Changing Policy and Practice in the Control of Pediatric Schistosomiasis

Abstract

Schistosomiasis is a chronic disease that affects ∼200 million people. The extended health impact of the disease has been estimated to exceed that of malaria or tuberculosis and to be nearer to that of HIV/AIDS. Within endemic areas, children carry the heaviest burden of infection. Infection/disease is controlled by the treatment of infected subjects with the anthelminthic drug praziquantel. Global initiatives from Partners of Parasite Control, including the World Health Organization (WHO), advocate regular school-based deworming strategies to reduce the development of severe morbidity, promote school–child health and development, and improve the cognitive potential of children. Until recently, preschool-aged children were excluded from schistosome treatment, creating a health inequity in affected populations. In 2010, the WHO updated their recommendations for the treatment of schistosomiasis in preschool-aged children (ie, children aged ≤5 years). This change was the culmination of several decades of research on schistosome epidemiology, immunology, and pathology in this age group. The recent development of a pediatric formulation of praziquantel (soon to enter clinical trials) should advance control efforts in preschool-aged children, with the goal of including these children in preventative chemotherapy (as currently occurs for soil-transmitted helminths). This review discusses the research work supporting the WHO revision of recommendations for treating preschool-aged children, as well as current barriers and knowledge gaps in pediatric schistosomiasis control.

Advances in the Diagnosis of Human Schistosomiasis

“…It is a sobering thought that despite extensive efforts, as indicated earlier, the global disease burden of schistosomiasis still remains unacceptably high. This persistence of the disease despite massive and integrated control programs over the last few decades (35,37,38) may be due in part to the lack of accurate diagnostic tools for case detection and community screening in areas where schistosomiasis is endemic.…”

Schistosomiasis therapeutics: whats in the pipeline?

“…PZQ is effective against adults (not juveniles/infective stages [18]) of all three human schistosomes as well as helminth infections in domestic and companion animal schistosomiasis. [19] It is also used to treat other human parasitic diseases such as hydatid disease. [20] Experimental studies show that PZQ is more effective against bisexual compared to single-sex infections and that the adult worms can survive low drug doses.…”

“…We have succeeded along with others [30] in having the WHO recommend that these children be treated against schistosomiasis with PZQ. [19] Although this recommendation was made in 2010, it has largely remained unimplemented due to the lack of a pediatric formulation of PZQ to overcome the bitter taste and risk of choking on the large tablets currently available. The pediatric formulation has now been developed and awaits clinical trials.…”

“…The pediatric formulation has now been developed and awaits clinical trials. [19] • Optimizing the timing of treatment with PZQ. Our studies and those of others [31,32] have shown that PZQ alters host immune responses accelerating the development of responses protective against reinfection [19] as well as reversing schistosome-related pathology.…”

“…[19] • Optimizing the timing of treatment with PZQ. Our studies and those of others [31,32] have shown that PZQ alters host immune responses accelerating the development of responses protective against reinfection [19] as well as reversing schistosome-related pathology. [33] Thus, there is a need to determine a strategy to maximize longer-term effects of PZQ beyond the transient reduction of infection and morbidity.…”