Mass gatherings and pandemic Flashcards
(49 cards)
What is a pandemic?
An epidemic of infectious disease spreading through human populations across a large region.
Give four examples of pandemics throughout history.
- Smallpox
- Tuberculosis
- HIV
- Influenza (2009)
True or false: influenza is usually more severe than other respiratory viral infections

Influenza involves a combination of respiratory and constitutional symptoms; list five.
- Respiratory
- Cough
- Sore throat
- Constitutional
- Fever
- Headache
- Muscle aches
Name four population subgroups who are more at risk of complications from influenza infections.
- Elderly
- Young
- Poor immune systems
- Pre-existing respiratory/cardiac/endocrine conditions
What is viral shedding?
Successful reproduction, expulsion, and host-cell infection caused by virus progeny.
When do adults shed the influenza virus?
Before symptoms begin through 5 to 10 days after illness onset.
True or false: there are three types of influenza viruses.

True or false: Influenza type A is responsible for epidemics.
Influenza type A is responsible for pandemics.

True or false: Influenza type B is responsible for epidemics.

What organisms are the natural hosts of influenza type A?
Wild birds
Influenza A has a natural host, but can also infect other organisms - give some examples.
- Humans
- Birds
- Pigs
- Horses
- Seals
- Whales
- Others
Influenza type B viruses are normally found in which species?
Humans.
True or false: influenza type C viruses cause mild illness in humans, and don’t cause pandemics or epidemics.

True or false: influenza types B and C are not classified according to subtype.

Influenza A viruses are divided into subtypes based on what feature?
Two proteins on the virus surface: hemagglutinin and neuraminidase.
What are the two subtypes of influenza A found in humans?
- Influenza A (H1N1)
- Influenza A (H3N2)
What is antigenic drift?
Small changes in the virus that happen continually over time, producing new virus strains that may not be recognised by antibodies of earlier strains.
What is antigenic shift?
Antigenic shift is an abrupt, major change in the influenza virus from re-assortment or adaptive mutation, resulting in a new influenza virus that can infect humans.
Is influenza A capable of antigenic drift, antigenic shift, or both?
Both.
Is influenza B capable of antigenic drift, antigenic shift, or both?
Antigenic drift.
List the naming convention components for influenza viruses.
- Antigenic type (A, B, C)
- Host of origin (swine, equine, etc. Human-origin viruses have no host of origin designation)
- Geographical origin
- Strain number
- Year of isolation
- Hemagglutinin and neuraminidase antigen description in parentheses (influenza A viruses only)
How do pandemics begin according to the WHO?
- An influenza virus develops the ability to infect humans and cause serious disease (unable to transmit efficiently between humans)
- Following further genetic change, the virus may become more efficient at passing from human to human, first within small groups or clusters (families or community networks)
- The virus is able to transmit readily between humans. It spreads rapidly because of the short incubation period and the infectious nature of influenza. Rapid global spread is aided by international travel
TL;DR: virus is able to infect humans, virus becomes more efficient at infection, virus is easily transmitted and spreads rapidly.
What is the meaning of ‘attack rate’?
The proportion of susceptible individuals exposed to a particular pathogen who become infected.