EPIDEMIC LISTERIOSIS - OBSERVATION OF 25 CASES DURING 15 MONTHS AT THE VAUDOIS-UNIVERSITY-MEDICAL-CENTER

  • 1 January 1985
    • journal article
    • research article
    • Vol. 115  (1) , 2-10
Abstract
A total of 25 cases (14 adults, 11 neonates) of Listeria monocytogenes infection were observed during a 15-mo. period (1983/1984) at the University Medical Center (CHUV) in Lausanne (Switzerland), in contrast to a mean of only 3 cases/yr during the period 1974-1982. Eleven of 14 adults had neuromeningeal disease (3 meningitis, 7 meningoencephalitis, 1 encephalitis) and 3 patients had septicemia, 2 of whom were pregnant women. Among 8 adults with CNS parenchymal infection, 6 had involvement of the brainstem (rhombencephalitis), none of whom had an underlying disease characteristically predisposing to L. monocytogenes infection. Prominent clinical features in all patients with neuromeningeal disease included altered consciousness, headache and fever, and in 7 out of 8 patients with parenchymal. CNS involvement an influenza-like illness was present prior to the development of neurological symptoms. Among the neuromeningeal cases the mortality rate was 45% (5 of 11), and 4 of 6 survivors had severe neurological sequelae. During this 15-mo. period L. monocytogenes had become the leading cause of adult bacterial meningitis in this hospital. This is the first report on epidemic listeriosis in Switzerland, although sporadic cases have been described for 20 yr. In contrast to previous years, a peak of L. monocytogenes infections during the winter months of 1983/1984 was found. The high incidence of human listeriosis was not associated with an increase in animal cases. The human cases were uniformly distributed over the area. Neither the source of infection nor its route of spread was identified. The tendency of the infection to involve younger and previously healthy patients remains unexplained. Of the L. monocytogenes strains isolated in this and surrounding hospitals during the outbreak 95% (38/40) belonged to the serotype 4b, compared to only 60% (9/15) of the strains isolated prior to this outbreak (between 1977 and 1982) in the same area. Phage determination of the 1983-1984 4b-strains showed that 92% (33/36) had the same lysotype, in contrast to only 44% (4/9) of the strains of type 4b isolated prior to 1983. This observation may indicate a common source of the outbreak.