Legionnaire's Disease is an infection caused by the Legionella pneumophilia bacterium which manifests as a severe type of pneumonia. The disease was first identified in the United States in 1976--and was subsequently named--when more than 200 Legionnaires participating in America's bicentennial celebrations in Philadelphia became ill. Thirty-four of those infected died. Authorities were at a loss to identify the cause. Only after prolonged and intenseinvestigations did researchers discover a previously unidentified bacteria which they believe was introduced into the air conditioning system through contaminated water supply. The disease is contracted through airborne transmission of the bacteria and progresses rapidly. Because it proves fatal in approximately 15-25% of reported cases, hospitalization is recommended in almost allinstances.
Following identification of the Legionella bacterium, it is now known that the outbreak of a disease in Pontiac, Michigan in 1968, named "Pontiac Fever,"was caused by the same species, as were outbreaks elsewhere which had previously gone unidentified. It is also believed to be the primary cause of atypical pneumonia in hospitalized patients and the second largest cause of bacterial pneumonia in the general public. The Center for Disease Control (CDC) recorded 1,241 cases in 1995, or an incidence of 0.48 in every 100,000 people. However, authorities believe more than 20,000 cases may occur in the United States annually. Reports of the disease have come from Africa, Australia, Europe,and North and South America and, while it is no respecter of race or sex, the mortality rate increases with the age of the patient and appears higher inmales. Cases reported in people younger than 35 are 0.1 of 100,000, the meanage of reported cases is 52.7 years, and there is an increased frequency to the age of 79. People at high risk are people who use ventilators, the middle-aged, those with diabetes, cancer, AIDS, end-stage kidney disease, or other immunosuppressing factors such as alcoholism or those receivingchemotherapeutic or steroidal medications.
Legionella pneumophilia bacteria survive, thrive, and multiply in the warm, moist conditions found in air conditioning cooling towers, showers, decorativefountains, humidifiers, respiratory therapy equipment, and whirlpool spas. Legionnaire's disease appears more prevalent in the summer, and more so in August, and is slightly more common in the Northern United States than elsewhere. The incubation period ranges from two to 10 days. Symptoms usually begin with one or two days of mild head and body aches, joint pain, and loss of energy, followed by high fever--up to 104 of chills, rigors, shortness of breath,chest pain, diarrhea, lack of coordination, a dry cough which often progresses to coughing up sputum and/or blood, and--on occasion seizures. Inflammationof the upper respiratory tract is uncommon, which is a helpful indicator indiagnosis. Treatment consists of antibiotics, which should begin as soon as the disease is suspected, and supportive inpatient treatment with fluids, electrolyte replacement, and oxygen administered by mask or, in sever cases, mechanical ventilator. The disease is not transmitted through person-to-person contact, and recovery usually leaves no chronic complications.