Zoonoses: Shifting boundaries Emily P. Mitchell Faculty of Veterinary Science, University of Pretoria, South Africa 1 FIDSSA 9-11 th November 2017
Koch s postulates Evidence required to establish the aetiologic relationship between microorganisms and disease: Robert Koch 1. The microorganism must be observed in every case of the disease 2. It must be isolated and grown in pure culture 3. The pure culture, when inoculated into animals, must reproduce the disease 4. The microorganism must be recovered 2 from the diseased animal
3 Zoonoses Bacteria Anthrax, Tuberculosis, Brucella, Bartonella, Q-fever, Campylobacter, Salmonella, Leptospira, Listeria, Pasteurella, Yersinia, Psittacosis, Streptococcus, Tularemia Virus Ebola, Crimean-Congo, Influenza, Hanta, HIV, Hepatitis E, Lassa, Marburg,Pox, Rabies, Rift Valley Fever, SARS, West Nile Rickettsia Lyme disease Protozoa Cryptosporidia, Giardia, Plasmodium, Toxoplasma Parasite Tapeworm, Sarcoptes, Toxocara, Trichinella Fungi Ringworm DM Morens et al Nature 2004
Environment Vectors Habitat Climate Biodiversity Human Contact Animal Pets Food Wildlife Genetics Immunity Age Density Nutrition Concurrent disease Stress A Muelenbachs New England J of Medicine 2015 G Rabozzi et al 2012 Safety and Health at Work Shared 4 pathogens: multi-host networks
THE WORLD WIDE WEB 5
Ebola virus outbreak High morbidity and mortality in animals Gorillas (90% 5000), chimpanzees, duikers EM Leroy et al., Science 2004; P Rouquet et al., Emerging Infectious Diseases 2005 Animal clinical signs Human exposure Human clinical signs Cost of control $80 billion (Nipah WNV, SARS, HPAI, Mad cow, RVF) Animal exposure Humans seek medical care World Bank 2012 6
Ebola virus outbreak Fruit eating bats: reservoir Deforestation, roads Dry season Bush meat Social KA Alexander et al., Plos Emerging Tropical Diseases 2015 7
Rabies: India 1990 s: 36% by 2009 JL Oaks et al Letters to Nature 2004; GE Swan et al, Biology Letters, 2006 8
MTB at the NZG 9 AL Michel et al J Zoo Wildlife Medicine 2003
Risk assessment HISTORY Economic circumstances Poor, disadvantaged people (urban and rural) Food hygiene Age Young, old Employment Customs officers, meat inspectors, veterinarians, hunters, meat butchers and traders, wildlife rehabilitators, farmers, aviary keepers Recent travel Zones of conflict, mass gatherings, petting zoos, tropics, vector areas Hobbies Pets, horses, hiking Concurrent disease or treatment Immune suppression 10 Corticosteroids
HYGIENE The good news Clean water, soap, sanitizers Don t get bitten Animals (dogs, bats, rodents), insects Use safety equipment Food preservation and preparation Vaccination 11
The challenge Life expectancy 48 (1955) 70 (2012) Childhood death <5 21m (1955) 10m (1997) Between animal and human medicine, there is no dividing line, nor should there be Medicine is a social science, and politics is nothing else but medicine on a large scale. Medicine as a social science has the obligation to point out problems and to attempt their theoretical solution. The physicians are the natural attorneys of the poor, and social problems fall to a large extent within their jurisdiction. 12 SS Myers PNAS 2013 Rudolph Virchow
Acknowledgements Dr Salim Parker, FIDSSA Prof Antoinette Kotze, NZG and NRF Professor L Blumberg, NICD Dr W Ramkrishna National Department of Health Dr S Strydom, Agriculture, Forestry and Fisheries Dr S Osofsky, Wildlife Conservation Society and Cornell University Dr M Hofmeyr, SANParks 13