Current Trends Human Arboviral Encephalitis -- United
States, 1982
In 1982, 185 laboratory-confirmed cases of human arboviral
encephalitis* were reported from 23 states (Figure 2); at least
four
cases were fatal. This is a 48% increase from the 125 cases
reported
in 1981, but is far below the peak of 2,113 cases reported in 1975
(Table 1).
California encephalitis (CE) accounted for 130 (70%) of all
encephalitis cases. Ohio reported the greatest number, 37,
followed
by Wisconsin with 29. No fatalities were reported. CE cases were
concentrated in the eastern United States, with most occurring in
the
Great Lakes area. Jamestown Canyon virus, a member of the CE virus
complex, was confirmed by the New York State Laboratories as the
etiologic agent producing encephalitis in an elderly population.
St. Louis encephalitis (SLE) virus, which caused 34 (18%)
cases,
was the second most commonly occurring etiologic agent. Most SLE
cases were reported from Texas (14), Mississippi (eight), and
Louisiana (four); Illinois and the southeastern states reported the
others. At least two cases were fatal, but information on the
clinical results of eight cases is not yet available.
Five states reported 12 eastern equine encephalitis (EEE)
cases;
two (17%)--one each in Florida and Georgia--were fatal. The
largest
number of cases (four) occurred in Georgia, and these were
concentrated in the southern part of the state.
Nine cases of western equine encephalitis were reported during
1982, all in the western United States, and no fatalities were
reported. Texas reported the largest number of cases (four).
Temporal distribution of encephalitis cases for which onset
dates
were provided is shown in Figure 3. Most cases (86%) occurred from
July through September; no cases with onset after October have been
reported. These data are consistent with periods of peak vector
density. Age and sex distribution of encephalitis patients in 1982
were typical of previous years, with SLE and EEE cases occurring in
the young and elderly age groups, CE cases affecting mainly young
age
groups, and males (64%) affected more frequently by all types than
females (Table 2).
A major epizootic of EEE involving pheasants, quail, and
several
hundred horses occurred on the East and Gulf coasts during the
summer
months. Reported WEE cases in horses were sporadic in the west.
Reported by Div of Vector-Borne Viral Diseases, Center for
Infectious
Diseases, CDC.
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