An investigation covering 12 years and involving data from over 500 hospitals across 25 states indicates that factors such as weather, geographic location, and whether an area is urban or rural significantly affect hospitalizations due to waterborne infectious diseases.
A study published on August 7, 2024, in the open-access journal PLOS Water, conducted by Victoria Lynch and Jeffrey Shaman from Columbia University, reveals that weather conditions, geographical positioning, and the distinction between urban and rural settings are important factors in hospitalizations for waterborne infectious diseases.
In the United States, waterborne infectious diseases, caused by various bacteria, parasites, and viruses, impact over 7 million individuals each year. Lynch and Shaman explored the connections between weather patterns and the rates of hospitalizations for these diseases, particularly examining how these links were affected by the source of drinking water, the setting (rural or urban), and the specific region.
The researchers focused on 12 specific pathogens that cause waterborne illnesses, such as Escherichia coli (a type of bacteria), Cryptosporidium (a parasite), Pseudomonas (a biofilm-forming bacterium), and the organism responsible for Legionnaires’ disease, as well as Norovirus. They analyzed data from 516 hospitals in 25 states collected from 2000 to 2011, sourced from the National Inpatient Sample (NIS) by the Healthcare Cost and Utilization Project (HCUP), alongside meteorological and soil data from the NASA/NOAA North American Land Data Assimilation System 2 (NLDAS-2).
From 2000 to 2011, there were a total of 57,335 hospitalizations linked to waterborne diseases among the 516 hospitals in the U.S. Notably, bacteria forming biofilms represented around 81 percent of these hospitalizations, with 66 percent attributed to respiratory infections caused by Pseudomonas alone. The rates of hospitalization for enteric and biofilm-associated bacterial infections were considerably higher in regions that relied on groundwater for drinking water, as opposed to surface water. Additionally, they discovered that factors like precipitation, water runoff, and rural settings were positively correlated with hospitalizations from certain enteric bacterial and parasitic infections, especially in the Midwest. For instance, parasitic hospitalizations (mainly due to Cryptosporidium) increased by 9 percent (95% CI: 4%-15%) with a one-standard-deviation rise in precipitation. In contrast, cases of biofilm-forming bacterial infections showed associations with soil moisture levels, which can indicate flooding. Particularly, incidences of Legionnaires’ disease rose by 124 percent (95% CI: 90%-157%) with a one-standard-deviation increase in soil moisture, marking it as the only infection type that occurred more frequently in urban settings. Overall, the relationships between hospitalization rates and weather conditions, geographic factors, and drinking water sources varied significantly based on the specific pathogens.
The researchers noted that they could not include data on specific water quality, which is essential for evaluating potential exposure routes for pathogens that may also be found in contaminated food, like E. coli. They also did not have data from large parts of the Southeast, where states had not reported monthly data to HCUP. Lynch and Shaman express hope that future studies will incorporate this missing information and additionally monitor outbreaks connected to extreme weather events, enhancing understanding of the ties between hydrometeorology and waterborne diseases.
The authors conclude, “Our findings illustrate how targeted analyses of specific pathogens can shed light on distinct exposure routes and risk factors associated with waterborne infectious diseases. This research can aid in the development of weather preparedness strategies, especially given the increasing severity and frequency of heavy rainfall due to climate change.”
