Persistent Hotspots in Schistosomiasis Consortium for Operational Research and Evaluation Studies for Gaining and Sustaining Control of Schistosomiasis after Four Years of Mass Drug Administration of Praziquantel

Kittur, Nupur; King, Charles H.; Campbell, Carl H.; Kinung’hi, Safari; Mwinzi, Pauline N. M.; Karanja, Diana M. S.; N’Goran, Eliézer K.; Phillips, Anna E.; Gazzinelli-Guimarães, Pedro Henrique; Olsen, Annette; Magnussen, Pascal; Secor, W. Evan; Montgomery, Susan P.; Utzinger, Jüerg; Walker, Joseph; Binder, Sue; Colley, Daniel G.

doi:10.4269/ajtmh.19-0193

Cited by 58 publications

(69 citation statements)

References 26 publications

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“…Villages were classified as "responders" if a decline exceeding the threshold was observed in both measures. 24 To supplement SCORE data on different treatment schedules and baseline infection prevalence and intensity, we derived data on a number of geographic and environmental features for each village, which are described in Table 2. All data-processing and subsequent statistical analysis were conducted in version 3.5.1 of the R software environment.…”

Section: Methodsmentioning

confidence: 99%

“…10,11 Kittur et al evaluated several definitions of PHSs in an analysis based on the first 3 years of SCORE data from Kenya and Tanzania and subsequently applied one of these definitions to describe the frequency and distribution of PHSs in the SCORE study. 11,24 Using this definition, we combined data from the SCORE studies with publicly available data related to geography, human population patterns, and climate to model characteristics that distinguish PHS villages from responders.…”

Section: Introductionmentioning

confidence: 99%

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Environmental Predictors of Schistosomiasis Persistent Hotspots following Mass Treatment with Praziquantel

Walker

Kittur

Binder

et al. 2020

The American Journal of Tropical Medicine and Hygiene

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Schistosomiasis control programs rely heavily on mass drug administration (MDA) campaigns with praziquantel for preventative chemotherapy. Areas where the prevalence and/or intensity of schistosomiasis infection remains high even after several rounds of treatment, termed "persistent hotspots" (PHSs), have been identified in trials of MDA effectiveness conducted by the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) in Kenya, Mozambique, Tanzania, and Côte d'Ivoire. In this analysis, we apply a previously developed set of criteria to classify the PHS status of 531 study villages from five SCORE trials. We then fit logistic regression models to data from SCORE and publically available georeferenced datasets to evaluate the influence of local environmental and population features, preintervention infection burden, and treatment scheduling on PHS status in each trial. The frequency of PHS in individual trials ranged from 35.3% to 71.6% in study villages. Significant relationships between PHS status and MDA frequency, distance to freshwater, rainfall, baseline schistosomiasis burden, elevation, land cover type, and village remoteness were each observed in at least one trial, although the strength and direction of these relationships was not always consistent among study sites. These findings suggest that PHSs are driven in part by environmental conditions that modify the risk and frequency of reinfection.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Environmental Predictors of Schistosomiasis Persistent Hotspots following Mass Treatment with Praziquantel

Walker

Kittur

Binder

et al. 2020

The American Journal of Tropical Medicine and Hygiene

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“…Despite treatment, there are hotspots where infection remains at persistently high levels 14,[134][135][136] . Hotspots can be caused by various programmatic factors such as poor treatment coverage/ adherence, movement of infected individuals and intense water contact.…”

Section: Evaluation Of Alternative Interventions and Strategiesmentioning

confidence: 99%

Economic evaluations of human schistosomiasis interventions: a systematic review and identification of associated research needs

et al. 2020

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Background: Schistosomiasis is one of the most prevalent neglected tropical diseases (NTDs) with an estimated 229 million people requiring preventive treatment worldwide. Recommendations for preventive chemotherapy strategies have been made by the World Health Organization (WHO) whereby the frequency of treatment is determined by the settings prevalence. Despite recent progress, many countries still need to scale up treatment and important questions remain regarding optimal control strategies. This paper presents a systematic review of the economic evaluations of human schistosomiasis interventions. Methods: A systematic review of the literature was conducted on 22nd August 2019 using the PubMed (MEDLINE) and ISI Web of Science electronic databases. The focus was economic evaluations of schistosomiasis interventions, such as cost-effectiveness and cost-benefit analyses. No date or language stipulations were applied to the searches. Results: We identified 53 relevant health economic analyses of schistosomiasis interventions. Most studies related to Schistosoma japonicum followed by S. haematobium. Several studies also included other NTDs. In Africa, most studies evaluated preventive chemotherapy, whereas in China they mostly evaluated programmes using a combination of interventions (such as chemotherapy, snail control and health education). There was wide variation in the methodology and epidemiological settings investigated. A range of effectiveness metrics were used by the different studies. Conclusions: Due to the variation across the identified studies, it was not possible to make definitive policy recommendations. Although, in general, the current WHO recommended preventive chemotherapy approach to control schistosomiasis was found to be cost-effective. This finding has important implications for policymakers, advocacy groups and potential funders. However, there are several important inconsistencies and research gaps (such as how the health benefits of interventions are quantified) that need to be addressed to identify the resources required to achieve schistosomiasis control and elimination.

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“…There are different de nitions of PHS. The approach adopted in the current study has been described elsewhere [13]. In brief, a village that failed to reduce the S. mansoni infection prevalence by at least 35% and/or failed to reduce the intensity of infection by at least 50% between baseline and year five testing is considered a PHS, while a village that ful ls these criteria is termed a low-prevalence setting.…”

Section: Introductionmentioning

confidence: 99%

“…In brief, a village that failed to reduce the S. mansoni infection prevalence by at least 35% and/or failed to reduce the intensity of infection by at least 50% between baseline and year five testing is considered a PHS, while a village that ful ls these criteria is termed a low-prevalence setting. Of note, PHS of schistosomiasis have been investigated in different parts of the world [14][15][16][17] and in the gaining and sustaining control studies of SCORE [13]. Prior research showed that various factors can contribute to the existence of PHS, including close proximity of human habitation to open surface water bodies where intermediate host snails proliferate, human behaviours, particularly in terms of water, sanitation and hygiene (WASH) parameters [18][19][20] and socioeconomic status of the study population [21,22].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of persistent hotspots of Schistosoma mansoni in western Côte d’Ivoire

Assaré

N’Tamon

Bellai

et al. 2020

Preprint

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Abstract Background Preventive chemotherapy with praziquantel is the cornerstone of schistosomiasis control. However, in some social-ecological settings, the prevalence and/or intensity of Schistosoma infection does not lower meaningfully despite multiple rounds of preventive chemotherapy, a phenomenon termed persistent hotspot (PHS). We assessed the characteristics of PHS in a Schistosoma mansoni -endemic area of Côte d’Ivoire. Methods In October 2016, a cross-sectional parasitological survey was conducted in 14 schools in the western part of Côte d’Ivoire, one year after multiple rounds of preventive chemotherapy. In each school, 50 children aged 9-12 years were randomly selected and invited to submit two stool samples and one urine sample. Stool samples were subjected to triplicate Kato-Katz thick smears for S. mansoni diagnosis. Urine samples were examined by a filtration method for S. haematobium eggs. PHS was defined as failure to achieve a reduction in the prevalence and/or intensity of S. mansoni infection of at least 35% and 50%, respectively after multiple rounds of preventive chemotherapy targeting school-aged children. A questionnaire was administered in six schools to obtain data on demographic characteristics, including human-water contact behaviours, water, sanitation and hygiene and history of preventive chemotherapy. A malacological survey was conducted in December 2016. Results The overall prevalence of S. mansoni and S. haematobium in the 14 surveyed schools was 9.5% and 2.6%, respectively. There were four PHS among six schools that underwent detailed investigation. The S. mansoni prevalence in the four PHS was 10.9% (95% confidence interval (CI): 6.4-15.5%), compared to 6.6% (95% CI: 1.4-11.8%) in the remaining two schools. The arithmetic mean of S. mansoni eggs per gram of stool (EPG) among infected children was 123.8 EPG in PHS and 18.7 EPG in the remaining two schools. A statistically significant difference between PHS and the other schools regarding praziquantel coverage was found with higher coverage rate observed in PHS (98.4% versus 89.0%, X 2 = 3.7, p = 0.001). There was no significant difference with regard to access to clean water in the two groups of schools. Children bathing in open freshwater bodies were at higher odds of S. mansoni infection (odds ratio (OR) = 4.5, 95% CI: 1.6-12.6). A total of 76 human-water contact sites (53 in PHS and 23 in the other schools) were examined and 688 snails were collected, including 92 Biomphalaria pfeifferi , 25 Bulinus forskalii , 16 Bu. globosus and one Bu. truncatus . Conclusion Children in PHS schools bathed more frequently in open freshwater bodies, and hence, they were potentially more exposed to S. mansoni . Our findings call for an integrated control approach, complementing preventive chemotherapy with behavioural change implementation in PHS settings.

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Persistent Hotspots in Schistosomiasis Consortium for Operational Research and Evaluation Studies for Gaining and Sustaining Control of Schistosomiasis after Four Years of Mass Drug Administration of Praziquantel

Cited by 58 publications

References 26 publications

Environmental Predictors of Schistosomiasis Persistent Hotspots following Mass Treatment with Praziquantel

Environmental Predictors of Schistosomiasis Persistent Hotspots following Mass Treatment with Praziquantel

Economic evaluations of human schistosomiasis interventions: a systematic review and identification of associated research needs

Characteristics of persistent hotspots of Schistosoma mansoni in western Côte d’Ivoire

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