Which of the following can cause an increase in the prevalence of the disease-: (A) Immigration of healthy persons, (B) Increased cure rate of disease, (C) Longer duration of illness, (D) Decrease in population
Answer is C. Ref: Parks 23rd edition Disease will be Prevalent so long it exist in the community. Longer the duration of the illness, longer will it persist in the community and hence higher will be its prevalence.