Laboratory-Acquired Dengue Virus Infection, United States, 2018

Tyler M. Sharp; Teresa G. Fisher; Kristin Long; Garry Coulson; Freddy A. Medina; Carolyn Herzig; Mary Beth Koza; Jorge Muñoz-Jordán; Gabriela Paz-Bailey; Zack Moore; Carl Williams

Disclosures

Emerging Infectious Diseases. 2020;26(7):1534-1537. 

In This Article

Conclusions

The presence of an open finger wound during work with high-titer DENV coupled with improper glove doffing suggests that laboratory-acquired infection by cutaneous exposure was the most likely route of DENV infection in this case. However, other routes of exposure, including mucosal, could not be ruled out.

Three previous cases of laboratory-associated DENV infection have been reported. In Nigeria, a laboratorian responsible for cleaning cages and disposing of mice infected with DENV-1 became infected, although mosquito-borne transmission could not be ruled out.[6] A laboratorian in Australia was infected while working with DENV-2,[7] although it could not be determined if infection occurred from a bite from an infected mosquito in the laboratory or potential mucocutaneous exposure while working with infectious virus. In South Korea, a laboratorian was infected with DENV-2 following a needle stick injury while filtering cell cultures of DENV-2.[8]

In this case, detection of NS1 antigen independently confirmed acute DENV infection, supported by detection of DENV IgM and >4-fold rise in DENV IgG and DENV neutralizing antibody. However, historic exposure to ≥1 flavivirus complicated interpretation of neutralizing antibody titers and precluded identification of the infecting DENV. Moreover, we could not rule out infection with DENV between collection of the baseline and acute specimens. The difficulty interpreting flavivirus neutralizing antibody patterns during secondary infections is well described.[12]

A study in Belgium conducted during 2007–2012 found that only 40% of laboratory-associated infections occurred following a known exposure event; a definitive cause of exposure could not be identified in nearly one third of cases associated with bloodborne pathogens.[13] Thus, laboratory-acquired infections, including those with DENV, likely occur more frequently than have been documented.

Titers of infectious DENV in human blood resulting from mosquito-borne transmission are typically 103–107 PFU/mL (14). At 109–1010 PFU/mL, the concentration of DENV the case-patient handled would have been 100 to 10 million times higher than the concentration found in the average blood specimen of a patient with DENV infection. Although BSL-2 containment is recommended for laboratory work with DENV, enhanced safety precautions including double-gloving are recommended when handling large-scale or high-titer virus.[15] This investigation highlights the importance of developing and maintaining risk assessment and management programs to mitigate exposures to infectious agents and emphasizing good microbiological practices and procedures training for laboratorians, including proper PPE donning and doffing techniques.

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