Meningococcal infections in England and Wales: 1994.

One thousand one hundred and twenty-nine isolates of Neisseria meningitidis from cases of invasive disease were submitted to the PHLS Meningococcal Reference Unit in 1994, a fall of 13% from the total of 1297 in 1993. One hundred and seventy-four cases were diagnosed serologically, making 1303 laboratory ascertained cases, compared with 1368 in 1993. The overall fall of 4% was similar to the 5% fall in notifications to the Office of Population Censuses and Surveys. The seasonal increase between the third and fourth quarters of the year was less apparent than usual in 1994, when a higher proportion of cases occurred during the summer months. Regional rates of infection varied, notably in the proportions of group C infections, which were highest in the south east. DNA based typing techniques have clarified the characterisation of previously non-typable organisms. B4PI.4 has been identified as a recently emergent strain, which is now responsible for a quarter of all group B infections. Considerable regional variation was observed in the use of serodiagnosis. The monthly distribution of cases diagnosed serologically was similar to that of cases confirmed by isolation, but the age profile was skewed towards older patients.