Aerosol transmission has been defined as the person-to-person transmission of a pathogen through the air by inhalation of infectious particles. Particles up to 100 m in size are considered inhalable (inhaled). Aerosol particles small enough to be inhaled into the oronasopharynx, with smaller, inhaled size ranges for example less than 10 m penetrate deeper into the trachea and lungs.
All of us can give off aerosols when we talk, breathe, sneeze, or cough. If we are infected with a respiratory virus such as the influenza virus, aerosols contain viral particles. Depending on their size, aerosols can spread over long distances, and when inhaled the virus settles on the mucosal surfaces of the respiratory tract and initiates infection.
Viral transmission can also occur when respiratory droplets containing viruses travel from the respiratory tract of an infected person to another person’s surface mucosa. Because these droplets are larger, they cannot travel over long distances like aerosols do, and are considered a form of contact transmission. It is certain that the Ebola virus is transmitted from person to person by droplets.
Medical procedures, such as intubation, can also produce aerosols. It is possible that healthcare workers could become infected by performing this procedure on patients with the Ebola virus disease. However, health workers will not pass the virus through aerosols to other people. In other words, there is no chain of respiratory aerosol transmission between infected people, such as the influenza virus.
In the laboratory, machines called nebulizers that are used to administer medicine to humans if inhaled can be used to produce aerosol-containing viruses for animal studies. A human being is likely to be infected with the Ebola virus which contains aerosols produced by the nebulizer.
Various laboratory animals have been infected with the Ebola virus (Zaire ebolavirus) using aerosols. In one study rhesus macaques infected with the Ebola aerosol virus used a space placed over an animal’s head. This procedure results in viral replication in the respiratory tract followed by death. Viral particles were detected in the respiratory tract, but no attempt was made to transmit the infection from one animal to another by aerosols.
In another study, cynomolgous macaques, rhesus macaques, and African green monkeys were able to become infected with the Ebola aerosol virus using sole headroom. The virus is replicated in the respiratory tract, and moves from regional lymph nodes to blood and then to other organs. Respiratory tract viral titers appear to be lower than in previous studies. No animal for animal transmission experiments were carried out.
When rhesus macaques are inoculated intramuscularly with the Ebola virus, the virus can be detected on mouth and nose swabs but the infection is not transmitted to the animals and is placed in separate cages. The authors concluded that airborne transmission of EBOV between non-human primates did not occur easily.
Pigs can also be infected with the Ebola virus. In one study, after dripping the virus into the nose, eyes and mouth, replication for high titers was detected in the respiratory tract, accompanied by severe lung abnormalities. Infected pigs can pass the infection on to infected pigs in the same pen, but this experimental setup does not allow differentiating between aerosols, droplets, or contact spread.
In another pig transmission experiment, the animals were infected oronasally as above, and placed in a room with cynomolgous macaques. The pigs were allowed to roam the floor, while the monkeys lived in stables. All the monkeys became infected, but their lungs had minimal damage. But it is not known how the virus was transmitted from pigs to monkeys. The design and size of the animal booth makes it impossible to tell whether transmission is by aerosol, small or large droplets in the air, or droplets created during floor cleaning that land in the NHP enclosure. The study also showed that transmission between apes in the same residential conditions was never observed.
Although experimental findings suggest that animals can be infected with the Ebola virus by aerosols, they do not provide definitive evidence for animals for animal transmission via this route. What is clear is that the virus does not transmit via respiratory aerosols between non-human primates.
We don’t know why, in humans or other primates, the Ebola virus cannot be delivered by respiratory aerosols. Viruses may not reach sufficiently high titers in the respiratory tract, or be stable in respiratory secretions, to be efficiently transmitted by this route. There are many other possibilities. A careful study of the Ebola virus in the human respiratory tract, and respiratory secretions but during the Ebola virus outbreak the main concern was saving people, not conducting experiments.
These experiments show major gaps in our understanding of transmission viruses in general, and specifically why the Ebola virus is not transmitted among primates by respiratory aerosols. So that there has not been found the spread of patients with the infection to other people. Until now, what has been found is the spread through body fluids and blood from sufferers to other people.
Ebola virus transmission through blood or body fluids is indeed very easy to spread considering that health workers can easily be infected from patients suspected of being infected with Ebola. Even people who die from Ebola can still spread Ebola to other people, so keep the contact as little as possible.
Prevention can be done by protecting yourself and cleaning your hands before touching your nose, mouth, wounds or food. Moreover, for medical workers including nurses, doctors, laboratory workers must use treated procedures to reduce direct contact with patients suspected of having Ebola.
Thus the fact about Ebola that Ebola cannot be transmitted through aerosols, namely air like only the influenza virus. The spread of aerosols in question is spread through patients who have been exposed to ebola through talking, sneezing, breathing, or coughing. The Ebola virus only spreads through the body fluids and blood of patients who have had direct contact with other people.
This is why patients with Ebola virus should be put in isolation because they need further tests until they are declared negative. Some patients who have tested negative are still being monitored considering that the Ebola virus can still be transmitted to other people. So it is not allowed for sufferers who have just recovered from the Ebola virus to breastfeed because they can still be contagious.