Case Series of Laboratory-Associated Zika Virus Disease, United States, 2016–2019

Susan L. Hills; Andrea Morrison; Shawna Stuck; Kayleigh Sandhu; Krystal L. Mason; Danielle Stanek; Julie Gabel; Matthew A. Osborne; Betsy A. Schroeder; Edhelene Rico; Cherie L. Drenzek; Glen R. Gallagher; Jennifer Fiddner; Lea A. Heberlein-Larson; Catherine M. Brown; Marc Fischer


Emerging Infectious Diseases. 2021;27(5):1296-1300. 

In This Article

Case Reports

Exposure to Zika Virus through Needlestick Injury

Case 1. In May 2016, a female researcher who worked in a Biosafety Level (BSL) 3 microbiology laboratory sustained a needlestick injury with a bifurcated needle; information on whether the skin was punctured was not available. The incident occurred during in vitro inoculation of human skin cells with wild-type Zika virus for vaccine research purposes. She was wearing 2 pairs of nitrile gloves and working in a biosafety cabinet. She immediately used a surgical sponge and chlorohexidine to scrub the wound for 15 minutes, then washed her hands with soap and water. After 9 days, she experienced a low-grade fever, generalized maculopapular rash, headache, myalgia, and fatigue; mild unilateral conjunctivitis occurred the next day. She did not live in an area with local Zika virus transmission, and in the month before illness onset she had no other risk factors for acquisition of Zika virus infection (i.e., no history of travel, no sexual contact with a traveler, and no history of blood transfusion or organ transplantation). She reported full resolution of her symptoms within 5 days. Zika virus infection was confirmed through the detection of Zika virus RNA in serum and urine and Zika virus IgM and neutralizing antibodies in serum (Table).

Case 2. In July 2018, a female researcher received an accidental needlestick injury while recapping a needle after inoculating a mouse with the Uganda Zika virus strain MR766 at a concentration of 107 PFU/mL.[6] At the time of the incident, she was working in a biosafety cabinet and was double gloved. She felt the stick from the needle on her left middle finger but did not see any blood. She immediately removed her gloves, washed her hands with soap and water, and applied alcohol. After 10 days, she became symptomatic with a pruritic maculopapular rash, arthralgia, and myalgia. Zika virus infection was confirmed on the basis of the detection of Zika virus RNA in urine and serologic testing (Table). There was no reported local Zika virus transmission where she lived, and apart from the needlestick injury she had no other risk factors for acquisition of Zika virus infection. She recovered completely within ≈2 weeks of symptom onset.

Other Laboratory-associated Zika Virus Exposures

Case 3. In November 2017, a male worker in a BSL-2 virology laboratory had onset of symptoms (day 0) of headache, arthralgia, myalgia, fatigue, and a rash that initially appeared on his face and spread to his whole body during the next 2 days. The arthralgia and myalgia became progressively more severe and debilitating through day 5, but recovery occurred by day 13. Zika virus infection was confirmed through detection of Zika virus RNA in serum and semen and with serologic methods (Table). He had no other risk factors for acquisition of infection and there was no local Zika virus transmission where he lived.

The patient reported that he typically worked with large quantities (4–100 L) of Zika virus in the laboratory but did not recall any specific exposure or incident of concern within the 2 weeks before illness onset. His activities included clarifying Zika virus materials through filters, performing pump-driven chromatography, using buffers to dilute concentrated Zika virus, and adding formaldehyde to initiate Zika virus inactivation. The recommended personal protective equipment (PPE) he routinely wore included a first PPE layer, donned in an external area, of disposable laboratory coat or coverall, booties, a hairnet, goggles, and 1 pair of gloves and a second PPE layer of a second coverall, hairnet, pair of gloves, and disposable face shield donned once inside the laboratory; no mask was used. He performed his work inside a biosafety cabinet when possible but could not do so when using larger containers (e.g., the biosafety cabinet could not accommodate the large vessels used for pouring liquid live virus through a funnel). The liquid could sometimes potentially splash. On 1 occasion during the probable exposure period, while he was working in a biosafety cabinet, a large droplet of live virus dripped onto his glove; he immediately changed the outer glove. He reported it was possible he might have rubbed his face with the back of a gloved hand; however, no confirmed mucus membrane exposure could be identified. An additional 12 employees working with Zika virus in the same laboratory were subsequently tested and showed no serologic evidence of recent or past Zika virus infection.

Case 4. In October 2019, a male researcher in a vaccine research laboratory experienced fever, rash, arthralgia, and conjunctival injection. His laboratory activities sometimes involved working with Zika virus, including performing serum neutralization testing, and he had worked with Zika virus 8 and 10 days before symptom onset. He routinely wore gloves in the laboratory, but more detailed PPE information was unavailable. An investigation did not identify any specific exposure or reported breach in biosafety procedures, and no sharps were used in the laboratory. He did not live in an area with a history of Zika virus transmission and he had no other risk factors for Zika virus infection. Confirmation of infection was by detection of Zika virus RNA in urine and by serologic methods (Table). Symptoms resolved within 8 days.