Controlling Soil-Transmitted Helminthiasis in Pre-School-Age Children through Preventive Chemotherapy

Pre-school age children account for 10%–20% of the 2 billion people worldwide who are infected with soil-transmitted helminths (STHs): Ascaris lumbricoides (roundworm), Trichuris trichiura (whipworm), and Ancylostoma duodenale/Necator americanus (hookworms). Through a systematic review of the published literature and using information collated at World Health Organization headquarters, this paper summarizes the available evidence to support the recommendation that pre-school children should be included in regular deworming programmes. The first section describes the burden of STH disease in this age group, followed by a summary of how infection impacts iron status, growth, vitamin A status, and cognitive development and how STHs may exacerbate other high mortality infections. The second section explores the safety of the drugs themselves, given alone or co-administered, drug efficacy, and the importance of safe administration. The third section provides country-based evidence to demonstrate improved health outcomes after STH treatment. The final section provides country experiences in scaling up coverage of pre-school children by using other large scale public health interventions, including vitamin A programmes, immunization campaigns, and Child Health days. The paper concludes with a number of open research questions and a summary of some of the operational challenges that still need to be addressed

Examining the Relationship between Urogenital Schistosomiasis and HIV Infection

Urogenital schistosomiasis is a parasitic infection caused by a worm, Schistosoma haematobium, which lives in the bloodstream of infected individuals. It affects at least 112 million people, mostly in sub-Saharan Africa, and has been suggested to be a risk factor for becoming infected with HIV. We reviewed publications in order to examine whether it seems likely that this parasitic infection could be a risk factor for HIV. Evidence from many types of studies supports the hypothesis that urogenital schistosomiasis does increase a person's risk of becoming infected with HIV. Studies also suggest that individuals who have both urogenital schistosomiasis and HIV have a more aggressive HIV infection and can more easily transmit HIV to their sexual partners. Praziquantel is an oral, nontoxic, inexpensive medication that is safe in pregnancy and is recommended for treatment of schistosomiasis. In areas where both infections co-exist, regular administration of praziquantel both to young girls and to sexually-active women may be an important approach to reducing HIV transmission. Our findings support the importance of making praziquantel more available to people who live in areas of the world where both urogenital schistosomiasis and HIV infection are widespread

Investigating a strategy for quantifying schistosome infection levels in preschool-aged children using prevalence data from school-aged children

In 2012, the World Health Organisation (WHO) set out a roadmap for eliminating schistosomiasis as a public health problem by 2025. To achieve this target, preschool-aged children (PSAC; aged 6 years and below) will need to be included in schistosomiasis treatment programmes. As the global community discusses the tools and approaches for treating this group, one of the main questions that remains unanswered is how to quantify infection in this age group to inform treatment strategies. The aim of this study was thus to determine whether a relationship exists between levels of schistosome infection in PSAC and school-aged children (SAC), that can be used to determine unknown schistosome infection prevalence levels in PSAC. A systematic search of publications reporting schistosomiasis prevalence in African PSAC and SAC was conducted. The search strategy was formulated using the PRISMA guidelines and SPIDER search strategy tool. The published data was subjected to regression analysis to determine if a relationship exists between infection levels in PSAC and SAC. The interaction between SAC and community treatment history was also entered in the regression model to determine if treatment history significantly affected the relationship between PSAC and SAC prevalence. The results showed that a significant positive relationship exists between infection prevalence levels in PSAC and SAC for Schistosoma mansoni (r = 0.812, df (88, 1), p = <0.0001) and S. haematobium (r = 0.786, df (53, 1), p = <0.0001). The relationship was still significant after allowing for diagnostic method, treatment history, and the African sub-region where the study was conducted (S. mansoni: F = 25.63, df (88, 9), p = <0.0001; S. haematobium: F = 10.20, df (53, 10), p = <0.0001). Using the regression equation for PSAC and SAC prevalence, over 90% of the PSAC prevalence studies were placed in the correct WHO classifications category based on the SAC levels, regardless of treatment history. The study indicated that schistosome prevalence in SAC can be extended as a proxy for infection levels in PSAC, extending on its current use in the adult population. SAC prevalence data could identify where there is a need to accelerate and facilitate the treatment of PSAC for schistosomiasis in Africa

Triple Co-Administration of Ivermectin, Albendazole and Praziquantel in Zanzibar: A Safety Study

This paper describes how the use of three drugs which are used separately in mass drug distribution programmes when given together appear safe for use in large populations which have been previously treated with the same drugs separately (Mectizan [ivermectin], albendazole and praziquantel). The target diseases—lymphatic filariasis, soil-transmitted worms and schistosomiasis—were prevalent in Zanzibar up to 2000 but have been largely controlled by mass drug administration. The Ministry of Health and Social Welfare, with the support of WHO, initiated a small scale trial in a population of triple therapy in over 5,000 people initially in two sites, and having found there were no severe adverse events associated with the combined treatment then upscaled to treat the whole of the eligible population of over 700,000. Similarly, there were no severe adverse events. This is the first time the three drugs have been used together at the same time at scale in Africa and provide a basis for expansion of integrated preventive chemotherapy of helminths (worms). The next steps need to be initiated in populations which have heavier worm loads and such interventions need to be subject to close monitoring and ethical review

A Multicentre Randomized Controlled Trial of the Efficacy and Safety of Single-Dose Praziquantel at 40 mg/kg vs. 60 mg/kg for Treating Intestinal Schistosomiasis in the Philippines, Mauritania, Tanzania and Brazil

Control of urinary and intestinal schistosomiasis is based on mass administration of praziquantel at the World Health Organization (WHO) recommended dose of 40 mg/kg, though some countries use 60 mg/kg. This multi-country randomized clinical trial compared the efficacy (cure and egg reduction rates three weeks post-treatment) and safety of these two doses for treating intestinal schistosomiasis in 856 patients in Brazil, Mauritania and Tanzania (Schistosoma mansoni), and The Philippines (S. japonicum). Transmission and infection intensities varied across the sites, but there was no bias or heterogeneity in efficacy outcomes. The two doses are equally effective in curing intestinal schistosomiasis; the higher dose may be less well tolerated, though effects are generally mild and transient. In endemic areas people can be re-infected; one year post-treatment patients on 60 mg/kg had fewer re-infections but this finding is difficult to explain. This study was conducted to respond to the demand for evidence about the dose of praziquantel when deployed in endemic countries. The results, along with those of systematic reviews, support the current WHO recommendation for using praziquantel at 40 mg/kg and should inform policy decisions in countries. The Philippines has already changed from 60 to 40 mg/kg after this study

Practical dosing of praziquantel for schistosomiasis in preschool-aged children

Objective Schistosomiasis is known to occur in preschool-aged children, but achieving accurate dosing of praziquantel in its current form is challenging. While waiting for a paediatric formulation, there is a need to develop a means for using the available products to treat this age group. Current 600-mg tablets are differently scored to give units of 150 mg (a quarter of a tablet) or 300 mg (half a tablet). Methods We examined several dosing schemes to dose accurately (40-60 mg/kg) children aged 3–72 months (weight range 4–25 kg, based on available weight-for-age growth references from sub-Saharan Africa and Brazil, n = 106,230). Results Adequate dosing can be achieved with formulations that can be split into four 150 mg quarters for children weighing 5 kg or more, and with tablets than can be split into two 300 mg halves for children weighing 10 kg or more. Giving ½ tablet for 5–7 kg; ¾ tablet for 8–10 kg; 1 tablet for 11–15 kg; 1 ½ tablet for 16–21 kg; and two tablets for 22–25 kg will have 100% of subjects correctly dosed within the target 40–60 mg/kg range. Conclusions Formulations that can be divided into four parts (to give 150 mg increments) are preferred for children weighing less than 11 kg; the same dosing can be applied with 600 mf praziquantel formulations that can be divided into four quarters or two halves from 11 kg body weight

Impact of Anthelminthic Treatment on Growth of PSAC

<p>A, <i>A. lumbricoides</i>; ALB, albendazole; H, hookworm; LEV, levamisole; MBD, mebendazole; T, <i>T. trichiura</i>.</p