Global Patterns of disease I

Question 1

What is epidemiology based on?

Answer 1

It is based on the ability to quantify occurrence of disease in populations

Question 2

What is a ‘case’ in epidemiology?

Answer 2

Person with disease, health disorder or suffering from event of interest

Question 3

What is prevalence?

Answer 3

Frequency of a disease in a population at a point in time. It is the number of cases in the population/ number of people in the population. It is used to measure the burden of disease in a population

Question 4

What is incidence?

Answer 4

Quantification of the number of new cases of a disease within a specified time interval

Question 5

What is the difference between prevalence and incidence ?

Answer 5

Incidence new cases whereas prevalence measures all cases

Question 6

How is incidence estimated?

Answer 6

By defining the time period and the denominator- the total population at risk. And an accurate test is needed to define a true case

Question 7

What is mortality?

Answer 7

Number of deaths from a disease. It is the deaths from disease in a given time period/ population at the start of the time period

Question 8

What does it mean when mortality= incidence?

Answer 8

Epidemic is stable

Question 9

Explain the relationship between prevalence and mortality

Answer 9

Define prevalence and mortality. For diseases where treatment confers survival benefit (e.g. ART for people living with HIV) the mortality falls as people start ART. Hence these people survive and overall population level prevalence increases.
For diseases that are rapidly fatal (e.g. Ebola) the mortality is rapid and high and so large number of cases but overall prevalence is low.

Question 10

What is morbidity?

Answer 10

Morbidity is the state of being diseased/ unhealthy

Question 11

What are mortality rates expressed as?

Answer 11

Number of deaths per 1000 individuals per year

Question 12

What are the leading causes of death?

Answer 12

Heart diseases, cerebra-vascular disease, respiratory infections, HIV/AIDs, COPD. In 3rd world countries, 58% due to malnutrition or deficiencies

Question 13

What are the leading causes of death due to infectious diseases

Answer 13

lower resp, HIV, diarrhoea disease, TB, malaria, measles. Infectious diseases are leading cause of death in sub-saharan Africa

Question 14

What are age standardised death rates?

Answer 14

The age-standardized mortality rate is a weighted average of the age-specific mortality rates per 100,000 persons, where the weights are the proportions of persons in the corresponding age groups of the WHO standard population-Measuring how many people die each year. Numbers help authorities determine whether they’re focusing on right public health actions to reduce numbers of preventable deaths and disease.

Question 15

What is the basic reproductive number?

Answer 15

Average number of secondary cases from the emergence of a single primary case

Question 16

What factors affect R0?

Answer 16

Duration of incubation period, peak infectiousness and how quickly infectiousness decreases

Question 17

Case studies of recent epidemics

Answer 17

SAR 2003, West Nile Virus 1999, HIV 1 1982, Malaria, MERS, Ebola, Zika

Question 18

What were the policy objectives in prevention and control of influenza A H1N1

Answer 18

minimise morbidity and mortality with fixed/variable budget. Buy time for vaccine development. minimise duration of epidemic and impact on economy and minis peak prevalence below a defined level to avoid collapse of healthcare system.