The Michigan Department of Health and Human Services' report on the outbreak of Legionnaires' disease has proven inconclusive.
The report was issued Thursday regarding the increase of Legionnaires during 2015 in Genesee County. MDHHS cannot conclude that the increase is related to the water switch in Flint nor can we rule out a possible association at this time.
From May 2015 through October 2015, 42 LD cases were reported in Genesee County. Data previously indicated three Legionnaires associated deaths from May 2015 through October 2015, however additional case information received has brought this number to four.
“While cases of Legionnaires disease are not expected in the winter, we remain fully engaged with the Genesee County Health Department as well as our federal partners at the Centers for Disease Control and Prevention to protect the health of Flint residents,” said Eden Wells, M.D., Chief Medical Executive with the MDHHS. “We remain diligent in our efforts to proactively and appropriately address the potential for future cases.”
Legionella is a type of bacteria commonly found in the environment that grows best in warm water, such as hot tubs, cooling towers, hot water tanks, potable water systems, and decorative fountains. When people are exposed to the bacteria, it can cause Legionellosis, a respiratory disease that can infect the lungs and cause pneumonia. The bacteria can also cause a less serious infection called Pontiac fever. Legionella is not transmitted person to person.
The state today also released an updated report for cases from June 2014 to March 2015. During that time, 45 LD cases were confirmed in Genesee County, including five associated fatalities. The report issued on January 13 originally identified seven fatalities during that time period.
Consistent with published literature, legionella related deaths are defined as fatalities that occurred within 30 days of hospital discharge. While the number of cases remain unchanged for LD in Genesee County, the total associated fatalities is now nine because some cases occurred outside of the 30 day period.
During LD outbreak investigations, clinical isolates, or case specimens, are often evaluated against environmental specimens to aid in determining an infection source. One reason that the increase in cases cannot be directly related to the change in Flint water supply is due to the lack of clinical Legionella isolates from case patients. Clinical isolates are necessary to interpret the findings of an environmental investigation in an outbreak. Although a limited number of clinical isolates are available from the 2015 cases, there are not enough to determine a conclusive environmental source.
Of the 87 total confirmed cases between June 2014 and November 2015, 31 people, or 35.6 percent, received city of Flint water to their residence. A total of 26 people, or 29.8 percent, had no known exposure to a Flint hospital on the city of Flint water system in the two weeks prior to illness, nor were their homes on the Flint water system. Other possible exposures were evaluated and no known community exposures were identified. Enhanced surveillance will continue in 2016.
MDHHS has been and continues to work with the Genesee County Health Department (GCHD), Michigan Department of Environmental Quality (DEQ), Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA) on this matter. MDHHS shared an initial report with local and federal partners in June 2015, and has continued to facilitate regular communication with our federal partners and GCHD to monitor cases.