Gastrointestinal (GI) illnesses are frequently linked to environmental factors, and heavy rainfall is a significant one. Storms and periods of intense rainfall can dramatically increase the levels of microbiological contaminants in untreated water sources. This is especially concerning for surface water supplies, which are directly exposed to runoff and environmental pollutants. One common manifestation of these illnesses is diarrhea, often identified using the 787.91 Diagnosis Code.
The 787.91 diagnosis code is part of the International Classification of Diseases, Ninth Revision (ICD-9), and specifically refers to diarrhea as a diagnosis. While seemingly straightforward, understanding the context in which this diagnosis code is used is crucial, especially when investigating public health concerns related to environmental factors like heavy rainfall.
A study conducted in New Jersey between 2009 and 2013 examined the relationship between heavy rainfall and hospitalizations for GI illnesses, using the 787.91 diagnosis code and other related ICD-9 codes (001-009.9 for specified gastrointestinal infections). The research, involving a substantial sample size of 47,527 cases, employed a time-stratified bi-directional case-crossover study design. This sophisticated approach helped to isolate the impact of heavy rainfall on GI hospitalization rates while controlling for other factors like temperature and humidity.
The study’s findings revealed a significant link between heavy rainfall and increased GI hospitalizations, particularly in areas relying on surface water sources for drinking water during warmer seasons. Specifically, positive associations were found with no time lag (immediate impact) and a 2-day lag after heavy rainfall events in surface water systems. This means that the risk of hospitalization for GI issues, indicated by diagnoses including the 787.91 diagnosis code, increased during and shortly after periods of heavy rainfall in these communities.
Interestingly, similar positive associations were also observed in areas with ‘Other’ water sources, which include very small community water systems, private wells, or sources with unknown characteristics, during the warm season but with a 4-day lag. However, groundwater systems did not show statistically significant positive associations during the warm season in this study.
These results underscore the critical role of water source type in mediating the impact of heavy rainfall on public health. Surface water systems, being more vulnerable to runoff contamination, appear to be a key pathway through which heavy rainfall events lead to increased GI illnesses, reflected in hospitalizations coded with 787.91 and related diagnoses.
The implications of these findings are clear. Water systems that utilize surface water sources need to implement robust preventative measures to safeguard public health, especially during and after heavy rainfall. Public health regulators and water system providers must collaborate to develop and implement system-specific prevention techniques. By focusing on protecting water sources from contamination during rainfall events, we can effectively reduce the incidence of GI illnesses and subsequent hospitalizations, thereby mitigating the public health impact associated with conditions represented by the 787.91 diagnosis code.
