(RxWiki News) Tuberculosis is still a concern in the US, and researchers are examining a related condition that may begin to cause more trouble.
A new study looked into nontuberculous mycobacteria, which cause no infections in some people, but in others can cause chronic lung infections and even death.
This study found that these bacteria were more likely to lead to death in people over the age of 55 and in certain US states.
"See your doctor if you start coughing up blood."
The term nontuberculous mycobacteria describes a number of different bacteria that can cause illness and infection in the lungs. According to the American Lung Association, the bacteria is related to tuberculosis, but cannot be spread between people.
According to the authors of this study, which was led by Mehdi Mirsaeidi, MD, of the Division of Pulmonary and Critical Care at the University of Illinois at Chicago, much is still to be learned about nontuberculous mycobacteria, which can be found in sources of water and in soil.
The researchers aimed to learn more about the spread of nontuberculous mycobacteria and rates of death associated with the bacteria among people in the US.
Using death record data from the National Center for Health Statistics, these researchers looked for instances of death related to nontuberculous mycobacteria from 1999 to 2010.
Dr. Mirsaeidi and team found 2,999 cases in the US in which nontuberculous mycobacteria disease was reported as the cause of death during this time. This amounted to an average rate of 0.1 deaths per 100,000 person-years.
The researchers found that deaths from nontuberculous mycobacteria were not evenly spread among all people in the US, both in terms of geographic location and in terms of demographic factors.
Hawaii had the highest nontuberculous mycobacteria rate (0.29 deaths per 100,000 person years) — a rate that the study authors noted was over nine times as high as the lowest state rate, seen in Michigan. Following Hawaii, Louisiana, Arizona, South Carolina, North Carolina and Florida had the next-highest rates.
Deaths from nontuberculous mycobacteria were also more likely to be seen in small and medium-sized metropolitan areas, areas which saw over 51 percent of these deaths. By contrast, large central metropolitan areas saw only 29 percent of nontuberculous mycobacteria-related deaths.
In terms of demographics, people who died from nontuberculous mycobacteria were more likely to be aged 55 years or older, female and non-Hispanic white. Age was the strongest risk factor seen, with 87 percent of nontuberculous mycobacteria-related deaths occurring in people aged 55 or older.
"Nontuberculous mycobacteria-related death numbers are rising and are unevenly distributed," wrote Dr. Mirsaeidi and team. "The strong association of nontuberculous mycobacterial disease with age suggests that its prevalence will increase as the United States population ages."
Further research is needed to learn more about nontuberculous mycobacteria and confirm these findings.
This study was published March 14 online by the journal PLOS ONE. No conflicts of interest were reported.