world society for the protection of animals zoonotic diseases and natural disasters professor stan...
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World Society for the Protection of Animals
Zoonotic Diseases and Natural Disasters
Professor Stan Fenwick
Veterinary Public Health
Murdoch University/WSPA
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WHO – “during floods, reports and rumours are common about problems created by animals such as dogs, rats, mice and snakes”
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Zoonoses associated with floods
• Leptospirosis• Anthrax• Rabies• Salmonellosis
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• 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
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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
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Zoonoses can be classified as follows
Type of infectious agent(e.g. bacteria, virus, parasite)
Type of reservoir hostMode of transmission
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Transmission of zoonotic infections may be direct, indirect via arthropod vectors, or
from environmental foci
Direct zoonosisCyclozoonosisMetazoonosisSaprozoonosis
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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 zoonoseseg. leptospirosis, anthrax, rabies
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• 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
Leptospirosis
World Society for the Protection of AnimalsMaintenance hosts
L. Hardjo
- cattle
L. pomona L. tarrasovi
- pigs
Many serovars, e.g.
L. australis, L. zanoni, L. copenhageni
– rodents (rats/mice)
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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.
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Occupational risks
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Recreational risks
Sabah, Malaysia, 2000, Eco-challenge race – 50 out of 80 athletes contracted leptospirosis.
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Other risks!!!!
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• 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
Transmission and Human Disease
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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
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Leptospirosis and floods
• 2002Thailand 50 cases, multiple serovars• 2006Brazil 193 cases, L.
copenhageni• 2008Guyana 68 cases (6 deaths), ?
serovars• 2009Fiji 8 cases (3 deaths), ?
serovars
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• 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
ANTHRAX
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• 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.
ANTHRAXTransmission and Human
Disease
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Cutaneous anthrax
Anthrax pneumonia
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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
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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
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• 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
RABIES
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1. Classical rabies2. Lagos bat virus3. Mokola virus4. Duvenhage virus5. European bat virus6. European bat virus7. Pteropus (Australian)
lyssavirus
Genotypes of Lyssavirus
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Distribution
New Zealand
Japan
UK
World wide, EXCEPT
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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
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• 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
RABIES Epidemiolo
gy
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• 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
RABIES Epidemiolo
gy
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• 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
RABIESTransmissio
n
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• 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
RABIESDisease
manifestations
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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
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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
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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!
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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
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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
populationse.g. Mosquito and tick/mite -borne infections
(Dengue, Japanese encephalitis, rickettsial infections)
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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
Saprozoonosis
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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
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Non-Zoonoses
• Bacterial infections• Viral infections• Parasitic diseases• Diseases associated with
nutrition
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Bacterial infections of animals
• Clostridial infections• Tetanus• Botulism• Blackleg• Enterotoxaemia
• Haemhorragic septicaemia (pasteurellosis)
• Secondary infections post-trauma• Respiratory• Skin• Mastitis
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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
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• 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
MAJOR TRANSBOUNDARY ANIMAL DISEASES
(blue indicates that diseases are recognised in Asia)
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• 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
CONSEQUENCES OF TRANSBOUNDARY ANIMAL DISEASES
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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
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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
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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
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EpidemiologyRisk factors for diseases following
floods• Overcrowding• Nutritional changes• Contaminated water supplies• Wounds and injuries• Inclement weather• Vectors• Other stressors
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Diagnosis of diseases in the field
• Minimal facilities• Temporary laboratory facilities• Access to permanent laboratory facilities
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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)
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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
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Control of Diseases following flooding
• General principles of disease control• Examples of disease control for
diseases potentially associated with flooding
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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”
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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”
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Emergency Preparedness“an animal or human disease
emergency can have serious socio-economic consequences, which may
affect a countries whole national economy”
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“The only thing more difficult than planning for an emergency is having to explain why you didn’t!”
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General Control Strategies for ZoonosesMeasures may need to be implemented on
individual/herd, local/community, national and international levels
1.Individual/herd: chemoprophylaxis, arthropod control and avoidance, hygiene, vaccination, clean water, safe food, disinfection of fomites, avoidance of close contact
2.Local/community: arthropod and rodent control, education, mass chemotherapy, eradication of animals, restriction of animal movement, vaccination, pasteurisation, isolation of patients, infection control
3.National/International: quarantine, restriction of imports, movement control for animals, international notifications and networks, international response teams
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Integration of medicine and
veterinary medicine in approaches to
control
“And most importantly”
(“ONE MEDICINE - ONE HEALTH”)
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Some examples of control from the
zoonoses
“it is vital to understand the epidemiology of a disease to
be able to control it”
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• 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
Leptospirosis control
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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
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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
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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.
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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
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• 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
Biosecurity is important for a number of reasons
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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.
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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
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Livestock Herd or relief camp
Wildlife
Other animalsNeighbor’s Animals
Visitors & Suppliers
*Purchased Products (Feed, etc )
*Purchased animals
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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
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To protect animal health
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To protectfood supplies and human health
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And to prevent the spread of disease causing hardship for affected
communities
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One way to concisely introduce Biosecurity and Biocontainment is to use
the acronym IRS
IRS stands for
Isolation-Resistance-Sanitation
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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 http://www.oie.int/wahis/public.php?page=home• 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
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OIE international health standards
Terrestrial Animal Health Code Manual of Diagnostic Tests and Vaccines for Terrestrial Ani
mals
• 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
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In summary
• Biosecurity relies on:• Controlled access• Protective equipment• Disinfection• Closed herds• Isolation on introduction
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Bio-security is not difficult ….it’s just inconvenient!