Encephalitis surveillance annual summary : 1977

In 1977 a total of 1,536 cases of encephalitis, resulting in 171 deaths, were reported to the Center for Disease Control. This total is 16% less than the 1976 total and 29% less than the average total for the preceding 5 years. The average for the preceding 5 years was increased by the 4,308 case total of 1975, a major epidemic year for St. Louis encephalitis activity. Of the 9 geographic divisions in the United States, the East North Central had the most cases (467), but the highest attack rate was associated with the East South Central. Cases were reported to have occurred in all states except Maine, Nevada, Oregon, Vermont, and Wyoming. In 1977, as in each year except 1975, the majority of cases (70%) were of indeterminate etiology. Of the other cases with known etiology, the majority (52%) were associated with arboviral infection, including St. Louis encephalitis (132 cases), California (65 cases), western equine (41 cases), and eastern equine (1 case); the next largest group consisted of cases associated with childhood infections (26%), including chickenpox (43 cases), mumps (43 cases), measles (32 cases), and rubella (l case). Sixty-three cases associated with herpes simplex infection accounted for 14% of the cases with an established etiology. The other cases of determined etiology, accounting for less than 10%, included 17 cases involving enterovirus infection, 14 with herpes zoster, 5 with respiratory virus infections, and 3 with infectious mononucleosis.SUGGESTED CITATION: Center for Disease Control: Encephalitis Surveillance Annual Summary 1977, Issued December 1979197