Zoonotic Diseases and Natural Disasters Professor Stan Fenwick Veterinary Public Health

1. Zoonotic Diseases and Natural Disasters Professor Stan Fenwick Veterinary Public Health Murdoch University/WSPA

2. WHO – “during floods, reports and rumours are common about problems created by animals such as dogs, rats, mice and snakes”

3. Zoonoses associated with floods Leptospirosis Anthrax Rabies Salmonellosis

4. Zoonoses are infections which are naturally transmitted between vertebrate animals and people • People, animals, insects and the inanimate environment are all involved in cycles of zoonotic infection

5. An appreciation of the zoonoses and attempts to control them requires a sound knowledge of the epidemiology of the diseases and the behaviour of both people and animals which may facilitate interspecies transmission

6. Zoonoses can be classified as follows Type of infectious agent (e.g. bacteria, virus, parasite) Type of reservoir host Mode of transmission

7. Transmission of zoonotic infections may be direct, indirect via arthropod vectors, or from environmental foci Direct zoonosis Cyclozoonosis Metazoonosis Saprozoonosis

8. Direct Zoonosis An infection which can be directly or mechanically transmitted to people from animals, and which is capable of being maintained in a single species of animal Most of the important zoonoses that can occur following flooding are direct zoonoses eg. leptospirosis, anthrax, rabies

9. Leptospirosis • Direct anthropozoonosis (or via fomites) • Host-adapted serovars, maintenance hosts act as carrier animals, inapparent infections • Herbivores long shedding, carnivores short • Severe infections in secondary hosts (humans and animals) • Over 200 serovars, all capable of infecting any animal • Moist environmental conditions favour survival outside hosts, endemic zones

10. Maintenance hosts L. pomona L. tarrasovi - pigs L. Hardjo - cattle Many serovars, e.g. L. australis, L. zanoni, L. copenhageni – rodents (rats/mice)

11. Occupational hazard in rice-growing communities – 200 deaths in Thailand and 6000 sick in 2000, cattle, pigs and rodents thought to be reservoirs, transmission via urine contaminating paddy fields.

12. Occupational risks

13. Recreational risks Sabah, Malaysia, 2000, Eco-challenge race – 50 out of 80 athletes contracted leptospirosis.

14. Other risks!!!!

15. Transmission and Human Disease • Contact with infected urine or contaminated water • Common occupational disease via intact mucous membranes, aerosols or skin abrasions • Anicteric disease iscommon form seen in Australia, vague symptoms, flu-like, fever, headache, myalgia • Icteric disease more severe, uncommon in Australia, this form commonly seen with rodent-associated serovars, jaundice, haemolytic crisis, can cause death • Person-person transmission rare, dead-end hosts

16. Symptom (n=179) % Headache (123) 68.7% Myalgia (109) 60.9% Severe Fever (102) 57.0% Sweats (101) 56.4% Chills (95) 53.1% Arthralgia (89) 49.7% Nausea (70) 39.1% Vomiting (62) 34.6% Back Pain (50) 27.9% Mild Fever (49) 27.4% Respiratory Symptoms 20.1% Conjunctival Suffusion 13.4% Renal Involvement (22) 12.3% Vision Disturbance (17) 9.5% Rash (15) 8.4% Diarrhoea (14) 7.8% Pulmonary Haemorrhage 5.6% Liver Involvement (4) 2.2% Symptoms of human leptospirosis

17. Leptospirosis and floods 2002 Thailand 50 cases, multiple serovars 2006 Brazil 193 cases, L. copenhageni 2008 Guyana 68 cases (6 deaths), ? serovars 2009 Fiji 8 cases (3 deaths), ? serovars

18. ANTHRAX • Bacillus anthracis, Gm +ve spore-forming rod • Worldwide, Russia, Asia, Africa, S.America • ‘Hot spots’ in warm humid areas where natural cycles exist • All mammals susceptible but pigs, dogs, cats relatively resistant • Birds can disseminate spores, chickens resistant, some birds susceptible • Spores have a long survival time in the environment

19. ANTHRAXTransmission and Human Disease • Animal by products, wool, hides, bone meal, meat, all involved in spore transmission • Cutaneous infections most common, inhalation, intestinal in rural areas, person to person rare • 1-7d incubation, spores germinate, bacteraemia, papules, vesicles, oedema (black), fatal septicaemia (toxins) • Agricultural workers, rural people, vets, travellers etc.

20. Cutaneous anthrax Anthrax pneumonia

21. Indonesia 2007 – several human deaths associated with eating meat from cattle that had died of anthrax (annual occurrence) Australia 2007 – cutaneous anthrax in a worker processing a dead cow for meat and bone meal Vietnam 2008–15 people died or became sick through eating a dead cow

22. Anthrax and floods No specific disease incidence data following floods Floods remove and deposit soil and can expose anthrax spores in endemic areas Seasonal flooding of rivers in southern africa has led to outbreaks of anthrax in cattle and wildlife Animals that have died as a result of disease or accident are eaten in some cultures, may pose a risk if anthrax cases occur

23. RABIES • Family Rhabdovirus, genus Lyssavirus • Direct zoonosis • Worldwide in all continents – few countries free, e.g. NZ • Some countries free by eradication e.g. UK While this disease is not directly associated with flooding, in SE Asia the potential congregation of large numbers of animals in relief camps and temporary shelters could result in the inclusion of rabid animals, particularly in India where rabies is widespread

24. Genotypes of Lyssavirus 1. Classical rabies 2. Lagos bat virus 3. Mokola virus 4. Duvenhage virus 5. European bat virus 6. European bat virus 7. Pteropus (Australian) lyssavirus

25. Distribution UK Japan New Zealand World wide, EXCEPT

26. Worldwide 30-50,000 deaths per year result from classical rabies It is estimated that a person dies from this infection every 15 minutes! Lancet 2002

27. RABIES Epidemiology • Dogs most important domestic hosts, other domestic animals can also be involved e.g. cats, cattle • Many wild reservoirs which differ between regions; principally canids (foxes, wolves, jackals) but also mongooses, skunks, raccoons, bats • Haematophagous, insectivorous and frugivorous bats all can transmit rabies and related viruses

28. RABIES Epidemiology • Animals differ in susceptibility, dogs show intermediate susceptibility, humans, cats and cattle highly susceptible, pigs resistant • Highest incidence in Asia, in particular India • Endemically stable, few new reports of infections extending in countries except raccoons in E. USA and Bat Lyssa Virus in Northern Europe

29. RABIESTransmission • Transmission to people mainly by bites via virus in saliva • Aerosol, transplacental and transmammary transmission in bats, found in bat saliva in zoos • Oral transmission in highly susceptible species (eg. foxes), not documented in people

30. RABIESDisease manifestations • Incubation 4d - 6y recorded, depending on where bitten • Clinical rabies invariably fatal • Prodromal period (behavioural changes) • Excitative period (hydrophobia, aerophobia in people); 1 dog in India bit 40 people/9 dogs in 4h • Paralytic period (may be predominant phase with some virus types - dumb rabies) – dangerous as may be easily misdiagnosed at this stage in animals

31. Now considered the 10th most common infectious cause of deaths in the world India - 30,000 deaths annually Pakistan - 2-5000 deaths per year Thailand – 2-300 deaths per year

32. Rabies and floods As for anthrax little specific information is available However, post-flooding, large numbers of uncontrolled dogs may congregate near relief camps This concentration of dogs will facilitate rabies transmission in the event of a rabid animal being present in the group After Hurricane Katrina public health officials warned of a possible increase in rabies cases as flood waters disrupted domestic and wild animals from their natural habitats

33. In a disaster area where rabies is endemic, assume that all dogs could potentially be rabid, and in particular keep well away from free roaming, aggressive dogs. Feed, describe, locate and leave!

34. Cyclozoonosis Infections which require at least two vertebrate hosts, one of which may be human, to complete their life cycle These include many of the parasitic zoonoses which are not usually associated with flooding, although handling dogs in a hydatid endemic region could result in infection e.g. Taenia solium, Echinococcus granulosus

35. Metazoonosis Diseases of vertebrate animals which can affect man, the infectious agents of which replicate, develop in, and are transmitted by, an invertebrate vector This group includes all the arthropod-borne infections, which should be considered following flooding due to a concurrent increase in vector populations e.g. Mosquito and tick/mite -borne infections (Dengue, Japanese encephalitis, rickettsial infections)

36. Saprozoonosis Diseases of vertebrate animals which can affect people, the infectious agents of which are either capable of replicating in inanimate sites, or require an inanimate environment for the development of an infectious stage of their life cycle eg. Histoplasmosis, Toxocara canis, enteric bacteria Salmonella can survive in contaminated water or soil for several months, assisting transmission between animals and from animals to people and is therefore a potential cause of animal and human infections following flooding

37. Salmonella Over 200 serovars, both host-adapted (S. typhi) and non-host adapted (S. typhimurium, S. enteritidis) Domestic and wild animal reservoirs, most infections asymptomatic Domestic animals show increased shedding and clinical disease following periods of intense stress e.g post flooding/congregation in relief camps Human infections via food, water or direct contact

38. Non-Zoonoses Bacterial infections Viral infections Parasitic diseases Diseases associated with nutrition

39. Bacterial infections of animals Clostridial infections Tetanus Botulism Blackleg Enterotoxaemia Haemhorragic septicaemia (pasteurellosis) Secondary infections post-trauma Respiratory Skin Mastitis

40. Viral infections of animals The majority of transboundary animal diseases are viral in origin, and, while not specifically associated with flooding, it is important to be aware of their potential to spread in stressed, contained animal populations, and to cause subsequent problems for affected rural populations

41. MAJOR TRANSBOUNDARY ANIMAL DISEASES • Rinderpest • FMD • Rift Valley Fever • Bovine spongiform encephalopathy (BSE) • Contagious bovine pleuropneumonia (CBPP) • Classical swine fever (CSF) • African swine fever • Highly pathogenic avian influenza (HPAI) • Peste de petits ruminants (PPR) • Newcastle disease (blue indicates that diseases are recognised in Asia)

42. CONSEQUENCES OF TRANSBOUNDARY ANIMAL DISEASES • Compromised food security • Major production losses for animal products • Loss of valuable livestock genetics • Increase in costs of production • Disruption to local and international trade • Inhibition of investment in livestock sector • Public health and environmental issues • Animal welfare concerns

43. Parasitic infections Moist conditions following flooding favour survival of worm eggs Post flooding, the congregation of animals in relief camps or other areas will facilitate parasite transmission In addition, stressed animals will be more prone to the effects of parasites Nematode and trematode infections most likely Ectoparasite infections will also increase – may result in tick-borne infections e.g. Babesiosis, theileriosis, flystrike

44. Diseases associated with nutrition Flood-damaged feeds Mycotoxicoses Toxic plants eaten due to lack of feed Inanition due to unusual feedstuffs Starvation Problems resulting from contaminated water

45. Occupational disease risks post-flooding Leptospirosis is the disease most commonly associated with floods due to the contamination of water with animal urine, in particular rodent urine Mosquito-borne diseases will also be a potential risk, e.g. dengue, Japanese encephalitis, malaria If large numbers of stray dogs are congregated on dry ground, then dog bites and potentially rabies are risks Infected wounds, tetanus, respiratory infections Food and waterborne diseases – Cholera, typhoid and other enteric infections from contaminated water and food

46. EpidemiologyRisk factors for diseases following floods Overcrowding Nutritional changes Contaminated water supplies Wounds and injuries Inclement weather Vectors Other stressors

47. Diagnosis of diseases in the field Minimal facilities Temporary laboratory facilities Access to permanent laboratory facilities

48. Minimal facilities Microscope, simple stains, McMaster slides, salt solutions, sample collection equipment Pen-side tests as developed (lepto dip stick – humans only; anthrax rapid tests – humans only) Anthrax is probably the only bacterial infection that simple laboratory facilities could diagnose, i.e. use of McFadyean’s polychrome methylene blue stain to identify the bacteria in blood smears Parasite diagnosis, worms, worm eggs Blood-borne parasites (Babesia, Theileria, Trypanosoma)

49. Temporary laboratory facilities Possible incubator, allowing simple bacteriology, although usefulness doubtful, ? Salmonella Refrigerator/freezer to allow storage of samples for retrospective diagnosis Serum sample storage; work with human agencies Simple test kits, e.g. rapid ELISA

50. Control of Diseases following flooding General principles of disease control Examples of disease control for diseases potentially associated with flooding