Published on March 14, 2008
ZOONOSES Dr. V. I. Bishor Research Assistant Research & Development Wing Institute of Animal Health & Veterinary Biologicals Palode, Trivandrum www.vbikerala.nic.in
WHO defines Zoonoses “Those diseases and infections which are naturally transmitted between vertebrate animals and man” According to Taylor et al. who in 2001 cata- Zoon: Animals , Noses : Diseases. logued 1,415 known human pathogens, 62% were of zoonotic origin. Rudolf Virchow was the first to use most emerging infectious diseases in humans the term in his Handbook of are zoonoses Communicable diseases. History of Zoonoses • Zoonoses have affected human health throughout times • A possible epidemic of bubonic plague was described in the Old Testament, in the First Book of Samuel. The so called Black Death emerged in the 14th century and caused vast losses throughout Asia, Africa, and Europe. The epidemic, which originated in the Far East, killed approximately one third of Europe’s population • Rabies was described in Mesopotamia, in hunting dogs, as early as 2,300 BC. Recognizable descriptions of rabies can also be traced back to early Chinese, Egyptian, Greek, and Roman records • Ancient accounts and modern hypotheses suggest that Alexander the Great, who died in Babylon in 323 BC, died of encephalitis caused by West Nile virus, a virus that has a wild bird reservoir.
In India 80 % of the population residing in approximately 575000 villages and thousands of small towns. Have close contact with domestic /wild animals population owing to their occupation. Stand at greater chance of acquiring zoonoses. Zoonoses Vs Major Killer diseases Disease Death in Millions Disease Death Pneumonia & Respiratory 3.5 Rabies 40000 Infections Yellow fever 30000 AIDS 2.3 JE 10000 Diarrhoeal Diseases 2.2 Ebola 1000 Tuberculosis 1.5 Monkey Pox 1000 Malaria 1.1 Measles 0.9
Classification of zoonoses Direct Zoonoses: Single vertebrate host: Rabies Cyclozoonoses: More than one vertebrate host: Taeniasis, Hydatid disease Metazoonoses: Requires both vertebrate and invertebrate host Eg. Arbovirus Saprozoonoses: Inanimate reservoirs and vertebrate host. eg:Histolasmosis. Anthrapozoonoses:: Animals to man Zoo anthroponoses: Man to Man Animals Eg : Human TB, Amoebiasis Amphizoonoses: Man Animals Eg: Streptococcal infections
Factors affecting Disease emergence. 1. Introduction of a new host species in to an ecosystem. 2. Introduction of infected host in to new ecosystem.eg : Marburg Disease 3. Change in population dynamic 4. Ecological changes that bring two previously sepearted ecosystem into contact. Eg. Trypansomiasis. 5. Change in habits including the food habits. 6. Technical changes brought about by man . Eg : Anisakiasis. 7. Mutation /genetic recombination of infectious agents . Eg Influenza.
Role of wild animals and Birds The ecologic changes influencing the epidemiology of zoonoses with a wildlife reservoir can be of natural or anthropogenic origin. These include, but are not limited to, Human population expansion and encroachment, reforestation and other habitat changes, pollution, and climatic changes. The movement of pathogens, vectors, and animal hosts: Such movement can, for example,occur through hu- man travel and trade, by natural movement of wild animals including migratory birds, and by anthropogenic movement of animals. Movement of infected wild and domestic animals is an important factor in the appearance of rabies in new locations Microbial changes or adaptation : These changes include mutations, such as genetic drift in viruses; activation and silencing of genes; genetic recombinations, such as genetic shift in viruses; and conjugation, transforma- tion, and transduction in bacteria. Natural selection and evolution also play a role. Severe acute respiratory syndrome (SARS) is a current example of likely microbial adaptation. This viral respi- ratory illness, caused by SARS-associated coronavirus, is believed to have emerged in Guangdong, China, in November 2002. SARS was first reported in Asia in February 2003, and over the next few months, the illness spread to a global epidemic before it was contained. According to the World Health Organization, 8,098 cases, including 774 fatalities, have occurred. The virus has an unknown reservoir, but wildlife is a likely source of infection.Natural infection has been demonstrated in palm civet cats in markets and also in raccoon dogs, rats, and other animals indigenous to the area where SARS likely originated.the live market and Restaurants in china sold small carnivors and several species of civet cat. Bush meat in Africa: a serious problem for the emergence of infection. (eg Ebola infection from Chimpanzee, Incidence of HIV 2 from sooty mangabeys) New Brucella spp. from marine mammals: The pathologic role of marine Brucella spp. in animals remains unclear, as does their zoonotic potential. In 2003, two human cases of community-acquired granulomatous central nervous system infections caused by marine Brucella spp. were reported
Important Zoonoses Brucella abortus/suis: occupational disease Brucellosis Brucella melitensis: Foodborne. Prevalent in most countries. Vaccination and brucellosis. In India annual loss of Rs 350 Million S19 vaccine is infective. Avoid accidental inoculation. due to brucellosis. RB-51 lacks LPS; so undetectable by common lab Control tests. This strain is Rifampicin resistant, which is the drug of choice in humans. Infection followed by the Test and slaughter policy accidental inoculation of RB 51 have reported in US. Immunisation: S19 Vaccine, RB-51 , 45/20 vaccine, Rev 1, Treatment in man Anthrax Control in Man 20000-100000 human cases per year in the world. Immunisation 90-99 % are cutanious anthrax. Animal Industry hygiene and management Potential Bioweapon( Pulmonary form of Anthrax). Medical care and management. Common in southern part of India. Control in animals. Suitable disinfectant Immunisation 3 % peracetic acid. Proper carcuss disposal 3-5 % formaldehyde. Care in handling livestock Management
Tuberculosis Most common infectious cause of death in the Mycobacterium tubeculosis which is virulent world.The disease kills 3 million people a year, for humans but not for cattle. with 7.3 million new cases annually. M. bovis in infective to man. In india about 40 % of the population is infected Infection of cattle by human strain is usually with TB. 2 out of 5 TB cases are found in india. self limiting and no cow-to-cow or cow-to-man About 5 lakh people in india die every year of TB, trasmission. more than 1000 every day- a patient per minute. M. Bovis can infect other animals as well as man. Man may also act as a reservoir for bovine bacilli. In india TB prevalent among cattle, Buffaloes and and can transmit to cattle. pigs. only 0.1 % of total cases are due to M. Bovis (USA). Data not avialble in India. Leptospirosis Primarly a disease of animals. Control Organism isolated from almost all Man is the Dead-End host., also act Rodents control free living species of animals. as a reservoir. sanitation In india disease is wide spread in Rodents and mammals acts as natu- proper management of Andaman, AP, Karnataka, Kerala, Animals ral reservoir. Tamil Nadu, W. Bengal. Immunisation They excreate leptospira for about 1 Personal hygiene and In Kerala L. grippotyphosa appeared to be the common serotype. year in rodents and weeks -months protection in other animals. Health education Plague Transmission Reemerging in many part of India. Primarly a disease of Rodents. Domestic rodents-rat flea-man Wild rodent-flea/direct contact -man Low temperature and High humidity Wild rodent-flea-domestic rodent-flea- favour the pathogen. Dogs acts as sentinel animals. man Man-human flea-man
Rabies Control of Animal Rabies 1. Immunisation of dogs should reach atleast 80 %of the Obstacles in Rabies control population in higly endemic areas identified through a 1. Absence or insufficient enforcement of existing good surviellance system based on a network of diagnos- legislation on animal rabies control( especially tic laboratories for dog vaccination and control of dog 2. Responsible pet ownerships including dog registration movementand population) and dog population control such as sterilisation, use of 2. Lack of affordable and high quality biologicals hormones, elimination of unwanted dogs . for both humans and animals. 3. The status of certain Rabies -free areas should be 3. lack of cooperation between the various national sectors/agencies/disiplines concerned maintained through strict implementation of national with Rabies control and lack of involvement of and international regulations on animal movement. NGOs which could contribute to rabies control 4. Community participation through the establishment 4. Lack of facilities and trained staff for the treat- of community funds, mobilisation of community ment of bitten and rabid patients. volunters during vaccination campaign should be pro- moted. Control of Human Rabies 1. Government should allocate sufficient funds to procurement of human rabies vaccine and immunoglobulins to be given at no cost to indigent risk bite cases. 2. Revised national guideline for pre and post exposure treatment based on WHO recom- mendation should be issued. 3. Training for health personals for post exposure treatment and handling of rabid patients should be provided, including health education with emphasis on precautionary measures to be taken to prevent potential transmission within family members when a rabid patient is cared for at home. 4. Pre exposure treatment of Children which may easily come in contact with dogs and cats of unknown origin when the family can afford it , sholud be considered
Japanese Encephalitis Most important cause of viral encephalitis in eastern and southern Asia. 30000-50000 cases reported annually. Of these about 25-30 % are fatel and 50 % reuslts in premanent neuropsychiatric sequelae. Major vector: Culex tritaeniorhynchus. The virus exists in a zoonotic transmission cycle A disease of rural population. with between mosquitoes and pigs and /or water birds. culex Tri. breeding in rice paddies and Human get infection by the bite of mosquitoes and pigs providing the main source of blood are dead-end host. meal. Control 1. MOSQUITO CONTROL 2. AVOIDING HUMAN EXPOSURE 3. IMMUNISATION Inactivated mouse brain vaccine, in china a live attenuated vaccine SA 14-14-2 strain is avilable.
Parasitic Zoonoses Toxoplasma gondii : Possibly the most wide spread & prevalent protozoan parasite on earth.In many countries the seroprevalence for women of child bearing age ranges between 30 and 45%. Seroprevalence is reported from almost all animals. Beef is not a major source of infection to humans. In US studies shows that 25% of the house cats were seropositive for toxoplasms. Sarcocystiosis: Herbivors are the intermediate host and carnivors and humans are the definitive host. Hu- man get infection by the consumption of uncooked beef or pork. Giardiosis: infect 2-5 % of the people. companion animals may be a good sourse of infection. Cryptosporidiosis: only C. parvum is zoonotic. An emerging problem in HIV patient . Sourse of infection may be calves, sheep, goat, deer, horses, dogs, cats and turkeys.1n 1993 a severe outbreak in USA : more than 403000 cases were reported. 12-27 % prevalence in HIV patients worldwide. Trematodes: F. hepatica, liver fluke of cattle affects about 2.4 million people worldwide. Clonorchis human liver flukes, a parasite of fish affects about 20 million people world wide , mainly in far east Asia. Cestodes: Taeniosis is a common problem in Asia and Africa. Neurocysticercosis alone causes more than 50000 deaths annually. Echinococcosis, where the humans are the intermediate host Nematodes Trichinella: a cosmopoliten helminth zoonosis. infection from meat of infected pigs, wild boars, horses, dog. Anisakiasis: larvae of Psedoterranova decipiens, a nematode parasite of marine manmmal. also with larvae of Anisakis. which infect sea fish. Tingling sore throat syndrome and ulceration of gut.
Food-borne zoonoses The inability of the non-industrialised Major cause of human intestinal diseases. countries to keep pace with the population Can be Infection/Intoxication Infections: Salmonellosiss, Brucellosis, growth, migration to rural to urban areas Camphylobacter , Listeriosis,E. coli and the demand for clean safe drinking Intoxication: Bacillus cereus, Botulism, water and proper sanitation are the rea- sons for food borne infections Consumption of raw or undercooked meat, crustaceans and fresh water 1. Through heating and rapid cooling of food fish and veghetables facilitate 2.Avoid raw or undercooked foods transmission of food borne 3.Pasteurise milk and avoid post infections. pasteurisation contamination 4.Proper sanitation at the farm and also in the processing plant Control of food borne 5.Water sanitation infections 6.Sanitary disposal of faeces 7.Avoid toxin containing fishes like puffer fish 8.Refrigerate fish immediately after catch 9.Proper surveillance of food poisoning 10. Public education
Emerging Zoonoses • Influenza: Mainly by Influenza A virus causes pandemic in humans. Usually the transmis- sion of avian or Animal influenza to man require a reassortment between human and avian influ- enza viruses.Such events occured in 57 and 68. in 1997, Hong Kong, new sub type H5 noticed in which all the genes of the virsus were derived from chicken influenza virus that was apparantly circulating among the chicken market of Hong Kong. Again in 1999 another outbrake with another type of Chicken influenza virus in man occured. The virus is of great concern in view of the potential for reassortment with a human influenza virus which will produce a virus with high human transmissibility which is compleate novel to the world. The recent (2004) infections are caused by H5N1 avian virus. • Filovirus: Ebola and Marburg, human infections from monkeys. • Hendra : First reported in Horses in 1994 in Australia. Bats may act as reservoir. • Nipha (Barking Pig Syndrome): ( Named after village Sungai nipha in Malaysia) reported in pigs from Malaysia during 1998 causing viral encephalitis in humans ( 265 cases and 105 death.).Pigs, dogs and humans were infected. • Hantavirus: HFRS, HPS. Rodent reservoir, aerosol transmission, reported from Asia and Americas
BSE-nvCJD Crisis Bovine spongiform encephalopathy (BSE) in the United Kingdom may provide more lessons than any other recent emergent zoonotic disease episode. The disease was first diagnosed in the United Kingdom in 1986; as of 1997, more than 170,000 cattle had been reported as infected, but modern statistical meth- ods have indicated that about one million cattle had been infected, roughly half of which entered the human food chain in the United Kingdom In 1995, the BSE agent was reported to be the cause of a new human zoonotic dis- ease, new-variant Creutzfeldt-Jakob disease. By 1997, 26 cases had been re- ported in the United Kingdom and one in France. A recent report from The Royal Society states that there is now a compelling case regarding new-variant Creutzfeldt-Jakob disease as the human manifestation of BSE. With such a small number of cases, it is impossible to predict future num- bers of cases of the human disease, BSE may be instructive in other ways, especially in its extension into the worlds of macroeconomics, international trade, political science, and even global gover- nance
Zoonoses and Immune status Immunocompromised persons , Elderly people, HIV patients, Patients under cancer treatment are more suceptible to zoonotic infection. Enteric infections by Salmonella, Camphylobactor and Cryptosporidia may result in life threatning Diarrhoea in these group. Systemic infections like Toxoplasmosis, Tuberculosis, Cryptococcosis, Q fever and Cat Scratch Fever may lead to fatel encephalitis and /or Pneumonia. Always seek the advice of a Veterinarian while selecting a pet Xenotransplantations and Zoonoses Xenotransplantations is the use of animal Management organs, tissues or cells for transplantation into humans to treat a variety of medical conditions. 1. Development of Xenotransplant-grade Domestic pigs are considered the most likely animals which meet the exacting microbial sources for transplantable organs, tissues and agent status. cells. 2. The implementation of a comprehensive The risk factors health surveillance and clinical investigation 1. The systemic presence of agents. programme for timely detection and response 2. The latent sequestration of agents in a to infectious diseses occuring in xenotransplant xenotransplanted organ( Salmonella , source of animals and colonies. Mycobacterium) 3. Strict application and monitoring of 3. Agents contamination of a xenotransplant husbandry and biosecurity practices. during harvesting procedure. 4. Support the development and refinement of Eg: Toxoplasma, Trichinella, Cryptiosporidium, Viruses like Influenza . diagnostic procedures.
Zoonosis -An International problem Most tremendous impact on evolution of man especially on societies/culture that domesticated and bred animals for food and clothing. Most frequent and dreaded risk to mankind. Transcend natural boundries, occur world wide International movement Impact on global economy and Health Importation of disease Ban on animals and Animal products Global surveillance in necessary Inter relationship among countries has led to the internationalisation of control effort to technical, Economical and Social fields.
Zoonoses Control: General Strategies Procure personels Training, allocation Hygiene in animal production Alter agricultural practices Disposal/recycling animal wastes Water supply/irrigation Type of Husbandry Law Establish/modify regulations Ordinences Helath certification Movement/shipment conditions Improve inspections Markets Procure facilities Severity of unrecognised, untreated diseases Export/import Prevalence/incidence of diseases Epidemiological conditions Importance of carriers, subclinical infections Medial/public health Routs of Transmission Intesectoral Veterinary/agricultural/wild life Density, composition, activity Land use Ensure awareness of high risk people Literacy rate Social norm Human factors Economic values of Animals Social value of Animal International/regional Information Exchange Agrement/codes/Technical cooperation Procure equipment, material Education Public motivation
Control of Zoonoses: strategies and tactices for control in Animals quarantine treat Infected/contact animals destroy Uncontrolled , owned suceptible identification animals control Control of animal capture / euthanize populations. Stray suceptible animals consider if pests or commensal Wild vertebrate reservoir Hunt, trap, poison,antifertility agents, predation Vectors environmental/ecological control chemical/biological agents/fertilty control Immunisation prophylactic treatment Chemotherapy Reduction of suceptibles. Alter environment change conditions, population Change Husbandry requirement quarantine of animals Entry to disease free area. Maintain Disease free /products/feeds Treat animals status Control animal movement protect animals at risk Control factors of environment
Control of Zoonoses: strategies and tactices to Control vehicles of Transmission. control risk factors associated with water, feeds, land, presonal. Hygiene in animal production proper use of drugs, biologicals, pesticides Establish food Develop and follow proper meat hygiene. Hygiene at slaughter inspection, judgement, and Hy- giene safe collection of milk, eggs,, seafood Hygiene in handling and processing foodstuffs safe handling, processing storage, marketing of foods. Ensure safety of other animal products(wool, Hygiene during collection, storage, hide, horn, bones, fat) processing, transport Safe collection systems, rendering plant operations, Safe disposal or use of product safety animal carcusses and Animal Carcuss disposal Ensure safe disposal by burning wastes. or burial Control hazards to water supplies. Decontaminate/disinfect: sites/vehicles/persons Excreta/garbage disposal Recycle safely as fertilizer, fuel, feed
Control of Zoonoses: strategies and tactices applicable to man 1.Health education Protect high risk 2. Immunisation, chemoprophylaxis. groups 3. Monitoring health status, including occupational health program Prevent infection 1. Medical intervention, isolation Prevent spread by man 2. Prevent environmental contamination 3. Prevent food contamination 4. Prevent animal contact Educate medical/ Prevent Veterinary personnel and 1. Imrove diagnosis Treat 2. Laboratory diagnosis Man Diagnose Improve diagnostic 3. Feedback to epidemiological and services control services infection 4. Referral capability 1. Referral capability Establish facilities and 2. Monitor treatment outcome Treat disease therapeutic regimens 3. Feedback to epidemiological services.
Role of Public helath Veterinarians. 1. Diagnosis, treatment, control and erradication of zoonotic diseases of major human health importance. 2. Use of biologicals(vaccines/sera) for prevention /control of zoonotic diseases. 3. Development and testing of newer drugs for important zoonotic diseases’ treatment. 4. Preparation of strategies and methods for the surveillance and control of important zoonotic diseases. 5. Development of suitable animal models for important zoonotic diseases. 6. Supervision of food hygienic practices in slaughterhouses, dairy frams and other food processing establishment. 7. Production of wholesome and safe foods of animal and non-animal origin. 8. Investigation of food borne and other zoonotic disease. 9. Statistical reporting of morbidity and mortality of food borne and other zoonotic diseases. 10. Epidemiological studies on zoonotic and food borne diseases. 11. Participation in environmental health programs. 12. Notification to higher authorities about a notifiable disease/exotic disease. 13. Health education to public about the source of infection, mode of transmission, personal hygiene, environmental hygiene and control measure against commonly occuring zoonoses. 14. Collaboration in medical relief during calamities and diseses. 15. Maintain close coordination with medical and public health department. 16. Conduct periodic meeting to review situation on the prevalence of zoonotic diseases in an area.
Public Health Implications of emerging Zoonoses. Morbidity and Mortality of new, emerging zoonoses Large out break : Tip of the iceberg : gross under reporting of infections through out the world. for eg only 10-30 % of the salmonella infections are reported even in developed countries. Invisible Diseases: Some disease may not be recognised as Zoonotic at the outset. these disease can spread undetected from many years particularly if the incubation period is too long or the number of cases in human or animals is too small, as happend in case of BSE/CJD and Nipha Virus. Influences on public health practices and structure. The threat of communicable Disease: Threat of spreading infection like Ebola from rural areas to larger cities. Risk of introduction of infections in other continents- a threat whole world. The Ebola virus attack contributed greatly to promoting the concept of emerging communicable disease among public health officials, stressing the renewed importance of microbes and the need of surveillance. A strong support to the opinion that the emergence of a killer disease in avery remote area of the world represent as threat for all humans, therby reinforcing the sense of belonging to the same world. Pandemic planning: Sharing and cross over of animal pathogens can cause a pandemic as we learned from the Influenza outbreak in Hong Kong. Global Alert and Response: Regarding the new infections and reservoirs. WHO/FAO/OIE/PAHO/ Uncertain Risks and precautionary Principle: for eg BSE Crisis changed the feeding method of Animals, introduced major rearrangement in the food safety issues, questioned the safety of using animal tissues for the production of human biologicals and medical devices( remember our sheep brain vaccine), This particular disease has led to the renewal of an old concept” The precautionary principle” Intersectoral collaboration for the control of zoonoses.: Need of high leval of Governmental commitment for the containment of infections and Co-ordination between Medical and Veterinary health services .
Finally.............................. Who will be the world’s expert on Zoonotic diseases?
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