Parasitic Diseases Branch, Division of Parasitic Diseases and Malaria, US Centers for Disease Control and Prevention, Atlanta, GA, USA; Guinea Worm Eradication Program, The Carter Center, Atlanta, GA, USA.
Biology Department, Vassar College, Poughkeepsie, NY, USA.
Lancet Microbe. 2022 Feb;3(2):e105-e112. doi: 10.1016/S2666-5247(21)00209-3. Epub 2021 Nov 23.
Dracunculiasis (also known as Guinea worm disease), caused by the Dracunculus medinensis nematode, is progressing towards eradication, with a reduction in cases from 3·5 million cases in the mid-1980s to only 54 human cases at the end of 2019. Most cases now occur in Chad. On April 19, 2019, a 19-year-old woman presented with D medinensis in an area within the Salamat region of Chad, where the disease had not been previously reported. We aimed to investigate the connection between this case and others detected locally and elsewhere in Chad using a combination of epidemiological and genetic approaches.
In this cross-sectional field study, we conducted household case searches and informal group interviews in the Bogam, Liwi, and Tarh villages in Chad. All community members including children were eligible for participation in the outbreak investigation. Adult female D medinensis associated with this outbreak were collected for genetic analysis (18 from humans and two from dogs). Four mitochondrial genes and 22 nuclear microsatellite markers were used to assess relatedness of worms associated with the outbreak in comparison with other worms from elsewhere in Chad.
Between April 12 and Sept 6, 2019, we identified 22 human cases and two canine cases of dracunculiasis associated with 15 households. Six (40%) of the 15 affected households had multiple human or canine cases within the household. Most cases of dracunculiasis in people were from three villages in Salamat (21 [95%] of 22 cases), but one case was detected nearly 400 km away in Sarh city (outside the Salamat region). All people with dracunculiasis reported a history of consuming fish and unfiltered water. Worms associated with this outbreak were genetically similar and shared the same maternal lineage.
Molecular epidemiological results suggest a point-source outbreak that originated from a single female D medinensis, rather than newly identified sustained local transmission. The failure of the surveillance system to detect the suspected canine infection in 2018 highlights the challenge of canine D medinensis detection, particularly in areas under passive surveillance. Human movement can also contribute to dracunculiasis spread over long distances.
The Carter Center.
麦地那龙线虫病（又称几内亚线虫病）由麦地那龙线虫引起，该病的病例正在减少，从 20 世纪 80 年代中期的 350 万例减少到 2019 年底的仅 54 例。目前大多数病例发生在乍得。2019 年 4 月 19 日，一名 19 岁妇女在乍得萨拉马特地区的一个以前未报告过该病的地区出现麦地那龙线虫感染。我们旨在通过结合流行病学和遗传学方法，调查该病例与当地和乍得其他地方发现的其他病例之间的联系。
在这项横断面现场研究中，我们在乍得的 Bogam、Liwi 和 Tarh 村庄进行了家庭病例搜索和非正式群体访谈。所有社区成员，包括儿童，都有资格参与疫情调查。从与此次疫情相关的成年女性麦地那龙线虫中采集样本进行遗传分析（人类样本 18 例，狗样本 2 例）。我们使用 4 个线粒体基因和 22 个核微卫星标记来评估与此次疫情相关的蠕虫与乍得其他地方的其他蠕虫之间的亲缘关系。
2019 年 4 月 12 日至 9 月 6 日，我们共发现与 15 个家庭相关的 22 例人类病例和 2 例犬病例。在受影响的 15 个家庭中，有 6 个（40%）家庭中有多个人类或犬类病例。在人类中，大多数麦地那龙线虫病例来自萨拉马特的三个村庄（22 例病例中的 21 例），但在近 400 公里外的 Sarh 市（萨拉马特地区外）发现了 1 例病例。所有患有麦地那龙线虫病的人都有食用鱼类和未经过滤的水的历史。与此次疫情相关的蠕虫在遗传上相似，具有相同的母系血统。
分子流行病学结果表明，此次疫情是由单一雌性麦地那龙线虫引起的点状暴发，而不是新发现的持续局部传播。2018 年监测系统未能发现疑似犬感染，这突出了犬感染麦地那龙线虫检测的挑战，尤其是在被动监测地区。人类的流动也可能导致麦地那龙线虫病远距离传播。
卡特中心。
