Epidemics, pandemics and the protection of the public Flashcards
What are the direct routes of transmission?
- Direct route (STI’s, scabies)
- Faeco-oral route (viral GE)
What are the indirect routes of transmission?
- Vector-borne (malaria, dengue)
- Vehicle-borne (viral GE, Hep B)
What route do airborne pathogens take?
Respiratory route - TB, Legionella
What is the latent period?
The period of time between which the person contracts the disease and the person becomes infectious.
What is the infectious period?
The period following the latent period, where the person is infectious but does not show symptoms.
What is the name of latent period+infectious period?
Incubation period
What is the difference between incubation period in viral and bacterial diseases?
Incubation period for bacterial is much longer than for viral.
What is an epidemic?
Serious outbreak in a single community, population or
region
What is a pandemic?
Epidemic spreading around the world affecting hundreds
of thousands of people, across many countries
What are the notifiable diseases?
- Anthrax
- Cholera
- Dysentery
- Leprosy
- Malaria
- Paratyphoid fever
- Plague
- Rabies
- Smallpox
- Typhoid fever
- Typhus fever
- Viral haemorrhagic fever (e.g. Ebola)
- Yellow fever
- Acute encephalitis
- Leptospirosis
- Ophthalmia neonatorum
- Relapsing fever
- Scarlet fever
- Viral hepatitis*
- Acute poliomyelitis*
- Diphtheria*
- Measles*
- Meningitis and Meningococcal septicaemia*
- Mumps*
- Rubella*
- Tetanus*
- Whooping cough*
*vaccine preventable
In a bird ‘flu outbreak on a farm, why are all of the farm workers immunised against seasonal ‘flu?
To prevent mixing of seasonal ‘flu antigens and bird ‘flu antigens.
What are the features of influenza B?
– Sporadic outbreaks
– Children
– Prone to mutation
– Human virus
What are the features of influenza C?
– Mild symptoms
– Stable human virus
What are the features of influenza A?
• Can infect: pigs, cats, horses, birds and sea mammals
• No proof reading mechanism – very prone to mutation
• Antigenic drift – flexibility, causes seasonal epidemics
• Segmented into 8 genes
• Genes swapping occurs during co-infection with human and avian flu virus → reassortment
& antigenic shift
What is the function of haemagglutanin?
– Virus binding and entry to cells
– 15 subtypes
– Immunity confers protection but only to specific subtype
What is the function of neuraminidase?
- Release of newly formed viruses from infected cells
- 9 subtypes
- Immunity to subtype reduces amount of virus released from cells resulting
in a less severe disease
What are ‘types’ of influenza?
- Seasonal
- Avian
- Swine
- Pandemic
What are the features of pandemic ‘flu?
- High morbidity
- Excess mortality
- Social disruption
- Economic disruption
When were the previous pandemics?
- 1918
- 1957
- 1968
What composition was Spanish ‘flu (1918)?
H1N1
What composition was Asian ‘flu (1957)?
H2N2
What composition was Hong Kong ‘flu (1968)?
H3N2
In pandemic ‘flu, what percentage of people will be infectious before symptom onset?
10%
How long will the first wave of pandemic ‘flu last?
3-5 months
