Pathogen transmission
[6] Transmission of pathogens can occur by direct contact, through contaminated food, body fluids or objects, by airborne inhalation or through vector organisms.
[8] Community transmission means that the source of infection for the spread of an illness is unknown or a link in terms of contacts between patients and other people is missing.
For example, low personal and food hygiene due to the lack of a clean water supply may result in increased transmission of diseases by the fecal-oral route, such as cholera.
[14] It includes both dry and wet aerosols and thus requires usually higher levels of isolation since it can stay suspended in the air for longer periods of time.
[citation needed] A common form of transmission is by way of respiratory droplets, generated by coughing, sneezing, or talking.
Transmission can occur when respiratory droplets reach susceptible mucosal surfaces, such as in the eyes, nose or mouth.
Before drying, respiratory droplets are large and cannot remain suspended in the air for long, and are usually dispersed over short distances.
For this reason, contagious diseases often break out in schools, where towels are shared and personal items of clothing accidentally swapped in the changing rooms.
[citation needed] Some diseases that are transmissible by direct contact include athlete's foot, impetigo, syphilis, warts, and conjunctivitis.
Transmission is either directly between surfaces in contact during intercourse (the usual route for bacterial infections and those infections causing sores) or from secretions (semen or the fluid secreted by the excited female) which carry infectious agents that get into the partner's blood stream through tiny tears in the penis, vagina or rectum (this is a more usual route for viruses).
[citation needed] Some infections transmissible by the sexual route include HIV/AIDS, chlamydia, genital warts, gonorrhea, hepatitis B, syphilis, herpes, and trichomoniasis.
[citation needed] While rare in regards to this sexual practice, some infections that can spread via manual sex include HPV, chlamydia, and syphilis.
Vehicles that may indirectly transmit an infectious agent include food, water, biologic products such as blood, and fomites such as handkerchiefs, bedding, or surgical scalpels.
A common strategy used to control vector-borne infectious diseases is to interrupt the life cycle of a pathogen by killing the vector.
[28][29] Main causes of fecal–oral disease transmission include lack of adequate sanitation and poor hygiene practices - which can take various forms.
[citation needed] The fecal-oral route of transmission can be a public health risk for people in developing countries who live in urban slums without access to adequate sanitation.
This is the typical mode of transmission for infectious agents such as cholera, hepatitis A, polio, Rotavirus, Salmonella, and parasites (e.g. Ascaris lumbricoides).
[citation needed] For diseases transmitted within an institution, such as a hospital, prison, nursing home, boarding school, orphanage, refugee camp, etc., infection control specialists are employed, who will review medical records to analyze transmission as part of a hospital epidemiology program, for example.
One proxy in the case of influenza is tracking of influenza-like illness at certain sentinel sites of health care practitioners within a state, for example.
[30] Tools have been developed to help track influenza epidemics by finding patterns in certain web search query activity.
Most recently, data from cell phones have been shown to be able to capture population movements well enough to predict the transmission of certain infectious diseases, like rubella.
[citation needed] The relationship between virulence and transmission is complex and has important consequences for the long term evolution of a pathogen.
Since it takes many generations for a microbe and a new host species to co-evolve, an emerging pathogen may hit its earliest victims especially hard.
[citation needed] Anything that reduces the rate of transmission of an infection carries positive externalities, which are benefits to society that are not reflected in a price to a consumer.
[35] The mode of transmission is also an important aspect of the biology of beneficial microbial symbionts, such as coral-associated dinoflagellates or human microbiota.
