Study Confirms New Target in Infectious Disease Mortality—C difficile and Other Diarrheal Diseases: Public Health Watch

It’s an occupational hazard for infectious disease and public health specialists that their jobs seem to require constant surveillance for new pathogens and outbreak threats.

And while this part of the job is well understood, it’s far from easy. More often than not, practitioners in these fields learn quickly that their “enemies” are usually moving targets, or an ever-changing array of diseases and bugs that are likely to overwhelm currently available drugs. Case in point: the findings of a new study published March 27 by the Journal of the American Medical Association (JAMA).

In an analysis designed to assess infectious disease mortality in the United States over the period of 1980 through 2014, the authors found that deaths declined overall. However, the study also concluded that deaths caused by “diarrheal diseases” increased over the same period.

“This analysis… provides local estimates, which have been previously masked by state averages,” study co-author Charbel El Bcheraoui, PhD, assistant professor of global health, Institute for Health Metrics and Evaluation (IHME), University of Washington, told Contagion^®. “Our hope is that this information will help decision makers allocate their resources and focus their efforts based on this more geographically-granular information.”

Dr. El Bcheraoui and his colleagues sought to estimate age-standardized mortality rates and trends, by US county, using “de-identified” death records obtained from the National Center for Health Statistics and population data from the US Census. Their objective was to get a picture of infectious disease mortality at the “micro” level, given that national and even state averages can obscure local trend differences, such as distinctions between urban and rural areas, among other statistical anomalies.

In all, over the 34-year study period, they found that nearly 4.1 million Americans died as a result of infectious diseases. Notably, though, while mortality rates associated with these pathogens were 41.95 per 100,000 population at the beginning of the period, in 1980, they declined by 18.7% to 34.10 per 100,000 population by 2014.

Although lower respiratory infections remained the leading cause of infectious diseases mortality in 2014, accounting for 26.87 per 100,000 population (or 78.8% of all infectious diseases deaths), deaths resulting from HIV declined sharply from a high of 15.87 per 100,000 population in 1994 to 2.04 per 100,000 population in 2014. This is not surprising given the development of antiretroviral therapy in the 1990s. Mortality from meningitis and tuberculosis (TB) also decreased over the study period in all US counties, from 1.36 to 0.41 per 100,000 population and from 1.52 to 0.25 per 100,000, respectively.

However, deaths related to diarrheal diseases such as Clostridium difficile (C. diff) increased from 0.41 to 2.41 per 100,000 population from 1980 to 2014. In all, these pathogens accounted for 7.1% of all infectious disease-related deaths in the United States in 2014.

Although additional epidemiologic research is needed to fully understand the cause of this increase, Dr. El Bcheraoui said, “This increase in C. diff is most probably driven by the aging of the US population and, with that, the increase in the hospitalization of the elderly. Clinicians [must] balance the need for antibiotics [with] their risks and follow the guidelines of infection control recommendations” in order to reduce mortality.

And, although like HIV, deaths caused by hepatitis also declined over the study period, from 0.49 to 0.29 per 100,000 population, Dr. El Bcheraoui added that we can perhaps expect an increase in this area in the coming years because both diseases are related to the ongoing opioid abuse epidemic in the United States.

“Drug use may increase some of the infections from needles and sexually transmitted diseases,” he explained. “As with all infectious diseases, we have to be vigilant and always increasing our efforts to prevent further infections across the United States.”

However, vigilance only works when you know what to look for.

Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous health care-related publications. He is the former editor of Infectious Disease Special Edition.