An outbreak investigation of a Maine poultry vaccine facility concluded last week that a spill infected about a third of the facility's 74 employees with salmonella poisoning, according to a notice on ProMED-mail, an information service of the International Society for Infectious Diseases.

The notice, also published in the CDC's Mortality and Morbidity Weekly Report, said that the state's Department of Health and Human Services started an investigation after two cases of salmonellosis were reported within two weeks last November and were easily traced back to an overflow of about 1.5 liters of liquid containing S. enteritidis in the plant's fermentation room. An employee cleaned up the spill with 5 percent bleach and a disinfectant, then brought the mop to another room to be autoclaved and thrown away. Investigators noted that working in this second room correlated strongly with getting ill. They also noted that facility had no established spill clean-up procedures and that employees had less than ideal practices in handwashing and wearing protective gear.

"The issues related to this cluster seem overtly clear. A laboratory accident results in a spill, and an inadequately documented clean-up together with poor infection control practices among the workers resulted in the outbreak of cases," a ProMED-mail moderator wrote in the Email bulletin. Although none of the employees appear to have suffered anything more than a mild case of the runs, the case may be just one more reminder of how easily accidents happen and how difficult their effects may be to contain.