However, epidemiological data have led to the understanding that EBOV does not undergo traditional airborne transmission. EBOV particles have been found in human alveoli, yet it is not known if small droplets containing EBOV form within the human respiratory tract. Here, we use the terms small droplet and aerosol interchangeably to describe particles that have the potential to form droplet-nuclei, and we use the phrases airborne and aerosol transmission synonymously to describe transmission via these particles.Ĭurrently no data exist for whether EBOV forms droplet nuclei. The size cut-off for the diameter of small droplets and large droplets has been disputed, with some proposing small droplets to be <20 µm, and the size of droplet-nuclei to be <5 µm. In order to better define biological aerosols, two categories have been created: small droplets and large droplets. The small droplets that can form these droplet nuclei are often called aerosols, but aerosols are also generally defined as any small liquid or solid particles that are suspended in air. Therefore, we review the present knowledge regarding EBOV transmission and examine how research could answer remaining questions.Īirborne or aerosol transmission of a virus occurs when small, virus-laden droplets evaporate before settling on surfaces, leaving behind infectious droplet nuclei that can travel long distances. Experiments should augment our knowledge about EBOV transmission and improve our current retrospective understanding. While authors have addressed what is known about EBOV transmission, many unanswered questions remain. Our knowledge about human-to-human EBOV transmission is based mainly on epidemiological evidence from previous outbreaks. Additionally, healthcare personnel are given precautions against droplet transmission. Airborne transmission via small aerosol droplets is unlikely from current EBOV epidemiology.Īssessing the potential routes of EBOV transmission, the United States Centers for Disease Control and Prevention (CDC) has communicated the scientific consensus that EBOV spreads only through direct contact with mucous membranes or through broken skin with infected blood or bodily fluids, contaminated objects such as needles, and contact with infected animals. EBOV has been detected in dried blood and persists on surfaces, so the possibility of fomite transmission exists. These infectious fluids can also be formed into droplets which travel in the air (range unknown, possibly 1 meter) and potentially infect others. Ebola virus (EBOV) has been isolated from bodily fluids including blood, stool, semen, saliva, and breast milk contact with these fluids from infected individuals creates a high risk of transmission. Potential routes of Ebola virus transmission and infection between people. Therefore, EBOV is highly infectious, for a low dose of virus is sufficient to cause disease, and EBOV is contagious it is shed in multiple bodily secretions and easily transmitted through contact with these fluids. Infectious doses of less than 10 plaque-forming units (pfu) of EBOV have been reported to cause viremia in NHPs, depending on the route of administration. Experiments involving non-human primates (NHPs) suggest EBOV can successfully infect after oral, conjunctival, respiratory, intramuscular, intraperitoneal and submucosal administration. There are also multiple potential routes of transmission, including direct contact, fomite, droplet, and aerosol ( Figure 1). In humans, EBOV has been found in variety of bodily fluids, including saliva, blood, breast milk, stool, and semen. How much virus is shed in different fluidsĮBOV found in a variety of bodily fluids Įbola virus (EBOV), species Zaire ebolavirus, one of five species of viruses in the genus Ebolavirus, has been identified as the etiological agent of the 2014 outbreak of Ebola virus disease (EVD). ![]() Sharing needles and handling the deceased or sick are high risk factors Very likely from epidemiology and experimental data Whether infectious fluids are formed into droplets by humansĪccidental infections in non-human primates, possibly from power washing ĮBOV infections without direct contact Persists on glass and in the dark for 5.9 days ĮBOV found in stool, semen, saliva, breast milk ![]() ![]() ![]() Whether AGPs produce EBOV aerosols that cause transmissionĮBOV stability in tropical climates and on surfaces Outbreaks contained without airborne precautions in the affected population Īirborne stability of EBOV in tropical climatesĮBOV detected after 90 min in experimental small aerosols Airborne/Aerosol (small droplet/droplet nuclei)ĮBOV can be aerosolized mechanically and cause lethal disease in non-human primates at low concentrations Ībility of the virus to become airborne through respiratory tract in humans and animals
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