By Kamaljit Singh

Accounts of highly infectious laboratory outbreaks should not read like a mystery novel. Sadly, in the absence of integrated reporting systems for laboratory-acquired illnesses, our investigations of such events can resemble a whodunit. The recent report of a multistate outbreak of Salmonella typhimurium infections offers a particularly disturbing example of how things can go wrong. In April, the US Centers for Disease Control and Prevention (CDC) reported that more than 70 individuals from 35 states had been infected with a particular strain of S. typhimurium, and at least ten people have been hospitalized with one death. Notably, almost two thirds of the infected individuals were either students in microbiology teaching laboratories or employees in clinical microbiology laboratories. As a result of the outbreak, the CDC appealed to members of the Association of Public Health Laboratories and the American Society of Microbiology through various electronic listservs for information about laboratory practices. But we can do better than this ad hoc approach.

An estimated 500,000 workers are employed in laboratories in the US, and an increasing number of these workers have chronic medical conditions or are on immunosuppressive therapy that may place them at increased risk of infection. Lab workers, including these subsets, face an increased risk of acquiring infectious agents by virtue of their jobs. However, the actual risk of a laboratory-acquired infection is difficult to accurately determine, as there is no systematic reporting protocol at either the state or the federal level. Current available data are limited to retrospective and voluntary surveys conducted via mail, anecdotal case reports, and outbreaks that happen to grab the attention of the scientific community or media.

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Kamaljit Singh is assistant director of clinical microbiology at Rush University Medical Center in Chicago.