Avian Influenza

AVS 332 - diseases

Is it zoonotic? Is it a reportable disease?

• AI does have zoonotic potential

• Yes it is reportable

Why do we care about AI

• having outbreaks since 2022

• impacts the food supply

• impacts the Economy

What type of virus is AI

• Type A orthomyxoviruses

  • Alphainfluenzavirus

  • Influenzavirus

What antigens characterized this virus

• two proteins

  • Hemagglutinin (H1 - H16)

  • Neuraminidase (N1 - N9)

What are the types of Influenza and which species are effected by the different types?

• Influenza A

  • wide range of animals, birds

• Influenza B

  • humans

• Influenza C

  • humans and pigs but rare

• Influenza D

  • cattle

How long is the infection?

• Variable incubation period

• up to 2 weeks

The morbidity and mortality rates

• LPAI (low pathogenic avian influenza) : low morbidity and mortality

• HPAI (high path) : causes severe systemic disease

  • mortality rates approach 100% in chickens, turkeys and other species of poultry

Mode of transmission : animal to animal

• ingestion

• inhalation

Modes of transmission : farm to farm

• infected birds

• equipment (tractors, vehicles, etc)

• clothing

Mode of transmission

Airborne dissemination can occur over short distances

What is the zoonotic potential?

• HPAI / LPAI : isolated cases in human who had direct contact with infected birds

  • causes respiratory infections

  • rare but can occur

  • does not spread human to human (unless mutated)

AI in mammals : what was found?

• Eurasian H5 HPAI - humans

• H7N2 - cats

• H3N8 and H3N2 - dogs

• red foxes

AI in mammals: Experimental infections

• pigs, ferrets, rats, rabbits, guinea pigs, mice, mink, nonhuman primates

AI in mammals : Farm Mink

• Had H5N1 HAPI

• outbreak 2022-2023 in Spain and Finland

• killed 200,000 mink

AI in mammals : Wild aquatic mammals

• sea lions

• harbor seals (17 cases reported in Maine)

• Sea otters (cases reported in Chile in 2023)

Diseases in Poultry

• highly virulent

• most birds in an affected flock die

What are the clinical signs for infected poultry

• sudden death, systemic disease, drop in egg production, neurological signs

• depression, anorexia, ruffled feathers

• combs swollen, cyanotic, conjunctivitis, and respiratory signs

Disease in wild birds

• disease often subclinical

  • some strains cause illness

• clinical signs

  • minimal in duks and geese

  • swans may be found dead

• experimental infections

  • gulls, passerine, psittacines

Post Mortem Lesions : Birds

• Chickens and turkeys

  • swollen sinuses

  • edematous comb and wattle

  • subcutaneous edema

  • petechiae

    • trachea

    • lungs

    • proventriculus

Sampling

• before collecting or sending any samples. the proper authorities should be contacted

• samples should only be sent under secure conditions and to authorized laboratories to prevent the spread of the disease

• HPAI samples may be zoonotic

Diagnosis : RT PCR

• clinical samples

• can distinguish different subtypes

Diagnosis : Viral antigen detection

• best for flocks, not individuals

Diagnosis : Serology

• AGID

• hemagglutination inhibition

• ELISA

Treatment?

• typically not treated

• HPAI : eradication methods

Treatment : what happens when secondary infections occur?

• antibiotics can be used

• antivirals are not approved for usage in birds

Treatment : Supportive care?

• increase temperature in poultry houses

USDA prevention Activities

• import restrictions

  • no live birds or bird products from infected countries

• Increasing surveillance of wild birds

• National H5 and H7 control program

• training for disease recognition

• improving diagnostics for rapid detection

Disinfection?

• sodium hypochlorite, 70% ethanol, oxidizing agents, quaternary ammonium compounds

• aldehydes, phenols, acids, providone - iodine

• Heat, ionizing radiation, low pH (pH 2)

  • 56 degrees C (133 degrees F) for a minimum of 60 mins