Kargbo-Labour Ibrahim, Bah Mohamed S, Melchers Natalie V S Vinkeles, Conteh Abdulai, Redwood-Sawyerr Victoria, Stolk Wilma A, Paye Jusufu, Sonnie Mustapha, Veinoglou Amy, Koroma Joseph B, Hodges Mary H, Weaver Angela M, Zhang Yaobi
National Neglected Tropical Disease Control Programme, Ministry of Health and Sanitation, Freetown, Sierra Leone.
Helen Keller International, Freetown, Sierra Leone.
Parasit Vectors. 2024 Mar 11;17(1):121. doi: 10.1186/s13071-024-06198-5.
Onchocerciasis is endemic in 14 of Sierra Leone's 16 districts with high prevalence (47-88.5%) according to skin snips at baseline. After 11 rounds of mass treatment with ivermectin with good coverage, an impact assessment was conducted in 2017 to assess the progress towards eliminating onchocerciasis in the country.
A cluster survey was conducted, either integrated with lymphatic filariasis (LF) transmission assessment survey (TAS) or standalone with the LF TAS sampling strategy in 12 (now 14) endemic districts. Finger prick blood samples of randomly selected children in Grades 1-4 were tested in the field using SD Bioline Onchocerciasis IgG4 rapid tests.
In total, 17,402 children aged 4-19 years in 177 schools were tested, and data from 17,364 children aged 4-14 years (14,230 children aged 5-9 years) were analyzed. Three hundred forty-six children were confirmed positive for Ov-16 IgG4 antibodies, a prevalence of 2.0% (95% CI 1.8-2.2%) in children aged 4-14 years with prevalence increasing with age. Prevalence in boys (2.4%; 95% CI 2.1-2.7%) was higher than in girls (1.6%; 95% CI 1.4-1.9%). There was a trend of continued reduction from baseline to 2010. Using data from children aged 5-9 years, overall prevalence was 1.7% (95% CI 1.5-1.9%). The site prevalence ranged from 0 to 33.3% (median prevalence = 0.0%): < 2% in 127 schools, 2 to < 5% in 34 schools and ≥ 5% in 16 schools. There was a significant difference in average prevalence between districts. Using spatial analysis, the Ov-16 IgG4 antibody prevalence was predicted to be < 2% in coastal areas and in large parts of Koinadugu, Bombali and Tonkolili Districts, while high prevalence (> 5%) was predicted in some focal areas, centered in Karene, Kailahun and Moyamba/Tonkolili.
Low Ov-16 IgG4 antibody prevalence was shown in most areas across Sierra Leone. In particular, low seroprevalence in children aged 5-9 years suggests that the infection was reduced to a low level after 11 rounds of treatment intervention. Sierra Leone has made major progress towards elimination of onchocerciasis. However, attention must be paid to those high prevalence focal areas.
盘尾丝虫病在塞拉利昂16个区中的14个区呈地方性流行，根据基线皮肤切片检查，流行率很高（47%-88.5%）。在进行了11轮覆盖良好的伊维菌素群体治疗后，2017年开展了一项影响评估，以评估该国在消除盘尾丝虫病方面取得的进展。
开展了一项整群调查，该调查要么与淋巴丝虫病（LF）传播评估调查（TAS）相结合，要么在12个（现14个）流行区采用LF TAS抽样策略单独进行。在现场使用SD Bioline盘尾丝虫病IgG4快速检测法对1-4年级随机挑选儿童的手指刺血样本进行检测。
总共对177所学校的17402名4-19岁儿童进行了检测，并分析了17364名4-14岁儿童（14230名5-9岁儿童）的数据。346名儿童被确诊为Ov-16 IgG4抗体阳性，4-14岁儿童中的流行率为2.0%（95%置信区间1.8%-2.2%），流行率随年龄增长而上升。男孩中的流行率（2.4%；95%置信区间2.1%-2.7%）高于女孩（1.6%；95%置信区间1.4%-1.9%）。从基线到2010年呈持续下降趋势。使用5-9岁儿童的数据，总体流行率为1.7%（95%置信区间1.5%-1.9%）。各地点的流行率范围为0至33.3%（中位流行率=0.0%）：127所学校<2%，34所学校为2%至<5%，16所学校≥5%。各地区的平均流行率存在显著差异。通过空间分析预测，沿海地区以及科伊纳杜古、邦巴利和通科利利区的大部分地区Ov-16 IgG4抗体流行率<2%，而在以卡伦、凯拉洪和莫扬巴/通科利利为中心的一些重点地区预测流行率较高（>5%）。
塞拉利昂大部分地区的Ov-16 IgG4抗体流行率较低。特别是，5-9岁儿童的血清流行率较低表明，经过11轮治疗干预后，感染已降至低水平。塞拉利昂在消除盘尾丝虫病方面取得了重大进展。然而，必须关注那些高流行重点地区。
