The Zika virus has been rapidly on the move in Central and South America. With global travel on the rise and new cases being confirmed daily in Canada, Europe and the United States, chances are this may be a condition you encounter in your practice.
What is Zika virus?
The Zika virus (ZIKV) is a RNA virus first identified in 1947 by researchers in Uganda studying yellow fever and was named after the forest in which it was discovered.1-3 The first recorded human infection was in 1952, and the virus has caused sporadic human infections in areas of Africa and Southeast Asia over the last 60 years.2 In 2007, a large outbreak occurred in the Pacific Islands and was the first evidence of ZIKV outside of Africa.4 Subsequent years saw the virus spread quickly to surrounding areas before arriving in South America, particularly Brazil, in 2015 where it has been suspected to correlate with an increase in the birth defect microcephaly.5
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The majority of cases of ZIKV are acquired through the bite of a specific species of infected mosquito, Aedes Aegypti.2,4,6 However, there are documented cases of mother-to-newborn transmission during labor as well as viral spread via blood transfusions and sexual contact.3,7,8 More recently, the American Red Cross requests that potential donors who have traveled to areas where ZIKV infection is active to wait 28 days before donating blood.9
Sexual transmission of ZIKV is possible, although only a few cases have been documented. In two cases, the infected men transmitted the virus to their female partners. The third case documents replication-competent ZIKV isolated from semen at least two weeks after illness onset with no detectable levels of the virus remaining in the bloodstream. In all three cases, the men developed symptoms of ZIKV.10
It is not known if asymptomatic individuals can sexually transmit the virus, and there have been no reported cases of infected female transmission to partners.10 At this time, the Centers for Disease Control (CDC) recommends that men who reside in or have traveled to an area of active ZIKV transmission who are concerned about sexual transmission of the virus might consider abstaining from sexual activity or using latex condoms consistently and correctly during sex.11
The implications of local non-vector transmission could pose a serious public health concern, especially for women of childbearing age given evidence of perinatal transmission and congenital infection.12,13
The Aedes mosquito in question is no stranger to viral transmission—this particular mosquito species is known to spread other illnesses including dengue and chikungunya viruses.2,4 Like other flying pests of its kind, the Aedes mosquito lays eggs in and/or near standing bodies of water such as pet bowls, flower pots, and vases and can breed in and outside the home.7,14 Furthermore, this aggressive species feeds most actively during the day and has a preference for people (as opposed to livestock or other animals). The mosquito acquires the virus after biting an infected individual and may then spread the virus to other people.