Interim Guidance for Managing Occupational Exposures to Zika Virus for Healthcare Personnel

Introduction

Zika virus is primarily spread by the bite of an infected Aedes species mosquito. Sexual and maternal-fetal transmission have also been well described. Transmission via transfusion of blood products has been reported in Brazil, but to date, transmission of Zika virus via blood transfusion has not been reported in the United States. There is currently no clinical evidence that Zika virus is transmitted through the air.

In June 2016, there was a report of possible Zika virus transmission from an infected person to a family member in the United States; the exact mechanism of transmission and whether transmission occurred in the home or in a healthcare setting are unclear. There have been no reports of transmission of Zika virus from infected patients to healthcare personnel (HCP) or to other patients in healthcare settings. However, transmission related to occupational exposure to Zika virus has occurred in laboratory workers, including one in 2016 in which a research laboratorian became infected via a needlestick injury.

To prevent occupationally-acquired infections and reduce the possibility of spreading infectious diseases, including Zika virus, in healthcare settings, HCP should adhere to Standard Precautions for all patient care activities (2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings [PDF – 226 pages]). Employers must comply with the Occupational Safety and Health Administration’s Bloodborne Pathogens standard (29 CFR 1910.1030), or similar OSHA State Plan standards, whenever employees have occupational exposure to blood, body fluids, or other potentially infectious materials. If HCP have an occupational exposure (see 3. Definition of Occupational Exposure) while caring for a patient with known or suspected Zika virus infection, they should follow facility/employer procedures including an occupational health assessment for potential exposure to infectious diseases (including bloodborne pathogens, such as HIV, hepatitis B virus, and hepatitis C virus), in addition to evaluation for potential Zika virus exposure.

This document provides guidance for facilities to determine when HCP should be tested for Zika virus infection following an occupational exposure and recommendations for post-exposure management. This document does not address all occupational healthcare that might be required or the necessary evaluation or follow-up for occupational exposures to other infectious diseases (e.g., bloodborne pathogens). This guidance is not intended for laboratory researchers or laboratory research personnel. The recommendations in this document will be updated as new information becomes available.

Definition of Healthcare Personnel

HCP are defined as all paid and unpaid persons working in healthcare settings who have the potential for exposure to infectious materials, including blood and body fluids, contaminated medical supplies and equipment, or contaminated environmental surfaces. HCP include, but are not limited to, emergency medical services personnel, dentists and dental technicians, clinical laboratory staff with patient contact, autopsy personnel, environmental services staff, nurses, nursing assistants, physicians, physician assistants, technicians, phlebotomists, therapists, pharmacists, students and trainees, contractual staff not employed by the healthcare facility, and persons not directly involved in patient care but potentially exposed to blood and body fluids (e.g., clerical, dietary, security, and maintenance personnel who work in a clinical setting or potentially handle clinical materials).

Definition of Occupational Exposure

An occupational exposure that might place HCP at risk for Zika virus infection is defined as a percutaneous injury (e.g., a needlestick or cut with a sharp object) or direct contact of mucous membrane or non-intact skin (e.g., skin that is abraded, cut, or has active dermatitis) with blood, tissue, or other body fluids that are potentially infectious. Knowledge about the presence of Zika virus and viral ribonucleic acid (RNA) in blood or body fluids continues to grow; as of this publication, Zika virus has been detected by viral culture in several different body fluids including blood,^1-3 urine,^4-6 amniotic fluid,⁷ a conjunctival swab,⁸ breast milk,⁹ semen,^10-14 vaginal secretions,¹⁵ and saliva.^6,16 Zika virus RNA, which might not represent infectious virus, has also been detected by reverse transcription-polymerase chain reaction (RT-PCR) in cerebrospinal fluid,^17-20 aqueous humor,²¹ cervical mucous,²² and nasopharyngea^l4,23 and endocervical swabs.^18,22

Evaluating and Managing HCP with Possible Occupational Exposure to Zika Virus

Initial management

If a possible occupational exposure occurs, exposed HCP should follow the established work-site exposure procedures, including:

Immediately washing wounds and skin sites that have been exposed to blood or body fluids with soap and water, and immediately flushing mucous membranes with copious clean water.
Immediately reporting the exposure to the appropriate department and individual(s) (e.g., Occupational Health Clinic, supervisor).

Assessment of the exposure incident and determination of the need for Zika virus testing

Determine the nature of the exposure incident, including the type of body fluid(s) to which the HCP was exposed, route of exposure, and what body part of the HCP was exposed.
If it is determined that an occupational exposure has occurred (see 3. Definition of Occupational Exposure), assess whether the source patient has had a possible Zika virus exposure. Possible Zika virus exposure is defined as travel to or residence in an area with risk of Zika virus transmission or sex without a condom with a partner who traveled to or lived in an area with risk of Zika virus infection. The timing of potential infectivity of the sexual partner of the source patient is defined in other CDC guidance.
Determine if the HCP’s occupational exposure occurred within the risk period for transmission. Based on limited available data, an 8 week interval between Zika virus exposure in the source patient (via travel or sexual risk factors) and the HCP’s occupational exposure to body fluids (with the exception of semen)^§ provides a reasonable estimate of the likely occupational transmission risk period.^†
If an occupational exposure occurred and the source patient is potentially infectious as defined above, then the HCP should be considered to have a possible occupational exposure to Zika virus, and Zika virus testing of the exposed HCP should be performed if the exposed HCP is pregnant.
Zika virus testing of other, non-pregnant exposed HCP can be considered on an individual basis. The exposed HCP should be counseled about symptoms of Zika virus infection and advised to seek evaluation and testing if symptoms develop within 2 weeks of the exposure. Testing of the exposed HCP is described in more detail below (see 4E. Laboratory Testing of Potentially Exposed HCP).
When a possible occupational exposure to Zika virus has occurred, CDC recommends testing the source patient, when possible, in accordance with CDC recommended testing algorithms.
If a source patient does not have risk factors for Zika virus infection, Zika virus testing of the source patient and exposed HCP is not recommended.
Even if a source patient’s serum has detectable Zika-specific IgM antibodies and is negative by nucleic acid testing (suggesting lack of infectious virus), other body fluids could remain infectious (e.g. semen§), as the persistence of virus varies depending on the type of body fluid. This might be important for occupational exposures that involve body fluids other than blood. See guidance about interpretation of testing for Zika virus infection.

Clinical Management of HCP with possible occupational exposure(s) to Zika virus

At present, there is no post-exposure prophylaxis or immunization for Zika virus. If the exposed HCP develops signs or symptoms consistent with Zika virus infection within 2 weeks of exposure, he or she should be evaluated by a healthcare provider. Zika virus infection should be considered as part of the differential diagnosis and additional Zika virus testing should be considered if indicated.

Counseling of HCP with possible occupational exposure(s) to Zika virus

All exposed HCP should receive confidential counseling to address their health and safety concerns and their risk of transmission to others. All HCP with a possible occupational exposure to Zika virus should be advised to take the following actions/precautions:

Avoid mosquito bites for three weeks post-exposure by wearing long-sleeved shirts and long pants and using EPA-registered insect repellents if in an area with a competent mosquito vector to reduce the risk of further mosquito-borne transmission.
Use condoms or abstain from sex with a pregnant partner for the entire pregnancy.
Use a condom during sex or abstain from sex with a partner for at least 8 weeks after exposure for women and for at least 6 months after exposure for men before trying to conceive. Regardless of pregnancy intent, couples who want to minimize their risk for sexual transmission of Zika virus should use a condom or abstain from sex for the same time periods.

If the source patient (see 4.B.v.) or HCP (see 4.E. Laboratory Testing of Potentially Exposed HCP) tests negative for Zika virus infection, the exposed HCP does not need to continue with the precautions above.

Laboratory Testing of Potentially Exposed HCP

If laboratory testing for Zika virus infection of the exposed HCP is recommended or being considered, a serum sample should be obtained immediately after the exposure incident (baseline).

For asymptomatic HCP for whom testing is indicated, an additional serum sample should be obtained between 2 – 12 weeks post exposure. The baseline and follow-up serum samples should be tested for Zika virus-specific IgM antibodies and any positive result confirmed by plaque reduction neutralization test. However, results of baseline testing for Zika virus among HCP should be interpreted in the context of underlying risk factors such as geographic location, local transmission, and travel history.

If an exposed HCP develops signs and symptoms consistent with Zika virus disease ≤ 2 weeks from exposure, both a urine and serum sample should be collected from the HCP and tested in accordance with CDC recommended testing algorithms. If all testing is negative, consider obtaining an additional serum sample at >2 weeks post-exposure to further evaluate for infection.

If Zika virus testing of the HCP is negative at baseline and remains negative at >2 weeks post-exposure, no further Zika virus testing is recommended. Further, if the source patient has been tested for Zika virus infection and found to be negative, follow–up testing of the exposed HCP (i.e., at > 2 weeks) should generally not be required.

Any positive test results should also be interpreted according to the most recent guidance.

Managing HCP Who Develop Zika Virus Infection Following an Occupational Exposure

At present, there is no specific treatment for Zika virus infection. Infected HCP should receive or be referred for appropriate counseling and care. See interim guidance on caring for pregnant women with possible Zika virus exposure.

Infected HCP should take steps to prevent mosquito bites for three weeks post-exposure to avoid risk of further mosquito-borne transmission. In addition, infected HCP should be advised to take the following actions/precautions:

Use a condom every time during sex or abstain from sex with a pregnant partner for the entire pregnancy.
Use a condom every time during sex or abstain from sex with any partner for at least 8 weeks after exposure if the infected HCP is a woman, and for at least 6 months if the infected HCP is male, before trying to conceive. Regardless of pregnancy status or intent, couples who want to minimize their risk for sexual transmission of Zika virus should use a condom or abstain from sex for the same time periods. See more information about managing Zika virus infection and necessary precautions to prevent transmission.

Work Restrictions

In general, HCP who have been exposed to or have Zika virus infection (symptomatic or asymptomatic) do not require work restrictions but should continue to adhere to Standard Precautions for all patient care activities. Exceptions (e.g., reassignment, furlough) should be considered for HCP with symptoms that might be attributed to another or additional contagious etiologic pathogen (e.g., symptomatic conjunctivitis) that normally result in work restrictions.

Footnotes

^§ Zika viral RNA has been detected for much longer periods in semen than in other body fluids; therefore in the event of an occupational exposure to semen, the period of potential occupational risk should be extended (e.g., 6 months). Extended risk periods could also be considered on a case by case basis for some source patients (e.g., immunocompromised).
^† The exact time interval between the source patient’s Zika virus exposure (via travel or sexual contact) and the occupational exposure that could result in Zika virus transmission to an exposed HCP is unknown. The estimate of this interval accounts for the incubation period and the possible duration of infectious virus in body fluids. Most symptomatic Zika virus disease patients develop symptoms within 2 weeks of their exposure. Zika viral RNA can be detected in most body fluids of the majority of patients for no more than 2 to 4 weeks. In some people, it can be detected for longer, but it is unknown whether detection of Zika viral RNA indicates presence of infectious virus and the potential for transmission. Zika virus is generally recovered from body fluids by virus culture for shorter periods of time after infection compared to detection of Zika viral RNA by RT-PCR.

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