An unusual transmission event of Neisseria meningitidis serogroup W135 type 2a in a healthcare setting, England, 2012.

We report an outbreak of Neisseria meningitidis sero-group W135, associated with a transient transmission event between asymptomatic individuals in a health-care setting. Two elderly persons subsequently developed invasive meningococcal disease. The duration and type of close contact for those directly involved in the probable transmission incident would not have warranted chemoprophylaxis according to current guidelines. Meningococcal infection in older persons usually presents with pneumonia rather than meningitis or septicaemia with purpura. We report a nosocomial outbreak of Neisseria menin-gitidis serogroup W135, phenotype 2a:P1.5, 2 associated with a transient transmission event between asymptomatic individuals in March 2012. Two elderly individuals admitted to the same hospital group (at different sites) presented within four days of each other with non-specific respiratory tract symptoms of infection. Initial microbiological analysis isolated N. menin-gitidis serogroup W135:2a:P1.5, 2 (porA genotype 5, 2, 36-2) from both patients' blood cultures. The identical microbiological phenotype/genotype of these isolates suggested an epidemiological link. The epidemiological investigation revealed that both patients had in the preceding weeks been admitted to different wards in the same hospital for unrelated illnesses, but had not been in contact with each other during that stay (admitted 19 and 16 days before the positive blood culture result, with stays of 10 and four days, respectively, for the initial admission). However, on the day of discharge, both were transported in the same hospital vehicle at the same time, one to a rehabilitation facility and the other to a care home. Both became ill with non-specific symptoms (however, respiratory infection was thought to be the most likely cause) within six and 10 days after transport, respectively. One patient remained at the rehabilitation unit for management of the disease and the other was read-mitted to hospital for treatment. Since the most likely epidemiological link between the two cases was the short transfer journey (duration 67 minutes), naso-pharyngeal swabs were obtained from the two staff members involved in the transport and another passenger who was on the vehicle at the same time as the cases, but for less than half an hour. One of the transport staff (in their 60s) was also found to be carrying serogroup W135:2a:P1.5, 2 (porA 5, 2, 36-2) and reported having had upper respiratory tract symptoms in the intervening period (symptom onset 16 days after the patient transport), but had not sought medical attention. The swabs from the second transport team member and the other passenger were …