In the public perception, it is often believed that only close contact with a patient can be infected, yet it is a misperception that needs to be corrected. In fact, the transmission of infection is more complex and varied than we thought, and far from being covered by “close contact”.
In the case of respiratory infections, the spread of the new coronary virus has taught us a deep sense of the partiality of this wrong zone. While the spread of close-range foam is one of its important modes of transmission, when patients cough, sneeze and speak, a large amount of it is sprayed, and people in close-range contact are at high risk of infection if they inhale it. In addition, however, there is an unnegligible route for aerosol transmission. Aerosol means a gaseous dispersion system consisting of solid or liquid particles suspended in a gas medium. In relatively closed, poorly ventilated environments, such as elevators, small rooms, etc., patients can produce virus-containing foam that can form aerosols in the air and be suspended for long periods of time. Even when there is no close and direct contact with the patient, others may enter the environment and inhale these aerosols containing the virus. For example, in some cases during the epidemic, residents of different floors of the same building, who had not been in close contact with the patients identified, were infected by sharing public spaces such as elevators, which was the spread of aerosols.
With air transport, certain viruses can survive and remain infectious for long periods of time. Like the measles virus, which is extremely contagious, in indoor settings with poor air flow, such as school classrooms, hospital waiting halls, etc., the air with the virus that patients excite can spread to a distance, and healthy people can be infected by inhalation of virus-contaminated air, even a few metres away or more. This suggests that, even without close physical contact, the risk of infection remains as long as it is in the contaminated air environment.
Water transmission is also an important route of infection and is not restricted by close contact with patients. Some intestinal infectious diseases, such as cholera Vibrio, hepatitis A virus, can be transmitted through contaminated water sources. If the water source is contaminated by the excreta of the patient and people drink water from the water source that has not been thoroughly decontaminated, it may cause large-scale infections. In such cases, there may have never been direct close interaction between the infected population and the patient, even though the water sources had been contaminated. For example, in some areas with poor sanitation, the contamination of public water systems may expose entire communities to the risk of infection, and they may be far from the initial patients.
There is also media transmission, in the case of mosquitoes, which can transmit diseases such as malaria, dengue fever, etc. A mosquito bites a patient infected with a virus or parasite, and then bites a healthy person, and it spreads to the latter. In the process, a healthy person may have never met or had close contact with a patient, but is infected by the mosquito medium. In the tropics and subtropical regions, mosquitoes thrive and the risk of vector-borne diseases is higher, i.e. they keep people away from patients and can be infected as long as they are located in areas where they are active and are not equipped to prevent them.
The same is true for food distribution. Some food contaminated with bacteria, viruses or parasites can lead to infection if eaten by healthy people. For example, when seafood contaminated with the virus is processed and made, the edible, even when it has no connection with patients infected with the virus, is affected by the consumption of contaminated food.
The notion that only close contact with a patient can be infected is too narrow. We live in an environment full of potential sources of infection, and the diversity of the routes of infection requires us to be more vigilant and to strengthen protection across the board. Maintaining a good ventilation environment, ensuring safe drinking water, working against mosquitoes, and focusing on dietary hygiene are important links in reducing the risk of infection. It is only by breaking this perception gap that we can more effectively prevent infection and protect ourselves and the health of others.
