K. PAVITHRA
Fourth Year B.V.Sc. & A.H. Student, Veterinary College and Research Institute
Tamil Nadu Veterinary and Animal Sciences University Tirunelveli
Introduction
Livestock plays major role in the well being of human, it contributes to health and wealth of human population. Human health and animal health is inextricably linked with one another, with the recent advancement in medical and veterinary sciences many diseases could be easily identified at earlier stages, but these continue to exert their impact on both human and animal health. The animal diseases in addition affecting the productivity and economic returns, it also takes its toll on human health by causing diseases in human. Animal diseases also raises the issue of food safety and food security and it also imposes trade restrictions.
Human and animal links
In the earlier days human population was dependent on livestock for transportation, agriculture activities, food, clothing, wool and hunting. Now, this linkage has changed a lot we are now mostly dependent on livestock for food and companionship, this is mainly due to increased population and change in human life style. The use of animals for transportation purposes has reduced a lot with the introduction of automobiles, but they are still used in certain parts of the world especially in hilly tracts and for use in military. People depend on livestock for milk, production of milk products, meat, eggs and hide. The milk, milk products, meat and egg forms important part of human diet and are considered as source of protein, energy and vitamins. The livestock plays important role in agriculture, they are used for ploughing the land and their fecal material are used manure for enriching the nutrient content of soil and soil fertility, thereby, increasing the crop yield. In addition, livestock also controls the weeds growing on land by feeding up on them. The hides of animals are used in leather making and in the preparation of apparels. In our country where more than 70 % of the population are closely associated with livestock, livestock farming provides employment to rural youths and also act as an additional source of income to them thus it increases the economic status of the farmers. Now a days with increasing stress in human life, pets play a major role in reducing the stress and improving the mental health of human. Animals are also used in gaming and racing purpose also. Thus animals plays major role in the health well being of human by increasing his economic status, contributing to meet his dietary needs and to his physical and mental health.
Human and animal diseases: The threats
The health of the livestock should be maintained optimally by adopting good management practices, providing quality feed, water, optimal living conditions, adequate ventilation, adopting proper disease control measures like vaccines, hygienic measures and biosecurity measures. When the health of the animals are not maintained optimally many diseases begin to evolve which affects the health and productivity of animals. It also provides opportunity for the passage of pathogens from animals to human beings.
Because of close contact between animals and humans by way of intensive livestock rearing practices and by contact with pet animals many diseases are transmitted between animals and humans. More than 61% of the infectious diseases affecting humans are known to be originating from animals, these are called as zoonotic diseases. These may be caused by viruses, bacteria, fungal, prions and parasitic agents. These zoonotic diseases may be transmitted by a variety of means like ingestion, inhalation, close contact, and via vectors and fomites. The transmission of pathogens via food chain i.e., foods of animal origin is of prime concern. Many of the zoonotic diseases are known to be endemic in our country and these diseases are transmitted continuously without getting noticed by the health sector, as these diseases may not be causing high mortality rates. These diseases gets noticed only when the morbidity and mortality rates increases. Some of the important zoonotic diseases of concern are brucellosis, anthrax , Q fever, salmonellosis, listeriosis, tuberculosis, avian influenza, rabies, trypanosomiasis, cryptosporidiois, scrapie, and several others. For many diseases animals act as reservoir host and they may not exceed any clinical signs in them but can transmit the disease agents to human beings. The ecomomic analysis reveal measures to control these zoonotic diseases in animals is much cheaper than controlling the diseases in human for example Zinsstag and his coworkers have reported in 2007 that if the brucellosis transmission between animals could be reduced by 52% , 51856 human brucellosis cases could be averted, for this intervention US $8.3 million would be incurred but it the overall benefit is US $26.6 million. The same is true for rabies control as well, where, instead of carrying out post exposure prophylaxis vaccination in humans, vaccinating the dogs would be far more economical.
The issue of rise in antimicrobial resistance among bacterial pathogens is another important issue, as it is often said to occur due to injudicious use of antimicrobial agents in animals production system like for growth promotion. Transmission of these resistant organisms from animals to humans can occur easily via food chain. Infections associated in resistant organism are difficult to treat and these may result in prolonged ailment period and increased mortality rates.
In addition to zoonotic diseases people who are occupationally closely associated with animals are also prone to other ailments like injuries, fractures, allergic reactions due to exposure to spore, pollens and danders. Livestock farming practices are also contributing to the global warming through the generation of greenhouse gases, carbon dioxide and methane. This in turn can favor the spread of more infectious diseases and vector borne diseases of both humans and animals. Due to the industrialization of agriculture and animal production, people with chronic illnesses are at higher risk, as their immune system may not be optimal. The presence of large number of animals in close proximity causes public health implications like emission of dioxins, ammonia and other allergenic dusts, the impact of which are not completely understood. Air quality is diminished in livestock farming areas, due to emissions of both coarse and fine particles, odorous gases and endotoxin, the major component of the outer membrane of gram negative bacteria. Potentially, pathogenic viruses, antimicrobial resistant bacteria can also be found in airborne particulate matter surrounding livestock farms. Water and soil quality may be affected, depending on local conditions, manure treatment methods adopted in the farm.
Conclusion
The livestock sector contributes significantly to the economic situation of the farmers and to the country as well but there is an inherent risk to humans as well particularly due to intensive farming practices. Therefore the health of the farm animals must be given due care to protect the human health. In this regard veterinarians play very important role in protecting human health.
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