More on the Zika Virus

Aedes aegypti mosquito (CDC)

Here is some more general information on the Zika virus. More information continues to emerge about this infection and the below represents a general understanding of these infections to date. 

Zika virus was first discovered in Uganda in 1947 and subsequently spread to Southeast Asia. There were outbreaks in Micronesia in 2007 and French Polynesia in 2013-2014. In May 2015 it was discovered in Brazil and now has been reported from numerous countries in South America, Central America and the Caribbean. Like Chikungunya before it, widespread infection in these areas is anticipated/ being documented. It is believed up to 4 million people in the Americas may ultimately become infected. 

Zika virus is primarily transmitted via the bites of day-biting Aedes mosquitoes, especially Aedes aegypti. These mosquitoes do exist in the United States but mostly reside in tropical and sub-tropical regions. Aedes albopictus mosquitoes are distributed more widely in the United States and are believed to be able to carry Zika virus as well but have not been implicated to the same extent as Aedes aegypti in the current outbreak. 

Only approximately 20% of people who become infected with Zika manifest symptoms. These

CDC

symptoms may include low-grade fever, conjunctivitis, rash and joint pains. These symptoms usually occur 2-12 days following a bite by an infected mosquito and symptoms typically resolve within 2-7 days. The major concern is a link to microcephaly in infants born to mothers who became infected while pregnant. In Brazil nearly 4,000 cases of microcephaly have been reported since October 2015, a greater than 20 fold increase over background microcephaly incidence. 

Zika virus infection was reported via sexual transmission (presumably via infected semen) in Texas; this is the third case of reported Zika virus transmission via sexual transmission to date. The CDC is currently recommending women who are pregnant (or trying to become pregnant) avoid travel to areas where active Zika virus transmission is occurring. They are also recommending that men who travel to transmission risk areas wear condoms for a time while in and after leaving these areas or abstain from sex. Although Zika virus appears to clear fairly rapidly from the blood of infected people it is unclear how long it may persist in semen. More information is needed to help better counsel people who have been in areas with ongoing Zika virus transmission.