Answer:
The prevalence of the disease is 0.015
Explanation:
Mathematically,
Disease Prevalence (P) = Incidence (I) * Average duration of the disease (D)
From the question, the Incidence is 500/100,000 person-years
Duration of the disease = 3 years
Prevalence = 500/100,000 * 3 = 0.015
Swelling is a sign because when you swell up then you know theres something wrong
because they work with a lot of people and they know when they see someone unhealthy
