Climate Change Could Trigger a Rise in Cases of C. Difficile

The incidence of Clostridioides difficile (C. diff) infections has declined in recent decades because of improved prevention. But climate change and the heavy flooding and water contamination that comes with it could spur a rise in outbreaks of this potentially fatal bacterial infection of the colon.

C. diff is commonly found in gut microbiome, but gastrointestinal disturbance such as the use of antibiotics, which upset the bacterial balance in the colon, can give rise to serious infections. Chemotherapy disrupts gut microbiome and patients have a 20% risk of developing a C. diff infection.

In the United States, C. diff infections are associated with hospital or long-term-care settings. C. diff is the most common cause of healthcare-associated infectious diarrhea.

Overall there are almost half a million cases each year.

C. diff spreads through spores, which can be found in human or animal waste and can be difficult to cleanse from surfaces. Symptoms of severe infection include diarrhea, abdominal cramping, nausea, fever and increased white cell blood count.

Authors of a 2020 study estimated the national burden of C. diff infections in 2017 to be 462,100 cases, a modest of 3% decrease from the 476,400 cases in 2011 but a decrease nonetheless. The numbers, however, represent a sizable 36% decrease in the healthcare-associated burden of c diff. Authors of this study found no change in CDI associated with community settings.

The decline in C. diff infections was partly attributed to more conservative use of fluoroquinolone, a broad-spectrum class of antibiotics that is directly linked to c diff infections.The fluoroquinolne antibiotics include Levaquin (levofloxacin), Cipro (ciprofloxacin) and Factive (gemifloxacin).

C. diff infections may increase overall as the globe becomes hotter and extreme weather events multiply.

A 2015 study of short-term incidents of C. diff infections following flood events in Massachusetts (2003-2007) found a strong association for higher infections among working age adults seven to 13 days following a flood. Emergency department and outpatient visits were elevated during that period.

Men were significantly more susceptible, possibly because of exposure during cleanup and rescue activities, wrote lead author Cynthia J. Lin, who was then at University of North Carolina’s Gillings School of Global Public Health and is now a researchers at ICF International, a consulting firm in Fairfax, Virginia.

Another study noted the potential for C diff infections in North Carolina where hog farming and the practice of storing animal waste in uncovered lagoons is widespread and vulnerable to spills. “Although pathogens from human waste carry greater risk for human infections than pathogens from hog waste, hogs in North Carolina produce a greater volume of waste than the entire statewide human population," wrote Arbor J.L. Quist, a Ph.D. candidate at University of North Carolina.

Hurricanes Matthew (2016) and Florence (2018) each inundated hog farm lagoons, causing contamination of waterways and private wells. “We found hurricane flooding to be associated with an 11% increase” in acute gastrointestinal illness and emergency department visits , wrote Quist. Outside of flooding events, people who lived in rural areas with high exposure to concentrated animal feeding operations (hog farms) were 54% more likely to visit emergency departments for C. diff. treatment.

There may be another reason climate change will bring about more C diff. Rising temperatures and erratic, violent weather have been linked to mental distress, because physical suffering increases and people become more anxious. Those who resort to antidepressant medications face an increased risk of CDI, according to Mary A.M. Rogers, lead author of a 2013 study.

Certain antidepressants were significantly related to C. diff infections. “The odds of testing positive for C. diff. were twice as high in patients who received mirtazapine (sold under brand name Remeron) than in those who did not,” she wrote. The risk of developing C. diff infections was almost as high for patients taking fluoxetine, which is sold under the brand name Prozac.