Zika virus is primarily spread through the bites of infected mosquitoes. Mosquitoes can become infected when they bite infected persons and can then spread the Zika virus to other persons they subsequently bite.
Zika virus historically has been found in Africa, Southeast Asia, and the Pacific Islands. The first case was identified in the Zika Forest in Uganda in 1947.1 In 2015, cases of Zika virus infection emerged in the Americas and the Caribbean.
Zika virus has the potential to spread anywhere that mosquitoes capable of spreading this virus are found. Aedes species mosquitoes are a principal vector (i.e., carrier) of Zika virus in the U.S. Aedes aegypti (commonly known as yellow fever mosquitoes) are typically concentrated in the southern U.S. as well as parts of the Southwest. Another vector for Zika virus is Aedes albopictus (commonly known as Asian Tiger mosquitoes), which are found in much of the southern and eastern part of the U.S. Aedes mosquitoes can also carry other arboviruses, including dengue, yellow fever, chikungunya, Japanese encephalitis, and West Nile. CDC provides information about surveillance of Aedes mosquitoes in the U.S.
Current science-based evidence suggests that approximately one out of five infected people develops symptoms of Zika virus, usually beginning 2-7 days after the bite of an infected mosquito. Symptoms are usually mild and can last 2–7 days. The most common symptoms of Zika virus infection are fever, rash, joint pain and red or pink eyes. Other symptoms include myalgia (muscle pain) and headache. These symptoms are similar to those of dengue fever or chikungunya. Neurological and autoimmune complications are infrequent but have been described in outbreaks in Polynesia and, more recently, Brazil.
During the first week of infection, Zika virus can be detected in the blood and is capable of being spread from an infected person to a mosquito that feeds on that person. Infected mosquitoes can then spread the virus to other people through bites. In some instances, having direct contact with infectious blood or other body fluids (such as semen through sexual transmission) of an infected person may result in transmission of the virus.
Zika virus can be spread from a pregnant woman to her fetus and has been linked to a serious birth defect of the brain called microcephaly in babies of mothers who had Zika virus while pregnant. Other problems have been detected among fetuses and infants infected with Zika virus before birth, such as absent or poorly developed brain structures, defects of the eye, hearing deficits, and impaired growth. CDC recommends special precautions for women who are or may become pregnant.
In areas affected by Zika virus transmission, protect yourself and others from possible exposure to Zika virus by always taking steps to prevent mosquito bites. There is no vaccine to prevent Zika virus and there is no specific treatment for individuals who become infected.
Although Zika virus is generally spread by the bites of infected mosquitoes, exposure to an infected person’s blood or other body fluids (such as semen through sexual transmission) may also result in transmission. Employers should train workers about their risks of exposure to Zika virus through mosquito bites and direct contact with infectious blood and other body fluids and how to protect themselves. Employers should also provide information about Zika virus infection, including modes of transmission and possible links to birth defects, to workers who are pregnant or may become pregnant or whose sexual partners are or may become pregnant. Outdoor workers may be at the greatest risk of exposure to Zika virus. Some workers, including those working with insecticides to control mosquitoes and healthcare workers who may be exposed to contaminated blood or other potentially infectious materials from individuals infected with Zika virus, may require additional protections (e.g., certain types of personal protective equipment, PPE). Employers must comply with universal precautions for potential bloodborne pathogens (BBP) exposures, as described in OSHA’s BBP standard (29 CFR 1910.1030), and any applicable requirements in OSHA’s PPE standards (29 CFR 1910 Subpart I), among other OSHA requirements.
Consult the CDC Zika website for the most up-to-date information to help employers implement effective worker protections.
Recommended employer actions:
Recommended worker actions:
Guidance on use of insect repellents for employers and workers:
Employers and workers in healthcare settings and laboratories should follow good infection control and biosafety practices (including universal precautions) as appropriate, to prevent or minimize the risk of transmission of infectious agents (e.g., Zika virus). Always follow universal precautions for potential BBP exposures, as described in OSHA’s BBP standard (29 CFR 1910.1030). In healthcare, standard precautions can be used to expand the universal precautions required by the BBP standard by adding several protections (including expanded PPE) not covered by the BBP standard. Standard precautions include, but are not limited to, hand hygiene and the use of PPE to avoid direct contact with blood and other potentially infectious materials, including laboratory specimens/samples. PPE may include gloves, gowns, masks and eye protection.
Hand hygiene consists of washing with soap and water or using alcohol-based hand rubs containing at least 60 percent alcohol.3 Soap and water are best for hands that are visibly soiled. Perform hand hygiene before and after any contact with a patient, after any contact with potentially infectious material, and before putting on and upon removing PPE, including gloves.
Laboratories should ensure that their facilities and practices meet the appropriate Biosafety Level (BSL) for the type of work being conducted (including the specific biological agents – in this case, Zika virus) in the laboratory. CDC has specific Biosafety Guidance for the Transportation of Specimens and for Work with Zika virus in the Laboratory. The Biosafety in Microbiological and Biomedical Laboratories (BMBL), 5th Edition also provides detailed
guidance on biosafety when working with arboviruses, including Zika, in Section VIII – F: Arboviruses and Related Zoonotic Viruses. Laboratories should handle Zika virus at BSL-2, including limiting access to laboratories and other work areas when work is occurring and conducting certain procedures in biosafety cabinets or other containment equipment. Some procedures may require BSL-3 precautions, including additional respiratory protection, based on the risk assessment of the proposed work.4 The BMBL guidance also describes BSLs in Section IV - Laboratory Biosafety Level Criteria (PDF).
Additionally, employers should ensure that workers:
Employers should consider enhanced precautions in situations where workers are at increased risk of exposure to Zika virus or other hazards. CDC recommends healthcare workers use standard precautions during patient care regardless of suspected or confirmed Zika infection status.5 While there is no evidence of Zika transmission through aerosol exposure, minimizing the aerosolization of blood or body fluids as much as possible during patient care or laboratory tasks may help prevent workers from being exposed to other pathogens. Additional protections, including engineering controls to ensure containment of pathogens or enhanced PPE to prevent or reduce exposure, may be necessary during any aerosol-generating procedures or other such tasks.
When working outdoors, follow the same precautions recommended above for general outdoor workers for protection against mosquito bites. Workers performing tasks related to mosquito control may need additional protection, depending on their job tasks.
Workers entering or working around areas with dense mosquito populations, such as ponds and other locations with standing water, may need enhanced skin protection to prevent mosquito bites. Employers should assess such workers’ risks of mosquito bites, and consider providing any additional protective clothing to fully cover workers’ exposed skin.
Workers who mix, load, apply, or perform other tasks involving wide-area (or area) insecticides may need additional protection to prevent or reduce exposure to hazardous chemicals.
The EPA regulates pesticide safety use through the Agricultural Worker Protection Standard (WPS). Although the WPS is a regulation for agricultural pesticides aimed at reducing the risk of pesticide poisonings and injuries among agricultural workers and pesticide handlers, its requirements may provide a model for protecting workers using insecticides in mosquito control operations. The EPA WPS page provides information on pesticide safety training, notification of pesticide applications, use of PPE, restricted-entry intervals after pesticide application, decontamination supplies, and emergency medical assistance.
Workers conducting mosquito control operations with insecticides may require respirators, which must be used in accordance with the respirator selection, medical clearance, fit-testing, and other requirements of OSHA’s Respiratory Protection standard (29 CFR 1910.134). Employers should monitor use of respirators by any worker who must drive vehicles (e.g., trucks used for insecticide application) to ensure that respirator use does not restrict the worker’s ability to operate the vehicle safely. OSHA’s Safety and Health Topics page on Respiratory Protection provides general information on respirator use and OSHA standards that may apply to the use of other chemicals.
Employers also must comply with any applicable requirements in OSHA’s PPE standards (29 CFR 1910 Subpart I), among other OSHA requirements.
CDC advises individuals, including workers, infected with Zika virus to6:
Paragraph 11(c) of the OSH Act, 29 USC 660(c), prohibits employers from retaliating against workers for raising concerns about safety and health conditions. OSHA encourages workers who suffer such discrimination to submit a complaint to OSHA. Workers have 30 days from an alleged reprisal to file their complaints.
When traveling to or through Zika-affected areas, follow the precautions described above for specific work activities. CDC guidance for travel to Zika-affected areas may also help employers and workers in travel-related operations, such as airlines, airline crew members, and cruise line workers take appropriate protective actions.
Employers should consider allowing flexibility in required travel for workers who are concerned about Zika virus exposure. Flexible travel and leave policies may help control the spread of Zika virus, including to workers who are concerned about reproductive effects potentially associated with Zika virus infection.
Consider delaying travel to Zika-affected areas, especially for workers who are or may become pregnant or whose sexual partners may become pregnant. CDC recommends that pregnant women in any trimester not travel to an area with active Zika virus transmission. CDC has published Zika Travel Information by region, which may assist workers and employers in making travel-related decisions or implementing precautions when traveling. Pregnant women, women who may become pregnant, and men with sexual partners who are or may become pregnant should consult with their healthcare providers about risks associated with Zika virus infection during pregnancy. More information can also be found on the CDC Zika and Pregnancy website.
Even if they do not feel sick, travelers returning to the United States from an area with Zika should take steps to prevent mosquito bites for three weeks so they do not pass Zika to mosquitoes that could spread the virus to other people. CDC provides information on mosquito bite prevention for travelers (PDF).
1. Hayes, Edward B. “Zika Virus Outside Africa,” Emerging Infectious Diseases, 15, 9, 1347–1350 (2009).
2. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, “CDC Health Information for International Travel, 2016 (Yellow Book).”
3. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, “Show Me the Science – When to Use Hand Sanitizer.”
4. U.S. Department of Health and Human Services, “Biosafety in Microbiological and Biomedical Laboratories (BMBL), 5th ed.”
5. Healthcare Infection Control Practices Advisory Committee, “2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings,” Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Human Services (HHS).
6. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, “Zika Virus – Symptoms, Diagnosis, & Treatment.”
*Accessibility Assistance: Contact OSHA’s Directorate of Technical Support and Emergency Management at (202) 693-2300 for assistance accessing PDF materials.
This document is not a standard or regulation, and it creates no new legal obligations. It contains recommendations as well as descriptions of mandatory safety and health standards. The recommendations are advisory in nature, informational in content, and are intended to assist employers in providing a safe and healthful workplace. The Occupational Safety and Health Act requires employers to comply with safety and health standards and regulations promulgated by OSHA or by a state with an OSHA-approved state plan. In addition, the Act’s General Duty Clause, Section 5(a)(1), requires employers to provide their employees with a workplace free from recognized hazards likely to cause death or serious physical harm.
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