Kleynhans Jackie, Treurnicht Florette Kathleen, Cohen Cheryl, Vedan Theesan, Seleka Mpho, Maki Lwando, von Gottberg Anne, McCarthy Kerrigan, Ramkrishna Wayne, McMorrow Meredith, Walaza Sibongile
Centre for Respiratory Diseases and Meningitis (CRDM), National Institute for Communicable Diseases (NICD) of the National Health Laboratory Service (NHLS), Johannesburg, South Africa.
South African Field Epidemiology Training Programme (SA-FETP), NICD of the NHLS, Johannesburg, South Africa.
Pan Afr Med J. 2019 May 21;33:42. doi: 10.11604/pamj.2019.33.42.16666. eCollection 2019.
We investigated an outbreak of influenza-like illness (ILI) at a boarding school in Eastern Cape Province, South Africa. We aimed to confirm the etiological agent, estimate attack rates and identify risk factors for illness.
We conducted a retrospective cohort study including senior school boarders (n=308). Students with ILI (cough and fever) were identified through school medical records. We also conducted a questionnaire-based cross-sectional study among senior students including boarders (n=107) and day students (n=45). We collected respiratory specimens for respiratory pathogen testing by real-time polymerase chain reaction from a subset of symptomatic students. We calculated attack rates of medically attended ILI (medILI) and identified factors associated with medILI using logistic regression. We calculated seasonal influenza vaccine effectiveness (VE) against medILI.
Influenza A (H3N2) virus was detected in 61% (23/38) of specimens. Attack rate for medILI was 13% among boarders (39/308) in the cohort study and 20% in both day students (9/45) and boarders (21/107) in the cross-sectional study. Playing squash was associated with medILI (aOR 5.35, 95% confidence interval [95% CI]: 1.68-17.07). Of the boarders, 19% (57/308) were vaccinated before the outbreak. The adjusted VE against medILI was 18% (aOR 0.82, 95% CI 0.38-1.78). The outbreak led to cancellation of several events and the need for academic remedial sessions.
We confirmed an influenza A (H3N2) virus outbreak with a high attack rate. The outbreak affected academic and sports activities. Participation in sports and social gatherings while experiencing ILI should be discouraged to reduce viral transmission and impact on school activities.
我们对南非东开普省一所寄宿学校爆发的流感样疾病（ILI）进行了调查。我们旨在确认病原体，估计发病率并确定患病的风险因素。
我们进行了一项回顾性队列研究，纳入了高中寄宿生（n = 308）。通过学校医疗记录识别出患有ILI（咳嗽和发热）的学生。我们还对包括寄宿生（n = 107）和走读生（n = 45）在内的高年级学生进行了基于问卷的横断面研究。我们从一部分有症状的学生中采集呼吸道标本，通过实时聚合酶链反应进行呼吸道病原体检测。我们计算了就医的ILI（medILI）发病率，并使用逻辑回归确定与medILI相关的因素。我们计算了季节性流感疫苗对medILI的有效性（VE）。
在61%（23/38）的标本中检测到甲型（H3N2）流感病毒。在队列研究中，寄宿生中medILI的发病率为13%（39/308），在横断面研究中，走读生（9/45）和寄宿生（21/107）中的发病率均为20%。打壁球与medILI相关（调整后的比值比[aOR] 5.35，95%置信区间[95%CI]：1.68 - 17.07）。在寄宿生中，19%（57/308）在疫情爆发前接种了疫苗。针对medILI的调整后VE为18%（aOR 0.82，95%CI 0.38 - 1.78）。此次疫情导致多项活动取消，并需要进行学业辅导课程。
我们确认了一次甲型（H3N2）流感病毒爆发，发病率很高。此次疫情影响了学术和体育活动。应避免在患ILI时参加体育和社交聚会，以减少病毒传播及对学校活动的影响。
