1. General Information

1. General Information

Among the 2,021 cases, 1,420 were male, accounting for 70.3%; 601 were female, accounting for 29.7%. Age distribution: under 15 years old, 591 cases, accounting for 29.2%; 16–30 years old, 709 cases, accounting for 35.1%; 31–45 years old, 421 cases, accounting for 20.8%; 46–60 years old, 224 cases, accounting for 11.1%; over 60 years old, 76 cases, accounting for 3.8%. Occupations: workers, 722 cases, accounting for 35.7%; cadres, 678 cases, accounting for 33.5%; residents, 326 cases, accounting for 16.1%; students, 198 cases, accounting for 6.8%; military personnel, 97 cases, accounting for 4.8%. Months of onset: January–March, 217 cases, accounting for 10.7%; April–June, 458 cases, accounting for 22.7%; July–September, 1,022 cases, accounting for 50.7%; October–December, 324 cases, accounting for 16.0%. Family history: 721 cases, accounting for 35.7%; social contact history: 1,136 cases, accounting for 56.2%; history of blood transfusion, blood product use, vaccination, or injection: 164 cases, accounting for 8.1%.