25. Epidemiology and prevention of airborne viral infections
Airborne viral infections
- Influenza
- Measles
- Mumps
- Rubella
- Varicella zoster
- Parainfluenza
- Varicella
- Epstein Barr virus
Measles
- Measles virus, a paramyxovirus
- Also called morbillivirus
- Highly contagious, serious disease
- Contagiosity index 95-99%
- Epidemiology
- Used to be a leading cause of infant death, blindness and disability
- Most commonly affects children < 12 months
- Vaccination caused an 80% drop in cases from 2000 to 2017
- During this time 21 million deaths have been prevented
- This has made the measles vaccine one of the best buys in public health
- Recently, measles has begun to bounce back
- Because of anti-vaxxers (pro-diseasers)
- Spread by coughing and sneezing
- Clinical features
- 1-3 deaths per 1000 in developed countries
- 150 deaths per 1000 in developing countries
- Due to these children being malnourished and having worse immunity
- Maculopapular rash
- Blindness
- Severe diarrhoea
- Otitis media (due to bacterial superinfection)
- Pneumonia (due to bacterial superinfection)
- Encephalitis
- Subacute sclerosing panencephalitis
- No specific treatment
- MMR vaccine
Rubella
- Rubella virus, a togavirus
- Epidemiology
- 100 000 are born with congenital rubella syndrome every year
- Clinical features
- Generally mild illness
- Part of TORCH (congenital rubella syndrome)
- Serious for pregnant women
- Causes deafness, blindness, in infants
- No specific treatment
- MMR vaccine
Influenza
- Type A and B exists – type A is most pathogenic
- Very hard to vaccinate against – antigens change constantly
- Antigenic drift – point mutations in the Haemagglutinin (H) and neuraminidase (N) genes
- Antigenic shift – two different strains combine to form a new strain with different surface antigens
- Pandemics in history
- Spanish flu (1918)
- Asian flu (1957)
- Hong Kong flu (1968)
- Swine flu (2009)
- Seasonal epidemics during winter
- Can cause severe illness in high risk populations
- Small children
- Elderly
- Pregnant women
- Chronically ill
- Vaccination
- Contains killed virus
- Recommended for at-risk populations
- Healthcare workers
- Children up to 5
- Elderly
- Pregnant
- COPD
- The serotype of the influenza virus changes all the time -> WHO must try to predict which serotype will cause epidemic every year and produce vaccine against that type
- For every year the vaccine is taken the more efficient it becomes
- Preventative measures
- Hand hygiene
- Covering mouth and nose when sneezing, use tissues
- Self-isolation when symptoms occur
- Avoid close contact with sick people
Mumps
- Mumps virus
- Clinical features
- Meningitis
- Pancreatitis
- Encephalitis
- Orchitis – male infertility
- MMR vaccine