Pathogen transmission

This article is about transmission of disease-causing pathogens. For other uses, see  Transmission.

Schematic representation of pathogen transmission routes(droplet, airborne, contact)-Pathogen transmission is the process via which a pathogen, or disease-causing agent, is passed from an infected host to another individual. This can occur regardless of whether the recipient was infected previously. The transmission can happen through various methods like direct contact, airborne droplets, bodily fluids, or contaminated surfaces. Understanding this process is important in the areas of medicine, public health, and biology for the prevention of communicable diseases.[1]

In medicine, public health, and biology, transmission (or Infectious disease transmission[2]) is the passing of a pathogen causing communicable disease from an infected host individual or group to a particular individual or group, regardless of whether the other individual was previously infected.[3] The term strictly refers to the transmission of microorganisms directly from one individual to another by one or more of the following means:

* Airborne transmission – very small dry and wet particles that stay in the air for long periods of time allowing airborne contamination even after the departure of the host.[4]
* Droplet transmission – small and usually wet particles that stay in the air for a short period of time. Contamination usually occurs in the presence of the host. Particle size > 5 μm.[5]
* Direct physical contact – touching an infected individual, including sexual contact[6]
* Indirect physical contact – usually by touching a contaminated surface, including soil[7]
* Fecal–oral transmission – usually from unwashed hands, contaminated food or water sources due to lack of sanitation and hygiene, an important transmission route in pediatrics, veterinary medicine and developing countries.[8]

Transmission can also be indirect, via another organism, either a vector or an intermediate host . Indirect transmission could involve zoonoses or, more typically, larger pathogens like macroparasites with more complex life cycles. Transmissions can be autochthonous or may involve travel of the microorganism or the affected hosts.[9][1]

## Contents

* 1 Definition
* 2 Routes of transmission
* 2.1 Airborne infection
* 2.2 Droplet infection
* 2.3 Direct contact
* 2.3.1 Sexual transmitted infection
* 2.3.2 Oral sexual
* 2.3.3 Oral
* 2.3.4 Mother-to-child transmission
* 2.3.5 Iatrogenic
* 2.4 Indirect contact
* 2.5 Transmission by other organisms
* 2.6 Fecal–oral
* 3 Tracking
* 4 Relationship with virulence and survival
* 5 Beneficial microorganisms
* 5.1 Vertical transmission
* 5.2 Horizontal transmission
* 5.3 Mixed-mode transmission
* 6 See also
* 7 References

## Definition[edit | edit source]

Neisseria gonorrhoeae

An infectious disease agent can be transmitted in two ways: as horizontal disease agent transmission from one individual to another in the same generation (peers in the same age group)[10] by either direct contact (licking, touching, biting), or indirect contact through air – cough or sneeze (vectors or fomites that allow the transmission of the agent causing the disease without physical contact)[11] or by vertical disease transmission, passing the agent causing the disease from parent to offspring, such as in prenatal or perinatal transmission.[12]

The term infectivity describes the ability of an organism to enter, survive and multiply in the host, while the infectiousness of a disease agent indicates the comparative ease with which the disease agent is transmitted to other hosts.[13] Transmission of pathogens can occur by direct contact, through contaminated food, body fluids or objects, by airborne inhalation or through vector organisms.[14]

Transmissibility is the probability of an infection, given a contact between an infected host and a noninfected host.[15]

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. It refers to the difficulty in grasping the epidemiological link in the community beyond confirmed cases.[16][17][18]

Local transmission means that the source of the infection has been identified within the reporting location (such as within a country, region or city).[19]

## Routes of transmission[edit | edit source]

The route of transmission is important to epidemiologists because patterns of contact vary between different populations and different groups of populations depending on socio-economic, cultural and other features. 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. Differences in incidence of such diseases between different groups can also throw light on the routes of transmission of the disease. For example, if it is noted that polio is more common in cities in underdeveloped countries, without a clean water supply, than in cities with a good plumbing system, we might advance the theory that polio is spread by the fecal-oral route. Two routes are considered to be airborne: Airborne infections and droplet infections.[20][21][22][23]

### Airborne infection[edit | edit source]

Main article: Airborne disease

"Airborne transmission refers to infectious agents that are spread via droplet nuclei containing infective microorganisms. These organisms can survive outside the body and remain suspended in the air for long periods of time. They infect others via the upper and lower respiratory tracts."[24] The size of the particles for airborne infections need to be < 5 μm. 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. i.e., separate ventilation systems or negative pressure environments are needed to avoid general contamination. e.g., tuberculosis, chickenpox, measles[25][26][27]

### Droplet infection[edit | edit source]

Main article: Respiratory droplet

Respiratory droplets are released through talking, coughing, or sneezing.[28]

A common form of transmission is by way of respiratory droplets, generated by coughing, sneezing, or talking. Respiratory droplet transmission is the usual route for respiratory infections. Transmission can occur when respiratory droplets reach susceptible mucosal surfaces, such as in the eyes, nose or mouth. This can also happen indirectly via contact with contaminated surfaces when hands then touch the face. Before drying, respiratory droplets are large and cannot remain suspended in the air for long, and are usually dispersed over short distances.[24] The size of the particles for droplet infections are > 5 μm.[26]

Organisms spread by droplet transmission include respiratory viruses such as influenza virus, parainfluenza virus, adenoviruses, rhinovirus, respiratory syncytial virus, human metapneumovirus, Bordetella pertussis, pneumococci, streptococcus pyogenes, diphtheria, rubella,[29] and coronaviruses.[30] Spread of respiratory droplets from the wearer can be reduced through wearing of a surgical mask.[28]

### Direct contact[edit | edit source]

Further information: Contagious disease

Direct contact occurs through skin-to-skin contact, kissing, and sexual intercourse. Direct contact also refers to contact with soil or vegetation harboring infectious organisms.[31] Additionally, while fecal–oral transmission is primarily considered an indirect contact route, direct contact can also result in transmission through feces.[32][33]

Diseases that can be transmitted by direct contact are called contagious. These diseases can also be transmitted by sharing a towel or items of clothing in close contact with the body if they are not washed thoroughly between uses. For this reason, contagious diseases often break out in schools, where towels are shared and so on.[34][7]

Some diseases that are transmissible by direct contact include athlete's foot, impetigo, syphilis, warts, and conjunctivitis.[35]

#### Sexual transmitted infection[edit | edit source]

Main article: Sexually transmitted infection

This refers to any disease that can be caught during sexual activity with another person, including vaginal or anal sex or through oral sex . Transmission is either directly between surfaces in contact during intercourse or from secretions which carry infectious agents that get into the partner's blood stream through tiny tears in the penis, vagina or rectum. In this second case, anal sex is considerably more hazardous since the penis opens more tears in the rectum than the vagina, as the vagina is more elastic and more accommodating.Some diseases transmissible by the sexual route include HIV/AIDS, chlamydia, genital warts, gonorrhea, hepatitis B, syphilis, herpes, and trichomoniasis[36][37][38][39]

#### Oral sexual[edit | edit source]

Sexually transmitted diseases such as HIV and hepatitis B are thought to not normally be transmitted through mouth-to-mouth contact, although it is possible to transmit some STDs between the genitals and the mouth, during oral sex. In the case of HIV this possibility has been established. It is also responsible for the increased incidence of herpes simplex in genital and oral infections.[40][41]

#### Oral[edit | edit source]

Diseases that are transmitted primarily by oral means may be caught through direct oral contact such as kissing, or by indirect contact such as by sharing a drinking glass . Diseases that are known to be transmissible by kissing or by other direct or indirect oral contact include all of the diseases transmissible by droplet contact and (at least) all forms of herpes viruses, namely Cytomegalovirus infections herpes simplex virus and infectious mononucleosis.[41] [42]

#### Mother-to-child transmission[edit | edit source]

Brocky, Karoly - Mother and Child (1846-50)

Main article: Vertically transmitted disease

This is from mother to child (more rarely father to child), often in utero, during childbirth (also referred to as perinatal infection) or during postnatal physical contact between parents and offspring. In mammals, including humans, it occurs also via breast milk (transmammary transmission). Infectious diseases that can be transmitted in this way include: HIV, hepatitis B and syphilis. Many mutualistic organisms are transmitted vertically.[43]

#### Iatrogenic[edit | edit source]

Transmission due to medical procedures, such as touching a wound, an injection or transplantation of infected material. Some diseases that can be transmitted iatrogenically include: Creutzfeldt–Jakob disease by injection of contaminated human growth hormone, MRSA and HIV.[44][45]

### Indirect contact[edit | edit source]

Indirect contact transmission, also known as vehicleborne transmission, involves transmission through contamination of inanimate objects. 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 vehicle may passively carry a pathogen, as in the case of food or water may carrying hepatitis A virus. Alternatively, the vehicle may provide an environment in which the agent grows, multiplies, or produces toxin, such as improperly canned foods provide an environment that supports production of botulinum toxin by Clostridium botulinum.[31]

### Transmission by other organisms[edit | edit source]

Aedes aegypti

Further information: Vector (epidemiology)

A vector is an organism that does not cause disease itself but that transmits infection by conveying pathogens from one host to another.[46]

Vectors may be mechanical or biological. A mechanical vector picks up an infectious agent on the outside of its body and transmits it in a passive manner. An example of a mechanical vector is a housefly, which lands on cow dung, contaminating its appendages with bacteria from the feces, and then lands on food prior to consumption. Biological vectors harbor pathogens within their bodies and deliver pathogens to new hosts in an active manner, usually a bite. Biological vectors are often responsible for serious blood-borne diseases, such as malaria, viral encephalitis, Chagas disease, Lyme disease and African sleeping sickness. Biological vectors are usually, though not exclusively, arthropods, such as mosquitoes, ticks, fleas and lice. Vectors are often required in the life cycle of a pathogen. A common strategy used to control vector-borne infectious diseases is to interrupt the life cycle of a pathogen by killing the vector.[47][48]

### Fecal–oral[edit | edit source]

1940 US WPA poster encouraging modernized privies

Main article: Fecal–oral route

In the fecal-oral route, pathogens in fecal particles pass from one person to the mouth of another person. Although it is usually discussed as a route of transmission, it is actually a specification of the entry and exit portals of the pathogen, and can operate across several of the other routes of transmission.[31]

Fecal–oral transmission is primarily considered as an indirect contact route through contaminated food or water. However, it can also operate through direct contact with feces or contaminated body parts, such as through anal sex.[32][33] It can also operate through droplet or airborne transmission through the toilet plume from contaminated toilets.[49][50]

Main causes of fecal–oral disease transmission include lack of adequate sanitation and poor hygiene practices - which can take various forms. Fecal oral transmission can be via foodstuffs or water that has become contaminated. This can happen when people do not adequately wash their hands after using the toilet and before preparing food or tending to patients.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. Here, excreta or untreated sewage can pollute drinking water sources . The people who drink the polluted water can become infected. Another problem in some developing countries, is open defecation which leads to disease transmission via the fecal-oral route.Even in developed countries there are periodic system failures resulting in a sanitary sewer overflow. This is the typical mode of transmission for infectious agents.[51][52][53]

## Tracking[edit | edit source]

See also: Mathematical modelling of infectious disease

Mathematical models in infectious diseases[54]

Tracking the transmission of infectious diseases is called disease surveillance. Surveillance of infectious diseases in the public realm traditionally has been the responsibility of public health agencies, on an international, national, or local level. Public health staff relies on health care workers and microbiology laboratories to report cases of reportable diseases to them. The analysis of aggregate data can show the spread of a disease and is at the core of the specialty of epidemiology. To understand the spread of the vast majority of non-notifiable diseases, data either need to be collected in a particular study, or existing data collections can be mined, such as insurance company data or antimicrobial drug sales for example.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.[55][56][57][58]

Because these traditional methods are slow, time-consuming, and labor-intensive, proxies of transmission have been sought. 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.[59] Tools have been developed to help track influenza epidemics by finding patterns in certain web search query activity. It was found that the frequency of influenza-related web searches as a whole rises as the number of people sick with influenza rises. Examining space-time relationships of web queries has been shown to approximate the spread of influenza[60] and dengue.[61]

Computer simulations of infectious disease spread have been used.[62] Human aggregation can drive transmission, seasonal variation and outbreaks of infectious diseases, such as the annual start of school, bootcamp, the annual Hajj etc. 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.[63]

## Relationship with virulence and survival[edit | edit source]

Pathogenicity and virulence of hepatitis A virus[64]

Pathogens must have a way to be transmitted from one host to another to ensure their species' survival. Infectious agents are generally specialized for a particular method of transmission. Taking an example from the respiratory route, from an evolutionary perspective viruses or bacteria that cause their host to develop coughing and sneezing symptoms have a great survival advantage, as they are much more likely to be ejected from one host and carried to another. This is also the reason that many microorganisms cause diarrhea.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. It is usually in the first wave of a new disease that death rates are highest. If a disease is rapidly fatal, the host may die before the microbe can be passed along to another host. However, this cost may be overwhelmed by the short-term benefit of higher infectiousness if transmission is linked to virulence, as it is for instance in the case of cholera or many respiratory infections. 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. This is recognized implicitly when vaccines are offered for free or at a cost to the patient less than the purchase price.[65][66][67][64]

## Beneficial microorganisms[edit | edit source]

The mode of transmission is also an important aspect of the biology of beneficial microbial symbionts. Organisms can form symbioses with microbes transmitted from their parents, from the environment or unrelated individuals, or both.[68]

### Vertical transmission[edit | edit source]

Vertical transmission refers to acquisition of symbionts from parents . Vertical transmission can be intracellular, or extracellular . Both intracellular and extracellular vertical transmission can be considered a form of non-genetic inheritance or parental effect. It has been argued that most organisms experience some form of vertical transmission of symbionts. Canonical examples of vertically transmitted symbionts include some components of the human microbiota .[69][70][68]

### Horizontal transmission[edit | edit source]

Some beneficial symbionts are acquired horizontally, from the environment or unrelated individuals. This requires that host and symbiont have some method of recognizing each other or each other's products or services. Often, horizontally acquired symbionts are relevant to secondary rather than primary metabolism, for example for use in defense against pathogens,but some primary nutritional symbionts are also horizontally acquired.[71] [72] [68]

### Mixed-mode transmission[edit | edit source]

Many microbial symbionts, including human microbiota, can be transmitted both vertically and horizontally. Mixed-mode transmission can allow symbionts to have the "best of both worlds" – they can vertically infect host offspring when host density is low, and horizontally infect diverse additional hosts when a number of additional hosts are available. Mixed-mode transmission make the outcome (degree of harm or benefit) of the relationship more difficult to predict, because the evolutionary success of the symbiont is sometimes but not always tied to the success of the host.[43]

## See also[edit | edit source]

* Bioaerosol
* Bugchasing
* Cross-species transmission
* Infectious disease: Transmission
* Transmission coefficient (epidemiology)
* Transmission risks and rates

## References[edit | edit source]

1. ↑ 1.0 1.1 Collier, Melissa; Albery, Gregory F.; McDonald, Grant C.; Bansal, Shweta (21 December 2022). "Pathogen transmission modes determine contact network structure, altering other pathogen characteristics". Proceedings. Biological Sciences. 289 (1989): 20221389. doi:10.1098/rspb.2022.1389. ISSN 1471-2954. Archived from the original on 29 April 2024. Retrieved 12 June 2024.
2. ↑ "Infectious Disease Transmission, Professional-to-Patient (Concept Id: C0206228) - MedGen - NCBI". www.ncbi.nlm.nih.gov. Archived from the original on 25 May 2024. Retrieved 23 May 2024.
3. ↑ Bush, Albert O.; Fernandez, Jacqueline C.; Esch, Gerald W.; Seed, J. Richard (2001). Parasitism: The Diversity and Ecology of Animal Parasites. Cambridge, UK: Cambridge University Press. pp. 391–399. ISBN 9780521664479.
4. ↑ Ather, Binish; Mirza, Taaha M.; Edemekong, Peter F. (2024). "Airborne Precautions". StatPearls. StatPearls Publishing. Archived from the original on 2024-02-29. Retrieved 2024-05-31.
5. ↑ Randall, K.; Ewing, E. T.; Marr, L. C.; Jimenez, J. L.; Bourouiba, L. (6 December 2021). "How did we get here: what are droplets and aerosols and how far do they go? A historical perspective on the transmission of respiratory infectious diseases". Interface Focus. 11 (6). doi:10.1098/rsfs.2021.0049. PMC 8504878. PMID 34956601.
6. ↑ Richard, Mathilde; Knauf, Sascha; Lawrence, Philip; Mather, Alison E; Munster, Vincent J; Müller, Marcel A; Smith, Derek; Kuiken, Thijs (February 2017). "Factors determining human-to-human transmissibility of zoonotic pathogens via contact". Current Opinion in Virology. 22: 7–12. doi:10.1016/j.coviro.2016.11.004. Archived from the original on 2023-01-09. Retrieved 2024-06-04.
7. ↑ 7.0 7.1 van Seventer, Jean Maguire; Hochberg, Natasha S. (2017). "Principles of Infectious Diseases: Transmission, Diagnosis, Prevention, and Control". International Encyclopedia of Public Health: 22–39. doi:10.1016/B978-0-12-803678-5.00516-6. ISBN 978-0-12-803708-9. PMC 7150340.
8. ↑ Stürchler, Dieter (31 October 2023). "Infections transmitted via the faecal-oral route: a simple score for a global risk map". Journal of Travel Medicine. 30 (6): taad069. doi:10.1093/jtm/taad069. ISSN 1708-8305. PMID 37158467.
9. ↑ "vector biology". NIH. Archived from the original on 16 March 2024. Retrieved 1 June 2024.
10. ↑ Horizontal Disease Transmission Archived 27 September 2007 at the Wayback Machine, online-medical-dictionary.org. date ?
11. ↑ Routes of transmission of infectious diseases agents Archived 15 March 2012 at the Wayback Machine from Modes of Introduction of Exotic Animal Disease Agents by Katharine M. Kurkjian & Susan E. Little of The University of Georgia College of Veterinary Medicine, date?
12. ↑ Vertical transmission Archived 28 March 2007 at the Wayback Machine (definition -- medterms.com) date?
13. ↑ "Glossary of Notifiable Conditions". Washington State Department of Health. Archived from the original on 7 January 2010. Retrieved 3 February 2010.
14. ↑ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 978-0-8385-8529-0.`{{cite book}}`: CS1 maint: multiple names: authors list (link)
15. ↑ J.H. Jones, Notes on R0 Archived 2014-09-12 at the Wayback Machine. Stanford University (2007).
16. ↑ "Novel Coronavirus (COVID-19) Resources". Archived from the original on 2021-03-10. Retrieved 2023-02-11.
17. ↑ "Gainers and losers in the time of nCoV". The Manila Times. 10 February 2020. Archived from the original on 18 April 2020. Retrieved 11 February 2023.
18. ↑ "Global economy looks woozy". Dallas Morning News. 28 February 2020. Archived from the original on 25 May 2022. Retrieved 11 February 2023 - via pressreader.com.(subscription required)
19. ↑ "Coronavirus disease 2019 (COVID-19) Situation Report – 47" (PDF). World Health Organization. Archived (PDF) from the original on 8 March 2020. Retrieved 8 March 2020.
20. ↑ "Chain of Infection Components". www.cdc.gov. 22 May 2023. Archived from the original on 8 April 2024. Retrieved 27 May 2024.
21. ↑ "What infections are, how they are transmitted and those at higher risk of infection". GOV.UK. Archived from the original on 19 December 2023. Retrieved 29 May 2024.
22. ↑ Azman, Andrew S.; Rudolph, Kara E.; Cummings, Derek A. T.; Lessler, Justin (1 May 2013). "The incubation period of cholera: A systematic review". Journal of Infection. 66 (5): 432–438. doi:10.1016/j.jinf.2012.11.013. ISSN 0163-4453. Archived from the original on 12 April 2024. Retrieved 16 June 2024.
23. ↑ Melnick, J L (July 1996). "Current status of poliovirus infections". Clinical Microbiology Reviews. 9 (3): 293–300. doi:10.1128/CMR.9.3.293. ISSN 0893-8512. Archived from the original on 2021-06-15. Retrieved 2024-06-16.
24. ↑ 24.0 24.1 NHMRC (2010). "Clinical Educators Guide for the Prevention and Control of Infection in Healthcare" (PDF). Commonwealth of Australia. Archived (PDF) from the original on 5 May 2022. Retrieved 10 November 2020.
25. ↑ Nabarro, Laura; Morris-Jones, Stephen; Moore, David A.J. (2020). "Infections Acquired by Airborne Transmission". Peter's Atlas of Tropical Medicine and Parasitology: 244–281. doi:10.1016/B978-0-7020-4061-0.00004-2. ISBN 978-0-7020-4061-0. PMC 7149766.
26. ↑ 26.0 26.1 "Prevention of hospital-acquired infections" (PDF). World Health Organization (WHO). Archived from the original (PDF) on 26 March 2020.
27. ↑ Siegel JD, Rhinehart E, Jackson M, Chiarello L, Healthcare Infection Control Practices Advisory Committee. "2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings" (PDF). CDC. p. 19\. Archived (PDF) from the original on 2019-08-02. Retrieved 2019-02-07. "Airborne transmission occurs by dissemination of either airborne droplet nuclei or small particles in the respirable size range containing infectious agents that remain infective over time and distance"
28. ↑ 28.0 28.1 "Respiratory Protection Against Airborne Infectious Agents for Health Care Workers: Do surgical masks protect workers?" (OSH Answers Fact Sheets). Canadian Centre for Occupational Health and Safety. 28 February 2017. Archived from the original on 2 March 2020. Retrieved 28 February 2017.
29. ↑ "What is Diseases contagious from droplets?". Archived from the original on 16 July 2015.
30. ↑ "Pass the message: Five steps to kicking out coronavirus". www.who.int. Archived from the original on 24 March 2020. Retrieved 24 March 2020.
31. ↑ 31.0 31.1 31.2 "Principles of Epidemiology: Chain of Infection". U.S. Centers for Disease Control and Infection. 2019-02-18. Archived from the original on 2020-07-23. Retrieved 2020-07-21. This article incorporates text from this source, which is in the public domain.
32. ↑ 32.0 32.1 LaMorte, Wayne W. (2016-01-06). "Common Vehicle Spread". Boston University School of Public Health. Archived from the original on 2020-05-14. Retrieved 2020-07-21.
33. ↑ 33.0 33.1 Whittier, Christopher A. (2017-04-16), "Fecal-Oral Transmission", in Bezanson, Michele; MacKinnon, Katherine C; Riley, Erin; Campbell, Christina J (eds.), The International Encyclopedia of Primatology, Hoboken, NJ, USA: John Wiley & Sons, Inc., p. 1, doi:10.1002/9781119179313.wbprim0193, ISBN 978-1-119-17931-3
34. ↑ Health (US), National Institutes of; Study, Biological Sciences Curriculum (2007). "Understanding Emerging and Re-emerging Infectious Diseases". NIH Curriculum Supplement Series [Internet]. National Institutes of Health (US). Archived from the original on 2023-06-26. Retrieved 2024-06-09.
35. ↑ Morse, Stephen A.; Mietzner, Timothy A.; Miller, Steve; Riedel, Stefan (2019). Jawetz, Melnick & Adelberg's Medical Microbiology (28th ed.). New York. ISBN 978-1-260-01202-6.
36. ↑ Garcia, Michael Ray; Leslie, Stephen W.; Wray, Anton A. (2024). "Sexually Transmitted Infections". StatPearls. StatPearls Publishing. Archived from the original on 2023-05-28. Retrieved 2024-05-28.
37. ↑ Wihlfahrt, Kristina; Günther, Veronika; Mendling, Werner; Westermann, Anna; Willer, Damaris; Gitas, Georgios; Ruchay, Zino; Maass, Nicolai; Allahqoli, Leila; Alkatout, Ibrahim (8 May 2023). "Sexually Transmitted Diseases—An Update and Overview of Current Research". Diagnostics. 13 (9): 1656. doi:10.3390/diagnostics13091656. Archived from the original on 1 June 2024. Retrieved 29 May 2024.
38. ↑ "About Sexually Transmitted Infections (STIs)". Sexually Transmitted Infections (STIs). 22 April 2024. Archived from the original on 6 June 2024. Retrieved 7 June 2024.
39. ↑ "Sexually transmitted infections (STIs)". www.who.int. Archived from the original on 2018-04-30. Retrieved 2024-06-10.
40. ↑ "About STI Risk and Oral Sex". Sexually Transmitted Infections (STIs). 27 March 2024. Archived from the original on 25 May 2024. Retrieved 8 June 2024.
41. ↑ 41.0 41.1 Queirós, Catarina; Costa, João Borges da (2 December 2019). "Oral Transmission of Sexually Transmissable Infections: A Narrative Review". Acta Medica Portuguesa. 32 (12): 776–781. doi:10.20344/amp.12191. ISSN 1646-0758. Archived from the original on 2 March 2022. Retrieved 28 May 2024.
42. ↑ Limeres Posse, Jacobo; Diz Dios, Pedro; Scully, Crispian (2017). "Viral Diseases Transmissible by Kissing". Saliva Protection and Transmissible Diseases: 53–92. doi:10.1016/B978-0-12-813681-2.00004-4. Archived from the original on 27 August 2022. Retrieved 11 June 2024.
43. ↑ 43.0 43.1 Ebert, Dieter (2013). "The Epidemiology and Evolution of Symbionts with Mixed-Mode Transmission". Annual Review of Ecology, Evolution, and Systematics. 44: 623–643. doi:10.1146/annurev-ecolsys-032513-100555.
44. ↑ Gürtler, Lutz G.; Eberle, Josef (August 2017). "Aspects on the history of transmission and favor of distribution of viruses by iatrogenic action: perhaps an example of a paradigm of the worldwide spread of HIV". Medical Microbiology and Immunology. 206 (4): 287–293. doi:10.1007/s00430-017-0505-2. ISSN 1432-1831. Archived from the original on 18 June 2022. Retrieved 31 May 2024.
45. ↑ Peer, Rafia Farooq; Shabir, Nadeem (2018). "Iatrogenesis: A review on nature, extent, and distribution of healthcare hazards". Journal of Family Medicine and Primary Care. 7 (2): 309–314. doi:10.4103/jfmpc.jfmpc_329_17. ISSN 2249-4863. Archived from the original on 2023-01-01. Retrieved 2024-06-09.
46. ↑ Pathogens and vectors Archived 24 January 2015 at the Wayback Machine. MetaPathogen.com.
47. ↑ Socha, Wojciech; Kwasnik, Malgorzata; Larska, Magdalena; Rola, Jerzy; Rozek, Wojciech (27 May 2022). "Vector-Borne Viral Diseases as a Current Threat for Human and Animal Health—One Health Perspective". Journal of Clinical Medicine. 11 (11): 3026. doi:10.3390/jcm11113026. Archived from the original on 24 May 2024. Retrieved 3 June 2024.
48. ↑ "Vector-borne diseases | EFSA". www.efsa.europa.eu. 6 December 2023. Archived from the original on 16 February 2024. Retrieved 11 June 2024.
49. ↑ Johnson, David L.; Mead, Kenneth R.; Lynch, Robert A.; Hirst, Deborah V.L. (March 2013). "Lifting the lid on toilet plume aerosol: A literature review with suggestions for future research". American Journal of Infection Control. 41 (3): 254–258. doi:10.1016/j.ajic.2012.04.330. PMC 4692156. PMID 23040490.
50. ↑ Jones, RM; Brosseau, L. M. (May 2015). "Aerosol transmission of infectious disease". Journal of Occupational and Environmental Medicine. 57 (5): 501–8. doi:10.1097/JOM.0000000000000448. PMID 25816216. S2CID 11166016.
51. ↑ Reid, Brie; Orgle, Jennifer; Roy, Khrist; Pongolani, Catherine; Chileshe, Modesta; Stoltzfus, Rebecca (5 February 2018). "Characterizing Potential Risks of Fecal–Oral Microbial Transmission for Infants and Young Children in Rural Zambia". The American Journal of Tropical Medicine and Hygiene. 98 (3): 816–823. doi:10.4269/ajtmh.17-0124. ISSN 0002-9637. Archived from the original on 11 March 2022. Retrieved 4 June 2024.
52. ↑ Zerbo, Alexandre; Castro Delgado, Rafael; Arcos González, Pedro (2022). "Conceptualization of the Transmission Dynamic of Faecal-Orally Transmitted Diseases in Urban Exposome of Sub-Saharan Africa". Risk Management and Healthcare Policy. 15: 1959–1964. doi:10.2147/RMHP.S372185. ISSN 1179-1594. Archived from the original on 2024-06-19. Retrieved 2024-06-15.
53. ↑ de Graaf, Miranda; Beck, Relja; Caccio, Simone M; Duim, Birgitta; Fraaij, Pieter LA; Le Guyader, Françoise S; Lecuit, Marc; Le Pendu, Jacques; de Wit, Emmie; Schultsz, Constance (February 2017). "Sustained fecal-oral human-to-human transmission following a zoonotic event". Current Opinion in Virology. 22: 1–6. doi:10.1016/j.coviro.2016.11.001. ISSN 1879-6257. Archived from the original on 2022-05-05. Retrieved 2024-06-15.
54. ↑ Xavier, Joao B.; Monk, Jonathan M.; Poudel, Saugat; Norsigian, Charles J.; Sastry, Anand V.; Liao, Chen; Bento, Jose; Suchard, Marc A.; Arrieta-Ortiz, Mario L.; Peterson, Eliza J.R.; Baliga, Nitin S.; Stoeger, Thomas; Ruffin, Felicia; Richardson, Reese A.K.; Gao, Catherine A.; Horvath, Thomas D.; Haag, Anthony M.; Wu, Qinglong; Savidge, Tor; Yeaman, Michael R. (April 2022). "Mathematical models to study the biology of pathogens and the infectious diseases they cause". iScience. 25 (4): 104079. Bibcode:2022iSci...25j4079X. doi:10.1016/j.isci.2022.104079. PMC 8961237. PMID 35359802.
55. ↑ Kretzschmar, Mirjam; Wallinga, Jacco (28 July 2009). "Mathematical Models in Infectious Disease Epidemiology". Modern Infectious Disease Epidemiology: 209–221. doi:10.1007/978-0-387-93835-6_12. Archived from the original on 14 April 2024. Retrieved 5 June 2024.
56. ↑ Keeling, M. J.; Danon, L. (2009). "Mathematical modelling of infectious diseases". British Medical Bulletin. 92: 33–42. doi:10.1093/bmb/ldp038. ISSN 1471-8391. Archived from the original on 2024-06-12. Retrieved 2024-06-10.
57. ↑ Grassly, Nicholas C.; Fraser, Christophe (June 2008). "Mathematical models of infectious disease transmission". Nature Reviews Microbiology. 6 (6): 477–487. doi:10.1038/nrmicro1845. ISSN 1740-1534. Archived from the original on 2024-06-15. Retrieved 2024-06-13.
58. ↑ Murray, Jillian; Cohen, Adam L. (2017). "Infectious Disease Surveillance". International Encyclopedia of Public Health: 222–229. doi:10.1016/B978-0-12-803678-5.00517-8. Archived from the original on 2023-05-21. Retrieved 2024-06-17.
59. ↑ Polgreen P.M., Chen E., Segre A.M., Harris M., Pentella M., Rushton G. (2009). "Optimizing Influenza Sentinel Surveillance at the State Level American". Journal of Epidemiology. 170 (10): 1300–1306. doi:10.1093/aje/kwp270. PMC 2800268. PMID 19822570.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
60. ↑ Ginsberg J., Mohebbi M.H., Patel R.S., Brammer L., Smolinski M.S., Brilliant L. (2008). "Detecting influenza epidemics using search engine query data" (PDF). Nature. 457 (7232): 1012–1014. doi:10.1038/nature07634. PMID 19020500. S2CID 125775. Archived from the original (PDF) on 2018-10-24.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
61. ↑ Chan E.H., Sahai V., Conrad C., Brownstein J.S. (2011). "Using Web Search Query Data to Monitor Dengue Epidemics: A New Model for Neglected Tropical Disease Surveillance". PLOS Negl Trop Dis. 5 (5): e1206. doi:10.1371/journal.pntd.0001206. PMC 3104029. PMID 21647308.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
62. ↑ Siettos CI, Russo L (15 May 2013). "Mathematical modeling of infectious disease dynamics". Virulence. 4 (4): 295–306. doi:10.4161/viru.24041. PMC 3710332. PMID 23552814.
63. ↑ Wesolowski A, Metcalf CJ, Eagle N, Kombich J, Grenfell BT, Bjørnstad ON, Lessler J, Tatem AJ, Buckee CO. (1 September 2015). "Quantifying seasonal population fluxes driving rubella transmission dynamics using mobile phone data". PNAS. 112 (35): 11114–11119. Bibcode:2015PNAS..11211114W. doi:10.1073/pnas.1423542112. PMC 4568255. PMID 26283349.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
64. ↑ 64.0 64.1 Pintó, Rosa M; Pérez-Rodríguez, Francisco-Javier; Costafreda, Maria-Isabel; Chavarria-Miró, Gemma; Guix, Susana; Ribes, Enric; Bosch, Albert (31 December 2021). "Pathogenicity and virulence of hepatitis A virus". Virulence. 12 (1): 1174–1185. doi:10.1080/21505594.2021.1910442. ISSN 2150-5594.
65. ↑ Gupta, Sunetra (19 July 2023). "Evolution of pathogen virulence". EMBO Reports. 24 (8): e57611. doi:10.15252/embr.202357611. ISSN 1469-221X. Archived from the original on 6 June 2024. Retrieved 6 June 2024.
66. ↑ Iwasa, Yoh; Hara, Akane; Ozone, Shihomi (7 December 2021). "Virulence of a virus: How it depends on growth rate, effectors, memory cells, and immune escape". Journal of Theoretical Biology. 530: 110875. doi:10.1016/j.jtbi.2021.110875. ISSN 1095-8541. Archived from the original on 9 June 2024. Retrieved 7 June 2024.
67. ↑ Rico-Hesse, R. (2010). "Dengue Virus Virulence and Transmission Determinants". Dengue Virus. Springer. pp. 45–55. ISBN 978-3-642-02215-9. Archived from the original on 2020-05-09. Retrieved 2024-06-16.
68. ↑ 68.0 68.1 68.2 Bright M, Bulgheresi S (March 2010). "A complex journey: transmission of microbial symbionts". Nature Reviews. Microbiology. 8 (3): 218–230. doi:10.1038/nrmicro2262. PMC 2967712. PMID 20157340.
69. ↑ Rosenberg, Eugene; Zilber-Rosenberg, Ilana (30 December 2021). "Reconstitution and Transmission of Gut Microbiomes and Their Genes between Generations". Microorganisms. 10 (1): 70. doi:10.3390/microorganisms10010070. ISSN 2076-2607. Archived from the original on 9 June 2024. Retrieved 8 June 2024.
70. ↑ Funkhouser, Lisa; Bordenstein, Seth (2013). "Mom Knows Best: The Universality of Maternal Microbial Transmission". PLOS Biology. 11 (8): e1001631. doi:10.1371/journal.pbio.1001631. PMC 3747981. PMID 23976878.
71. ↑ Nussbaumer, Andrea; Fisher, Charles; Bright, Monika (2006). "Horizontal endosymbiont transmission in hydrothermal vent tubeworms". Nature. 441 (7091): 345–348. Bibcode:2006Natur.441..345N. doi:10.1038/nature04793. PMID 16710420. S2CID 18356960.
72. ↑ Kaltenpoth, Martin; Engl, Tobias (2013). "Defensive microbial symbionts in Hymenoptera". Functional Ecology. 28 (2): 315–327. doi:10.1111/1365-2435.12089. hdl:11858/00-001M-0000-000E-B76B-E.

* v
* t
* e

Concepts in infectious disease (Outline)

Determinants|

| Agent|

* Biofilm
* Germ theory of disease
* Infectivity
* Infectious dose
* Pathogenicity
* Attack rate
* Quorum sensing
* Virulence
* Endotoxin
* Exotoxin
* Case fatality rate
* factors
* Antimicrobial resistance
* Drug resistance
* Horizontal gene transfer
* Multidrug-resistant bacteria
* Host tropism

|

Host|

* Burn
* Comorbidity
* Diabetes
* Host–pathogen interaction
* Immune response
* Immunodeficiency
* Immunosuppression
* Microbiome health
* Opportunistic infection
* Risk of infection
* Susceptible individual
* Age
* Gender
* Nutrition status
* Vaccination status
* Genetic predisposition
* Behavioral/lifestyle factors
* Smoking
* Pregnancy
* Stress levels

Environment|

* Access to water, sanitation and hygiene
* Air quality
* Biodiversity loss
* Climate change
* Climate zones
* El Niño
* Tropical diseases
* Commerce
* Deforestation
* Ecology
* Humidity
* Injection drug use
* Natural disaster
* Flood
* Poultry and livestock
* Poverty
* Travel
* Urbanization
* Vector control
* War and conflict

Transmission|

| Basic
concepts|

* Asymptomatic carrier
* Chain of infection
* Fomite
* Host
* Incubation period
* Index case
* Infectious period
* Latent period
* Natural reservoir
* Opportunistic infection
* Silent/Subclinical infection
* Superinfection
* Super-spreader
* Viral load
* Window period

|

Modes|

| Endogenous|

* Endogenous overgrowth
* Normal flora overgrowth
* Endogenous reactivation
* Microbial translocation
* Endogenous seeding
* Biofilm formation

|

Exogenous|

| Cross-species|

* Spillover infection
* Vector
* Zoonosis
* Reverse zoonosis

|

Human-to-human
/Cross-infection|

* Contagious disease
* Source
* Nosocomial/Hospital
* Iatrogenic/Medical care
* Generational difference
* Vertical/Congenital
* Prenatal
* Perinatal
* Neonatal
* Horizontal
* Breakthrough infection

Environment-
to-human|

* Sapronosis

Routes|

| Respiratory|

* Air
* Bioaerosol
* Aerosol-generating procedure
* Dental aerosol
* Respiratory droplet

|

Linked to
Vascular system|

* Blood-borne disease
* Percutaneous inoculation
* Injection site
* Intravenous line
* Insect bite
* Animal bite
* Surgical intervention
* Postoperative wound
* Surgical site infection
* Vector-borne
* Mosquito
* Tick

Gastrointestinal|

* Food
* Contamination
* Breastmilk
* Water
* Feces

Cutaneous|

* Burn
* Fomite
* Soil
* Open wound

Genitourinary|

* Sex

Trans-placental|

* Prenatal

Cervico-vaginal|

* Perinatal

Other|

* Ocular (Eye) mucosal membrane

Modelling|

* Agent-based model
* Animal disease model
* Attack rate
* Basic reproduction number
* Compartmental models in epidemiology
* Critical community size
* Force of infection
* Herd immunity
* Infection rate
* Machine learning
* Multiplicity of infection
* Serial interval
* WAIFW matrix

Occurrence
in population|

* Cluster
* Endemic
* Epidemic
* Curve
* Farr's laws
* Holoendemic
* Hyperendemic
* Incidence
* Inequality
* Mesoendemic
* Outbreak
* Pandemic
* Prevalence
* Seasonality
* Geographic distribution
* Sporadic
* Syndemic
* Twindemic

Anatomical
location|

* Respiratory
* Ear-Nose-Throat/Upper respiratory tract
* Chest/Lower respiratory tract
* Gastrointestinal
* Intestinal
* Genitourinary
* Nervous system
* Skin
* Soft tissue
* Bone
* Joint
* Cardiovascular
* Systemic/Generalized
* Blood
* Tooth
* Mouth
* Fetus
* Eye

Prevention
and Control
measures|

| Pharmaceutical|

* Antibiotic
* prophylactic
* Antifungal
* Anthelmintic
* Ascaricide
* Antimicrobial
* Antimicrobial stewardship
* Antiseptic
* Antiviral
* Asepsis
* Combination
* Drug safety
* Immunization
* Immunotherapy
* Monoclonal antibody therapy
* Inoculation
* Phage therapy
* Pre-exposure prophylaxis
* Post-exposure prophylaxis
* Repurposed drugs
* Vaccination
* efficacy/effectiveness
* booster
* resistance
* Vaccine-preventable disease
* Ring vaccination

|

Non-
pharmaceutical|

* Contact tracing
* Cordon sanitaire
* Disease surveillance
* Disinfection
* Flattening the curve
* Hygiene
* Food hygiene
* Hand washing
* Gloves
* Isolation
* Barrier nursing
* Lockdown
* Notification
* list
* Protective sequestration
* Public health
* Community health services
* Health communication
* Health education
* Outbreak response
* Quarantine
* Respiratory source control
* N95 respirator
* Surgical mask
* PPE
* Safe sex
* Sanitation
* Screening
* Social distancing
* Sterilization
* Transmission-based precautions
* Travel restrictions
* Universal precautions
* Vector control
* Wastewater surveillance
* Zoning

Emerging
infections|

* Antigenic drift
* Antigenic shift
* Antimicrobial resistance surveillance
* EARS-Net
* Biosecurity
* CRISPR
* Disease X
* Emergent virus
* Evolutionary epidemiology
* Genetic epidemiology
* Global Health Initiatives
* Microbial phylogenetics
* One Health Model
* Genomic reassortment
* Re-emerging disease
* Reverse zoonosis
* Selection pressure
* Synthetic biology
* Viral phylodynamics

Other|

* Discovery
* Eradication
* Economics of Infectious Diseases
* Infectious disease (medical specialty)
* Infectious disease informatics
* Microbial bioterrorism
* Pandemic prevention
* Tropical disease
* Tropical medicine

*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template