or Zika virus disease, is spread to people through the bite of an infected mosquito. The most common symptoms of the disease are fever, rash, joint pain and red or inflamed eyes. Cases are typically mild and last several days to 1 week. Severe cases leading to hospitalization are rare.

While the disease has historically been limited to Africa, Southeast Asia and the Pacific Islands, the Pan American Health Organization reported the first case of Zika fever in Brazil in May 2015. Since October 2015, the disease has spread to Barbados, Bolivia, Colombia, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname and Venezuela, according to the Pan American Health Organization. The disease is likely to spread into more countries, the CDC said, including the United States. While no reported cases have originated in the U.S., it has been seen in an increasing number of American travelers returning home from abroad.

In November 2015, Brazil’s ministry of health linked Zika virus to several deaths and a vast increase in the number of infants with microcephaly, a birth defect in which a newborn’s head circumference is smaller than average. There have been more than 3,800 reported cases of microcephaly in Brazil since October, the ministry reported, far surpassing the annual average incidence of 160 cases. Microcephaly can lead to developmental and life-threatening problems, according to the CDC. A preliminary analysis suggested that the greatest risk for microcephaly is associated with infection during the first trimester.

For 2015, Brazilian officials estimated between 440,000 and 1.3 million cases of Zika in their country, according to an MMWR report.

The CDC recommends that pregnant women, regardless of trimester, should postpone travel to the areas with ongoing Zika virus transmission.

Transmission

Zika virus is spread chiefly through the bite of an infected mosquito of the Aedes species, the same type of mosquito that has been known to carry chikungunya and dengue fever. The species is aggressive and known to bite during daylight hours.

The virus remains in the blood during the first week of infection, and can be passed to another mosquito during this time. Transmission from mother to child at birth is rare. There is at least one case of the Zika virus spreading through sexual contact.

Symptoms

About 20% of persons infected will become ill from the virus. Other than the most common effects, symptoms include muscle pain, headache, pain behind the eyes and vomiting. No deaths have been recorded.

These symptoms are similar to that of dengue fever and chikungunya.

Treatment and prevention

There is no vaccine or medication that specifically treats or prevents Zika fever. The CDC advises patients get plenty of rest and fluids. Medication typically used to treat fever and pain can be helpful. Symptomatic patients, however, should avoid aspirin and nonsteroidal anti-inflammatory drugs until dengue can be ruled out.

For pregnant women who must travel to areas of high Zika transmission, the CDC recommends taking precautions to prevent mosquito bites. This includes:

wearing long-sleeved shirt and long pants;
using mosquito repellents with at least 20% DEET;
remaining in screened or air-conditioned rooms;
using a bed net when sleeping in an area exposed to the outdoors; and
eliminating or limiting areas of standing water to prevent mosquito breeding.

Patients with Zika fever should guard against being bitten by a mosquito during the first week to prevent spreading the virus.

Additional information:

http://www.cdc.gov/zika/index.html