Optimizing Delivery of Mass Drug Administration for Schistosomiasis

Point-of-care circulating cathodic antigen positivity and associated factors in school children one year after mass praziquantel administration in an endemic district in Ghana

Background

Mass drug administration of praziquantel is expected to reduce Schistosome carriage in treated children in endemic communities. However, the effectiveness of this annual exercise has not been assessed in Ghana. Therefore, this study aimed to detect viable Schistosoma mansoni infection using point-of-care circulating cathodic antigen (POC-CCA) positivity as proxy and associated factors in children previously treated with praziquantel in an endemic municipality in Ghana.

Materials and methods

This cross-sectional study was done in the Assin Central municipality in the Central Region of Ghana. School children, less than 16 years of age, treated with 40 mg/kg of praziquantel (treatment period: February-March 2019), provided early morning urine (∼40 mL) and stool (∼4 g) samples. Immediately, POC-CCA (ICT International, South Africa) was done, while S. mansoni ova were detected in formalin fixed samples using microscopy later. Additionally, participant's socio-demographic information and factors associated with S, mansoni infection transmission were collected from each child.

Results

A total of 520 children participated in the study (males-51.9%, majority age range [9-11 years, 34.4%]). Overall, 244 (46.9%) were positive for urinary CCA with no S. mansoni detected by microscopy. POC-CCA positivity was higher in females (48.4%), children with 2-3 siblings (49.3%), children aged 6-8-year range (55.4%) and residents of Brofoyedur (52%). However, age (x2 = 16.1, p = 0.0003) and town of residence (x2 = 11.7, p = 0.019) associated with CCA positivity. Further, location of water body (x2 = 16.4, p = 0.008), frequency of water contact (x2 = 12.3, p = 0.015) and handling of the Biomphalaria intermediate host (x2 = 5.1, p = 0.024) associated with POC-CCA outcome.

Conclusion

About 47% of the school children were positive for CCA, one year after mass praziquantel administration in the Assin Central municipality. Varied factors associated with the post-praziquantel administration POC-CCA positivity. This study should be replicated in other endemic areas to identify groups at risk of parasite persistence or reinfection to inform modification of control and preventive measures.

The role of environmental enteric dysfunction in the pathogenesis of Schistosoma mansoni-associated morbidity in school-aged children

Background

Studies have implicated schistosomiasis as a cause of intestinal barrier disruption, a salient feature of environmental enteric dysfunction (EED), as eggs translocate from the sterile bloodstream through the gut wall. We examined the longitudinal impact of praziquantel (PZQ) treatment on a) EED biomarkers and b) Insulin growth factor I (IGF-1), a key driver of childhood linear growth, since EED has been implicated in linear growth stunting.

Methodology

290 children infected with S. mansoni in Brazil were treated with PZQ at baseline. EED biomarkers lipopolysaccharide (LPS) and intestinal fatty acid binding-protein (I-FABP) were measured, as well as IGF-1 at baseline, 6 and 12-months. Multivariate regression analysis was applied to assess associations between S. mansoni intensity and plasma biomarkers (LPS, I-FABP, and IGF-1), controlling for potential confounding variables.

Principal findings

At baseline, S. mansoni infection intensities were 27.2% light, 46.9% moderate, and 25.9% heavy. LPS concentrations were significantly reduced at the 12-month visit compared to baseline (p = 0.0002). No longitudinal changes were observed for I-FABP or IGF-1 in the 6- or 12-month periods following baseline treatment. After 6-months, I-FABP concentration was significantly higher in high vs low intensity (p = 0.0017). IGF-1 concentrations were significantly lower among children with high and moderate vs low intensity infections at each study visit.

Conclusions/significance

We report that S. mansoni infection impacts LPS, I-FABP and IGF-1. These findings suggest a mechanistic role for EED in schistosomiasis-related morbidities, particularly linear growth.

Schistosoma mansoni is a tropical parasitic infection that causes intestinal schistosomiasis. In infected humans, the parasite worms shed eggs that migrate across the gut barrier, which damages intestinal structure and function. In children, intestinal schistosomiasis leads to anemia, undernutrition, and linear growth stunting. The mechanistic pathways between schistosomiasis and stunting are not fully understood, but this research explores the role of environmental enteric dysfunction (EED) in schistosomiasis-related morbidity. EED is an intestinal condition that affects children living in areas of poor water, sanitation, and hygiene and also leads to impaired growth and stunting. In a longitudinal cohort of Brazilian children infected with S. mansoni, we measured blood biomarkers of EED and linear growth at three time points over 12 months. All of the children were treated for schistosomiasis at baseline, and after 12 months, we observed a significant decrease in a marker of EED, suggesting improvement in gut integrity. We also found that children who had higher parasite egg burden at the baseline visit had lower levels of insulin-like growth factor-1, a hormone that drives growth in children. Our findings suggest that EED may play a role in schistosomiasis-related stunting and furthers our understanding for S. mansoni pathogenesis in children.

An assessment of implementation and effectiveness of mass drug administration for prevention and control of schistosomiasis and soil-transmitted helminths in selected southern Malawi districts

Background

Mass drug administration (MDA) is one of the key interventions recommended by WHO for prevention and control of neglected tropical diseases (NTD). In Malawi, MDA is widely carried out annually since 2009 for prevention and control of schistosomiasis and soil-transmitted helminths (STH). No study has been carried out to assess effectiveness of the MDA approach and to document perceptions of health providers and beneficiaries regarding use of MDA. This study was done to understand how well MDA is being implemented and to identify opportunities for improvement in MDA delivery in Malawi.

Methods

Designed as a cross-sectional and multi-methods research, the study was carried out in three southern Malawi districts of Chiradzulu, Mangochi and Zomba. In each district, four health centres and 16 villages were randomly selected to participate. A mixed-methods approach to data collection focusing on quantitative data for coverage and knowledge, attitudes and practices assessments; and qualitative data for assessing perceptions of health providers and beneficiaries regarding MDA was used. Quantitative data were processed and analyzed using IBM SPSS software version 26 while qualitative data were analysed using NVivo 12 for Windows.

Results

Knowledge levels about schistosomiasis and STH in the districts varied according to disease aspects asked about. Majority are more knowledgeable about what schistosomiasis is (78%) and whether STH are treatable with drugs (97%); with least knowledgeable about the organism that transmits schistosomiasis (18%), types of schistosomiasis (11%) and what causes STH (20%). In 2018 and 2019 the districts registered high coverage rates for praziquantel and albendazole using community-based MDA (73–100%) and using school-based MDA (75–91%). Both the health authorities and community members perceived the MDA approach as good because it brings treatment closer to people.

Conclusion

With the high MDA coverage obtained in communities and schools, the effectiveness of MDA in the target districts is satisfactory. There are, however, several challenges including disproportionate knowledge levels, which are hampering progress towards attainment of the 2030 global NTD goals. There is a need for promotion of community participation and partnerships as well as implementation of other recommended interventions for sustainable prevention and control of schistosomiasis and STH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-07925-3.

Effect of maternal praziquantel treatment for Schistosoma japonicum infection on the offspring susceptibility and immunologic response to infection at age six, a cohort study

In areas endemic to schistosomiasis, fetal exposure to schistosome antigens prime the offspring before potential natural infection. Praziquantel (PZQ) treatment for Schistosoma japonicum infection in pregnant women has been demonstrated to be safe and effective. Our objectives were to evaluate whether maternal PZQ treatment modifies the process of in utero sensitization to schistosome antigens potentially impacting later risk of infection, as well as immune response to S. japonicum. We enrolled 295 children at age six, born to mothers with S. japonicum infection who participated in a randomized control trial of PZQ versus placebo given at 12-16 weeks gestation in Leyte, The Philippines. At enrollment, we assessed and treated current S. japonicum infection and measured serum cytokines. During a follow-up visit four weeks later, we assessed peripheral blood mononuclear cell (PBMC) cytokine production in response to soluble worm antigen preparation (SWAP) or soluble egg antigen (SEA). Associations between maternal treatment group and the child's S. japonicum infection status and immunologic responses were determined using multivariate linear regression analysis. PZQ treatment during pregnancy did not impact the prevalence (P = 0.12) or intensity (P = 0.59) of natural S. japonicum infection among children at age six. Among children with infection at enrollment (12.5%) there were no significant serum cytokine concentration differences between maternal treatment groups. Among children with infection at enrollment, IL-1 production by PBMCs stimulated with SEA was higher (P = 0.03) in the maternal PZQ group compared to placebo. Among children without infection, PBMCs stimulated with SEA produced greater IL-12 (P = 0.03) and with SWAP produced less IL-4 (P = 0.01) in the maternal PZQ group compared to placebo. Several cytokines produced by PBMCs in response to SWAP and SEA were significantly higher in children with S. japonicum infection irrespective of maternal treatment: IL-4, IL-5, IL-10, and IL-13. We report that maternal PZQ treatment for S. japonicum shifted the PBMC immune response to a more inflammatory signature but had no impact on their offspring's likelihood of infection or serum cytokines at age six, further supporting the safe use of PZQ in pregnant women. Trial Registration: ClinicalTrials.gov NCT00486863.