Most infectious diseases have a common exposure type that they are commonly associated with which can quickly point the physician in the right direction upon presentation. A patient's ability (or not) to properly prevent interactions with the bugs, where they work and live, and what kinds of foods they eat and where they get them from are all important basic questions about their day to day life can elucidate exposures these patients have had. It is important to consider the socioeconomics of the patient's situation when dealing with an infectious disease because it can help direct what the next level of testing should be.
For undocumented workers, they are frequently not afforded some of the luxuries of native citizens. Their situation forces them to take jobs and live in places that are less desirable. By working in the fields they have a much higher exposure to bugs that spread diseases. By living in houses that may not be properly insulated or treated for pests, they further risk exposure to bugs and rodents that can spread infections to them. They unfortunately do not have much of a choice when first settling in a new place and so much tolerate these conditions and the risk of disease.