J Infect Dis. 2017 Feb 15;215(4):554-558.

Detection of Ebola Virus RNA Through Aerosol Sampling of Animal Biosafety Level 4 Rooms Housing Challenged Nonhuman Primates.

Harbourt DE1, Johnston SC1, Pettitt J2, Warren TK1, Dorman WR1.

1 United States Army Medical Research Institute of Infectious Diseases
2 Integrated Research Facility, Ft Detrick, Maryland.



Ebola virus disease is a serious illness of humans and nonhuman primates (NHPs). Direct contact has been shown to be the primary source of Ebola (EBOV) transmission. We used a high-volume air sampler to determine whether EBOV could be detected during 3 independent studies with EBOV-challenged NHPs. Viral RNA was recovered during days 9 and 10 of Study I and days 7 and 8 of Study III. Viral RNA levels were below limits of detection during all other collections. The results demonstrate that the biosafety level 4 (BSL-4) suit protects workers from aerosols in a BSL-4 environment using proper engineering and administrative controls.

KEYWORDS: BSL-4; Ebola; aerosol sampling; aerosol transmission; animal model; nonhuman primate

PMID: 28011922



Ebola Virus Disease is a serious contagious disease of high mortality affecting humans that was first discovered in the Yambuku region of Zaire in 1976 (1).  Since its discovery, transmission between humans has been noted through direct contact with infectious fluids but the role of aerosol transmission continues to be debated today.  The 2014 West Africa outbreak resulted in the deaths of 11,300 people including over 500 healthcare workers (2, 4).  Since personal protective equipment and infection control practices vary between healthcare workers root cause determination for the source of transmission remains difficult to evaluate.  Nonhuman primates have been shown to have greater than 106 pfu/mL virus in serum and tissues during peak infection and data from the 2014 outbreak has shown that humans can lose up to 10L/day of fluids during EBOV infection (3, 4).  Many of these fluids could potentially be highly infectious and since EBOV has been shown to remain airborne for up to three hours under laboratory conditions indicates that transmission through infectious aerosols must be considered during future EBOV outbreaks (5).  Despite the highly infectious nature of EBOV, through specialized engineering controls, training programs and the protective envelope of the positive pressure encapsulating suit, no known laboratory acquired infections have occurred in the United States related to BSL4 studies with EBOV.  This demonstrates that while exposure to infectious aerosols could be a possible source of nosocomial transmission of EBOV, it is unlikely to be factor for laboratory acquired infections under BSL4 conditions provided all of the appropriate procedures are followed.



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