Background & Surveillance
What is the difference between a clinical approach and a public health approach to health?
The clinical approach focuses on the health of individuals, diagnosing and treating diseases on a person-to-person basis. The public health approach focuses on the health of populations, emphasizing prevention, surveillance, and the control of diseases within communities.
What is the first step in an outbreak investigation?
The first step is to establish the existence of an outbreak, which involves reviewing data and identifying whether the number of cases exceeds the expected baseline for a given period.
What is disease prevalence, and how is it different from incidence?
What is the main goal of disease control in a community setting?
The main goal of disease control is to reduce the spread of infectious diseases and protect the population from illness. This is achieved through interventions like vaccination, quarantine, health education, and improving sanitation.
What is a cohort study and how does it differ from a case-control study?
A cohort study follows a group of individuals over time to observe how exposure to a certain factor affects the incidence of disease. It compares the exposed group to an unexposed group.
A case-control study, on the other hand, compares individuals with a disease (cases) to those without (controls) and looks backward to determine how exposure to a risk factor may have influenced the disease.
What are the different types of surveillance used in public health?
The main types of surveillance are:
What is the difference between experimental and observational studies?
How do epidemiologists calculate the incidence rate?
What is herd immunity, and how does it help control disease spread?
Herd immunity occurs when a significant portion of a population becomes immune to a disease (through vaccination or previous infection), reducing the likelihood of transmission and protecting individuals who are not immune.
What is an ecological study and when would it be used?
An ecological study examines the relationship between exposure and disease at a population level rather than an individual level. It uses aggregate data, such as average levels of exposure or disease rates across different regions or time periods. It is useful for identifying trends, but it cannot establish causality.
What are the key attributes of a good surveillance system?
How do you identify and interpret trends in outbreak data?
Trends can be identified by analyzing epi curves, line listings, and maps. Epidemiologists look for patterns in the timing (when), location (where), and affected groups (who) to understand the spread and identify the cause of an outbreak.
What are some strategies for controlling infectious diseases in urban areas?
How do contact tracing and isolation help in controlling an infectious disease outbreak?
Contact tracing involves identifying and notifying individuals who may have been exposed to an infected person, so they can take preventive measures. Isolation involves separating infected individuals from the healthy population to prevent further spread of the disease.
What is the primary advantage of a randomized controlled trial (RCT)?
The primary advantage of a randomized controlled trial (RCT) is that it minimizes bias by randomly assigning participants to different intervention or control groups, ensuring that the groups are comparable and that any observed effects are likely due to the intervention rather than other confounding factors.
How do epidemiologists calculate and interpret the relative risk of exposure to a disease during an outbreak?
Relative risk (RR) is calculated as the ratio of the risk of disease in the exposed group to the risk in the unexposed group:
RR=(a/(a+b))(c/(c+d))RR = \frac{(a / (a + b))}{(c / (c + d))}RR=(c/(c+d))(a/(a+b))
Where:
How would you apply the Bradford Hill Criteria to determine causality in an outbreak?
The Bradford Hill Criteria include factors like:
What strategies can be implemented at the national level to prevent an epidemic?
National strategies include:
What is quarantine, and how does it differ from isolation in the context of disease control?
Quarantine involves separating and restricting the movement of individuals who may have been exposed to a contagious disease, even if they are not showing symptoms. Isolation refers to separating individuals who are already infected with a contagious disease to prevent transmission to others.
What is the purpose of using blinding in epidemiological studies, and how does it improve the study's validity?
Blinding is used to prevent bias in data collection and analysis. In single blinding, the participant does not know which treatment they are receiving, while in double blinding, both the participants and researchers do not know the treatment assignment. It helps ensure that the outcomes are not influenced by expectations or preconceived notions, improving the validity of the results.
What are the ethical considerations when implementing a surveillance system?
Answer: Key ethical considerations include:
How would you calculate the basic reproductive number (R0) for an outbreak and what does it signify?
R0 is the average number of secondary cases caused by a single infected individual in a fully susceptible population. It is calculated by considering factors like transmission rate, contact rate, and duration of infectiousness.
What is the significance of effective reproductive numbers (Re) in determining the success of control measures?
The effective reproductive number (Re) represents the average number of secondary cases produced by an infected individual in a partially susceptible population. A Re < 1 indicates that the disease is under control and will eventually decline. Control measures such as vaccination or social distancing can reduce Re, making it a key indicator of whether interventions are successful in stopping an outbreak.
How does vaccination contribute to controlling an epidemic, and what role does vaccine coverage play?
Vaccination helps control epidemics by increasing the immunity of a population, preventing new infections, and reducing the spread of the disease. Vaccine coverage (the percentage of the population that is vaccinated) is critical: higher coverage leads to better herd immunity and reduces the chances of an epidemic.
What disease is the Pokémon Zubat often associated with, and how does it relate to the concept of transmission and public health?