Influenzas

Question 1

What family do these belong to?

Answer 1

Orthomyxoviridae: enveloped, Influenza A is responsible for all pandemics, segmented, classification based on HA and NA glycoprotein spikes

Question 2

What’s the difference between HA and NA?

Answer 2

Responsible for viral entry, target of vaccines, high rates of mutation versus viral release, penetrates mucus.

Question 3

What happens if two different strains enter the animal?

Answer 3

Genetic reassortment, can contain new HA, NA or both and offers little cross protection

Question 4

What are the two types of genetic reassortment?

Answer 4

Antigenic shift: rapid changes in the genome versus antigenic drift: small changes over time

Question 5

What are the characteristics of avian influenza?

Answer 5

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.

Question 6

What are the pathogenic strains of influenza?

Answer 6

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

Question 7

What is the incubation period and clinical signs?

Answer 7

Inc period is between 1 and 7 days; signs depend on strain, host, severity of disease, mortality rates

Question 8

How is it transmitted?

Answer 8

Can be ingested or inhaled, usually because of breach of protocol in biosecurity.

Question 9

What are the signs in the low pathogenicity strain?

Answer 9

Subclinical includes respiratory signs, sinusitis, 5-30% decrease in egg production, low morbidity and mortality

Question 10

What are the signs in the high pathogenicity strain?

Answer 10

High mortality, sudden death if peracute, cyanosis/edema/petechiae/CNS signs. Lesions are variable and can include edema, hemorrhage, necrosis in visceral organs

Question 11

How is this diagnosed and treated?

Answer 11

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.

Question 12

What happened in the H5N2 outbreak?

Answer 12

Largest response to an animal disease outbreak ever.

Question 13

What are two other strains that caused problems?

Answer 13

H7N8 and H7N9

Question 14

Details on equine influenza

Answer 14

Highly contagious, H3N8 is the strain, outbreaks when acutely infected horse introduced in susceptible group

Question 15

Clinical signs for equine influenza?

Answer 15

Coughing that is nonproductive, high fever (can be biphasic), cough may stay for weeks. high morbidity and low mortality.

Question 16

Replication for equine and risks

Answer 16

In respiratory epithelial cells, 3 weeks for epithelium to regenerate, risk for bacterial infections

Question 17

Lesions for equine

Answer 17

Early: rhinitis and tracheitis with loss of epithelium. Late: epithelial hyperplasia with proliferation of type 2 pneumocytes

Question 18

Diagnosis and treatment

Answer 18

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.

Question 19

Prevention of equine

Answer 19

Risk based vaccinations, may need boosters every 6 months

Question 20

Canine influenza

Answer 20

Strains are H3N8 and H3N2, reportable in some states.

Question 21

Transmission

Answer 21

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

Question 22

What are the signs?

Answer 22

Coughing (resembles kennel cough), possibly fever and pneumonia

Question 23

Diagnosis and treatment

Answer 23

PCR on nasopharyngeal swabs. Most dogs recover in a few weeks.

Question 24

Prevention

Answer 24

Isolated for 21 days, vaccine is risk based.