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Zoonotic Diseases and Natural Disasters

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

8 eg. leptospirosis, anthrax, rabies
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 is common 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 Symptoms of human leptospirosis
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%

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 ANTHRAX Transmission 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 7. Pteropus (Australian) lyssavirus
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 RABIES Transmission 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 RABIES Disease 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 deaths per year Thailand – 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 Feed, describe, locate and leave!
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 e.g. Taenia solium, Echinococcus granulosus
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 (Dengue, Japanese encephalitis, rickettsial infections)
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 Bovine spongiform encephalopathy (BSE)
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 Compromised food security Major production losses for animal products
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 Epidemiology Risk 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

51 Definition of Prevention
“Actions aimed at eradicating, eliminating, or minimizing the impact of disease and disability. The concept of prevention is best defined in the context of levels, traditionally called primary, secondary, and tertiary prevention”

52 Definition of Control “The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction”

53 Emergency Preparedness
“an animal or human disease emergency can have serious socio-economic consequences, which may affect a countries whole national economy”

54 “The only thing more difficult than planning for an emergency is having to explain why you didn’t!”

55 General Control Strategies for Zoonoses
Measures may need to be implemented on individual/herd, local/community, national and international levels Individual/herd: chemoprophylaxis, arthropod control and avoidance, hygiene, vaccination, clean water, safe food, disinfection of fomites, avoidance of close contact Local/community: arthropod and rodent control, education, mass chemotherapy, eradication of animals, restriction of animal movement, vaccination, pasteurisation, isolation of patients, infection control National/International: quarantine, restriction of imports, movement control for animals, international notifications and networks, international response teams John Last is a legendary figure in the area of prevention, known by many people as the “father of prevention” John Last has held academic positions with the British Medical Research Council in London, at the Universities of Sydney, Vermont (USA), and Edinburgh and has been professor of epidemiology and community medicine at the University of Ottawa since He was the editor of the 11th 12th and 13th editions of Public Health and Preventive Medicine and editor emeritus of the 14th edition ("Maxcy-Rosenau-Last"); editor of the 1st, 2nd , 3rd and 4th editions of the Dictionary of Epidemiology, and author of the 1st and 2nd editions of Public Health and Human Ecology.

“And most importantly” Integration of medicine and veterinary medicine in approaches to control (“ONE MEDICINE - ONE HEALTH”)

57 Some examples of control from the zoonoses
“it is vital to understand the epidemiology of a disease to be able to control it”

58 Leptospirosis control
Vaccination of cattle, pigs, deer, dogs Need virulent, local serovars in vaccines, little cross-immunity, killed, annual revaccination Protective clothing Avoid contact with animal urine/contaminated water Control of wild reservoirs e.g. rodents DD - influenza, meningitis, hepatitis, dengue, scrub typhus Doxycycline prophylaxis for humans

59 Vaccination for specific diseases
Anthrax –animals, human vaccine used in US HS and clostridial vaccines used in ruminants Avian influenza and ND vaccines for poultry FMD, PPR, CSF – vaccines available for animals Rabies - vaccine available for animals and humans Japanese encephalitis – human vaccine available Typhoid and cholera – human vaccines available

60 Occupational safety Staff, VERU teams, volunteers, owners
Hygiene, hand-washing facilities Protective clothing – boots, gloves, glasses, masks Prophylactic drugs – malaria, antibiotics Vaccination Record keeping and incident reporting

61 BIOSECURITY An understanding of the principles of biosecurity is vital for individuals working in Disaster Management, in particular when developing and managing temporary shelters or relief areas, and in assisting communities to prevent disease.

62 Biosecurity is …. A series of Management Practices that are employed to reduce the chance of importing infectious diseases into a country, a region, a village or a relief camp These practices can also help to slow the spread of infectious diseases if disease incursions occur

63 Biosecurity is important for a number of reasons
Following a natural disaster factors are present that potentially increase the spread and prevalence of infectious diseases in animal populations. Many of the diseases are of food safety or economic concern Stressed animals are more prone to infectious diseases A vibrant agricultural community is an important resource in producing and maintaining a healthy environment and assisting affected populations to recover from disasters

64 In order to effectively begin to develop a biosecurity program it is important to review the risk areas that may be present Risk assessment helps to determine the areas or factors that are most likely to lead to the spread of infectious agents Risk management is the second step. Here a preventive plan is developed and implemented. Risk communication is the final step. In this step, all members of the management team, farmers, suppliers and service personnel are informed of the plan to ensure cooperation and buy-in.

65 Roles and responsibilities
Development of a biosecurity plan for relief camps or the disaster area is initially the responsibility of the veterinarian in charge of the DM team in consultation with the VERU team leader and senior government staff Once protocols have been established, they should be enforced as far as possible by the DM/VERU team members and government staff

66 Livestock Herd or relief camp
*Purchased Products (Feed, etc ) *Purchased animals

67 Biosecurity usually involves screening and testing incoming animals, quarantine or isolation for newly purchased or returning animals, and finally a monitoring or surveillance system to detect disease incursions. Some of these activities may be difficult to integrate into a disaster response plan, however it is important to be aware of the principles of biosecurity

68 To protect animal health

69 To protect food supplies and human health

70 And to prevent the spread of disease causing hardship for affected communities

71 Isolation-Resistance-Sanitation
One way to concisely introduce Biosecurity and Biocontainment is to use the acronym IRS IRS stands for Isolation-Resistance-Sanitation

72 World Animal Health Information Database (WAHID) Interface
Before biosecurity protocols can be developed it is important to know the diseases endemic in the country, this information is not always available Government vets in the team can supply information WAHID is a very useful source of global information The WAHID Interface provides access to all data held within OIE's new World Animal Health Information System (WAHIS). It replaces and significantly extends the former web interface named Handistatus II System

73 OIE international health standards
Terrestrial Animal Health Code Manual of Diagnostic Tests and Vaccines for Terrestrial Animals The Health Codes detail measures to be used to prevent the transfer of infectious agents pathogenic for animals and humans While principally for use in international animal movements these codes are a very useful source of information to assist the development of biosecurity plans

74 In summary Biosecurity relies on: Controlled access
Protective equipment Disinfection Closed herds Isolation on introduction

75 Bio-security is not difficult ….it’s just inconvenient!

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