Bovis ISSN 2398-2993

Pathogen transmission: overview

Synonym(s): Fomite, aerosol, biosecurity, feco-oral, disease transmission

Contributor(s): Josh Wafula-Aleri, Nick Lyons

Introduction

  • Veterinarians are often required to investigate and mitigate the adverse effects of disease outbreaks by instituting specific control measures as well as advising on presumptive control measures.
  • Having a sound understanding and basic knowledge on the different routes of transmission not only enhances pathogen containment in the event of an outbreak but also supports herd level planning for preventing introduction, including enhanced biosecurity.
  • It is important to know which diseases are already present/absent on farm, so as to design biosecurity measures accordingly.

Methods of pathogen transmission

  • Pathogen transmission can be broadly classified as either horizontal or vertical.
  • Horizontal transmission is more common and describes the spread of a pathogen between individuals, either in the same or in different populations.
  • Vertical transmission is less common and encompasses the spread of a pathogen to the fetus(es) or developing embryo(s) while in gestation or via suckling.
    • Genetic diseases do not truly come under the heading of vertical transmission, as the term “transmission” should be reserved for infectious diseases. However, a short section on such diseases is included at the end of this article.

Horizontal disease transmission

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Vertical disease transmission

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Conclusion

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Cavanagh, J A, Tammen I, Windsor P A, Bateman J F, Savarirayan R, Nicholas F W & Raadsma H W (2007) Bulldog dwarfism in Dexter cattle is caused by mutations in ACAN. Mammalian Genome 18 (11), 808-814 PubMed.

Other sources of information

  • Constable P D, Hinchcliff K W, Done S H & Gruenberg W (2016) Veterinary Medicine: A Textbook of the Diseases of Cattle, Horses, Sheep, Pigs and Goats. 11th edn. Elsevier, USA.
  • Thrusfield M (2013) Veterinary Epidemiology. Elsevier, USA.
  • Dohoo I R, Martin W & Stryhn H E (2003) Veterinary Epidemiologic Research.
  • Chethanond U-S A (1999) The Epidemiology of Enzootic Bovine Leukosis in Dairy cattle in New Zealand. A thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary  Science at Massey University USA.
  • Anderson R M, May R M, & Anderson B (1992) Infectious diseases of humans: dynamics and control. Vol 28. Oxford University Press, UK.
  • Soulsby E J L (1968) Helminths, Arthropods and Protozoa of Domesticated Animals. Lea & Febiger, USA.


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