Disease vector

In epidemiology, a disease vector is any living[1] agent that carries and transmits an infectious pathogen to another living organism;[2][3] agents regarded as vectors are organisms, such as parasites or microbes. The first major discovery of a disease vector came from Ronald Ross in 1897, who discovered the malaria pathogen when he dissected a mosquito.[4]

## Contents

* 1 Arthropods
* 2 Plants and fungi
* 3 Mammals
* 4 World Health Organization and vector-borne disease
* 5 Vector-borne zoonotic disease and human activity
* 6 See also
* 7 Notes
* 8 References
* 9 Bibliography
* 10 External links

## Arthropods[edit | edit source]

Aedes aegypti mosquitoes, the species that transmits Zika, dengue, chikungunya, and yellow fever viruses

Arthropods form a major group of pathogen vectors with mosquitoes, flies, sand flies, lice, fleas, ticks, and mites transmitting a huge number of pathogens. Many such vectors are haematophagous, which feed on blood at some or all stages of their lives. When the insects feed on blood, the pathogen enters the blood stream of the host. This can happen in different ways.[5][6]

The Anopheles mosquito, a vector for malaria, filariasis, and various arthropod-borne-viruses (arboviruses), inserts its delicate mouthpart under the skin and feeds on its host's blood. The parasites the mosquito carries are usually located in its salivary glands (used by mosquitoes to anaesthetise the host). Therefore, the parasites are transmitted directly into the host's blood stream. Pool feeders such as the sand fly and black fly, vectors for pathogens causing leishmaniasis and onchocerciasis respectively, will chew a well in the host's skin, forming a small pool of blood from which they feed. Leishmania parasites then infect the host through the saliva of the sand fly. Onchocerca force their own way out of the insect's head into the pool of blood.[7][8]

Triatomine bugs are responsible for the transmission of a trypanosome, Trypanosoma cruzi, which causes Chagas disease. The Triatomine bugs defecate during feeding and the excrement contains the parasites, which are accidentally smeared into the open wound by the host responding to pain and irritation from the bite.[9][10][11][12]

There are several species of Thrips that act as vectors for over 20 viruses, especially Tospoviruses, and cause all sorts of plant diseases.[13][14]

* A mosquito shortly after obtaining blood from a human (note the droplet of blood plasma being expelled as the mosquito squeezes out excess water). Mosquitos are a vector for several diseases, including malaria

* The deer tick, a vector for Lyme disease pathogens

## Plants and fungi[edit | edit source]

Some plants and fungi act as vectors for various pathogens. For example, the big-vein disease of lettuce was long thought to be caused by a member of the fungal division Chytridiomycota, namely Olpidium brassicae. Eventually, however, the disease was shown to be viral. Later it transpired that the virus was transmitted by the zoospores of the fungus and also survived in the resting spores. Since then, many other fungi in Chytridiomycota have been shown to vector plant viruses.[15]

Many plant pests that seriously damage important crops depend on other plants, often weeds, to harbour or vector them; the distinction is not always clear. In the case of Puccinia graminis for example, Berberis and related genera act as alternate hosts in a cycle of infection of grain.[16]

More directly, when they twine from one plant to another, parasitic plants such as Cuscuta and Cassytha have been shown to convey phytoplasmal and viral diseases between plants.[17] [15]

## Mammals[edit | edit source]

Rabies is transmitted through exposure to the saliva or brain tissue of an infected animal. Any warm-blooded animal can carry rabies, but the most common vectors are dogs, skunks, raccoons, and bats.[18]

## World Health Organization and vector-borne disease[edit | edit source]

The World Health Organization (WHO) states that control and prevention of vector-borne diseases are emphasizing "Integrated Vector Management (IVM)",[19] which is an approach that looks at the links between health and environment, optimizing benefits to both.[lower-alpha 1][20]

In April 2014, WHO launched a campaign called "Small bite, big threat" to educate people about vector-borne illnesses. WHO issued reports indicating that vector-borne illnesses affect poor people, especially people living in areas that do not have adequate levels of sanitation, drinking water and housing.[21]

## Vector-borne zoonotic disease and human activity[edit | edit source]

Figure 1. This figure shows how the Flavivirus is carried by mosquitos in the West Nile virus and Dengue fever. The mosquito would be considered a disease vector.

Several articles, recent to early 2014, warn that human activities are spreading vector-borne zoonotic diseases.[lower-alpha 2] Several articles were published in the medical journal The Lancet, and discuss how rapid changes in land use, trade globalization, and "social upheaval" are causing a resurgence in zoonotic disease across the world.[22]

Examples of vector-borne zoonotic diseases include:[23]

* Lyme disease
* Plague
* West Nile virus

Many factors affect the incidence of vector-borne diseases. These factors include animals hosting the disease, vectors, and people.[23]

Humans can also be vectors for some diseases, such as Tobacco mosaic virus, physically transmitting the virus with their hands from plant to plant.

## See also[edit | edit source]

* Airborne disease
* Asymptomatic carrier
* Fomite
* Globalization and disease
* Insect vectors of human pathogens
* Insect vectors of plant pathogens
* VectorBase: genomic database of invertebrate vectors of human pathogens
* List of diseases caused by insects
* Natural reservoir
* Waterborne disease
* 2007 Yap Islands Zika virus outbreak

## Notes[edit | edit source]

1. ↑ "IVM strategies are designed to achieve the greatest disease control benefit in the most cost-effective manner, while minimizing negative impacts on ecosystems (e.g. depletion of biodiversity) and adverse side-effects on public health from the excessive use of chemicals in vector control."[20]
2. ↑ "Vector-borne zoonotic diseases are those that naturally infect wildlife and are then transmitted to humans through carriers, or vectors, such as mosquitoes or ticks."[22]

## References[edit | edit source]

1. ↑ "Vector-borne diseases". Archived from the original on 2023-01-04. Retrieved 2023-01-21.
2. ↑ "Vector". WordNet Search 3.1. Princeton University. Archived from the original on 4 March 2016. Retrieved 7 April 2014.
3. ↑ Last, James, ed. (2001). A Dictionary of Epidemiology. New York: Oxford University Press. p. 185\. ISBN 978-0-19-514169-6. OCLC 207797812. Archived from the original on 2023-02-05. Retrieved 2023-01-21.
4. ↑ Prevention, CDC-Centers for Disease Control and (2017-03-28). "CDC - Malaria - About Malaria - History - Ross and the Discovery that Mosquitoes Transmit Malaria Parasites". www.cdc.gov. Archived from the original on 2017-12-09. Retrieved 2020-10-23.
5. ↑ "Classification of Animal Parasites". plpnemweb.ucdavis.edu. Archived from the original on 2017-10-06. Retrieved 2023-01-21.
6. ↑ Garcia, Lynne S. (August 15, 1999). "Classification of Human Parasites, Vectors, and Similar Organisms". Clinical Infectious Diseases. 29 (4): 734–736. doi:10.1086/520425. PMID 10589879.
7. ↑ "8.20D: Arthropods as Vectors". 23 June 2017. Archived from the original on 16 June 2022. Retrieved 21 January 2023.
8. ↑ "PEOI Foundations of Public Health". Archived from the original on 2018-08-01. Retrieved 2023-01-21.
9. ↑ "CDC - Chagas Disease - Detailed Fact Sheet". 11 April 2022. Archived from the original on 16 August 2019. Retrieved 21 January 2023.
10. ↑ "Coronavirus disease 2019 (COVID-19) from Mayo Clinic - Mayo Clinic". Mayo Clinic. Archived from the original on 2023-01-21. Retrieved 2023-01-21.
11. ↑ "CDC - Chagas Disease - General Information". 13 April 2022. Archived from the original on 20 December 2022. Retrieved 21 January 2023.
12. ↑ "Chagas disease". Archived from the original on 2019-04-28. Retrieved 2023-01-21.
13. ↑ "Thripidae - an overview | ScienceDirect Topics". Archived from the original on 2022-06-16. Retrieved 2023-01-21.
14. ↑ "Thysanoptera - an overview | ScienceDirect Topics". Archived from the original on 2022-06-16. Retrieved 2023-01-21.
15. ↑ 15.0 15.1 R. S. Mehrotra (2013). Fundamentals of Plant Pathology. Tata McGraw-Hill Education. pp. 342–. ISBN 978-1-259-02955-4.
16. ↑ Peter W. Price (1980). Evolutionary Biology of Parasites. Princeton University Press. pp. 61–. ISBN 0-691-08257-X.
17. ↑ Haynes, A R. et al. Comparison of two parasitic vines: Dodder (Cuscuta) and Woe vine(Cassytha). Florida Dept Agric & Consumer Services. Division of Plant Industry. Botany Circular No. 30. January/February 1996
18. ↑ "Raccoons and public health". The Humane Society of the United States. Archived from the original on 2022-03-24. Retrieved 2022-04-01.
19. ↑ "Handbook for Integrated Vector Management" (PDF). World Health Organization. Archived (PDF) from the original on 19 February 2018. Retrieved 3 December 2015.
20. ↑ 20.0 20.1 "Vector-borne disease". The Health and Environment Linkages Initiative (HELI). Geneva, Switzerland: World Health Organization. Archived from the original on 16 March 2014. Retrieved 7 April 2014.
21. ↑ Parrish, Ryan (7 April 2014). "WHO focuses on vector-borne diseases for World Health Day 2014". Vaccine News Daily. Chicago, Illinois. Archived from the original on 6 February 2015. Retrieved 7 April 2014.
22. ↑ 22.0 22.1 Purlain, Ted (5 December 2012). "Lancet addresses emerging infectious vector-borne diseases". Vaccine News Daily. Chicago, Illinois. Archived from the original on 7 April 2014. Retrieved 7 April 2014.
23. ↑ 23.0 23.1 University of California - Santa Cruz (30 November 2012). "Emerging vector-borne diseases create new public health challenges". Science Daily. Rockville, Maryland. Archived from the original on 8 April 2014. Retrieved 7 April 2014.

## Bibliography[edit | edit source]

* "Better environmental management for control of dengue". The Health and Environment Linkages Initiative (HELI). Geneva, Switzerland: World Health Organization. Archived from the original on 6 April 2014. Retrieved 7 April 2014.
* "Division of Vector-Borne Diseases (DVBD)" (Multimedia). Fort Collins, Colorado: Centers for Disease Control and Prevention (CDC). Archived from the original on 1 January 2015. Retrieved 7 April 2014.
* "Issue Brief Series: Vector-borne Diseases" (PDF). Healthy Environments for Children Alliance. Geneva, Switzerland: World Health Organization. Archived (PDF) from the original on 27 February 2021. Retrieved 7 April 2014.
* "Malaria control: the power of integrated action". The Health and Environment Linkages Initiative (HELI). Geneva, Switzerland: World Health Organization. Archived from the original on 8 April 2014. Retrieved 7 April 2014.
* Pawan, J.L. (1936). "Transmission of the Paralytic Rabies in Trinidad of the Vampire Bat: Desmodus rotundus murinus Wagner, 1840." Annual Tropical Medicine and Parasitol[clarification needed], 30, April 8, 1936:137–156.
* Pawan, J.L. "Rabies in the Vampire Bat of Trinidad with Special Reference to the Clinical Course and the Latency of Infection." Annals of Tropical Medicine and Parasitology. Vol. 30, No. 4. December 1936
* Quammen, David (4 April 2013). "Planet of the Ape; 'Between Man and Beast,' by Monte Reel". The New York Times. Archived from the original on 6 April 2013. Retrieved 7 April 2014.
* "Vector-borne diseases". Articles about vector-borne disease. Vaccine News Daily. Chicago. Archived from the original on 2022-08-17. Retrieved 2023-01-21.

## External links[edit | edit source]

* WHO page on vector-borne diseases Archived 2022-12-18 at the Wayback Machine

* Biological mosquito eradication in Monte Verde, Honduras Archived 2019-03-25 at the Wayback Machine
* The National Center for Biotechnology Information, Vector-borne Diseases: Understanding the Environmental, Human Health, and Ecological Connections Archived 2022-11-12 at the Wayback Machine
* Science Direct, Current Research in Parasitology and Vector-borne Diseases Archived 2022-10-17 at the Wayback Machine
* Science Direct, Vector-borne Diseases Archived 2022-07-10 at the Wayback Machine
* CDC Diseases Carried by Vectors Archived 2021-06-01 at the Wayback Machine

* 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

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