A study today in the Journal of the American Medical Association (JAMA) quantifies, for the first time, infectious disease deaths in America from 1980 through 2014 at the county level, showing a downward trend in all categories except diarrheal diseases.
While the study shows certain public health triumphs, such as a reduction of deaths from HIV/AIDS, it highlights the disparities that exist on a county level when it comes to accessing healthcare.
"We know from other work that social determinants of health, including wealth, followed by good access to medical and healthcare, are big predictors for outcomes," Jeffery Duchin, MD, the immediate past chair of the Infectious Disease Society of America's Public Health Committee, told CIDRAP News. He was not involved in the study.
Deaths down 19%
To conduct the study, researchers from the University of Washington analyzed de-identified death records from the National Center for Health Statistics (NCHS) and population counts from the US Census Bureau to measure age-standardized mortality rates of lower respiratory infections, diarrheal diseases, HIV/AIDS, meningitis, hepatitis, and tuberculosis by county, year, and sex.
Overall, deaths from infectious diseases dropped significantly over the study period. In 1980, infectious diseases caused 41.95 deaths per 100,000 persons. By 2014, that dropped to 34.10, a reduction of 18.7%.
The drop was most significantly seen in men, who in 1980 died from infectious diseases at a rate of 56.37 deaths per 100,000 persons, but by 2014 saw that number lower to 39.22 deaths per 100,000 persons. Women's deaths from infectious diseases declined only slightly, from 33.11 to 29.97 deaths per 100,000 persons.
Respiratory infections, diarrhea top list
Lower respiratory infections were the leading cause of infectious disease deaths, accounting for 78.8% of all infectious disease mortality (26.87 deaths per 100 000 persons) between 1980 and 2014. In 1980, lower respiratory infections caused 36.21 deaths per 100,000; by 2014, that number was reduced to 26.87 deaths per 100,000 persons.
Counties in Louisiana, Arkansas, Alabama, Tennessee, Kentucky, and Georgia had the highest rates of respiratory mortality, with East Feliciana Parish, Louisiana, having the highest rate, at 87.70 deaths per 100,000 persons. All counties with increasing rates of death from respiratory disease (12.3%) over the course of the study period were found in southern and eastern states.
The only cause of infectious disease mortality that increased from 2000 to 2014 was diarrheal diseases, also the second-leading cause of infectious disease mortality in 2014, accounting for 7.1% of infectious disease deaths, with 2.41 deaths per 100,000 person. A geographic corridor spanning Missouri to Maine represented the highest number of fatal cases of diarrheal diseases.
After respiratory illnesses and diarrhea, HIV/AIDs was the most common cause of infectious disease death, accounting for 2.40 deaths per 100,000 persons in 2014.
Rates of HIV-related deaths did not begin to decrease until 1994, when mortality from the disease peaked at 15.87 deaths per 100,000 persons. "HIV/AIDS mortality increased first in some of the wealthiest US counties on the West Coast, but has shifted to some of the poorest counties in the southeastern United States," the authors of the study said, showing that HIV trends reflected availability and advancement of medical treatments.
The county with the highest absolute mortality rate due to HIV/AIDS was Union County, Florida, the site of a large correctional facility.
Meningitis, tuberculosis, and hepatitis all caused less than 1 death per 100,000 persons each in 2014. Rates of death due to both meningitis and tuberculosis decreased in all US counties from 1980 to 2014.
Wide county-level disparities
Study author Charbel el Bcheraoui, PhD, assistant professor of global health at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington said he was surprised by some of the extreme county-level disparities seen in the study.
"These large disparities are most probably due to variation in risk factors such as alcohol, drugs, or smoking, as well as socioeconomic factors and access to quality medical care," he said in an interview.
"These results underscore the need to monitor the transmission of infectious diseases carefully and to help prevent outbreaks. On our end we will continue updating these results by tracking infectious disease mortality to monitor the trends in geographic disparities," he said.
Mar 27 JAMA study