Objective: To investigate the clinical and epidemiological characteristics of influenza A (H3N2) infected patients in Jinhua area, and therefore to improve the understanding of infection with H3N2 influenza virus. Methods: The pharynx swab specimens for pathogenic detection were collected from acute respiratory infection (ARI) cases in the fever clinic of the sentinel hospital in Jinhua area from 2014 to 2017. Descriptive statistics method was used to analyze the clinical features and pathogenics characteristics of the patients infected with H3N2 influenza virus. The t test or χ(2) test of independent samples were used for comparison between groups. Results: A total of 3 803 cases of acute respiratory infection (ARI) were reported in the sentinel hospital in Jinhua area from 2014 to 2017. Among them, 245 cases (6.4%) of H3N2 influenza were diagnosed, including 153 males (62.4%) and 92 females (37.6%), aged from 0.5 to 95 years, with an average age of (50.1+15.7) years. They were divided into 5 age groups, with 107 (43.7%) patients aged 60 years and older. The incidence of major diseases was 43.7%. There was no significant difference in the gender in different age groups (χ(2)=4.581, P=0.333). The seasonal peak of H3N2 influenza A virus infection was mainly in summer (In June-September), but was also seen in other months. In the 4 years from 2014 to 2017, there were a total of 4 peaks, which occurred in July-September, July-August, June-August, and June-August. The body temperature of most patients (73.1%) was between 38.0 and 38.9 ℃. The main positive signs of H3N2 influenza A virus infection were different degrees of pharyngeal hyperemia and tonsillar enlargement. Fever (>38 ℃), cough, dizziness, fatigue, sore throat, headache, chills, shortness of breath, runny nose, myalgia, expectoration, nasal congestion were the main symptoms of H3N2 cases. The proportion of abnormal X-ray/CT manifestations in H3N2 influenza A virus infection cases was lower than that of other influenza viruses. 89.8% of the patients were positive for H3N2 influenza A. The average lymphocyte count was (1.1±0.5) × 10(9)/L, total platelet count (157±39) × 10(9)/L in H3N2 influenza A infection group, which were lower than those in other influenza positive patients [(1.2±0.6)×10(9)/L and (165±42) × 10(9)/L], while the neutrophil count (3.6±0.8) × 10(9)/L was higher than that in other influenza positive patients (3.4±1.0) × 10(9)/L(all P<0.05). Conclusions: Patients with H3N2 influenza A in Jinhua mostly presented with throat congestion and tonsillar enlargement in varying degrees, fever (>38 ℃), cough and sputum production. The seasonal peak of influenza A was in summer (June-September). Elderly aged 60 years or older were the susceptible group.
目的： 分析H3N2甲型流感患者的临床特点与流行病学特征。 方法： 收集2014年1月至2017年12月浙江省金华地区哨点医院发热门诊就诊的急性呼吸道感染病例，采集咽拭子标本进行病原学检测，对H3N2甲型流感患者的临床特点及发病特征进行描述性分析，并与流感病毒阴性组进行对比。组间比较采用独立样本t检验或χ(2)检验。 结果： 2014—2017年浙江省金华地区哨点医院共报告急性呼吸道感染病例3 803例，其中实验室确诊H3N2甲型流感病例245例（6.4%）。245例中，男153例，女92例；年龄0.5~95.0岁，平均（50.1±15.7）岁，分为5个年龄段：0.5~17.0岁59例，男35例，女24例；18~39岁36例，男25例，女11例；40~59岁43例，男22例，女21例；60~79岁48例，男30例，女18例；≥80岁59例，男41例，女18例。不同年龄段H3N2病例的性别构成比较差异无统计学意义（χ(2)=4.581，P=0.333）。H3N2甲型流感的发病季节高峰主要集中在夏季（6—9月），其余月份均呈散发状态；2014—2017年4年间共出现4个发病高峰，分别出现在7—9、7—8、6—8和6—8月。245例中，179例（73.1%）的体温在38.0~38.9 ℃，表现为不同程度的咽部充血和扁桃体肿大、发热、咳嗽、咳痰、头晕、疲乏、咽痛、头痛、恶寒、气促、流涕、肌痛及鼻塞。H3N2甲型流感患者的淋巴细胞计数平均为（1.1±0.5）× 10(9)/L，血小板平均为（157±39）×10(9)/L，低于其他流感病毒阳性患者的（1.2±0.6）和（165±42）×10(9)/L；中性粒细胞计数为（3.6±0.8）×10(9)/L，高于其他流感病毒阳性患者的（3.4±1.0）×10(9)/L（均P<0.05）。X线胸片或胸部CT表现为不规则、分布广泛的斑片状阴影等。 结论： H3N2流感的临床表现为不同程度的咽部充血和扁桃体肿大、发热、咳嗽及咳痰等；发病季节高峰主要集中在夏季（6—9月）；60岁及以上老年人为易感人群。.
Keywords: Epidemiology; Influenza A virus; Influenza, human.