The association between Zika virus infection during pregnancy and severe birth defects has led to worldwide efforts to prevent more infections. Zika was first identified in 1947, with a geographical distribution primarily in tropical regions of Africa, Southeast Asia and the Pacific Islands. However, since 2015 we have seen the virus spread through South America, Central America, and the Caribbean. Spread to the southern half of the United States is possible, because the and mosquitoes that can transmit the virus to humans live in these regions as well. In late July 2016, the Florida Department of Health identified an area in one neighborhood of Miami with active transmission of Zika virus. Locally acquired cases have also been reported in the U.S. territories of Puerto Rico, Virgin Islands and American Samoa, as well as neighboring Mexico.

Although most infected people are asymptomatic, the critical issues with Zika infection are with its associated risks, namely severe birth defects and Guillain-Barré syndrome. The primary birth defect is microcephaly, a condition that reduces head size and is a sign of incomplete brain development, which can be accompanied by a host of severe outcomes, such as hearing loss, vision problems, developmental delays and intellectual disability. Guillain-Barré syndrome is an autoimmune disease that attacks the nervous system and can lead to muscle weakness, paralysis, and even death in about 5 percent of those affected. Several countries that have experienced Zika outbreaks recently have reported increases in people who have Guillain-Barré syndrome. This potential relationship is under further investigation by the U.S. Centers for Disease Control and Prevention (CDC). These potential complications of Zika infection are the impetus behind efforts to control and prevent the spread of Zika.

From an occupational health standpoint, industrial hygienists play an important role in protecting workers, their families, and their community from Zika. This is especially true for employees who work outdoors, travel to areas with Zika, or work in the healthcare sector. The focus of this article is on the preventive measures that can be taken by an organization whose workers may be at risk. Zika virus is an arbovirus (transmitted by arthropods) in the same genus as dengue fever, yellow fever, and West Nile viruses. Mosquito-borne transmission from an infected human to another human is similar to dengue and other similar species. The signs and symptoms of Zika infection are often mild if present at all, and only about 20 percent of infected individuals show any symptoms. Two to seven days following exposure (for example, a mosquito bite), mild fever, a rash, and/or joint pain may be observed. In addition, headache, conjunctivitis (red eyes), and muscle pain may be reported. The symptoms, if any, typically only last up to a week. Thus, Zika infections are largely underreported, facilitating its spread both regionally and worldwide.

Zika virus transmission is primarily associated with the and mosquitoes. and bite primarily during the day. These species are most active for approximately two hours after sunrise and several hours before sunset, but they can bite at night in well-lit areas. is common to urban tropical areas and many parts of the southern half of the United States. , known as the Asian tiger mosquito, is also common to urban areas and similar regions of the U.S., but the potential for transmission of Zika to humans is lower compared to . 

In addition to mosquito-borne transmission to humans, Zika virus can likely be transmitted as a blood-borne pathogen. Zika can also be transmitted sexually from an infected person to his or her partners. Blood transfusions, needle sticks, and contact with blood can transmit the virus. The virus can be found in the blood for about a week after initial infection. Zika remains in semen longer than in blood. Unfortunately, the actual period of communicability is unknown at this time. Lastly, the virus can be transmitted in the blood from a pregnant mother to her fetus, during pregnancy or at delivery. Protecting pregnancies from the devastating impact of Zika virus infection and potential severe outcomes is our primary concern.