Legionellosis 2001

Rates presented are per 100,000 population and are based on the 2000 U.S. Census.

  Cases Incidence
Total 23 0.4
Race-specific cases and rates1
White  14 0.3*
Black  5 1.0*
Other2   0  
Sex-specific cases and rates
Female 8 0.3*
Male 15 0.5*

Legionellosis is a respiratory infection caused by Legionella bacteria, most commonly Legionella pneumophila. These bacteria are transmitted by contaminated water aerosols, which are then inhaled. Those at greatest risk of acquiring infection are those over age 50, especially with a history of smoking, and those with weakened immune systems. The severe form of legionellosis, commonly known as "Legionnaires’ Disease", is characterized by pneumonia, fever, and myalgia. A milder, self-limiting form of the illness, known as Pontiac Fever, is characterized by fever, cough, and myalgia. Neither infection is transmissible person-to-person.

There were 23 cases of legionellosis reported in Indiana in 2001, for a rate of 0.4 cases per 100,000 population. This represents a 44% decrease over the previous year. In addition, the incidence was well below the previous five-year average incidence of 47 cases (Figure Leg1). Legionellosis infection occurs any time of year, and there does not appear to be any seasonal pattern.

Age-specific rates were highest among adults ages 60-69 (1.4) and adults ages 70 and older (1.1) (Figure Leg2). The sex-specific rate for males (0.5) was higher than that for females (0.3).  The race-specific rate for blacks (1.0) was higher than that for whites (0.3).

There were no outbreaks of legionellosis reported in Indiana in 2001.

For more information on legionellosis, please visit: http://www.in.gov/isdh/25461.htm


1 - Race was unknown for 4 of the reported cases.

2 - "Other" includes American Indian/Alaska Native, Asian, Native Hawaiian/Pacific Islander, and multiracial. 

* - Rate based on less than 20 cases and should be considered unstable.