BACKGROUND: The first outbreak of autochthonous Zika transmission in the continental United States was recognized when two Zika positive individuals working within 120 meters of each other were identified. Further investigation at these workplaces identified five additional infected individuals at one and an infected customer of the business at the other. Occupation is routinely collected through the course of the Florida Department of Health’s (DOH) investigations, case work locations and type of workplace were tracked in order to identify potential clusters of cases as well as to identify populations for targeted education.
METHODS: Case workplaces were surveyed if other coworkers reported a Zika-like illness. In some cases, testing was also done for outside workers at six surrounding businesses and two concerned businesses that requested testing. The survey consisted of a short questionnaire related to mosquito exposures at work, recent Zika-like illness, and general Zika risk factors. A urine sample was collected and tested at the state public health laboratory using polymerase chain reaction testing. In some cases, serum and sometimes whole blood were also collected from employees reporting symptoms more than two weeks prior to the interview.
RESULTS: A total of 15 workplace investigations took place during the course of the local investigations, including four construction sites, four semi-open workplaces that left their doors open, four hotel/condo properties, one open-air business, and two enclosed spaces (including one with doors that frequently opened). Overall, there were seven index cases and an additional 422 people were tested with 21 people at six businesses testing positive. In addition, workplace exposures were suspected in 66 individual cases. Of the 252 local cases reported in Florida as of December 18, 37% were potentially linked to the workplace. The most common jobs associated with potential Zika exposure included construction workers, outdoor restaurants, valet attendants, and retail workers.
CONCLUSIONS: These investigations highlight the potential risk for mosquito exposure at the workplace, particularly at workplaces with open-air areas. Health departments should collect information on occupation and workplace as part of ongoing Zika case investigations. Even workplaces without an easily identifiable work-associated location where mosquitoes may be present can still be at risk; break areas, employee parking locations, and other opportunities to be bitten by mosquitoes should also be taken into consideration. Collection of occupation and possible risk for mosquito exposures at work as part of surveillance can facilitate identification of focal mosquito-borne disease activity.