Conserving Animal Health for a Better Tomorrow

Deepa Raju MenonPost-doctoral Research Associate,

Southern Research & Outreach Centre,University of Minnesota, MN.

Overview

Definitions Animal diseases - impact Signs of health and disease Classification of diseases Disease control and prevention PRRS Summary Conclusion

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Definitions

• Health - a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity (WHO, 1946)

• Epidemiology - is the science that studies the incidence, distribution, causes and control of diseases in a population

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What is Disease?

Any disruption of the normal function and health of an animal that is typically manifested by distinguishing signs and symptoms

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Impact of Animal Diseases

• Loss of animal productivity

• Cost of treatment

• Market disruption

• Affecting human health

• Loss of income

• Food insecurity and poor nutrition5

Types of Diseases - Population

• Endemic - farm level - constant presence• Epidemic or transboundary - highly

infectious, sudden increase, one country• Pandemic - several countries, newer organism• Sporadic - infrequent, irregular• Outbreak - limited area• Zoonotic - man animal(Perry et al., 2001)

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Classification of Diseases - Etiology

• Bacterial - Brucellosis, Tetanus• Viral - Avian influenza, Pox• Parasitic - Mange, Taeniasis• Fungal - Aspergillosis, Ringworm• Protozoal - Coccidiosis, Babesiosis• Managemental - Indigestion, Poisoning • Metabolic - PEM, Rickets

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Disease is Multifactorial

• Agent (infectious) factors

• Host animal factors

• Environmental factors– Management– Feed and water quality– Ventilation– Comfort– Weather

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Disease / Epidemiological Triangle

HOST

ENVIRONMENTPATHOGEN

DISEASE

Resistance, age and immunity

Facilities and management

(Temperature, pH)

Virulence and persistence

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Transmission

• Disease occurs when the host’s defences are overwhelmed by stressors, malnutrition, or high levels of infectious agent

• Vertical• Horizontal• Direct• Indirect - air borne, fomite, vector

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Factors in Disease Proliferation

• Reservoirs: - where organisms live

• Amplifiers: reservoirs where organisms proliferate

• Vehicles: inanimate objects / materials - fomites and biologicals

• Vectors: carriers

–Mechanical vectors: biting insects

– Biological vectors: must propagate in the vector

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Ports of Entry and Exit for Disease Agents

Source: Epidemiology Concepts for Disease in Animal Groups http://people.vetmed.wsu.edu/jmgay/courses/EpiMod2.htm12

Spectrum of Disease Severity

Source: Epidemiology Concepts for Disease in Animal Groups http://people.vetmed.wsu.edu/jmgay/courses/EpiMod2.htm 13

“Iceberg” Concept - Infections

EXPOSURE WITHOUT INFECTION

INFECTION WITHOUT CLINICAL ILLNESS

MILD ILLNESS

SEVEREDISEASE

DEATH Clinical Disease

Sub Clinical Disease

14Source: Epidemiology Concepts for Disease in Animal Groups http://people.vetmed.wsu.edu/jmgay/courses/EpiMod2.htm

Signs / Evaluation of Health

• Postures, alertness, activity• Skin, eyes, nose/ muzzle, mouth• Appetite, thirst and elimination• Body temperature, respiration, heartbeat and

pulse• Body condition, weight and production• Hematology and biochemistry

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Record Keeping for Assessment

• Feed and water intake

• Occurrence, clinical signs and time of death

• Occurrence of abortions

• Occurrence of mortality and culls

• Lesions at slaughter or post mortem16

Disease Prevention

Susceptible animal

Infected animal

Exposure

Remove infectionDetect and remove or treat

Stop transmissionDirect and indirect

Enhance resistanceAcquired, passive, active or inherent

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Steps to Manage Health Risks

Biosecurity

• Isolation

• Acclimation

• Testing

• Vaccination

• Disinfection18

Why Biosecurity?

• Improved animal welfare

• Improved production, productivity, profit

• Increase value of the herd

• Decreased use of medicines

• Less antibiotic resistance

Prevention is better than cure

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Prevention and Control of Diseases

• Maintain a closed herd

• Isolate, test and treat incoming animals

• Control visitors and motor vehicles

• Avoid contact with wildlife and domestic

species

• Feed and water - free of contamination20

• Truck and foot dips

• Using all-in, all-out flow

• Using shower-in, shower-out

• Keeping facility clean, disinfect

• Fencing, fans and curtains

• Rodent, bird and insect control

SOPs for Biosecurity

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Quarantine

• All incoming stock - quarantined in

isolation

• Initial 30-days - any signs of illness

• Another 30-days period - acclimation

• Reputed suppliers

• Retest animals if necessary22

Pathogen Elimination

• Blanket treatment - antibiotics, vaccine

• Identifying carriers (test and cull)

• Depopulation

• Complete cleaning - sanitation

• Repopulation with pathogen free stock

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Disinfection

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• Remove all excess dirt / debris

• Wash with detergent or soap

• Immerse or wet with a disinfectant

• Phenolic-based (Lysol) or quaternary ammonium-based (Roccal D) are most effective

• Bleach is effective against most viruses and bacteria but it's inactivated by organic material

Porcine Reproductive and Respiratory Syndrome

• Blue-eared pig disease

• Mystery swine disease

• Swine Infertility and Respiratory Syndrome (SIRS)

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PRRS

• Etiology: RNA virus

• Genus: Arteri virus

• Family: Arteriviridae

• Two distinct strains

–Variants of varying virulence26

PRRS - Epidemiology

• Highly contagious

• Reproductive failure in sows

• Respiratory disease in young pigs

• Enters swine herd

• Immunosuppression

• Survives in cold wet conditions

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PRRS - Why a Big Problem

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Spreads through:• Milk, colostrum, intrauterine, semen

• Feces, urine, saliva, blood

• Windborne -aerosol up to 6 miles

• Contaminated needles and flies

• Infected hands, boots and protective clothing

PRRS - Reproductive Form

• Late gestation abortions

• Stillbirths

• Mummified fetuses

• Weak neonates

• High rate of return to estrus

• Problem may persist and recur for many months

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PRRS - Respiratory Form

• Anorexia

• Fever

• Dyspnea, polypnea, coughing

• Unthriftiness

• High mortality in young pigs

• Low mortality in older pigs

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Healthy v.s Diseased

Signs Healthy Diseased

Postures

Appetite

Respiration rate

Body temperature31

Differential Diagnosis - PRRS

• Parvo virus

• Mycoplasmosis (Mycoplasma hyopneumoniae)

• Pasteurellosis (Pasturella multocida)

• Brucellois (Brucella suis)

• Leptospirosis (Leptospira pomona)

• Streptococcus suis

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PRRS - Treatment

• Maintain a closed herd

• Segregate and rear young pigs off site

• Antibiotic therapy

• Depopulate and thoroughly clean weaner unit

• Routine procedures - not done during the acute

phase of the disease

• Serum inoculation of naive gilts 33

PRRS - Control

• Difficult, unreliable and frustrating

• Infection of breeding stock results in immunity

• Maternal immunity in piglets from seropositive sows

• Eradication of the virus

• Create a stable positive system - swine herd lives with the disease

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PRRS - Challenges

• Highly infectious-only small amount of virus necessary to infect a herd

• Persistent infection up to 200 days -shedders

• Mutates easily- commercial vaccines less effective

• Simple blood tests cannot differentiate between field strain and vaccine strain of virus

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PRRS - Testing

• Rope sampling of oral fluids

• Blood testing

ELISA

PCR

FAT

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References

• Pugh, D. G and Baird, N. (2011). Sheep and Goat Medicine. 2nd ed., Elsevier.

• Mathew, G. J. (2009). Diseases of the Goat. 3rd ed., Wiley- Blackwell.

• Merck Veterinary Manual 10th Edition (2010). Kahn, C. M. and Line, S. Eds., Merck.

• Straw, B. E., Zimmerman, J. J., D'Allaire, S., and Taylor, D. J. (2006). Diseases of swine 9th ed., Blackwell Publishing.

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References

• Biosecurity protocols for the prevention of spread of PRRS virus -- by Andrea Pitkin, Satoshi Otake and Scott Dee. https://www.aasv.org/aasv/PRRSV_BiosecurityManual.pdf

• PRRS.org -- the official site for USDA's PRRS Coordinated Agricultural Project (CAP) research and educational outreach resources.

• Spickler, Anna Rovid. "Title of Factsheet." "Date of Factsheet (Last Updated)." At http://www.cfsph.iastate.edu /DiseaseInfo/factsheets.php

• Control of Communicable Diseases Manual. http://navybmr.com/study%20material/CCDM.pdf

• Dohoo, I., martin, W., and Stryhm, H. Veterinary Epidemiological Research (2005) 2nd ed.

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Summary

Define: Disease, health and epidemiology

Classifications: Etiology, Population, Clinical signs

Epidemiological Triangle

Proliferation: Reservoirs, Amplifiers, Vehicle, Vectors,

Transmission: Vertical, Horizontal, Direct, Indirect

Iceberg Concept

Biosecurity

Conclusion

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Understanding epidemiology helps us to prepare better to control and prevent diseases, reduce health hazards and economic losses, thus ensuring healthier animals for a

better tomorrow.

THANK YOU