The local hospital emergency department has recently experienced an increase in gastroenteritis cases among migrant farmworkers. The local health department is informed of this rise in cases and schedules a case mapping of local:

1. bars frequented by migrant workers.
2. farm fields employing migrant workers.
3. housing for migrant workers.
4. restaurants frequented by migrant workers.

The correct answer is 3. housing for migrant workers.  

Explanation:

The neglected infectious diseases in the Americas continue to affect millions of people, but above all, those communities made up of the indigenous populations of the countries and the Afro-descendants born on the continent. In both cases, these and other populations in general, represent the poorest and most marginalized groups in their countries. To this concern, the Pan American Health Organization presents here a first view of the geographical distribution of priority neglected infectious diseases in the Americas.

3) housing for migrant workers.

Explanation:

When you want to track down the origin of an infectious disease, you must start with the residence of the diseased.

In this case, migrant workers only live temporarily in the places at which they work, and many use trailer homes or share living spaces with several people. They aren't on vacation, they moved there to work and after their work is finished, they will return home. Hopefully they will be able to take the largest possible amount of money, so they really try to spend very little. Unfortunately, that results in bad living conditions that are not necessarily healthy or appropriate, but offer cheap alternatives. That overcrowding also results in higher disease rates.