Effectiveness of Four Different Interventions Against Schistosoma haematobium in a Seasonal Transmission Setting of Côte d’Ivoire: A Cluster Randomized Trial

Abstract

Background Annual mass drug administration (MDA) using praziquantel is the cornerstone of schistosomiasis morbidity control, but is not sufficient to interrupt transmission. We implemented a cluster-randomized trial to compare the effectiveness of four different intervention packages to interrupt transmission of Schistosoma haematobium in a seasonal transmission setting of Côte d’Ivoire. Methods Sixty-four localities with a S. haematobium prevalence in school children aged 13-14 years above 4% were randomly assigned to one of four intervention arms over a 3-year period: (1) the current standard strategy consisting of annual MDA before peak of transmission; (2) annual MDA after peak of transmission; (3) biannual MDA; and (4) standard MDA combined with snail control. The primary outcome was prevalence and intensity of S. haematobium infection in children aged 9-12 years 1 year after the final intervention, using urine filtration performed by experienced microscopists. Results By study end, we observed the lowest S. haematobium prevalence in the biannual MDA, compared to the standard treatment arm (0.6% vs. 7.5%; odds ratio [OR] = 0.07, 95% confidence interval [CI] = 0.02 to 0.24). The prevalence in arms 2 and 4 was about 3.5%, which was not statistically significantly different from the standard strategy (both ORs 0.4, 95% CI = 0.1 to ~1.8). New cases of infection were still observed in all arms at study end. Conclusions Biannual MDA was the only regimen that outperformed the standard treatment. All strategies resulted in decreased prevalence of infection, however none of them was able to interrupt transmission of S. haematobium within a 3-year period.

Effects of paediatric schistosomiasis control programmes in sub-Saharan Africa: A systematic review

“…mansoni (n = 10) and both species (n = 8) respectively. Schistosomiasis control strategies were predominantly MDA only in 24 studies and one study each on WASH only [ 19 ]; MDA and WASH [ 20 ]; MDA and snail control [ 21 ]; MDA, behaviour change and snail control [ 22 ]; education and behaviour change [ 23 ]; and MDA and education [ 24 ]. In terms of the diagnostics techniques applied, the majority of studies utilised Kato Kats (n = 10) followed by urine filtration (n = 9); a combination of Kato Katz and urine filtration (n = 6); reagent strips and urine filtration (n = 1) and one study each in Kato Katz and PCR; Kato Katz and ultrasonography; and urine filtration, ELISA and Kato Katz.…”

“…It has been observed that as children get older, their vulnerability to contracting schistosomes increases. In the two study sites, high infection reduction rates (between 96.7 and 99.7%) were attained [ 20 ]. The village that used the canal had a noticeably higher rate of re-infection.…”

“…In the overall analysis displayed in Table 3 , schistosomiasis prevalence decreased significantly throughout most of the studies with participants infected with both S . haematobium [ 6 , 15 , 16 , 18 , 20 , 25 , 32 , 35 , 37 , 39 , 44 ] and S . mansoni [ 21 , 28 , 31 , 33 , 34 , 40 ].…”

“…The review indicates that including vector control in schistosomiasis control programmes has great potentials to disrupt schistosomiasis transmission especially in areas where there is high prevalence and noncompliance to MDA [ 52 ]. Niclosamide is a vector control chemical that has been used as molluscides in the studies included in the review as part of combined intervention strategies in study [ 20 , 22 ]. The results shows a better chance of controlling schistosomiasis and definitely reduced the chances of reinfections.…”

Prevalence and risk factors of schistosomiasis and hookworm infection in seasonal transmission settings in northern Côte d’Ivoire: A cross-sectional study

“…Prevalence and transmission of schistosomiasis and hookworm in the northern part of Co ˆte d'Ivoire is very low. This calls for attempts to interrupt transmission, as has been tried in a large cluster-randomized trial over a 3-year period prior to this study [48]. Although S. haematobium transmission could not be fully interrupted, preventive chemotherapy, coupled with mollusciding, resulted in marked prevalence reduction.…”