PART I (time to completion: 5 minutes)
The investigators concluded that the misting device was the source of aerosols that caused the outbreak. They were reluctant to publish the results until the laboratory was able to demonstrate that viable Legionella could be isolated from aerosols produced by the machine. This was expected to take several weeks. In mid-December, the machine was removed from grocery store A and sent to CDC for further study. Since it was apparent that other mist machines were likely to be contaminated with Legionella, the Food and Drug Administration (FDA) was notified. The FDA developed guidelines for maintaining these mist machines. In early January, the Bogalusa newspaper printed the first article about the outbreak, without knowing its cause. This story was quickly picked up by the New Orleans paper and national news services. Soon, Bogalusa was overrun by reporters wanting to find out the cause of the outbreak. They focused their attention on the paper mill in the center of town, and demanded to know the culture results from the cooling towers.
The Louisiana state health department issued a press release and an electronic mail notification message to other health officials describing the mist machine findings. Grocery industry officials were notified about the potential problem in trade newspapers and at meetings. The electronic mail message became public and was widely quoted in newspaper articles.
The type of misting device implicated in the outbreak was new to the grocery industry. These misters produced a visible fog that attracted shoppers, but had no other practical use. They did not help to preserve produce. The health department received reports of similar types of machines used in other settings, such as amusement parks and indoor aquariums. The findings were published in CDC's weekly bulletin, the Morbidity and Mortality Weekly Report (MMWR), after laboratory staff were able to isolate Legionella organisms from aerosols produced by the machine. Subsequent publication of findings in the Journal of Infectious Diseases was used to reach an even wider audience of health care professionals and to ensure that physicians specializing in the treatment of Legionnaires' disease and other infectious diseases were aware of this previously unrecognized vehicle for transmission of Legionella.
This lesson was reformatted from the Centers for Disease Control site [http://www.cdc.gov/excite/index.htm]
References