Lecture 1: introduction Flashcards
What did we learn about the bubonic plague?
Bubonic plague:
•Late Medieval period
•Killed a third of Europe
•The word (but not the practice) of quarantine was first developed. It was already practiced in Roman times.
o The word “quarantine” is derived from the Italian word quaranta, which means 40, referring to the 40 days of isolation.
What is the difference between isolation and quarantine?
Difference quarantine and isolation:
•Quarantine: You are suspected of the disease because you e.g. came into contact with a person with the disease
o This robbing of someone’s freedom is a human rights issue, whether you agree with the necessity or not
• Isolation: You have the disease and are trying to stop spreading it.
What did we learn about the Spanish flu
Spanish flu:
• 1918/1919
• Called the Spanish flu because the Spanish were the first to admit they were suffering from an epidemic and wrote about it in their newspapers. It then became associated with Spain
• Killed ~100 million people worldwide and infected a third of the population worldwide
• Only control method used was quarantine.
o This led to less affected areas like Japan
What is the history of penicillin and antibiotics?
Penicillin/antibiotics
•Major breakthrough in the battle against infectious diseases
•Discovered by Sir Alexander Flemming
•Was especially used against syphilis in the early days, but also made surgery possible
•Before COVID, the “big thing” in infectious diseases was antibiotic resistance
What is the history of vaccinations?
Vaccination
• Vaccination programs are still probably the most cost-effective medical interventions that we have
o Social interventions like proper nutrition and hygiene might save even more lives
• Edward Jenner: developed the first (pox) vaccine in the UK in 1796, “inventor of vaccines”
o This was, however already being experimented with in other parts of the world
o In the Netherlands, in Groningen Geert Reinders did research on vaccination and immunity in 1774, predating Jenner.
• Helps with controlling, eliminating and eradicating diseases. E.g. smallpox was eradicated with vaccines.
o Control: When the disease is controlled to the extent of an accepted threshold. E.g. we could argue measles is controlled in the Netherlands. Once in a while there is a case, but generally we are happy with how we are dealing with it. Malaria is also controlled
o Eliminate: eradication regionally. So some diseases may be eradicated in Europe, but not in other parts of the world (e.g. polio is eliminated in some parts of the world)
o Eradicate: The infectious agent is no longer present anywhere in the world (except maybe a strain in a lab somewhere)
o For some diseases, the goal of eradication is almost impossible. E.g. measles is only a human reservoir, making it easier to control (as animals aren’t involved). The difficulty in eradicating measles lies in its high infectivity. In addition, building a good immunity to measles is difficult before a particular age. The vaccine is given at the age of 14 months in the Netherlands. Before that time, the measles can still spread. In high-endemic countries the vaccine is given at 12 months, which results in a lower protection. This is still worth it because of the high risk of contracting measles. E.g. Ebola is present in animals, so even if we remove it from all humans, it will still be present in animals that can infect humans.
What was the influence of HIV/AIDS on infection prevention?
HIV/AIDS:
• The importance of multi-component and social interventions was acknowledged on a global scale for the first time.
o Encouraging abstinence and stigmatisation probably contributed a lot to the spread of HIV/AIDS.
o Microcredits for women actually helped, as female empowerment influenced many factors of women’s lives which made them less likely to contract HIV.
o Peer/Self-help groups were found to be very important for treatment adherence
• Social interventions are important, in addition to the medical interventions!
What is the influence of COVID on infection prevention?
COVID:
• Different sciences are needed! Psychology/behavioural science is needed to predict e.g. the behaviour of youngsters when bars and clubs reopen. This information can then be used to predict the influence on the spread of infection.
What are containment strategies?
Containment strategies: interventions that limit or reduce the spread of diseases
Why is it hard to make a decision as a policy maker?
As a policy maker, it is very hard to make the right decision as there are so many factors involved. Vaccines might seem like a quick and easy fix, but even when they work very well, it might not be known how long they work. So, the evidence that you have does not provide certainty. Secondly, the evidence that you need to combine often is very difficult to compare. Evidence-based medicine is very relevant in clinical studies, but developing an intervention that has to work on a community level it is very difficult to compare one package of interventions to another package of interventions in a similar context. The randomized control group does not exist. In addition, sometimes policies need to be developed now and evidence will be provided later (like at the start of the COVID pandemic).
Context is also very relevant. The same package of interventions that works in the Netherlands might not work in Belgium or France or the US or South-Africa or South-Sudan. Informed decision-making is to Dirk arguing why you make this particular choice while using the most relevant evidence/knowledge present.
What is the PRECEED/PROCEED model?
There are many different models/frame works/etc for developing interventions, like the PRECEED/PROCEED model. This problem first focusses on: what is the problem, for who is it a problem what behavioural and environmental aspects causing the behaviour, what are the factors causing this behaviour and environment? Then it goes one step deeper and looks at the origins of these factors in policies or education. When this is determined, the place in the policy system to intervene can be determined. Then it proceeds to phase 6.
Phase 1: Social assessment
Phase 2: Epidemiologic assessment
Phase 3: Behavioral & environmental assessment
Phase 4: Educational & ecological assessment
Phase 5: Administrative policy assessment
Phase 6: Implementation
Phase 7: Process evaluation
Phase 8: Impact evaluation
Phase 9: Outcome evaluation
Environment for for example malaria: lots of standing water/breeding sites for mosquitos.
Behaviour & lifestyle for malaria: sleeping under a bed net and using repellent
Predisposing factors: attitude/skill related factors of the individual
Reinforcing factors: socially supported. What is your social environment doing and saying?
Enabling factors: do you or does society have the means to do it?
What are the 5 steps in health intervention?
Five steps in health intervention:
- What is the problem (is it a priority health problem)?
a. How many people get sick, die? What are the consequences of this? What does it mean for the stigma they experience? For who is it a problem? What is the economical consequence (money lost by intervention vs. money lost by no intervention in e.g. absence from work or finding cancer at a later stage)? - What factors cause the problem?
a. E.g. why are young children in India more susceptible to rabies? Knowing the problem makes it easier to come to a solution. - How can these factors be changed?
- What overall intervention strategies are most appropriate and cost effective (including what do people want and what are their needs?)?
- What needs to be done to reach the goals? With what (sub)populations shall work be done, and in what sequence, to solve the problem?
Are communicable diseases relevant everywhere?
Communicable diseases are mostly present in low-income countries, but are also very relevant in high-income countries. E.g. in the Netherlands, there is not much polio or measles due to our vaccination programme, but we still need to continue our vaccination programme to prevent it from becoming epidemic again.
What are the tree corners of the epidemiological triangle?
Agent, environment and host.
Agent: Cause of the disease. Transmission, infectivity, pathogenicity, virulence
Environment: Favourable. Socio-economic factors, physical factors, ideological/cultural factors
Host: Susceptibility. Behaviour, biological factors
What is the difference between a vector and a host?
Difference vector and host: Host can get ill from the disease, vector cannot get ill from the disease and just spreads it.
How can the epidemiological triangle help to find interventions?
Epidemiological triangle can be used to find interventions: change the environment (e.g. close schools to stop covid spread), change host susceptibility (vaccination).
