Role of the Veterinarians and One Health in the Fight Against Zoonoses
Dr. B.P. Shukla
Department of Veterinary Surgery & Radiology
College of Veterinary Science and Animal Husbandry (NDVSU-Jabalpur Campus)
MHOW-453446 (M.P.)
Zoonosis is another name for a zoonotic disease. This type of disease passes from an animal or insect to a human. Some don’t make the animal sick but will sicken a human.
Zoonotic diseases range from minor short-term illness to a major life-changing illness. Certain ones can even cause death
What are Zoonotic Diseases?
Zoonosis refers to the transmission of diseases between animals and humans. Such diseases are termed Zoonotic Diseases. Zoonotic diseases range from mild to severe, while in extreme cases can even be fatal.
- Zoonoses may be bacterial, viral, or parasitic, or may even involve unconventional agents for the transmission of the disease.
- WHO in 1959 defined Zoonoses as “those diseases and infections which are naturally transmitted between vertebrate animals and man”.
- World Zoonoses Day is observed every year on July 6 to create awareness on zoonotic diseases, how to prevent them, and what actions to take when exposed.
Classification of Zoonotic Diseases
The classification of diseases is usually done on the basis of the pathogen causing the disease. With the advancement in science, scientists and medical professionals have been able to identify and study in detail the etiological agents causing the diseases. Etiological agents usually refer to the causative agent of a diseased condition. The zoonoses are classified on the basis of three factors:
- According to the etiological agents
- According to the mode of transmission
- According to the reservoir host
- According to the etiological agents- there is a further classification under this as:
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- Bacterial zoonoses: e.g. anthrax
- Viral zoonoses: e.g. rabies
- Rickettsial zoonoses: e.g. Q-fever
- Protozoal zoonoses: e.g. toxoplasmosis
- Helminthic zoonoses: e.g. echinococcosis
- Fungal zoonoses: e.g. cryptococcosis
- Ectoparasites: e.g. scabies
- According to the reservoir host: A reservoir is usually a living host of a certain species, such as an animal or a plant, inside of which a pathogen survives, often (though not always) without causing disease for the reservoir itself. A cascading effect is caused by the extinction of a species, leading to an increase in the population of the reservoir species.
- Anthropozoonoses– Infections transmitted to men from lower vertebrate animals e.g. rabies.
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- Zooanthroponoses- Infections transmitted from man to lower vertebrate animals e.g.diphtheria
- Amphixenoses- Infections maintained in both man and lower vertebrate animals and transmitted in either direction e.g. salmonellosis
Transmission of Zoonotic Diseases
Zoonotic diseases are transmitted through various means. The chances of diseases getting transmitted increase due to the expansion of transition zones between adjacent ecosystems when forests are cleared off for agricultural purposes. This is because the environment is overlapped for wild and domesticated animals. Some of the most common ways of transmission of the diseases are:
- Direct zoonoses-These are transmitted from an infected vertebrate host to a susceptible host (man) by direct contact, by contact with a fomite or by a mechanical vector. E.g. Rabies
- Cyclozoonoses– These require more than one vertebrate host species, but no invertebrate host for the completion of the life cycle of the agent. E.g. echinococcosis.
- Metazoonosis- These are transmitted biologically by invertebrate vectors, in which the agent multiplies and/or develops and there is always an extrinsic incubation (prepatent) period before transmission to another vertebrate host. E.g. plague
- Saprozoonosis- These require a vertebrate host and a non-animal developmental site like soil, and plant for the development of the infectious agent e.g. cryptococcosis
Zoonotic Disease Prevalent in India
Some of the zoonotic diseases which are prevalent in India are the Nipah virus, Avian Influenza, Rabies, Japanese encephalitis, Leptospirosis, Hantavirus, SARS (Severe Acute Respiratory Syndrome), Cysticercosis, Anthrax, Plague, Echinococcosis and Schistosomiasis, Kyasanur forest disease (KFD), etc.
Factors influencing zoonoses diseases
- Microbial adaptation
- Genetic change
- Climate and weather change
- Human behaviour and demographic factors
- Overpopulation
- Deforestration
- Movememnt of pathogens , vectors and animal host
ROLE OF VETERINARIANS IN PREVENTION OF ZOONOTIC DISEASES
Diagnosis, Surveillance, Epidemiology, Control, Prevention and Elimination of zoonotic diseases:
https://www.oie.int/en/what-we-do/global-initiatives/one-health/
- Most private veterinary practitioners contribute to public health during routine practice. Both large and small animal practitioners become skilled diagnosticians for acute and chronic diseases of animals that may affect the owners and their families and the surrounding communities.
- routine health examinations, maintaining immunization regimens, implementing parasite control programs, advising on the risks of animal contact for immunocompromised individuals, facilitating the use of guide and service dogs for people with disabilities, and promoting the benefits of the human-animal bond for the disabled and elderly, as well as war veterans and others suffering from post-traumatic stress disorder.
veterinarians also diagnose, investigate, and control indirect zoonoses and non-zoonotic communicable diseases that affect human health. Examples include West Nile disease and coccidioidomycosis among pet animals, and bovine leukosis, foot and mouth disease, fowlpox, and many other diseases that affect the food supply
MANAGEMENT OF HEALTH ASPECTS OF LABORATORY ANIMAL FACILITIES AND DIAGNOSTIC LABORATORIES
- The challenges of recognizing resurgent infectious diseases and developing novel therapeutics have placed unprecedented emphasis on managing and maintaining laboratory animal colonies for research and diagnostic efforts.
- Providing these services both successfully and humanely falls to the veterinarians in these institutions.
- Because few nations have the individual capacity to provide these services internally, increasing emphasis is being placed on international collaboration and reference centers, many of which focus on zoonotic diseases and comparative medicine. Because most outbreaks of zoonotic disease occur in tropical regions devoid of local surveillance and diagnostic and response capacity, the role of these international collaboration and reference centers likely will expand, requiring larger numbers of trained, experienced veterinary personnel.
- Building on the information from public health surveillance, research institutions must follow with a greater understanding of the interactions between hosts, parasites, vectors, pathogens, and the environment.
HEALTH EDUCATION AND EXTENSION
- Training new veterinary practitioners and disseminating new capabilities to those already in practice falls largely on the nation’s academic (especially land-grant) institutions, virtually all veterinarians help educate the public on the threat of infectious and noninfectious diseases.
PRODUCTION AND CONTROL OF BIOLOGIC PRODUCTS AND MEDICAL DEVICES
- Ensuring that animal drugs, vaccines, and devices are safe and efficacious
Another important function regarding biologic agents is the regulation of their storage, use, and transfer.
GOVERNMENT OR LEGISLATIVE ACTIVITY
- State Veterinarian who is responsible for protecting the livestock, poultry, and aquaculture industries directly, and the public indirectly, through the prevention, early detection, containment, and eradication of economically important livestock, poultry, and fish diseases that, in many cases, are transmissible to people
- The State Veterinarian regulates the importation, transportation, and processing of animals and is responsible for the control and eradication of poultry and livestock diseases, regulation of fish farming, and emergency response programs.
