Guidelines for the management of accidents involving microorganisms: a WHO memorandum.

The response to an emergency resulting from an accident involving microorganisms, whether in a laboratory or during needs to be graded according to the degree of hazard to human or animal health created by the circumstances of the accident and the properties of the organisms concerned. A categorization of microorganisms by risk groups is proposed for the purposes of accident management, and the factors influencing assignment to risk groups are described. Organizational responsibilities at government health authority and local levels are outlined and emphasis is placed on contingency planning. Medical surveillance is proposed for persons who work in laboratories with dangerous microorganisms, as a means of recognizing accidents that might otherwise go undetected. The response to exposure in a laboratory or transport-associated accident includes emergency safety measures at the site, hazard assessment, and action by the public health or veterinary authorities. The management of exposed persons is considered in relation to the immediate post-exposure period, the potential incubation period, and the onset of illness. Prophylactic treatment, surveillance, and the transport and isolation of infected persons are described. A distinction is drawn between the consequences of accidents recognized at the time of their occurrence and those that are only recognized by onset of illness in the exposed persons.