Smear infection is a possible route of transmission for various infectious diseases through contact with contaminated surfaces. In particular, colds and gastrointestinal infections are transmitted by the route of smear infection.
What is a smear infection?
Since poor hygiene is the engine of smear infection, consistent, regular hand washing with soap or a mild disinfectant is the best preventive measure. Smear infection is when germs are transmitted indirectly from one person to another via contaminated surfaces or food. In contrast to droplet infection, the germ carrier does not have to be directly present for transmission. Germs are transmitted that can survive in the environment without a host for a longer period of time and maintain their infection potential. In the case of smear infection, a distinction is made between direct and indirect contact infection. In direct contact infection, transmission occurs from human or animal to human. Shaking hands is a classic example of this. In the case of indirect contact infection, the infection occurs through touching contaminated objects, for example when sharing a drinking glass. Transmission via contaminated water or contaminated food is also possible in this way via smear infection.
Languages, transmission, and progression
Smear infection is usually a problem of poor hygiene. In most cases, the germs are transferred to a surface via dirty hands. The pathogens on the hand can come from a variety of sources. The majority of smear infections are caused by germs excreted in the stool. Less commonly, bacteria, especially streptococci and staphylococci, are spread through ulcerated wounds. In addition, viral vesicles can be the source of smear infection. From these sources, the pathogens are transferred with infectious material such as saliva, urine, or stool to a dead or living surface, to the water, or even into the soil. Classic sources of infection in everyday life are, for example, door handles, computer keyboards or toilet seats. They are touched by the germ carrier, who leaves pathogens on the surface with the touch. If another person touches the contaminated surface, the germs get onto the skin. Although the skin forms a good barrier, small injuries are welcome gateways for germs to enter. Mucous membranes are more susceptible to the entry of germs. For example, you pick up germs with your hand at a door handle and then rub your eyes or eat with unwashed hands. The pathogens already come into contact with the sensitive mucous membranes of the eye or, via the food, with those of the digestive tract. If enough germs have been transmitted by the smear infection to survive the immune system‘s initial resistance, they can multiply in the organism and lead to clinical symptoms.
Examples of diseases
To be transmitted via smear infection, pathogens must be able to survive in the environment for an extended period of time. Classic germs for this route of transmission are influenza viruses and MRSA, as well as adenoviruses that cause colds, conjunctivitis, and gastrointestinal infections. However, hepatitis A, bacterial dysentery, cholera, typhoid, polio and other dangerous epidemics are also transmitted by this route. Pathogenic intestinal bacteria excreted with feces, such as dysentery bacteria and the notifiable salmonella, play the largest role in smear infections. Intestinal pathogenic viruses are also frequently transmitted, as they are excreted in large numbers in the stool and the bacterial count required for infection is quite low. These viruses include rotaviruses, noroviruses and adenoviruses. Unicellular intestinal parasites such as cryptosporidia and giardia can also be transmitted via smear infection. However, they play only a minor role, since infections occur only rarely and under very unhygienic conditions. In addition, the number of pathogens required for a successful smear infection is quite high and the germs are excreted in relatively small numbers.
Prevention
Since poor hygiene is the driver of smear infection, the best preventive measure is also the simplest: consistent, regular hand washing with soap or a mild disinfectant. This is especially true before eating, as germs can otherwise very easily get onto the mucous membranes of the digestive tract here.When using public toilets, cleaning the toilet seat with a suitable disinfectant can also protect against smear infection with hepatitis A viruses, for example. In times of high incidence of colds, it is quite reasonable to stop greeting people by shaking hands to avoid smear infection from person to person.
