Sightsavers Cameroon Country Office, Immeuble No 1067 bis Rue 1750 Nouvelle Route Bastos, P.O. Box 4844, Bastos, Yaoundé, Cameroon.
Sightsavers Ghana Country Office, The Elizabeth, No. 39, Senchi Link Airport Residential Area, P.O. Box 18190 KIA, Accra, Ghana.
BMC Infect Dis. 2024 Oct 14;24(1):1156. doi: 10.1186/s12879-024-10071-2.
This study examined onchocerciasis transmission in Kwanware and Ottou in the Wenchi Health District of Ghana, where persistent onchocercal microfilariae (mf) levels have been reported since 2012.
This study was conducted from 2019 to 2021 and involved the following: (i) reviewing past records of ivermectin mass drug administration (MDA); (ii) conducting a treatment coverage evaluation survey (CES); (iii) conducting key informant interviews; (iv) prospecting blackfly breeding sites; (v) collecting and dissecting blackflies; and (vi) conducting parasitological and serological surveys.
(i) The review indicated ongoing MDA treatment for the past 27 years, with a reported coverage of over 65% in the last 17 yearly rounds; (ii) estimated treatment coverage by the CES in 2019 was 71.3%, with most of those not taking medicine stating that they were not offered; (iii) however, the key informant interviews revealed insufficiencies in reaching a significant number of people for treatment due to remote settlement, mobility, transport logistical issues, failure to register some people for treatment, leading to a false impression of good coverage, and a short distribution time; (iv) the most productive breeding was found within 5 km of Kwanware-Ottou; and (v) blackfly daily biting rates were highest in Kwanware and Ottou, with 199 and 160 bites per day, respectively. Infection in blackflies was found only in Kwanware and Ottou, with infectivity rates of 5.9‰ (per 1000) and 6.7‰, respectively. (vi) The mf prevalence in Ottou and Kwanware, respectively, was 40.0% and 30.0% among adults aged ≥ 20 years, and the anti-(Onchocerca volvulus) Ov16 IgG4 antibodies seroprevalence rates were 8.3% and 13.3% among children aged 5-9 years. These values were reduced to undetectable levels at a radius of 10 km from Ottou.
This study confirms that active onchocerciasis transmission centres on Kwanware/Ottou and is confined to a 10 km radius despite 27 yearly treatment rounds. The main contributing factors are suboptimal coverage and high biting rates. Identifying and targeting such a focus with a combination of interventions will be cost-effective in accelerating onchocerciasis elimination in Ghana.
本研究考察了加纳温奇卫生区的 Kwanware 和 Ottou 中的盘尾丝虫病传播情况，自 2012 年以来，该地区一直报告存在持续的盘尾丝虫微丝蚴 (mf) 水平。
本研究于 2019 年至 2021 年进行，包括以下内容：（i）审查伊维菌素大规模药物治疗（MDA）的过去记录；（ii）进行治疗覆盖率评估调查（CES）；（iii）进行关键知情人访谈；（iv）探测采采蝇滋生地；（v）收集和解剖采采蝇；以及（vi）进行寄生虫学和血清学调查。
（i）审查表明，过去 27 年来一直在进行 MDA 治疗，在过去的 17 年中，报告的覆盖率超过 65%；（ii）2019 年 CES 估计的治疗覆盖率为 71.3%，大多数未服药的人表示他们没有得到治疗；（iii）然而，关键知情人访谈显示，由于偏远的定居点、流动性、运输后勤问题、未能为一些人登记治疗等因素，无法为相当数量的人提供治疗，导致覆盖率良好的假象，以及分配时间短；（iv）在 Kwanware-Ottou 附近 5 公里范围内发现了最具生产力的滋生地；（v）Kwanware 和 Ottou 的采采蝇日叮咬率最高，分别为 199 和 160 次/天。仅在 Kwanware 和 Ottou 发现了采采蝇感染，感染率分别为 5.9‰（每 1000 只）和 6.7‰。（vi）Ottou 和 Kwanware 分别为成年人年龄≥20 岁的 mf 患病率为 40.0%和 30.0%，儿童年龄为 5-9 岁的抗（盘尾丝虫） Ov16 IgG4 抗体血清阳性率分别为 8.3%和 13.3%。在距离 Ottou 半径 10 公里处，这些值降至无法检测到的水平。
本研究证实，尽管进行了 27 年的年度治疗，但 Kwanware/Ottou 仍然是活跃的盘尾丝虫病传播中心，范围限制在 10 公里半径内。主要促成因素是覆盖率不足和高叮咬率。通过联合干预措施确定并针对这种焦点将是加速加纳盘尾丝虫病消除的具有成本效益的方法。
