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Influenza Virus Activity -- Texas, 1983-1984 Season

Analyses of reported cases of influenza, school absentee levels, and influenza virus isolates indicate that Texas experienced intense influenza activity in January and February 1984. The influenza epidemic was more severe, when measured by number of reported cases, than epidemics during the 1981-1982 and 1982-1983 seasons.

Cases of influenza are reported weekly by numeric totals to the Bureau of Epidemiology, Texas Department of Health, through a morbidity reporting system. This system encompasses over 500 reporting sources, including physicians, city and county health departments, and hospitals. Influenza viruses isolated in the state are reported through a virus surveillance system with 18 participating laboratories. A telephone surveillance system was used to ascertain levels of school absenteeism and operated from January through March 1984. Public school districts randomly chosen from an alphabetic listing were telephoned to determine total number of schools in the district, total enrollment at each school, and number absent at each school for each day of the epidemic. An absentee level of 10% or greater for any school on any day was considered positive evidence of influenza activity.

A total of 102,437 influenza cases were reported in February compared with fewer than 22,000 in February for each of the preceding 2 years. These 102,437 reported cases are the highest number of influenza cases reported to the Bureau of Epidemiology for any month since record collection began in 1920.

A total of 1,039 influenza viruses were isolated in Texas from November 1, 1983, through April 30, 1984. Seventy-two percent of these were isolated from specimens collected from January 22 through February 18 (weeks 4-7 of the epidemic). Influenza type A(H1N1) virus represented 50% of all influenza viruses reported. Influenza B and influenza A(H3N2) comprised 48% and 2%, respectively. In March, 82% of the influenza viruses reported were type B.

Two hundred forty-two districts, representing 903 schools in 209 counties, were contacted between January 2 and March 30. Over 40% of the 315 schools surveyed during January 22-February 18 experienced absentee levels greater than 10%; 9% had absentee levels greater than 20%. During January 29-February 4, 70% of the 79 schools surveyed had absentee levels above 10%. No districts contacted after March 11 reported a school with an absentee level of 10% or greater. Reported by WP Glezen, MD, Influenza Research Center, Baylor College of Medicine, Houston, JP Taylor, MPH, JN Perdue, Bureau of Epidemiology, CE Alexander, MD, State Epidemiologist, Texas Dept of Health.

Editorial Note

Editorial Note: This information from Texas documents the unusually high rate of influenza morbidity in association with widespread increases in school absenteeism in January and February and highlights at the state level the trends seen regionally and nationally during the past influenza season (1).


  1. CDC. Influenza--United States, 1983-1984 season. MMWR 1984;33:417-21.

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