Influenzas Flashcards
What family do these belong to?
Orthomyxoviridae: enveloped, Influenza A is responsible for all pandemics, segmented, classification based on HA and NA glycoprotein spikes
What’s the difference between HA and NA?
Responsible for viral entry, target of vaccines, high rates of mutation versus viral release, penetrates mucus.
What happens if two different strains enter the animal?
Genetic reassortment, can contain new HA, NA or both and offers little cross protection
What are the two types of genetic reassortment?
Antigenic shift: rapid changes in the genome versus antigenic drift: small changes over time
What are the characteristics of avian influenza?
A, natural reservoir is aquatic birds. Barrier between them and humans exists, this likes alpha 2,3 receptors in respiratory and GI cells whereas human likes alpha 2,6 in the respiratory system.
What are the pathogenic strains of influenza?
Low: most viruses, results in subclinical signs, like respiratory and reduced egg production. Most countries free of these. High: fowl plague from H5 and H7 mutations. Both produce disease in domestic poultry
What is the incubation period and clinical signs?
Inc period is between 1 and 7 days; signs depend on strain, host, severity of disease, mortality rates
How is it transmitted?
Can be ingested or inhaled, usually because of breach of protocol in biosecurity.
What are the signs in the low pathogenicity strain?
Subclinical includes respiratory signs, sinusitis, 5-30% decrease in egg production, low morbidity and mortality
What are the signs in the high pathogenicity strain?
High mortality, sudden death if peracute, cyanosis/edema/petechiae/CNS signs. Lesions are variable and can include edema, hemorrhage, necrosis in visceral organs
How is this diagnosed and treated?
PCR, report cases to animal health authorities since vx needs approval of state vet. If low, treat with heat and antibiotics. If high, euthanize. Zoonotic potential low.
What happened in the H5N2 outbreak?
Largest response to an animal disease outbreak ever.
What are two other strains that caused problems?
H7N8 and H7N9
Details on equine influenza
Highly contagious, H3N8 is the strain, outbreaks when acutely infected horse introduced in susceptible group
Clinical signs for equine influenza?
Coughing that is nonproductive, high fever (can be biphasic), cough may stay for weeks. high morbidity and low mortality.
Replication for equine and risks
In respiratory epithelial cells, 3 weeks for epithelium to regenerate, risk for bacterial infections
Lesions for equine
Early: rhinitis and tracheitis with loss of epithelium. Late: epithelial hyperplasia with proliferation of type 2 pneumocytes
Diagnosis and treatment
Prolonged coughing and rapidly spreading febrile disease. do PCR on nasopharyngeal swabs. Allow rest and supportive care. Rest 1 week for each day with fever, for a minimum of 3 weeks to regenerate epithelium.
Prevention of equine
Risk based vaccinations, may need boosters every 6 months
Canine influenza
Strains are H3N8 and H3N2, reportable in some states.
Transmission
Shed large amounts of virus before clinical signs, aerosolized resp secretions, remains infectious for 48 hours. Most have clinical signs and infection is year round
What are the signs?
Coughing (resembles kennel cough), possibly fever and pneumonia
Diagnosis and treatment
PCR on nasopharyngeal swabs. Most dogs recover in a few weeks.
Prevention
Isolated for 21 days, vaccine is risk based.
