Infectious Disease Mortality Rates Drop Nationally, Widen Among Counties

Ali Mokdad, PhD

Although infectious disease mortality rates in the US have declined at a progression influenced by advancing vaccines and therapies in the past 3 decades, there is still a concerning trend of mortality rate disparity among counties, according to a recent study.

Researchers from the Institute for Health Metrics and Evaluation at the University of Washington, Seattle, recently compared the overall deaths from particular infectious diseases in the US in 2014, in comparison to rates from 1980. Though the total annual deaths increased from 72,220 (95% UI; 69,877-74,712) to 113,650 (95% UI; 108,764-117,942) in that span, the rate per 100,000 persons decreased due to raised population.

The per-population mortality decrease was relevant in most common infectious diseases, including lower respiratory infections (25.79% [95% UI; 22.02-29.43]), diarrheal disease (483.96% [95% UI; -17.66-622.24]), meningitis (69.55% [95% UI; 66.98-71.52]), hepatitis (40.74% [95% UI; 32.30-48.49]), and tuberculosis (83.31% [95% UI; 81.97-84.50]).

HIV/AIDS, which was reported as the cause of death in 7.04% of all US infectious disease-related deaths in 2014, increased by 25.82% (95% UI; 23.78-28.03) from 1985 to 2014. However, researchers noted this increase reflects that most US counties had no reported deaths from the disease at baseline. Its mortality rate peaked in 1994, at 15.87 per 100,000 persons (95% UI; 15.73-16.01).

In 2014, lower respiratory infections remained the most lethal infectious disease in the US, accounting for 78.8% of all disease-related deaths. Per 100,000 persons, it registered at 26.87 (95% UI; 25.79-28.05) deaths. Its absolute mortality inequality among counties — as gauged by the difference between 10^th and 90^th percentile of distribution — was the largest among diseases, at 24.5 deaths per 100,000 persons. HIV/AID’s relative mortality inequality ratio of 10.0 between counties in the 90^th and 10^th percentile was the greatest among observed infectious disease.

Diarrheal disease mortality was the only observed disease to increase from 2000 to 2014, raising in nearly all counties (99.97%). Notable increases were reported in the Northeast, Midwest, Southwest, and Pacific coast.

Infectious disease mortality rates were most strongly reported in the eastern region of the US in 2014, with the most severe rates of death per 100,000 occurring in counties in the Southeast. This region’s counties also hosted the most increases of lower respiratory infection mortality (24.89% of counties).

Researchers attributed individual disease trends to their own recent history of therapy or even prophylaxis development, while continued mortality issues with lower respiratory infection and diarrheal disease are linked to economic burden. The disease accounted for a combined $46.3 billion of personal health care spending in the US in 2013, researchers wrote — a cost that is likely to increase in the future due to population aging and growth.

“Hence, it is necessary to focus on infectious diseases prevention through public health strategies to decrease their burden,” researchers wrote. “There is also a need to improve access to and quality of health care throughout the United States to improve health outcomes and increase immunization coverage for vaccine-preventable diseases such as hepatitis and meningitis.”

Ali H. Mokdad, PhD, professor of Globabl Health, Epidemiology, and Health Services at the University of Washington, told MD Magazine the rates were all surprising to find — and that’s coming from an experienced public health researcher. He said the overall growing disparity of infectious disease mortality among counties is an indication of national health traveling backwards.

“We spend more on health than anyone else, we debate health, and yet our results are showing that people are being left behind,” Mokdad said.

Mokdad drew concern with the disparity of mortality between financially affluent and poorer counties. He noted the HIV/AIDs epidemic of the 1980s originated in richer regions — often, big cities — and spread to rural regions. When antiretroviral therapies (ART) came to the forefront of HIV treatment options, urban areas were faster to adopt life-saving changes to care while poor regions lagged behind — similar to the trend of tobacco use over years, Mokdad said.

“Some places in our country do even worse against these disease than third-world countries,” Mokdad said. “The huge disparities are shocking.”

With this most recent data available, counties and region can begin to individually access their own success and challenges with infectious disease, Mokdad said. He hopes it drives communities to ask more questions about their methods of prevention and resources, and to abandon failed practices. The risk of infectious disease spread is too frequent and severe to allow leniency on the issue.

“They can pop up at anytime, and when they do, they’re devastating,” Mokdad said. “Many of the bacteria and things we have treatment for, there’s a resistance to them.”

The study, "Trends and Patterns of Differences in Infectious Disease Mortality Among US Counties, 1980-2014," was published online in JAMA this week.