This investigation implicates Campylobacter jejuni as the cause of this outbreak, most likely from a municipal water system contaminated by wastewater runoff from an adjacent concentrated animal feeding operation. In addition to environmental and statistical findings, this conclusion is consistent with prior investigations that demonstrate Campylobacter outbreaks of similar size are historically associated with contaminated water.[2–7] Although laboratory testing of the water in this investigation did not yield any positive results, samples were not taken until long after the contamination event, and test results might have been affected by switches among wells supplying the system over time. These findings also suggest that routine coliform testing might not be a good indicator of the presence of Campylobacter species. Further, it is possible that Campylobacter in particular might be viable but not necessarily detectable by culture in water systems.[9,10] The use of both culture and culture-independent diagnostic tests (PCR) were needed to detect the initial cluster of cases and early recognition of this outbreak. If culture alone had been used, only two cases would have been reported, one of which did not occur in a city A resident. Of those two culture-confirmed cases, one patient refused the interview and the other had typical Campylobacter exposures, such as live poultry, which might not have prompted such a rapid response. This investigation demonstrates the importance of considering exposure to untreated water sources as a potential cause for Campylobacter outbreaks. Including this risk factor in initial questioning could help to expedite outbreak investigations. Ultimately, early recognition and a coordinated response by several state and local agencies greatly facilitated this successful public health intervention.
Southwest Nebraska Public Health Department; Nebraska Department of Environmental Quality; Nebraska Department of Agriculture.
Morbidity and Mortality Weekly Report. 2019;68(7):169-173. © 2019 Centers for Disease Control and Prevention (CDC)