Assessing the Risk of Laboratory-Acquired Meningococcal Disease

Abstract

Neisseria meningitidis is infrequently reported as a laboratory-acquired infection. Prompted by two cases in the United States in 2000, we assessed this risk among laboratorians. We identified cases of meningococcal disease that were possibly acquired or suspected of being acquired in a laboratory by placing an information request on e-mail discussion groups of infectious disease, microbiology, and infection control professional organizations. A probable case of laboratory-acquired meningococcal disease was defined as illness meeting the case definition for meningococcal disease in a laboratorian who had occupational exposure to an N. meningitidis isolate of the same serogroup within 14 days of illness onset. Sixteen cases of probable laboratory-acquired meningococcal disease occurring worldwide between 1985 and 2001 were identified, including six U.S. cases between 1996 and 2000. Nine cases (56%) were serogroup B; seven (44%) were serogroup C. Eight cases (50%) were fatal. All cases occurred among clinical microbiologists. In 15 cases (94%), isolate manipulation was performed without respiratory protection. We estimated that an average of three microbiologists are exposed to the 3,000 meningococcal isolates seen in U.S. laboratories yearly and calculated an attack rate of 13/100,000 microbiologists between 1996 and 2001, compared to 0.2/100,000 among U.S. adults in general. The rate and case/fatality ratio of meningococcal disease among microbiologists are higher than those in the general U.S. population. Specific risk factors for laboratory-acquired infection are likely associated with exposure to droplets or aerosols containing N. meningitidis. Prevention should focus on the implementation of class II biological safety cabinets or additional respiratory protection during manipulation of suspected meningococcal isolates.

Laboratory‐Acquired Serogroup A Meningococcal Meningitis

“…Laboratory-acquired meningococcal disease is infrequent but the risk appears to be underappreciated 6) . A case of laboratory-acquired meningococcal infection is defined as meningococcal disease in a laboratory worker who had laboratory exposure to a N. meningitidis isolate within 14 d before the onset of illness and who has illness with the serogroup that matches the source isolate [4][5][6] .…”

“…Boutet et al in Great Britain demonstrated that laboratory workers exposed to N. meningitidis are at significantly higher risk of developing infection than the general population 4) . Recently, these data were expanded 5,6) . A total of 16 cases were described in the literature since 1985, with six cases reported in the United States 5) .…”

“…A case of laboratory-acquired meningococcal infection is defined as meningococcal disease in a laboratory worker who had laboratory exposure to a N. meningitidis isolate within 14 d before the onset of illness and who has illness with the serogroup that matches the source isolate [4][5][6] . We report the first recent case of laboratory acquired serogroup A meningococcal disease infection.…”

“…Currently, N. meninigitidis is considered a biosafety level-II organism and CDC guidelines recommend using a biosafety cabinet when manipulating samples that have a high potential for droplet or aerosol production such as centrifuging, grinding and blending procedures and for activities involving production of quantities or concentrations 5,7) . Both microbiology and research laboratory workers handling meningococcal isolates should strongly consider vaccination with the quadrivalent meningococcal vaccine or quadrivalent meningococcal conjugate vaccine which includes serogroup A, C, Y and W-135 capsular polysaccharides [5][6][7][8] . Antibodies generated from vaccines, as opposed to conjugate vaccines, are usually not persistent, meningococcal polysaccharide therefore, revaccination should be considered 3-5 yr after receipt of the initial dose of meningococcal polysaccharide vaccine in persons with ongoing meningococcal exposure 6,18) .…”

“…Meningococci are usually transmitted from person to person through close contact with contaminated aerosols and secretions from the human nasopharynx. Laboratory-acquired infection has been reported infrequently but laboratory technicians are at increased risk [4][5][6] . Most of the reported cases of laboratory-acquired infections occur in clinical microbiology laboratories and have been due to serogroups B and C. For reasons that are unclear, the reported mortality of laboratory-acquired N. meningitidis sepsis or meningitis is ~50% 4,5) , which is higher than mortality from endemic infections.…”