How does each of the following conditions influence the prevalence of a disease in a population?

How does each of the following conditions influence the prevalence of a disease in a population? For each scenario, assume that no other changes occur. Your choices are: increases prevalence, decreases prevalence, or has no effect on prevalence.

·         A treatment is developed that prolongs the life of people suffering from the disease

·         A new measure is developed that prevents new cases of disease from occurring

·         There is immigration of a large number of healthy people into the population.

. The case-fatality rate for the disease increases

My answers please check to confirm

1.Treatment prolonging life of people suffering from the disease will Increase the prevalence

2,  new measure preventing new cases from occurring will Decrease the prevalence

3.Immigration of healthy people into the population will  Decrease prevalence

4. Increase case fatality rate will decrease prevalence