Influenza

Question 1

Influenza

general features

Answer 1

Segmented (-) ssRNA
Enveloped
A B and C types

A type recognized by hemagglutinin and Neuraminidase

Question 2

Human Subtypes

Current ones

Answer 2

Combination of H1, H2, H3 and N1 and N2

H1N1 and H3N2

Question 3

Influenza transmission

Answer 3

Only from swine and fowl to humans. Can infect a host of organisms but those are not transmissible to humans

In tropics - all years
In temperate - originate in like australia

Question 4

Influenza
Incubation
Duration
Symptoms

Answer 4

24hrs to 5 days

3 days to 4 weeks

Fever, malaise, headache, myalgias, cough, sore throat, clear nasal discharge, nasal congestion

Question 5

Influenza syndrome

Answer 5

More likely in infants and children (smaller airways, weaker immunity - cause otitis media) and Pregnancy

Question 6

Transmission

Answer 6

Droplets and contact

Viral HA binding to sialylated glycans (A2,6 linked) of epithelial cells of respiratory tract mucosa

Question 7

Pathogenesis

Answer 7

Pro inflammatory cytokines - IFNA, IFNG, TNFA, IL6
Direct viral damage - NS1 and NA induced apoptosis

Pulmonary Inflammation - direct viral damage, and inflammatory mediators

Influenza can cause PNEUMONIA

Question 8

Complications

Answer 8

Sets the stage for bacterial complications

Question 9

immunity

Answer 9

Non specific - IFN
Cellular - CTL and IFN G
Humoral - Neutralizing Ab against HA and NA

Question 10

Reason for annual epidemics of influenza

Answer 10

Antigenic drift - accumulation of point mutations in HA and NA

Question 11

Reason for pandemics

Answer 11

Antigenic drifts (RNA segment ressortments) 
Interspecies transmission

Question 12

Diagnosis Lab

Answer 12

PT -PCR
NA enzymatic activity
Immunoassays Virus isolation
Serology

Question 13

Prevention

Answer 13

Good Hygiene

Vaccination