Presentation on theme: "Zoonotic Diseases and Natural Disasters"— Presentation transcript:
1 Zoonotic Diseases and Natural Disasters Professor Stan FenwickVeterinary Public HealthMurdoch 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 LeptospirosisAnthraxRabiesSalmonellosis
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 hostMode of transmission
7 Direct zoonosis Cyclozoonosis Metazoonosis Saprozoonosis Transmission of zoonotic infections may be direct, indirect via arthropod vectors, or from environmental fociDirect zoonosisCyclozoonosisMetazoonosisSaprozoonosis
8 eg. leptospirosis, anthrax, rabies Direct ZoonosisAn infection which can be directly or mechanically transmitted to people from animals, and which is capable of being maintained in a single species of animalMost of the important zoonoses that can occur following flooding are direct zoonoseseg. leptospirosis, anthrax, rabies
9 LeptospirosisDirect anthropozoonosis (or via fomites)Host-adapted serovars, maintenance hosts act as carrier animals, inapparent infectionsHerbivores long shedding, carnivores shortSevere infections in secondary hosts (humans and animals)Over 200 serovars, all capable of infecting any animalMoist 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.
15 Transmission and Human Disease Contact with infected urine or contaminated waterCommon occupational disease via intact mucous membranes, aerosols or skin abrasionsAnicteric disease is common form seen in Australia, vague symptoms, flu-like, fever, headache, myalgiaIcteric disease more severe, uncommon in Australia, this form commonly seen with rodent-associated serovars, jaundice, haemolytic crisis, can cause deathPerson-person transmission rare, dead-end hosts
17 Leptospirosis and floods 2002 Thailand 50 cases, multiple serovars2006 Brazil 193 cases, L. copenhageni2008 Guyana 68 cases (6 deaths), ? serovars2009 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 existAll mammals susceptible but pigs, dogs, cats relatively resistantBirds can disseminate spores, chickens resistant, some birds susceptibleSpores 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 transmissionCutaneous infections most common, inhalation, intestinal in rural areas, person to person rare1-7d incubation, spores germinate, bacteraemia, papules, vesicles, oedema (black), fatal septicaemia (toxins)Agricultural workers, rural people, vets, travellers etc.
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 mealVietnam 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 areasSeasonal flooding of rivers in southern africa has led to outbreaks of anthrax in cattle and wildlifeAnimals 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. NZSome countries free by eradication e.g. UKWhile 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 Lyssavirus1. Classical rabies2. Lagos bat virus3. Mokola virus4. Duvenhage virus5. European bat virus6. European bat virus7. Pteropus (Australian) lyssavirus
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 EpidemiologyDogs most important domestic hosts, other domestic animals can also be involved e.g. cats, cattleMany wild reservoirs which differ between regions; principally canids (foxes, wolves, jackals) but also mongooses, skunks, raccoons, batsHaematophagous, insectivorous and frugivorous bats all can transmit rabies and related viruses
28 RABIES EpidemiologyAnimals differ in susceptibility, dogs show intermediate susceptibility, humans, cats and cattle highly susceptible, pigs resistantHighest incidence in Asia, in particular IndiaEndemically stable, few new reports of infections extending in countries except raccoons in E. USA and Bat Lyssa Virus in Northern Europe
29 RABIES TransmissionTransmission to people mainly by bites via virus in salivaAerosol, transplacental and transmammary transmission in bats, found in bat saliva in zoosOral transmission in highly susceptible species (eg. foxes), not documented in people
30 RABIES Disease manifestations Incubation 4d - 6y recorded, depending on where bittenClinical rabies invariably fatalProdromal period (behavioural changes)Excitative period (hydrophobia, aerophobia in people); 1 dog in India bit 40 people/9 dogs in 4hParalytic 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 annuallyPakistan deaths per yearThailand – deaths per year
32 Rabies and floodsAs for anthrax little specific information is availableHowever, post-flooding, large numbers of uncontrolled dogs may congregate near relief campsThis concentration of dogs will facilitate rabies transmission in the event of a rabid animal being present in the groupAfter 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 CyclozoonosisInfections which require at least two vertebrate hosts, one of which may be human, to complete their life cycleThese include many of the parasitic zoonoses which are not usually associated with flooding, although handling dogs in a hydatid endemic region could result in infectione.g. Taenia solium, Echinococcus granulosus
35 (Dengue, Japanese encephalitis, rickettsial infections) MetazoonosisDiseases of vertebrate animals which can affect man, the infectious agents of which replicate, develop in, and are transmitted by, an invertebrate vectorThis group includes all the arthropod-borne infections, which should be considered following flooding due to a concurrent increase in vector populationse.g. Mosquito and tick/mite -borne infections(Dengue, Japanese encephalitis, rickettsial infections)
36 SaprozoonosisDiseases 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 cycleeg. Histoplasmosis, Toxocara canis, enteric bacteriaSalmonella 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 SalmonellaOver 200 serovars, both host-adapted (S. typhi) and non-host adapted (S. typhimurium, S. enteritidis)Domestic and wild animal reservoirs, most infections asymptomaticDomestic animals show increased shedding and clinical disease following periods of intense stress e.g post flooding/congregation in relief campsHuman infections via food, water or direct contact
39 Bacterial infections of animals Clostridial infectionsTetanusBotulismBlacklegEnterotoxaemiaHaemhorragic septicaemia(pasteurellosis)Secondary infections post-traumaRespiratorySkinMastitis
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 DISEASESRinderpestFMDRift Valley FeverBovine spongiform encephalopathy (BSE)Contagious bovine pleuropneumonia (CBPP)Classical swine fever (CSF)African swine feverHighly 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 DISEASESCompromised food securityMajor production losses for animal productsLoss of valuable livestock geneticsIncrease in costs of productionDisruption to local and international tradeInhibition of investment in livestock sectorPublic health and environmental issuesAnimal welfare concerns
43 Parasitic infectionsMoist conditions following flooding favour survival of worm eggsPost flooding, the congregation of animals in relief camps or other areas will facilitate parasite transmissionIn addition, stressed animals will be more prone to the effects of parasitesNematode and trematode infections most likelyEctoparasite infections will also increase – may result in tick-borne infections e.g. Babesiosis, theileriosis, flystrike
44 Diseases associated with nutrition Flood-damaged feedsMycotoxicosesToxic plants eaten due to lack of feedInanition due to unusual feedstuffsStarvationProblems 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 urineMosquito-borne diseases will also be a potential risk, e.g. dengue, Japanese encephalitis, malariaIf large numbers of stray dogs are congregated on dry ground, then dog bites and potentially rabies are risksInfected wounds, tetanus, respiratory infectionsFood and waterborne diseases – Cholera, typhoid and other enteric infections from contaminated water and food
46 Epidemiology Risk factors for diseases following floods OvercrowdingNutritional changesContaminated water suppliesWounds and injuriesInclement weatherVectorsOther stressors
47 Diagnosis of diseases in the field Minimal facilitiesTemporary laboratory facilitiesAccess to permanent laboratory facilities
48 Minimal facilitiesMicroscope, simple stains, McMaster slides, salt solutions, sample collection equipmentPen-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 smearsParasite diagnosis, worms, worm eggsBlood-borne parasites (Babesia, Theileria, Trypanosoma)
49 Temporary laboratory facilities Possible incubator, allowing simple bacteriology, although usefulness doubtful, ? SalmonellaRefrigerator/freezer to allow storage of samples for retrospective diagnosisSerum sample storage; work with human agenciesSimple test kits, e.g. rapid ELISA
50 Control of Diseases following flooding General principles of disease controlExamples 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 levelsIndividual/herd: chemoprophylaxis, arthropod control and avoidance, hygiene, vaccination, clean water, safe food, disinfection of fomites, avoidance of close contactLocal/community: arthropod and rodent control, education, mass chemotherapy, eradication of animals, restriction of animal movement, vaccination, pasteurisation, isolation of patients, infection controlNational/International: quarantine, restriction of imports, movement control for animals, international notifications and networks, international response teamsJohn 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.
56 (“ONE MEDICINE - ONE HEALTH”) “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, dogsNeed virulent, local serovars in vaccines, little cross-immunity, killed, annual revaccinationProtective clothingAvoid contact with animal urine/contaminated waterControl of wild reservoirs e.g. rodentsDD - influenza, meningitis, hepatitis, dengue, scrub typhusDoxycycline prophylaxis for humans
59 Vaccination for specific diseases Anthrax –animals, human vaccine used in USHS and clostridial vaccines used in ruminantsAvian influenza and ND vaccines for poultryFMD, PPR, CSF – vaccines available for animalsRabies - vaccine available for animals and humansJapanese encephalitis – human vaccine availableTyphoid and cholera – human vaccines available
61 BIOSECURITYAn 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 campThese 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 concernStressed animals are more prone to infectious diseasesA 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 presentRisk assessment helps to determine the areas or factors that are most likely to lead to the spread of infectious agentsRisk 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 staffOnce protocols have been established, they should be enforced as far as possible by the DM/VERU team members and government staff
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
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 IRSIRS stands forIsolation-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 availableGovernment vets in the team can supply informationWAHID is a very useful source of global informationThe 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 CodeManual of Diagnostic Tests and Vaccines for Terrestrial AnimalsThe Health Codes detail measures to be used to prevent the transfer of infectious agents pathogenic for animals and humansWhile 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 equipmentDisinfectionClosed herdsIsolation on introduction
75 Bio-security is not difficult ….it’s just inconvenient!
Your consent to our cookies if you continue to use this website.