Pandemics Flashcards
Learning Objectives
- Understanding:
- The nature of pandemics
- Causes of pandemics
- Methods of controlling pandemics
- Gaining awareness of The historical and current impact of pandemics on human populations
What’s the difference between an epidemic and a pandemic?
- Epidemic: The occurrence in a defined region of cases of a disease in the human population in excess of normal expected numbers
- Pandemic: An epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people
Why do pandemics occur?
- Emergence / introduction of a new disease capable of infecting humans
- Or the Re-emergence of a disease not seen in human populations for many years Leading to a serious illness that is readily transmissible & sustainable in the human population
- Mechanisms to allow easy and sustainable spread in human population
- Wholly susceptible population
How is a Pandemic declared?
- WHO uses the conditions on the previous slide to decide whether to declare a pandemic.
- Declaration of a pandemic has largely been replaced by a declaration of a Public Health Emergency of International Concern – PHEIC
Why are pandemics potentially damaging to societies in terms of health impacts?
- High morbidity: Difficult to treat patients adequately! Medical services/facilities overwhelmed. Staff exhaustion/morale, Shortages of medicines etc, Shortages of PPE, Shortages of beds. Rehabilitation of cases. Mental health
- High mortality: May be difficult to dispose of the dead, Legal issues, Social/personal impact
- Long term health concerns: Failure/delay in treating other health problems, Increased morbidity/mortality from untreated conditions. Long term impact of infection on individuals. Impact on health care staff
Why are pandemics potentially damaging to societies in terms of social and economic impacts? (PART 1)
Impact on the workforce:
- Immediate – reduction in available workforce, lockdowns, lost income.
- Long term – loss of jobs, loss of skills, lost income.
- Impact on physical and mental health
Impact on infrastructure
- Transport (food, fuel distribution)
- Power
- Water/waste
- Security/law & order/justice services
Why are pandemics potentially damaging to societies in terms of social and economic impacts? (PART 2)
Economic damage
- Damage to national/international trade
- Damage to travel/transport industries/tourism
- Business & store closures/job losses/furloughs/unemployment
Social impact
- Impact of control measures (e.g. Lockdowns)
- Damage to education
- Damage to social structures
- Fake news/conspiracies/blaming external groups
- Social unrest
- [Long term social change]
How do we minimise the immediate effects of a pandemic?
- Try to reduce the number of cases
- Delay the peak number of cases
- Reduce the height peak number of infections
- Spreas the cases over a longer period of time
How do we control a pandemic?
Requires:
- A very high level of national & international collaboration in all relevant fields
- Active & effective epidemiological, surveillance & public health systems
- High grade medical care & facilities
- Collaborative research: understanding organisms
- Social responsibility by national populations: Preventing social breakdown
- Good and unimpreded flows of accurate information within & between nations neutralising rumours
- Political will
What are some health and public health interventions that humans can take?
- Epidemiological investigation & surveillance
- Detection, isolation & treatment of cases & quarantine of contacts: effective surveillance system, active & effective test & trace system
- Social distancing: Minimize disease transmission, morbidity & mortality by reducing contact between individuals
- Reduce demands on medical/health-care services: Encourage home nursing, Minimise use of medical facilities by those who can be cared for at home. Delay treatment for other non urgent conditions
What is the difference between quarantine & isolation?
- These are control & preventive measures. They are a legacy of the many pandemics over the centuries.
- Quarantine: restrict the movement of well persons who may have been exposed to a disease, to prevent the spread of the disease to the healthy
- Isolation: separate persons ill with a communicable disease from those who are healthy
Provide a brief history of how quarantine was used in the legacy of the Black Death
- From a Venetian dialect form of the Italian quaranta giorni, - “40 days”
- In 1377, the Rector of the port of Ragusa, (Dubrovnik in Croatia) officially imposed the “trentina” a 30-day isolation period for ships & people.
- Detention of forty days (quarantina) instituted by the city of Marseille in 1383 & became the standard period of quarantine
- 1896 – quarantine replaced by port health inspection
What is the R0 / Rt(Re) concepts?
- R0 (Basic reproduction number), is the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection
• Rt or Re (Effective reproduction number) is the number of cases generated in the current state of a population, which does not have to be the uninfected state.
What happens if these values are below 1?
- The disease will decline. This can be achieved by:
- Increasing Herd immunity: Allow infection to run unchecked/with some limits, Vaccination
- Physical intervention: Respiratory system protection, Hygiene measures, Lockdowns, Test & trace, Isolation/quarantine of cases/contacts
What do masks do?
Masks do 2 things:
- Source protection: Reduced virus transmission from the wearer
- Wearer protection: Reduced rate of infection of the wearer
- WHO advice: Wear a fabric mask unless you’re in a particular risk group
When should you wear a medical/surgical mask?
- Are over 60
- Have underlying medical conditions
- Are feeling unwell
- Are looking after an ill family member
Describe Face shields as defensive measures against infections?
- Plastic face shields
- Alone these are not a fully effective defence against COVID-19 infection
- Good at arresting most large droplets
- Lighter particles can enter the open areas around the visor
- Shield + mask is a good defence
Describe social distancing as defensive measures against infections?
- Most expelled particles travel less than 2 metres
- Smaller particles and aerosols can travel much further
- Distancing will reduce risk, not eliminate it & needs to be combined with other measures (e.g. masks).
Describe handwashing as defensive measures against infections?
- Regular handwashing is an essential part of basic hygiene
- Handwashing removes/kills pathogens preventing transmission from hands to mucous membranes
- Soap/detergents kill COVID-19
- Hand sanitisers containing at least 60% alcohol are also effective
Describe ventilation as a defensive measure against pandemics
- Research shows that being in a room with fresh air can reduce the risk of infection from particles by over 70%
- Kitchen or bathroom extractor fans, used correctly and regularly, help to remove infected particles
- Air conditioners (especially those using fresh air & not recirculation) present little risk of spreading the virus.
How can pandemics be transmitted through surfaces?
- Lab tests showed that some pathogens can survive: quite well on hard surfaces (several days), less well on surfaces like cardboard & paper (24 hours)
- These tests were artificial
- Much current advice on surface cleaning is based on these early reports.
- *NB. Evidence suggests that items such as surfaces & packaging are not an important route of infection with COVID-19. This does not mean that surface cleaning should be abandoned
Do preventative measures work?
- Non-pharmaceutical
- Appear to be effective against many respiratory infections
- During Covid, flu & other RTI numbers were very
low - Better vaccination?
- Fewer samples taken?
- Laboratories redirected?
List the historical effects of pandemics
- Antonine plague: decline of the Roman empire
- Plague of Justinian: prevented spread of Byzantine Empire into Italy, changed the course of European history
- Smallpox: Major factor in the Spanish conquest of the Aztec & Incan civilizations
- Black death: Created a series of religious, social & economic upheavals, profoundly affected European history
Describe what happened during the Black Death
- A massive outbreak of plague ravaged Europe throughout
the 14th Century - Estimated killed 75 - 200 million people in the 14th
century alone - 45 - 60% of the population of Europe wiped out
- Reduced world’s population from ca. 450 million to 350 -
375 million by 1400 - Took 150 years for Europe’s population to recover
What was the origin of the Black Death?
- Originated in China 1331, Halfed their popn to 60 million
- Entered Constantinople in 1347
- Reportedly first introduced to Europe at Caffa in the Crimea in 1347
- Genoese carried the plague by ship to Sicily & southern
Europe, whence it spread north - Several existing conditions such as war, famine, & weather
contributed to the severity of the Black Death.
What affects did The Black Death have on people around the world?
- Profoundly affected the way people thought about their world
- The Church: Declined as people became disillusioned
- Feudal system declined
- Literature: Chronicled by famous writers, philosophers &
rulers such as Boccaccio & Petrarch. - Art: Several themes persisted especially dealing
with the frailty of life & the triumph of death - Flagellants: Religious movement seeking redemption
through mortification of the flesh - Attacks on minorities: Jews, lepers, foreigners
Describe Influenza
- Enveloped RNA viruses (Orthomyxoviridae)
- RNA viruses have very high mutation rates – correlated with enhanced virulence & evolvability*
- Influenza viruses - 4 strains, 3 can affect humans
List the 4 types of influenza viruses and their features
- Influenza A: wild aquatic birds are natural hosts! the most virulent & causes the most severe disease, the cause of pandemics/panzootics
- Influenza B: less common than influenza A, almost exclusively infects humans
- Influenza C: infects humans, dogs & pigs, least common type in humans, causes mild disease in children
- Influenza D: pigs & cattle
Describe the features of influenza in general
- Seasonal epidemics: Can cause excess deaths (>25,000 in UK in some years)
- Occasional severe pandemics
- Spreads easily
- Many symptoms similar to Covid-19 infection
– People infective before symptoms appear
– Spread by: droplet inhalation, via contaminated hands - Transmission risk reduced if people cover their mouth & nose when coughing, & wash their hands regularly
Describe the epidemiology of influenza
- Incubation period 2-4 days
- All age groups affected
- Health care workers at high risk due to increased exposure & risk further spread to vulnerable individuals
Who are the People at risk of severe disease or complications are?
- pregnant women
- children < 59 months
- the elderly (>65Y)
- individuals with chronic medical conditions
- individuals with immunosuppressive conditions (e.g. HIV/AIDS, chemotherapy or steroids, malignancy)
- health care workers
