Zika virus is spread to people through mosquito bites. 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. It is transmitted to people primarily through the bite of an infected Aedes species mosquito, that includes the Aedes aegypti mosquito, which also spreads dengue virus, yellow fever virus and Chikungunya. It can also be spread by Aedes albopictus mosquitoes, commonly known as the Asian Tiger Mosquito.
The most common symptoms of Zika virus disease are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting from several days to a week. Severe disease requiring hospitalization is uncommon. Zika virus is diagnosed through PCR (polymerase chain reaction) and virus isolation from blood samples. Diagnosis by serology can be difficult as the virus can cross-react with other flaviviruses such as dengue, West Nile and yellow fever.
The disease was first identified in Uganda in 1947. Outbreaks did not occur outside of Africa until 2007, when it spread to the South Pacific. It has been found recently in Latin America and the Carribean. In May 2015, the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infection in Brazil. Allegedly more than 4,000 babies in Brazil have reportedly been born with microcephaly. Microcephaly is a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age. Babies with microcephaly often have smaller brains that might not have developed properly. Moreover, it may be that 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, but this is rare. It is now being studied how some mothers can pass the virus to their babies. To date, there are no reports of infants getting Zika virus through breastfeeding. Because of the benefits of breastfeeding, mothers are encouraged to breastfeed even in areas where Zika virus is found.
Despite overwhelming reports about the correlation of the virus and pregnancy, more studies are needed to further characterize this relationship. Until more is known, CDC recommends special precautions for pregnant women and women trying to become pregnant. Moreover, just recently (February 5, 2016), CDC advised men who traveled in areas with Zika infection who have pregnant partners take extra precaution. This is based on a reported case of Zika virus spreading through sexual contact in Dallas County, Texas, where a person who had traveled to an area that had cases of the virus infected a partner who had not traveled.
In response to these reports, 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. The World Health Organization (WHO) has declared an international emergency over the disease.
Sources: Centers for Disease Control and Prevention (CDC)