Human-to-human transmission

Spread of an infection from one person to another

Human-to-human transmission (HHT) is an epidemiologic vector,[1][2][3][4][5][6][7][8] especially in case the disease is borne by individuals known as superspreaders. In these cases, the basic reproduction number of the virus, which is the average number of additional people that a single case will infect without any preventative measures, can be as high as 203.9.[9][10] Interhuman transmission is a synonym for HHT.[11]

The World Health Organization designation of a pandemic hinges on the demonstrable fact that there is sustained HHT in two regions of the world.[12]

## Synopsis

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Relevant microbes may be viruses, bacteria, or fungi, and they may be spread through breathing, talking, coughing, sneezing, spraying of liquids, toilet flushing or any activities which generate aerosol particles or droplets or generate fomites, such as raising of dust.[13][14]

Transfer efficiency depends not only on surface, but also on pathogen type. For example, avian influenza survives on both porous and non-porous materials for 144 hours.[13]

The microbes may also be transmitted by poor use of cutlery or improper sanitation of dishes or bedlinen. Particularly problematic are toilet practices, which lead to the fecal–oral route. STDs are by definition spread through this vector.[citation needed]

## List of HHT diseases

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Examples of some HHT diseases are listed below.[citation needed]

* measles: vaccine available
* mumps: vaccine available
* chicken pox: vaccine available
* small pox[15]
* bubonic plague: slim non-nil risk[16]
* pneumonic plague: 1910-11 Manchurian plague[17]
* tuberculosis
* Norovirus[18][19]
* monkeypox[20]
* SARS-CoV-1
* SARS-CoV-2: vaccine available
* MERS
* Avian flu
* Sexually transmitted infections (STIs) or sexually transmitted diseases (STDs):
* Syphilis, aka French pox[15]

## References

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1. ^ Chowell G, Blumberg S, Simonsen L, Miller MA, Viboud C (2014). "Synthesizing data and models for the spread of MERS-CoV, 2013: Key role of index cases and hospital transmission". Epidemics. 9: 40–51\. doi:10.1016/j.epidem.2014.09.011. PMC 4258236. PMID 25480133.
2. ^ Virlogeux V, Feng L, Tsang TK, Jiang H, Fang VJ, Qin Y, Wu P, Wang X, Zheng J, Lau EH, Peng Z, Yang J, Cowling BJ, Yu H (2018). "Evaluation of animal-to-human and human-to-human transmission of influenza A (H7N9) virus in China, 2013–15". Scientific Reports. 8 (1): 552. Bibcode:2018NatSR...8..552V. doi:10.1038/s41598-017-17335-9. PMC 5765021. PMID 29323268.
3. ^ Majumder MS, Brownstein JS, Finkelstein SN, Larson RC, Bourouiba L (2017). "Nosocomial amplification of MERS-coronavirus in South Korea, 2015". Transactions of the Royal Society of Tropical Medicine and Hygiene. 111 (6): 261–269\. doi:10.1093/trstmh/trx046. PMC 6257029. PMID 29044371.
4. ^ De Graaf M, Beck R, Caccio SM, Duim B, Fraaij PL, Le Guyader FS, Lecuit M, Le Pendu J, De Wit E, Schultsz C (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. PMC 7102779. PMID 27888698.
5. ^ Geoghegan JL, Senior AM, Di Giallonardo F, Holmes EC (2016). "Virological factors that increase the transmissibility of emerging human viruses". Proceedings of the National Academy of Sciences. 113 (15): 4170–4175\. Bibcode:2016PNAS..113.4170G. doi:10.1073/pnas.1521582113. PMC 4839412. PMID 27001840.
6. ^ Kucharski A, Mills H, Pinsent A, Fraser C, Van Kerkhove M, Donnelly CA, Riley S (2014). "Distinguishing Between Reservoir Exposure and Human-to-Human Transmission for Emerging Pathogens Using Case Onset Data". PLOS Currents. 6. doi:10.1371/currents.outbreaks.e1473d9bfc99d080ca242139a06c455f (inactive 2024-11-02). PMC 3946006. PMID 24619563.`{{cite journal}}`: CS1 maint: DOI inactive as of November 2024 (link)
7. ^ Herfst S, Böhringer M, Karo B, Lawrence P, Lewis NS, Mina MJ, Russell CJ, Steel J, De Swart RL, Menge C (2017). "Drivers of airborne human-to-human pathogen transmission". Current Opinion in Virology. 22: 22–29\. doi:10.1016/j.coviro.2016.11.006. PMC 7102691. PMID 27918958.
8. ^ Riou J, Althaus CL (2020). "Pattern of early human-to-human transmission of Wuhan 2019 novel coronavirus (2019-nCoV), December 2019 to January 2020". Eurosurveillance. 25 (4). doi:10.2807/1560-7917.ES.2020.25.4.2000058. PMC 7001239. PMID 32019669.
9. ^ Li Q, Guan X, Wu P, Wang X, Zhou L, Tong Y, et al. (January 2020). "Early Transmission Dynamics in Wuhan, China, of Novel Coronavirus-Infected Pneumonia". The New England Journal of Medicine. 382 (13): 1199–1207\. doi:10.1056/NEJMoa2001316. PMC 7121484. PMID 31995857.
10. ^ Riou J, Althaus CL (January 2020). "Pattern of early human-to-human transmission of Wuhan 2019 novel coronavirus (2019-nCoV), December 2019 to January 2020". Euro Surveillance. 25 (4). doi:10.2807/1560-7917.ES.2020.25.4.2000058. PMC 7001239. PMID 32019669.
11. ^ Meyer A, Esposito JJ, Gras F, Kolakowski T, Fatras M, Muller G (1991). "First appearance of monkey pox in human beings in Gabon". Médecine Tropicale: Revue du Corps de Santé Colonial. 51 (1): 53–7\. PMID 1649373.
12. ^ Friscolanti M (4 June 2009). "Canada's Pandemic Influenza Plan". Canadian Encyclopedia.
13. ^ a b Cook 2013, p. 208.
14. ^ Abad FX, R. M. Pintó, A. Bosch (October 1994). "Survival of enteric viruses on environmental fomites". Applied and Environmental Microbiology. 60 (10): 3704–10\. Bibcode:1994ApEnM..60.3704A. doi:10.1128/AEM.60.10.3704-3710.1994. PMC 201876. PMID 7986043.
15. ^ a b Welford MR, Bossak BH, Carter DA (22 December 2009). "Validation of Inverse Seasonal Peak Mortality in Medieval Plagues, Including the Black Death, in Comparison to Modern Yersinia pestis-Variant Diseases". PLOS ONE. 4 (12): e8401. Bibcode:2009PLoSO...4.8401W. doi:10.1371/journal.pone.0008401. PMC 2791870. PMID 20027294.
16. ^ Kool JL (2005). "Risk of Person-to-Person Transmission of Pneumonic Plague". Clinical Infectious Diseases. 40 (8): 1166–1172\. doi:10.1086/428617. PMID 15791518.
17. ^ Wilson M (24 March 2020). "The untold origin story of the N95 mask". Fast Company.
18. ^ Kumar Nag P (2018). Office Buildings: Health, Safety and Environment. Springer. p. 85\. ISBN 978-981-13-2577-9.
19. ^ Robilotti E, Deresinski S, Pinsky BA (2015). "Norovirus". Clinical Microbiology Reviews. 28 (1): 134–164\. doi:10.1128/CMR.00075-14. PMC 4284304. PMID 25567225.
20. ^ Learned LA, Reynolds MG, Wassa DW, Li Y, Olson VA, Karem K, Stempora LL, Braden ZH, Kline R, Likos A, Libama F, Moudzeo H, Bolanda JD, Tarangonia P, Boumandoki P, Formenty P, Harvey JM, Damon IK (2005). "Extended interhuman transmission of monkeypox in a hospital community in the Republic of the Congo, 2003". The American Journal of Tropical Medicine and Hygiene. 73 (2): 428–34\. doi:10.4269/ajtmh.2005.73.428. PMID 16103616.

### Sources

[edit]

* Cook N (2013). "10.1 Introduction; the role of fomites in the virus transmission". Viruses in Food and Water: Risks, Surveillance and Control. Cambridge: Woodhead Publishing. pp. 205–215\. ISBN 978-0-85709-887-0.
* Larson EL, Liverman CT (2011). "Understanding the Risk to Healthcare Personnel: Fomite Persistence". Preventing Transmission of Pandemic Influenza and Other Viral Respiratory Diseases: Personal Protective Equipment for Healthcare Personnel: Update 2010. Washington: National Academies Press. p. 41\. ISBN 978-0-309-16254-8.

* v
* t
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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
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* Biodiversity loss
* Climate change
* Climate zones
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* Tropical diseases
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* 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

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