Uganda Public Health Fellowship Program - Field Epidemiology Track, Makerere University School of Public Health, P.O. Box 7072, Kampala, Uganda.
Uganda National Expanded Program on Immunization, Ministry of Health, Kampala, Uganda.
BMC Infect Dis. 2018 Jan 8;18(1):21. doi: 10.1186/s12879-017-2941-4.
In April 2015, Kamwenge District, western Uganda reported a measles outbreak. We investigated the outbreak to identify potential exposures that facilitated measles transmission, assess vaccine effectiveness (VE) and vaccination coverage (VC), and recommend prevention and control measures.
For this investigation, a probable case was defined as onset of fever and generalized maculopapular rash, plus ≥1 of the following symptoms: Coryza, conjunctivitis, or cough. A confirmed case was defined as a probable case plus identification of measles-specific IgM in serum. For case-finding, we reviewed patients' medical records and conducted in-home patient examination. In a case-control study, we compared exposures of case-patients and controls matched by age and village of residence. For children aged 9 m-5y, we estimated VC using the percent of children among the controls who had been vaccinated against measles, and calculated VE using the formula, VE = 1 - OR, where OR was the Mantel-Haenszel odds ratio associated with having a measles vaccination history.
We identified 213 probable cases with onset between April and August, 2015. Of 23 blood specimens collected, 78% were positive for measles-specific IgM. Measles attack rate was highest in the youngest age-group, 0-5y (13/10,000), and decreased as age increased. The epidemic curve indicated sustained propagation in the community. Of the 50 case-patients and 200 controls, 42% of case-patients and 12% of controls visited health centers during their likely exposure period (OR = 6.1; 95% CI = 2.7-14). Among children aged 9 m-5y, VE was estimated at 70% (95% CI: 24-88%), and VC at 75% (95% CI: 67-83%). Excessive crowding was observed at all health centers; no patient triage-system existed.
The spread of measles during this outbreak was facilitated by patient mixing at crowded health centers, suboptimal VE and inadequate VC. We recommended emergency immunization campaign targeting children <5y in the affected sub-counties, as well as triaging and isolation of febrile or rash patients visiting health centers.
2015 年 4 月，乌干达西部的卡姆文盖区报告了麻疹疫情。我们对该疫情进行了调查，以确定有助于麻疹传播的潜在接触源，评估疫苗有效性（VE）和疫苗覆盖率（VC），并提出预防和控制措施。
在本次调查中，将发热和全身性斑丘疹，加上以下至少 1 种症状的患者定义为疑似病例：卡他症状、结膜炎或咳嗽。将疑似病例且血清中检测到麻疹特异性 IgM 的患者定义为确诊病例。为了发现病例，我们查阅了患者的病历并对患者进行了家访。在病例对照研究中，我们将病例患者的暴露情况与按年龄和居住地匹配的对照进行了比较。对于 9 个月至 5 岁的儿童，我们使用对照中接受过麻疹疫苗接种的儿童百分比来估计 VC，并使用公式 VE = 1 - OR 来计算 VE，其中 OR 是与具有麻疹疫苗接种史相关的 Mantel-Haenszel 比值。
我们发现 2015 年 4 月至 8 月期间出现了 213 例疑似病例。采集的 23 份血标本中，有 78%为麻疹特异性 IgM 阳性。年龄最小的 0-5 岁组麻疹发病率最高（13/10000），随着年龄的增加而降低。流行曲线表明社区中持续传播。在 50 名病例患者和 200 名对照中，42%的病例患者和 12%的对照在可能的暴露期间就诊于卫生中心（OR = 6.1；95%CI = 2.7-14）。在 9 个月至 5 岁的儿童中，VE 估计为 70%（95%CI：24-88%），VC 估计为 75%（95%CI：67-83%）。所有卫生中心都观察到过度拥挤的现象；没有病人分诊系统。
麻疹在本次疫情中的传播是由于拥挤的卫生中心中病人的混合、VE 不理想和 VC 不足所致。我们建议在受影响的分区针对 <5 岁的儿童开展紧急免疫接种运动，并对到卫生中心就诊的发热或出疹患者进行分诊和隔离。
