In C++

How to go about representing an individual's person health status in lets say an island

For example in an island that contains 500 people and initially ttheres a certain amount of people who've been carrying a disease. Each person comes in contact with 5 people a day and theres a probability of 10 percent for the infected individual to infect the "healthy" person when coming in contact with that person who'se been carrying the disease. After 5 days the people who've been infected get cured and arent able to get infected again even if they come in contact with another person who is infected.

How do I show the number of people that get infected each day?