Update: Outbreak of Acute Febrile Illness Among Athletes Participating in Eco-Challenge-Sabah 2000—Borneo, Malaysia, 2000

THIS REPORT SUMMARIZES INFLUENZA ACtivity in the United States during November 26, 2000-January 13, 2001. 1 Influenza activity was low to moderate but increasing in the United States.Since October 1, the most frequently isolated viruses were influenza A (H1N1) and were well matched antigenically with the 2000-01 influenza A (H1N1) vaccine strain.During October 1, 2000-January 13, 2001, World Health Organization collaborating laboratories and National Respiratory and Enteric Virus Surveillance System laboratories in the United States tested 26,789 specimens for influenza: 1545 (6%) were positive.Of these, 1132 (73%) were influenza A and 413 (27%) were influenza B. Of the 1132 influenza A isolates collected, 457 (40%) have been subtyped: 441 (96%) were A (H1N1) and 16 (4%) were A (H3N2).Of the 56 influenza A (H1N1) isolates characterized antigenically at CDC, 53 (95%) were A/New Caledonia/ 20/99-like (H1N1) viruses, the H1N1 component of the 2000-01 vaccine strain, and three (5%) were A/Bayern/ 07/95-like (H1N1) viruses.The A/New Caledonia/20/99 vaccine strain produces high titers of antibody that are cross-reactive to A/Bayern/07/95-like (H1N1) viruses. 2 Ten influenza A (H3N2) viruses and 20 influenza B viruses were characterized; all were similar antigenically to vaccine strains A/Panama/2007/99 (H3N2) and B/Beijing/184/93, respectively.The percentage of positive influenza infections, an important indicator of influenza activity, increased from 4% during the week ending November 25 to 15% during the week ending January 13.During November 6, 2000-January 13, 2001, 2%-3% of patient visits to U.S. sentinel physicians were for influenzalike illness (ILI).* During the week ending January 13 (week 2), patient visits for ILI were at baseline levels (0-3%) in seven of nine surveillance regions.Levels were above baseline in the Pacific (6%) and West South Central (4%) regions.During the same week, widespread † influenza activity was reported in Rhode Island and Virginia, and regional activity was reported in 21 states (Alabama, Arizona, Colorado, Connecticut, Idaho, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Minnesota, Mississippi, Nevada, North Carolina, Oregon, Tennessee, Texas, Utah, Washington, and Wyoming); 26 states reported sporadic activity, and one state did not report.The 122 Cities Mortality Reporting System attributed 7.7% of recorded deaths to pneumonia and influenza (P&I).This percentage was below the epidemic threshold ‡ of 8.5% for week 2. The percentage of P&I deaths has remained below the epidemic threshold for each week since October 1. Reported by: Participating state and territorial epidemiologists and state public health laboratory directors.WHO collaborating laboratories.National Respiratory and Enteric Virus Surveillance System laboratories.Sentinel Physicians Influenza Surveillance System.Surveillance Systems Br, Div of Public Health Surveillance and Informatics, Epidemiology Program Office; Mortality Statistics Br, Div of Vital Statistics, National Center for Health Statistics; WHO Collaborating Center for Reference and Research on Influenza, Respiratory and Enteric Virus Br, and Influenza Br, Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases; and an EIS Officer, CDC.*Temperature of Ͼ100.0°F (Ͼ37.8°C) and either cough or sore throat in the absence of a known cause.