Muguku Peter Wachira, Odhiambo Fredrick, Sang James, Sigei Emmanuel, Khalayi Lydia, Abade Ahmed M
Kenya Field Epidemiology and Training Program (K-FELTP), Nairobi, Kenya.
Division of National Malaria Control Program (NMCP), Nairobi, Kenya.
Am J Trop Med Hyg. 2025 May 6;113(1):49-56. doi: 10.4269/ajtmh.24-0681. Print 2025 Jul 2.
Malaria epidemiology in Kenya is heterogeneous because of geographic and climatic differences. Semi-arid and arid zones are prone to seasonal increases in malaria cases above expected levels after rainy seasons, leading to malaria outbreaks. In November 2023, Marsabit County experienced a 155% increase in rainfall above its monthly average. The malaria surveillance system detected a 345% increase in cases, rising from 210 during Epiweek 1 to Epiweek 6 of the previous year to 934 in 2024. An outbreak investigation was conducted to guide prevention and control efforts. We reviewed routine surveillance data from December 2023 to February 2024, abstracted data from 12 facilities that surpassed action thresholds (5-year weekly median + third quantile), conducted data quality assessments, and conducted two community-focused group discussions. The data were analyzed as frequencies and proportions. Of the 757 malaria cases abstracted, the median age was 17 years (interquartile range: 10-28 years), with 227 cases (30.0%) in individuals aged 10-20 years. Males accounted for 424 cases (56.0%), 421 cases (55.6%) were tested using Plasmodium falciparum (P. falciparum)-specific rapid diagnostic tests, and 44.4% were tested using microscopy. Among the cases identified via microscopy tests, 94.9% involved P. falciparum, 2.7% involved Plasmodium vivax, and 2.4% involved Plasmodium ovale. There were 90 cases (11.9%) of severe malaria and three deaths. The reporting accuracy was 90% for a third of the facilities, and the completeness of monthly summaries was 39%. Potential exposures reported by the community included proximity to a national park, proximity to stagnant water, and sleeping outside during herding. The outbreak was predominantly due to P. falciparum malaria but also involved non-falciparum malaria, with most cases occurring in males aged 10-20 years. We recommend the continuous monitoring of malaria species to improve malaria surveillance.
由于地理和气候差异，肯尼亚的疟疾流行病学情况各不相同。半干旱和干旱地区在雨季过后，疟疾病例往往会季节性增加，超过预期水平，从而导致疟疾暴发。2023年11月，马萨比特县降雨量比月平均水平增加了155%。疟疾监测系统检测到病例增加了345%，从前一年流行周第1周的210例增至2024年流行周第6周的934例。开展了一次疫情调查以指导预防和控制工作。我们审查了2023年12月至2024年2月的常规监测数据，从12家超过行动阈值（5年每周中位数+第三四分位数）的医疗机构提取了数据，进行了数据质量评估，并开展了两次以社区为重点的小组讨论。数据按频率和比例进行分析。在提取的757例疟疾病例中，中位年龄为17岁（四分位间距：10 - 28岁），10至20岁的个体中有227例（30.0%）。男性占424例（56.0%），4个21例（55.6%）使用恶性疟原虫特异性快速诊断检测进行检测，44.4%使用显微镜检测。在通过显微镜检测确诊的病例中，94.9%为恶性疟原虫感染，2.7%为间日疟原虫感染，2.4%为卵形疟原虫感染。有90例（11.9%）为重症疟疾，3例死亡。三分之一的医疗机构报告准确率为90%，月度总结的完整性为39%。社区报告的潜在暴露因素包括靠近国家公园、靠近积水以及放牧时睡在户外。此次疫情主要由恶性疟原虫疟疾引起，但也涉及非恶性疟原虫疟疾，大多数病例发生在10至20岁的男性中。我们建议持续监测疟疾病种以改善疟疾监测。
