Hospitalization for Clostridium Difficile in the US elderly: Associations with livestock operations

In the US, over 300,000 cases of Clostridium difficile associated-diarrhea (CDAD) occur annually in hospitals or long-term care facilities and incidence has risen over the past two decades. Though CDAD is considered to be a hospital acquired disease, there is some evidence of environmental and zoonotic associations with bacteria spores observed in calves and the disease itself presenting in various animals. We have demonstrated a clear seasonal pattern which also indicates a strong environmental influence. CDAD seasonality may be driven by seasonal patterns in livestock production or manure waste management. All 1,054,125 hospitalization records for the US elderly with C. difficile were abstracted from the Centers for Medicare and Medicaid Services (CMS) database for a 14-year period (1991-2004). Livestock production data for 2002 was extracted from the Census of Agriculture collected by the U.S. Department of Agriculture. Data was aggregated on a county basis and disease rates were calculated. Considering only counties with production of egg laying chickens, the rates of CDAD hospitalization in the elderly was correlated with density of animals in the county. After controlling for the rurality of the county, average annual temperature and precipitation increased rates of CDAD were significantly associated with density of egg layers (RR= 1.007, 95%CI= (1.005,1.010) and density of hogs (RR= 1.01, 95%CI=(1.010,1.014)) in the county. However, no relationship was seen in counties with cattle production. These findings suggest that the seasonal pattern seen in CDAD hospitalization in the elderly may be associated with zoonotic transmission and require further investigation.