What are the main COVID-19 prevention measures?
- Hand hygiene & disinfection
- Face masks & PPE
- Physical distancing
- Reduced contact (tiers/lockdowns)
- Air filters & ventilation
- Fresh air circulation
These measures are essential to reduce transmission of the virus.
What are examples of non-airborne disease prevention?
- Condoms (STIs)
- Clean needles
- Hygiene & disinfecting surfaces
- Quarantine
- Insect repellent
These methods help prevent the spread of diseases that are not transmitted through the air.
Why is infection control challenging in new outbreaks?
- Modes of transmission often unclear
- SARS-CoV-2 aerosol spread took time to establish
- Ebola virus persists in semen → sexual transmission
- Pets (e.g. cats) can transmit SARS-CoV-2
- 10% of Hep C infections have unknown source
Understanding transmission is crucial for effective control measures.
Why are infectious diseases increasing in Europe/UK?
- Global connectivity
- Population growth & agricultural expansion
- Habitat encroachment → zoonoses
- Climate change expands vector ranges
- Aedes mosquitoes spreading across Europe
These factors contribute to the rise in infectious disease cases.
Which viruses do Aedes mosquitoes transmit?
- Chikungunya
- Rift Valley fever virus
- Dengue virus
- Yellow fever virus
Aedes mosquitoes are significant vectors for several viral diseases.
Which virus has been eradicated globally by vaccination?
Smallpox virus (Variola)
This was a major public health achievement through vaccination efforts.
Key facts about smallpox virus?
- dsDNA enveloped virus
- Hairpin loops at genome ends
- CFR ~30%
- Killed up to 300 million in 20th century
- Ancient evidence in mummies (1500 BC)
Smallpox was a devastating disease before its eradication.
What are examples of active immunisation?
- Attenuated vaccines (MMR, vaccinia)
- Inactivated (‘dead’) vaccines (influenza)
- mRNA vaccines (SARS-CoV-2)
- Viral vector vaccines (SARS-CoV-2)
Active immunisation involves stimulating the immune system to produce a response.
What is passive immunisation?
- Transfer of antibodies
- Used when no other therapy available
- e.g. chickenpox in pregnancy
- Used as post-exposure prophylaxis (e.g. rabies)
Passive immunisation provides immediate protection but does not induce long-term immunity.
Smallpox eradication timeline (high yield)?
- 1958: WHO campaign begins
- 1967: Intensified programme
- 1977: Last natural case (Somalia)
- 1979: Certification of eradication
- 1980: WHO declares eradication globally
This timeline highlights the key milestones in the eradication of smallpox.
Key features of measles virus?
- Airborne transmission
- R0 = 12–18
- (–)ssRNA, enveloped
- IFR ~0.2% (up to 10% if malnourished)
- Rare complication: SSPE
- No antiviral treatment
Measles is highly contagious and can lead to severe complications.
How is the measles vaccine made?
Live attenuated
The vaccine is created by attenuating the virus through passage in chicken embryo fibroblasts.
How effective is measles vaccination?
- 93% protection (1 dose)
- 97% protection (2 doses)
- Provides sterilising immunity
- Requires ~95% coverage for herd immunity
High vaccination coverage is crucial for controlling measles outbreaks.
Global measles mortality trends?
- 1980: 2.6 million deaths
- 2014: 73,000 deaths
- Large reduction due to vaccination
Vaccination has significantly decreased measles-related deaths worldwide.
Why is polio historically feared?
- Visible paralysis in survivors
- Iron lung dependency (e.g. Paul Alexander)
The impact of polio on individuals and society has led to a strong focus on eradication efforts.
Key features of poliovirus?
- (+)ssRNA, non-enveloped
- Picornavirus
- Transmitted fecal–oral
- Replicates in intestines → spreads to CNS
- R0 = 4–7
- Stable in environment
- 3 serotypes (no cross-protection)
Understanding the characteristics of poliovirus is essential for prevention and control.
What fraction of polio infections cause paralysis?
1 in 200
This statistic highlights the severe consequences of poliovirus infection.
What is the polio hygiene paradox?
- Pre-modern infections happened early → mild disease
- Better hygiene delayed infection → more severe paralytic disease
This paradox illustrates the complex relationship between hygiene and disease severity.
What is post-polio syndrome?
- Fatigue, weakness, pain, muscle atrophy
- Occurs decades after initial infection
- Affects ~80% of survivors
This syndrome can significantly impact the quality of life for polio survivors.
Compare the Salk and Sabin polio vaccines.
Salk (1955):
* Inactivated
* Injected
* Prevents disease
* Limited effect on transmission
Sabin (1961):
* Live attenuated
* Oral
* Prevents transmission
* Rarely reverts → vaccine-derived outbreaks
Both vaccines have played crucial roles in polio eradication efforts.
Where is wild poliovirus still endemic today?
- Afghanistan
- Pakistan
These countries continue to face challenges in eradicating polio.
What are vaccine-derived polioviruses?
- Polioviruses evolved from Sabin vaccine strains
- Can regain pathogenicity
- Cause outbreaks (esp. type 2)
Vaccine-derived strains pose a risk to public health in areas with low vaccination coverage.
What is the current approach to polio eradication?
- Global Polio Eradication Initiative (GPEI)
- Focus on safer genetically engineered OPV type 2 vaccines
The GPEI aims to eliminate polio through innovative vaccination strategies.
