Table 2. Most common aetiologies and outcome data in epidemiological studies on acute viral encephalitides

Study area and period	Group size	Specified (%)	Major aetiologies	Fatal outcome	Permanent disability	Recovery
Entire USA 1953-58 1	139	100 (72%)	20 arbovirus 22 mumps 13 HSV	10%	15%	75%
Olmsted County, USA 1950-81 2	189	29 (15%)	12 arbovirus 6 mumps 4 HSV	4%		78%
Glasgow, UK 1964-67 3	68	14 (20%)	12 HSV 1 measles 1 adenovirus	16%	10%	74%
London, UK 1963-78 4	60	12 (20%)	9 HSV 3 EBV 2 mumps	15%	28%	57%
Middle Hessia, Germany 1979-86 5	53	21 (39%)	9 HSV 4 VZV 3 adenovirus	30%	19%	51%
Helsinki, Finland 1945-63 6	108	19 (17%)	5 arbovirus 4 mumps 3 adenovirus	10%
Helsinki, Finland 1967-78 7	191	79 (41%)	24 HSV 13 mumps 7 coxsackie B	6%	22%	51%

References: 1) Meyer et al. 1960; 2) Beghi et al. 1984; 3) Miller and Ross 1968; 4) Kennard and Swash 1981;
5) Büttner and Dorndorf 1988; 6) Klemola et al. 1965; 7) Koskiniemi et al. 1981