Equine Influenza

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Information about Equine Influenza
Health & Medicine

Published on October 8, 2009

Author: Pranavvet

Source: slideshare.net

Description

This presentation was prepared as assignment, in my 4th year of B.V.Sc & A.H. Degree Course. There were recent outbreaks in my hometown Pune few months back when I presented this in front of my classmates and teachers. This presentation covers all aspects of Equine influenza including Clinical, epidemiological and preventive factors.

Equine Influenza Presentation by Pranav Pandit 2005-19

Its an acute viral respiratory disease of equines characterized by nasal discharge and cough

Etiology Caused by influenzavirus A from Orthomyxoviridae Two immunologically distinct subtypes A/equine/Prague/1/56 (H7N7) A/equine/Miami/2/63 (H3N8) ( in all recent outbreaks) Antigenic Drift accounts for several various strains forming different lineages.

Caused by influenzavirus A from Orthomyxoviridae

Two immunologically distinct subtypes

A/equine/Prague/1/56 (H7N7)

A/equine/Miami/2/63 (H3N8) ( in all recent outbreaks)

Occurrence All equines, everywhere in world except Australia New-Zealand and Iceland. Transport of horses by aircraft in short period increases the spread ( South Africa and Hong Kong) Outbreak is associated with introduction of virus into population of susceptible Horses Clinically affected Horse Horse that is not clinically ill Vaccinated horse but infected Morbidity: 98% in susceptible population Mortality < 1% most cases associated with secondary bacterial infection. Disease in vaccinated population has got milder disease by lower morbidity and mortality Recently reported to be jumped to dogs. (Janet M. Daly, et al. 2008 and Crawford P.C et al. 2005)

All equines, everywhere in world except Australia New-Zealand and Iceland.

Transport of horses by aircraft in short period increases the spread ( South Africa and Hong Kong)

Outbreak is associated with introduction of virus into population of susceptible Horses

Clinically affected Horse

Horse that is not clinically ill

Vaccinated horse but infected

Origin and Transmission Origin must be an affected horse But Proximate source could be fomites like veterinary clothing, equipments etc. Transmission by Aerosol (35 meters), assisted by coughing. Survives 24-36 hours

Origin must be an affected horse

But Proximate source could be fomites like veterinary clothing, equipments etc.

Transmission by

Aerosol (35 meters), assisted by coughing.

Survives 24-36 hours

Animal Risk Factors Age All age groups susceptible (MDA lost by age of 2 months) Most cases at the age of 2 years. as a result of accumulation of unexposed young animals Timing Husbandry and management practices (sale, transport, race show)

Age

All age groups susceptible (MDA lost by age of 2 months)

Most cases at the age of 2 years.

as a result of accumulation of unexposed young animals

Timing

Husbandry and management practices (sale, transport, race show)

Immunity: Depends on means of exposure Aft infection protective immunity remains for 1 year for homologous strain Natural infection : IgA in nasal secretion IgGa & IgGb in serum Inactivated alum-adjuvanted vaccine: IgG(T) Immunity against vaccination is for 3-4 months and is specific for the subtypes. Antigenic drift renders immunity less protective

Immunity: Depends on means of exposure

Aft infection protective immunity remains for 1 year for homologous strain

Natural infection : IgA in nasal secretion IgGa & IgGb in serum

Inactivated alum-adjuvanted vaccine: IgG(T)

Immunity against vaccination is for 3-4 months and is specific for the subtypes.

Antigenic drift renders immunity less protective

Economic Importance

Economic Importance Inconvenience in racing stables and has capacity to stop whole racing industry in country for months Breaks training and exercise. International restrictions and movements

Inconvenience in racing stables and has capacity to stop whole racing industry in country for months

Breaks training and exercise.

International restrictions and movements

Clinical findings Sudden Outbreak and Rapid Spread Milder disease in immune animals IP 2-3 days Starts with Fever (38.5-41°C) Dominant Sign Cough dry and hacking in beginning and moist later lasts for 1-3 weeks Cough easily stimulated by manual stimulation of trachea NASAL DISCHARGE if occurs is watery Abnormal lung sounds CRACKLES, WHEEZES Depression, anorexia reluctance to move & reduced endurance Uncomplicated cases may recover within 7-14 days

Sudden Outbreak and Rapid Spread

Milder disease in immune animals

IP 2-3 days

Starts with

Fever (38.5-41°C)

Dominant Sign Cough dry and hacking in beginning and moist later lasts for 1-3 weeks

Cough easily stimulated by manual stimulation of trachea

NASAL DISCHARGE if occurs is watery

Abnormal lung sounds CRACKLES, WHEEZES

Depression, anorexia reluctance to move & reduced endurance

Uncomplicated cases may recover within 7-14 days

Diagnosis Virus isolation or indirect demonstration through nasophyraryngeal swabs or serology HA and HI tests to detect antigen and antibodies 3-4 fold increase in HI antibody titer, in paired sera collection days 14-21 days apart provides retrospective conformation Rapid test- membrane bound enzyme immuno-assay ELISA, PCR

Virus isolation or indirect demonstration through nasophyraryngeal swabs or serology

HA and HI tests to detect antigen and antibodies

3-4 fold increase in HI antibody titer, in paired sera collection days 14-21 days apart provides retrospective conformation

Rapid test- membrane bound enzyme immuno-assay

ELISA, PCR

Differential Diagnosis

Treatment No Specific Treatment Amantadine under investigation (Safety and efficacy) Oseltamivir, zanamivir Antibiotic Treatment: Potentiated Sulfonamides (15-30 mg/kg PO, IM or IV), Ceftioufur (2.2mg/kg IM), Procain Penicillin(20000 IU/kg IM). Supportive Treatment: Dust free Environment, NSAIDs (judiciously as they can mask the complications) Corticosteroids are contraindicated Cough suppressant are also contraindicated as cough is major mechanism of clearance

No Specific Treatment

Amantadine under investigation (Safety and efficacy)

Oseltamivir, zanamivir

Antibiotic Treatment: Potentiated Sulfonamides (15-30 mg/kg PO, IM or IV), Ceftioufur (2.2mg/kg IM), Procain Penicillin(20000 IU/kg IM).

Supportive Treatment: Dust free Environment, NSAIDs (judiciously as they can mask the complications)

Corticosteroids are contraindicated

Cough suppressant are also contraindicated as cough is major mechanism of clearance

Control Increase Immunity of individual as well as Population Reduce opportunities of spread of virus Prevent introduction of spread of virus

Increase Immunity of individual as well as Population

Reduce opportunities of spread of virus

Prevent introduction of spread of virus

Vaccination Vaccine efficacy is limited due to short duration and poor immunity compared with the immunity gained aft natural infection Inactivated virus generally from the strains derived from outbreaks at least a decade ago Inactivated subunit vaccine contain immun-stimulating complex (ISCOM)

Vaccine efficacy is limited

due to short duration and poor immunity compared with the immunity gained aft natural infection

Inactivated virus generally from the strains derived from outbreaks at least a decade ago

Inactivated subunit vaccine contain immun-stimulating complex (ISCOM)

Timing Foals: depends on immune status of mare Mare vaccinated more than once yearly then vaccination of foal delayed until 24 weeks Foals of unvaccinated mare can be vaccinated at the age of 1 month Booster once a year Race horses and Show Horses Booster vaccination to timed at the time of greatest exposure possibility Vaccination during racing season is disliked by trainers cause of transitory swelling and reaction, but do not affect the performance

Timing

Foals: depends on immune status of mare

Mare vaccinated more than once yearly then vaccination of foal delayed until 24 weeks

Foals of unvaccinated mare can be vaccinated at the age of 1 month

Booster once a year

Race horses and Show Horses

Booster vaccination to timed at the time of greatest exposure possibility

Vaccination during racing season is disliked by trainers cause of transitory swelling and reaction, but do not affect the performance

Control Measures Quarantine At least 21 days Degree of isolation about 32 meters Measure during outbreak Remove clinically affected Ventilation of shed and barns No new introduction for 4 weeks aft 1 st case is identified Movement of horses in barn is avoided Suspend training and racing Vaccination of clinically normal animals

Quarantine

At least 21 days

Degree of isolation about 32 meters

Measure during outbreak

Remove clinically affected

Ventilation of shed and barns

No new introduction for 4 weeks aft 1 st case is identified

Movement of horses in barn is avoided

Suspend training and racing

Vaccination of clinically normal animals

References Crawford PC, Dubovi EJ, Castleman WL, Stephenson I, Gibbs EP, Chen L, et al. Transmission of equine influenza virus to dogs. Science. 2005;310:482–5. Otto M. R., C.C. Gay, D.C. Blood & K. W Hinchcliff, Veterinary Medicine A textbook of the diseases of cattle, sheep, pigs, goats and horses. 9 th edition. Book Power 2003 P.J. Quinn, B.K. Markey, M.E.Carter, W.J. Donnelly and F.C. Leonard, Veterinary Microbiology and Microbial Diseases. Blackwell Science. 2002.

Crawford PC, Dubovi EJ, Castleman WL, Stephenson I, Gibbs EP, Chen L, et al. Transmission of equine influenza virus to dogs. Science. 2005;310:482–5.

Otto M. R., C.C. Gay, D.C. Blood & K. W Hinchcliff, Veterinary Medicine A textbook of the diseases of cattle, sheep, pigs, goats and horses. 9 th edition. Book Power 2003

P.J. Quinn, B.K. Markey, M.E.Carter, W.J. Donnelly and F.C. Leonard, Veterinary Microbiology and Microbial Diseases. Blackwell Science. 2002.

Acknowledgment Dr. Meshram and Dr. Pawalkar My Dear colleagues And my classmates Thank You

Dr. Meshram and Dr. Pawalkar

My Dear colleagues

And my classmates

Thank You

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