Virus meningo-encephalitis in Austria. I. Epidemiological features.

This paper reports on an epidemiological study of 304 cases of virus meningo-encephalitis hospitalized at the Neurological Clinic at Graz during the 1953 epidemic in Styria, Austria. The epidemic showed a distinct seasonal periodicity, with an increase in the number of new cases during the period June-September; the monthly percentage of paralytic and encephalitic cases was, however, lowest in July and August. While no epidemic centre could be distinguished, 78% of all patients came from rural, usually wooded, areas. The maximum morbidity occurred between the ages of 11 and 30 years. The severity of the disease increased with age, save for the group 1-10 years old.A history of insect bites was noted in a large proportion of patients, one-third reporting tick bites, and many others, mosquito bites. The author finds both the period of incubation of the illness and the chain of infection to be very variable; there appeared to be cases caused by family contact, possibly through droplet- or dust-borne infection, and a possibility of infection through foodstuffs.But for fatigue, concomitant illness or injury, and other precipitating factors, some cases might have been abortive; such factors also appear to determine the severity of the illness.