Zoonotic Diseases and Natural Disasters

1
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 host Mode of
transmission
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Transmission of zoonotic infections may be
direct, indirect via arthropod vectors, or from
environmental foci Direct zoonosis Cyclozoonosis
Metazoonosis Saprozoonosis
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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 zoonoses eg. leptospirosis,
anthrax, rabies
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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

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Maintenance hosts
L. pomona L. tarrasovi - pigs
L. Hardjo - cattle
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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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

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Symptoms of human leptospirosis
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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

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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

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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.

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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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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

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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
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Distribution
UK
Japan
New Zealand
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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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

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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

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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

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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

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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 populations e.g.
Mosquito and tick/mite -borne infections (Dengue,
Japanese encephalitis, rickettsial infections)
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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
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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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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)
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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

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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 McFadyeans 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 didnt!
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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

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And most importantly
Integration of medicine and veterinary medicine
in approaches to control
(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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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

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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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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

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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
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?pagehome
  
• 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 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

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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 .its just
inconvenient!