Final

What is the single greatest determinant of economic costs of an FMD outbreak in Canada?

The immediate closure of all export markets for Canada’s livestock and meat products

What type of virus is foot and mouth disease?

Picornaviridae, aphthovirus

• positive sense RNA virus

• 7 distinct serotypes

• 60 subtypes and periodic de novo generation of new subtypes

• NOT cross protective

Who and what is impacted by FMD?

• Primarily cloven hoofed domestic and wildlife animals (swine, sheep, goats, cattle and water buffalo) (also elephants, hedgehogs, nutrias, armadillos, capybara, rodents)

• Causes massive production losses in dairy and swine industry

• Causes high mortality in young animals

Where is FDM absent, sporadic and endemic?

Absent (mostly): Australasia, North America, Europe

Sporadic: South America

Endemic: Africa and Asia

Pathogenesis of picornavirus (FMD) ☆

1) 100 nucleotide of the virus has a cloverleaf structure that binds viral polypeptide 3C and host proteins to form a nucleoprotein complex, which is an absolute requirement for viral replication

2) Has an internal ribosome entry site (IRES) which is needs a host ribosome’s to bind and translation of proteins

Pathogenesis of picornavirus (FMD) cell manipulations

1) rapid shut down of host cell protein translation

2) leaves more materials like amino acids and ribosomes to build more virus

3) switching off pro- and anti- apoptotic signals to keep the cell living as long as possible

This allows for more virus to be created and delays the time for an early immune response to be induced. This could also be a strategy to produce chronic and persistent infections.

Pro-apoptotic signals shut down host cells transcription and translation.

Anti-apoptotic signals reduces interferon and tumor necrosis factor (TNF-a) response thus the virus will eliminate TNF -a receptors on the cell.

When is FMD inactivated and where does it survive?

Inactivated: pH below 6.5 and above 11, ultra-high pasteurization, dry surfaces and UV light (sunlight)

Survives: milk, milk productions (conventional pasteurization), bone marrow (frozen), lymph glands and some meat products, dried serum (organic material), and will survive for weeks in organic rich material (cold temperatures and moisture)

Transmission of FMD

Main source: infected vesicle (blister)

Respiratory aerosols both direct (animal) and indirect (man). Fomites (contact) through boots, clothing, and hands. Feeding through infected animal products like milk, meat, organs/glandular tissue. Others like artificial insemination, and biological like vaccines and hormone preparations.

Incubation of FMD

After natural exposure animals usually develop clinical signs on average after 3 to 8 days (can be 1-21 days)

Transmission: maintenance host FMD

Sheep and goats harbor virus in pharynx for about 4-6 months. Clinical signs are mild and hard to detect, thus diagnosis is delayed. They include fever, lameness (hoof vesicles) and inappetence (oral vesicles). This allows for the virus to accumulate, spreading it and acting as fomites.

Transmission: Amplifier host FMD

Swine exhale 30-1000 times more virus than sheep or cattle. Clinical signs can be severe. There may be fever, lameness due to severe vesicles coronary bands, and anorexia due to vesicles around the snout. A dog sitting pig is not normal.

Indicator host FMD

Cattle have lesions that are more severe and are manifested earlier than swine and small ruminants. Clinical signs include marked fever, depression and dullness, drooling salivation, and serous discharge. Causes low milk production, mastitis, abortion, decreased fertility (breeding problems), and ill-thriftiness (the failure to gain weight). Also hoof lesions in the interdigital space, on the coronary bands, and lameness.

Tiger heart in young animals ☆

Myocardial degeneration and necrosis, is fatal

True or false: FMD is mildly zoonotic and not a public health concern

True

Hand foot and mouth disease

Picornaviridae: Coxsackie A group virus

Why is FMD considered a production killer?

It is horrible for the bottom line and spreads like wildfire. Morbidity is 100% and mortality is variable depending on the strain of virus and its virulence and susceptibility of the host (50% in young animals and 5% in adults)

Direct costs of FMD

• loss of capital (livestock)

• compensation to producer

• eradication costs (stamping out): infected animal slaughter and welfare slaughter

• carcass disposal

Indirect costs of FMD

• empty farms (down time)

• animals stuck in transition (at the border)

• loss of export markets

• loss of public confidence in the product (consumer fear of unsafe food)

embargo costs of FMD for cattle

• decrease in breeding animals that leads to a population drop

  • eventually the market balances and borders open to exports but some of the market share may be lost permanently since there is not enough cattle for export or other countries have already stepped into to fulfill the demand

Detection FMD

1) serology: antibodies to structural (vaccine strain) and non-structural (field strain) proteins and both (field strain)

2) virus isolation:

• primary cell lines: bovine thyroid cells, pig, calf, and lamb kidney cells

• BHK-21 (hamster kidney) and IB-RS-2 (pig kidney) lines

3) clinical examination: vesicles and general health of the animal

4) nucleic acid tests: PCR

5) pathology

FMD surveillance (OIE requirements)

1) early warning system throughout the production, marketing and processing chain to report suspicious cases

2) regular and frequent clinical inspection and serology testing of high risk animals

3) an effective program to follow up on suspicious cases

4) random and targeted surveys acceptable

Clinical surveillance

aims at detecting suspect animals displaying clinical signs and used to confirm lab testing positive animals

Virological surveillance

used to monitor risk population, confirm clinical cases and positive serological tested animals and to test normal mortality

Serological testing

antibody testing for positive animals (either vaccinated or infected)

FMD control

• quarantine suspect animals

• stamping eradication program: used by all non-endemic (epidemic) disease free countries to eradicate FMD

• decontamination (disinfectants): premises should be disinfected immediately following detection of virus

• sodium hydroxide (2%) and bleach products, sodium carbonate (4%), citric acid (0.2%), Virkon-S, others less effective

Anthrax

Bacillus anthracis

disease of warm blooded animals

Who is susceptible to the acute form of anthrax?

herbivores (ruminants and equidae)

24-48 hours appearing ill

Who are relatively resistant to anthrax and contract a less acute form?

Carnivores (canine and swine)

Anthrax bacteria

Gram positive non motile spore that grows well on common median (blood culture). The vegetative form multiplies and kills host, forms box cars in rows

athrax spores

the predominate form in the environment. Sporulate in nutrient poor environments and in the presence of oxygen (aerobic). Spores germinate in environment rich in amino acids, nucleosides, glucose (blood or tissue). Very resistant to temperature extremes, pH, desiccation and chemicals (disinfectants), UV light: lives 50-250 years as spore form. Spore inactivation: 5% hypochlorite (strong bleach), paraformaldehyde vapour, phenol and autoclaving. A lethal dose is 2500-55000 spores or one deep breath at time of release (very small)

Three main forms of anthrax in humans

Cutaneous

Gastrointestinal

Inhalational

(others include meningitis, sepsis, renal and ophthalmic)

Cutaneous anthrax

95% of cases → enters through cuts or abrasions (through handling contaminated animals, animal products or other objects)

Incubation 1-12 days, infection begins as small papule (pruritic) to vesicle (1-2 days) to eschar (necrotic ulcer) sometimes secondary vesicle. Other symptoms include swollen lymph nodes, fever, malaise and headache

5-20% fatality without antibiotics, <1% fatality with antibiotic treatment

Dead Septicemia and toxemia

Gastrointestinal anthrax

Usually appears in livestock ingesting spores. In people by eating contaminated meat or drink, 1-7 days incubation after meat consumption.

Oropharynx: base of tongue, tonsils, sore throat, dysphagia, fever regional lymphadenopathy. Lower GIT: acute necrosis and inflammation of the gut: nausea, vomiting (with or without blood), dysentery (bloody diarrhea), fever and malaise

Without treatment fatality → 25-65%

Death caused by septicemia toxemia and stock

Differential diagnosis for gastrointestinal anthrax

acute appendicitis, ruptured viscus, diverticulitis, disease that acute cervical lymphadenitis or acute gastritis, dysentery

Differential diagnosis cutaneous anthrax

spider bite (brown recluse), ecthyma gangrenosum, ulceroglandular tularemia, plague, staphylococcal or streptococcal cellulitis, herpes simplex virus. Treatment includes hyperbaric chamber or surgery to cut it out.

Inhalational anthrax

“woollsorter’s disease”

2500-55000 spores are lethal

Incubation 1-43 days (median of 10 days) bioterrorism inhalation anthrax has 4-6 days of incubation

Symptoms include non-productive cough, fatigue myalgia, fever; see brief period of improvement then relapse to death (dyspnea, cyanosis and shock)

Case fatality 85-97% without antibiotics. 75% with antibiotic treatment. 45% with intensive therapy (death can occur with hours of symptoms)

Pathogenesis of anthrax

lung → macrophage engulfs spore → spore germinate in macrophage in lymph nodes and release from dead macrophage → vegetative bacteria divides extracellularly (septicemia) and releases toxins (exo and endotoxins: toxemia) → mild illness to fulminating disease and rapid death (shock hemorrhage, dyspnea)

pathogenesis anthrax: pOX1

encodes for protective antigen (PA), lethal factor (LF) and edema factor (EF)

pathogenesis anthrax: pOX2

encoded for proteins that synthesize polyglutamic acid capsule helps protect dividing bacteria to evade engulfment and phagocytosis

3 actions of pOX1 and pOX2

1) PA combines with LF to form Lethal toxin (LT)

2) PA combines with EF to form Edema toxin (ET)

3) 7 x PA form heptame: pore in cell membrane and allows lethal and edema toxin inside the cell

Lethal toxin (anthrax)

Common affect is the impairment of host defense and immunity. Virtually all cells involved in immune functions require MAPK pathways for proper function. Alters innate immunity (macrophages neutrophils and dendritic cells) and adaptive immunity (lymphocytes)

Lethal toxin neutrophils

Inhibition of chemotaxis: loss of filamentous actin assembly (p38 kinase and ERK kinase)

Decrease production of superoxide anions: drop in pus production (p38 kinase and ERK kinase) augmented if pre-exposed to TNF-a. Cripples innate immunity.

Lethal toxin (macrophages)

Macrophages are important mediators of inflammatory responses: produce pro-inflammatory cytokines (TNF-a, IL-6, IL-1-B, IL-10 and others) impaired by MAPK activity. Cytokines important in activation, direction and magnitude of inflammatory and immune responses. Reduced chemotaxis and phagocytosis (similar to neutrophils).

Stages of lethal toxin

macrophage death, lethal toxin will induce swelling and lysis of macrophages (necrosis). Initially univalent cation permeability (K) followed by ATP depletion. Loss of mitochondrial function. Shutdown of protein synthesis and eventual loss of membrane integrity. Activation of macrophages with agonists of Toll like receptors makes macrophages more susceptible to LT

Macrophage death and cell mechanisms of lethal toxins ☆

1) Nalp1B gene (chromosome 11)

2) Modulation of Wnt target genes

3) LRP6 (lDL protein receptor on macrophages) and a co-receptor Wnt target genes

4) Lethal Toxin blocks survival pathways of activated macrophages

Explain the cell mechanisms of lethal toxins ☆

1) Nalp1B gene (chromosome 11): codes for NLR proteins and these are part of inflammasomes (activators of inflammatory cascades like Caspase). Lethal toxin activates caspase 1 and inflammasomes induces a inflammatory cascade and macrophage death

2) Modulation of Wnt target genes: inactivation of GSK - 3B (kinase): see increased macrophage necrosis

3) LRP6 (lDL protein receptor on macrophages) and a co-receptor Wnt target genes: assist in protective antigen uptake into macrophages

4) Lethal Toxin blocks survival pathways of activated macrophages: LT indirectly inactivates NF-KB (cell activation and cell survival) allowing TNF-a to induced apoptosis

Lethal toxin adaptive immunity

Impairment of cognitive interactions between dendritic cells and T lymphocytes- priming lymphocytes. Decrease in up-regulation of co-stimulatory molecules: ‘loss of second signal’ (can therefore acquire anergy and apoptosis), inflammatory cytokines

Edema factor

a Ca2+ and calmodulin dependent adenylate cyclase: increase cellular cAMP levels and thus activate intracellular Protein kinase A activity

Elevated cAMP (perinuclear); affects cAMP levels in other compartments within the cell: thus loss of intracellular cAMP homeostasis.

Impairs phagocytosis, superoxide anion production (activation of Protein Kinase A). Increased cAMP blocks MAPK, ERK, and JNK pathways, which decreases neutrophil, macrophage function and T lymphocyte proliferation

Lethal and Edema toxin

Cooperate synergistically (more potentate affect) since they target similar spectrum of cell types but operates with different mechanisms (more toxic)

Following treatment of Lethal toxin the skin lesion has a characteristic black pigment, why?

Cutaneous anthrax. Melanin producing cells (melanoma cell lines) produce melanin as melanocytes activate melanin.

Ecology of anthrax

exist in 2 micro environments 1) low-lying depressions with standing water and devitalized plant material 2) rock lands with dry courses of water

Dry weather usually forces grazing animals to feed closer to the ground where are often concentrated. Exposure typically occurs through inhalation or ingestion of dust. Infected animals (carriers and dead) shed microbe in urine and feces. Mosquitoes and biting flies will transfer organism from animal to animal (fomites)

Three forms of anthrax in animals

Peracute (sudden death… drops dead): Ruminants like cattle, sheep, goats, and antelope

• sudden death

• bloody discharge from body orifices

• incomplete rigor mortis

• rapidly bloat

Acute (24-48 hours appearing ill): Ruminants and equine

• Ingestion (enteritis, severe colic, high fever, weakness, death within roughly 48 to 96 hours)

• Insect bite/vector (hot, painful swelling, spreads to throat, sternum, abdomen, external genitalia, death)

Subacute-chronic (<48 hours): Swine, dogs, cats

• less common than subacute-chronic death, but in sudden death, localized swelling of throat (laryngeal edema)

• death by asphyxiation

• ingestion of spores: anorexia, vomiting, enteritis (gastrointestinal anthrax)

Diagnosis and treatment of anthrax

Never open carcass and no necropsies (autopsies)!! Sample blood from a closed system (venipuncture) and cover with disinfectant gauze (10% formaldehyde). Treat with penicillin, ciprofloxacin or doxycycline. The government of Canada says incineration is the best and prefered method especially for open carcass. Burn the carcass to ash slowly and hot then decontaminate ashes. Alternatively burial, decontaminant (10% formaldehyde, 5% lye). Also vaccinate herd.

Vaccination of anthrax

Vaccinate in endemic areas like Saskatchewan in summer of 2006. Vaccinate (Sterne strain) with attenuated spore vaccine (toxigenic, non-encapsulating). This is licensed for livestock only. Immunity within 10 days following injection. Use in pets as off label, but this can get a reaction with adjuvant. Could be useful in working dogs.

Control of anthrax

Report to the authorities, quarantine the area, do not open carcass (no necropsies), minimize contact, wear protective clothing (mask and gloves), vaccination of susceptible animals.

Destroy carcasses by burning (best0slow and hot) or bury with decontaminate. Decontaminate soil and carcass, hydrogen peroxide, peracetic acid or 10% formalin. No high pressure cleans because they can aerosolize the disease. Quick lime IS NOT recommended.

Clean surfaces with 1:10 household bleach. Preliminary disinfection with 10% formaldehyde and 4% glutaraldehyde. Clean with hot water, scrubbing, protective clothing. Then a final disinfection with one of the following (10% formaldehyde, 4% glutaraldehyde, 3% hydrogen peroxide, or 1% peracetic acid)

Bioterrorism

the use, or threatened use of biological agents to promote or spread fear of intimidation upon an individual, specific group, or the population as a whole for religious, political, ideological, financial or personal purposes. Biological agents target plants, animals and people.

Agroterrorism

A subset of terrorism and is defined as the deliberate introduction of an animal or plant disease with the goal of generating dear, causing economic losses, and or undermining social stability. The use, or threatened use of biological (to include toxins), chemical, or radiological agents against some component of agriculture in such a way as to adversely impact the agriculture industry or any component thereof, the economy, or the consuming public. The ultimate goal is causing economic crises in the agricultural and food industries, social unrest, and loss of confidence in government.

Bioterrorism vs agroterrorism

biological agents targeting humans, animals, and plants vs biological chemical and radioactive gents targeting mainly agricultural products, like animals and plants and can impact workers and other industries involved in food supply

Why choose agroterrorism?

the odds of harming people are remote, since the goal is to disrupt domestic and international trade and to potentially damage domestic food supplies. The goal is to cause fear. Attacking crops and animals is not as emotional as choosing human targets, so there is less chance of retaliation. The use of an agent may go undetected for days to weeks. Therefore there is plausible deniability.

Identification of Agroterrorism

• history of animals yields unrewarding

• traceback- no commonality between dead animals among live animals

• history of the incident may be suspicious

• similar outbreaks in different parts of the region or country

• odd presentation of disease (unusual signs)

• a common disease with high morbidity and mortality

• disease present in the wrong time of the year

• independently these may not be disconcerting but when 2 or more of these occur it may suggest an act of agroterrorism

Who is affected by agroterrorism?

Damage can be local, regional and national economics via loss in trade, embargos, that could affect many products. Impact can occur within the first 24 hours. Direct costs of control eradication include diagnostics, surveillance, depopulation, cleaning, disinfection, indemnity, salaries such as for law enforcement, military, veterinarians, etc, and welfare slaughter. By extension other industries are affected like restaurants, suppliers (trucking, slaughter plants), public entertainment and vacationing (tourism, zoos, hunting/fishing, banned local and international transport and so forth). The total affect of agroterrorism may take years to fully realize the damage.

Livestock vulnerability to agroterrorism

The density of animals, mixing of animals (at auction markets), transport of animals, feedlot slaughter plants. Having no previous immunity to exotic diseases, as there are few effective vaccines that cross protect. Difficult to acquire large numbers of vaccines or mass produce vaccines that could stop and disease outbreak. Centralized feed supply and distribution (if contaminate feed it would affect many farms in many different locations). Additionally poor records of animals and expanded international trade and travel and the ever-present danger of exotic diseases in many trading countries. Poor monitoring at international borders and ovement of wild animals across borders. Inadequate on-farm biosecurity. Lack of foreign animal disease awareness.

Prevention of agroterrorism

Excellent biosecurity, excellent rapid monitoring (surveillance), and reporting system and a rapid and effective response. On the farm, good sanitation, restricted movement, know the people and animal source. Local control of auction markets and other forms of animal mixing, animal identification tracing, control of movement. Regional control of movement, notifications of local governing agencies, quarantine imports. National notifications of local governing agencies, quarantine imports, and notify outbreaks to the OIE. Agencies involved are the Canadian Food Inspection Agency, Public Health Agency of Canada, and low enforcement and military.

COVID19

B coronavirus caused SARS-CoV and MERS-CoV. Some coronavirus are isolated from bats. 96% genetic similarities between human COVID-19 and bat SARS-CoVID.

Clinical disease COVID 19

Variable and asymptomatic, mild pneumonia, fulminating ARDS (acute respiratory distress syndrome) and organ failure. Incubation 3-24 days long. Mortality rates 2.9 percent.

Treatment of COVID 19

Supportive care: intubation ventilation and oxygenation

Promising drugs: remdesivir (most promising anti-viral drug) adenosine analog alters RNA replication (also used to treat ebola and marburg virus)

Chloroquine: is anti-malarial (which may inhibit RNA polymerase-alter viral replication)

NOT RECOMMENDED glucocorticoids and NSAID

Best COVID-19 vaccine type

Nucleic acid (RNA or DNA): genetic material, enter the host cell (Dendritic cell macrophage) - these make up the antigen

Pfizer and Moderna (mRNA - spike protein)

COVID 19 in animals

Ferrets and the rest of the Mustelidae family, cats (including big cats in zoos), dogs, syrian hamsters and non human primates are all susceptible.

Serology (in italy) showed that 3.4% of dogs and 3.9% of cats caught COVID.

Pigs and chickens were resistant.

SARS: coronavirus

36 members of Coronaviridae: induce respiratory and intestinal infections in both animals and people. Survives 2-3 days on dry surfaces and in stool and up to 4 days in respiratory droplets.

Viral life cycle of SARS

S-protein binds to cell surface receptors and needed for membrane fusion. Binds to host angiotensin converting enzyme 2 (ACE2): lung, intestine, liver, heart, vascular endothelium, testis, kidneys, immune cells, brain and thyroid

Immune cells (dendritic cells) disseminate virus throughout the body. The virus replicates in cells and then is released by budding to infect other cells (injures cells)

Cellular injury SARS

Alters immune function via inflammation and immune suppression. Increases expression to chemokines (CCL5, CXCL10, CCL3), which facilitate virus replication and block immune response. Includes apoptosis: T cells and epithelial cells. Inhibits interferon production. Activates NF-kB, which increases inflammation in lungs. Binds to cytochrome oxidase-II in mitochondria, and has extensive cytopathic effect.

Pathogenesis/Transmission SARS

respiratory droplets or fecal/urine contamination from man or animal → virus invades respiratory tract epithelium (viral replication destroys epithelium). Inflammatory cells invade tissue injuring capillaries and blood-gas barrier. → fibrin in alveoli and injury to Type-II pneumocytes causes decrease surfactant (collapse of alveoli) SARS → SARS: severe acute respiratory syndrome, or ARDS → death (acute respiratory failure)

infect circulating immune cells (macrophages and T cells) transports virus to other tissues and carrying immune cells die (immunosuppressive). Will get secondary opportunistic pathogen infections → extra respiratory tissue involved in immune function are injured by virus (hepatitis)

3 stages of lung injury SARS

Acute: ARDS

Proliferative: pneumocyte hyperplasia, cellular exudate

Final stage: alveolar and septal fibrosis: severity related to duration of SARS

Type I pneumocytes (lung cells)

90-95% of cells in lung, gas exchange, squamous cells (thin)

In ARDS die as a result to diffuse alveolar damage

Type II pneumocytes (lung cells)

surfactant (surface tension) divides in injured lung to form Type I pneumocytes

multiply to line the alveolar surface

Susceptible animals to SARS

cynomolgus macaques, mice, rats, cats, ferrets

Resistant animals to SARS

swine, chickens, African green monkeys

What to do if you suspect SARS?

1) Quarantine and stop movement

2) Contact PHAC, CFIA

3) Test to confirm (PCR: fast, simple, and accurate)

re-test for bacteria at least 3x

What of disease diagnosis

Biology of the disease/epidemiology: understanding the characteristics of the agent, virulence, environmental stability, susceptibility to disinfectants, movement between different animal species and people etc

How of disease diagnosis

data acquisition (monitor temperatures at borders, health declaration of travelers, laboratory tests (PCR, FIA), sputum samples, lung biopsy. Transfer of this information to veterinary and human, governing bodies

Response of disease diagnosis

monitor to reduce further contact, treat and vaccinate, quarantine animals and people in contact, reduce social contact test (distancing and suspension of activities, school work and so forth). Slaughter eradication, depopulation of animals (like in the example of civet cats)

Why do we get coronavirus induced SARS? `

Stability in the environment is moderate at best. Absence of protective immunity (no herd immunity): 70-80% of the population is not immune and the virus spreads fast. The lack of the effective antiviral drugs or effective vaccines. Potential for nosocomial infections (hospital staff unaware that they have SARS). Spread by carriers (people with partial immunity in early stages of disease).

What are replacement heifers for?

to increase the population of animals on farm

Bluetongue disease and red mites

Red “biting” mites in the genus culicoides midges

Bovine TB effective tests

Skinfold test