Poor living and working conditions for migrant farmworkers is a contributing factor to outbreaks like this. Workers who are present illegally or are otherwise marginalized and taken advantage of, even if they are part of legal guest-worker programs, suffer conditions where poor housing facilities or the need to work under great time pressures leads to inadequate sanitation.
A 2017 story [0] illustrates this:
>Kristina Espinoza, a labor department investigator who recently visited the farm, described a "makeshift labor camp" that was "dangerous" and "unsanitary," according to court documents. [...] Gonzalez had workers shower in nine stalls inside a cargo container; there was no functional sewage system, so wastewater accumulated underneath the container, Espinoza said. The electrical cord used to light the facility was exposed to standing water, posing a risk of electrocution, according to court documents. The workers shared one toilet in the trailer and had access to port-a-potties.
[0] http://www.latimes.com/business/la-fi-farmworker-abuse-20170...