A city, an outbreak, and a contaminated well. Surely this sounds like some kind of modern version of the John Snow cholera outbreak
and the Broad St. pump. But unfortunately, it’s this week’s US Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report
with a much more recent example of how bad sanitation and contaminated water can affect a city.
In 2017, a city in Nebraska experienced an outbreak of Campylobacter jejuni
that drove home the realities of One Health, the theory that the health of humans, animals, and the environment are all connected. It all began on a March day in 2017, when the Southwest Nebraska Public Health Department got a call regarding a spike in campylobacteriosis cases—5. The condition, campylobacteriosis –infection due to Campylobacter jejuni
is reportable, indicating labs and hospitals are required to report them to the health department. Typically, a single case of Campylobacter
was reported in this particular city every 3 years, making the infection quite rare.
When epidemiologists and health department investigators began responding to the spike in cases, the initial thought was the source might be ground beef. In fact, the investigation questionnaire did not contain a question regarding consumption of untreated drinking water. After evaluating the distribution of poultry and ground beef within 2 local restaurants and a grocery store, epidemiologists found that there was no shared consumption of the potential products.
Like something out of a detective film, just as the investigators were meeting with business owners and working to identify the source of the outbreak, several people complained of standing water that “smelled of cattle manure” along a roadside ditch that just happened to be close to 2 municipal water wells.
Tipped off by this report, an on-site investigation was conducted and investigators stumbled across a disturbing finding—in the process of pumping large volumes of livestock wastewater from a concentrated animal feeding operation via a center pivot irrigation system, a malfunction had occurred. Although it was meant to flood an adjacent farmland, the malfunction had allowed the wastewater to flood a road ditch 15 feet from the 2 municipal water well houses, 6 days prior to when the first case was reported.
Further digging by water operators confirmed the standing water, and pump records indicated that the wells were indeed pumping water that was contaminated during that time. Unfortunately, water goes through the well system without any disinfection or filtration processes, and samples from the wells in question were negative for coliforms and Campylobacter.
Following this, the Nebraska Department of Environmental Quality and the Department of Agriculture became involved in investigating 2 concentrated animal feeding operation waste lagoons. Following a March 16, 2017, investigation, it was discovered that water from the waste lagoons had been pumped through a pivot that flooded a nearby farm and went into a ditch near 1 of the wells.
Of the 6 confirmed cases and 33 probable cases, 31% of these individuals ended up seeking medical care and 8% were hospitalized. Data analysis revealed a statistically significant association between sick people and consumption of untreated, unboiled municipal tap water (Odds Ratio = 7.84). The 2 wells considered to be associated with infection were removed from service and no additional cases occurred. Investigators noted that the outbreak is similar to historical outbreaks of Campylobacter
with contaminated water as a source. They recommended more routine coliform testing, and though the water samples were not positive, they weren’t taken until long after the contamination event.
This outbreak is a stark reminder that even centuries after John Snow removed the handle to the Broad St. pump to halt the spread of cholera, water contamination can still be a source of outbreaks.