Bio: E. Sellin is an academic researcher. The author has contributed to research in topics: Schistosoma haematobium & Bulinus. The author has an hindex of 4, co-authored 11 publications receiving 130 citations.
TL;DR: It is concluded that a combined school- and community-based strategy is effective in attaining a high coverage among school-age children in countries where school enrolment is low and where primary schools cannot serve as the exclusive drug distribution points.
Abstract: A combined school- and community-based campaign targeting the entire school-age population of Burkina Faso with drugs against schistosomiasis (praziquantel) and soil-transmitted helminthiasis (albendazole) was implemented in 2004–2005. In total, 3,322,564 children from 5 to 15 years of age were treated, equivalent to a 90.8% coverage of the total school-age population of the country. The total costs of the campaign were estimated to be US$ 1,067,284, of which 69.4% was spent on the drugs. Delivery costs per child treated were US$ 0.098, in the same range as school-based only interventions implemented in other countries; total costs per child treated (including drugs) were US$ 0.32. We conclude that a combined school- and community-based strategy is effective in attaining a high coverage among school-age children in countries where school enrolment is low and where primary schools cannot serve as the exclusive drug distribution points. The challenge for Burkina Faso will now be to ensure the sustainability of these disease control activities.
TL;DR: The emergence pattern of Schistosoma curassoni cercariae from Bulinus umbilicatus, whose adult worms parasitize bovine, caprine, and ovine ungulates in Niger, is of a circadian type with a mean emission time at 0855 hr 1 hr 6 min, characteristic of the schistosome species parasitizing domestic or wild cattle as mentioned in this paper.
Abstract: The emergence pattern of Schistosoma curassoni cercariae from Bulinus umbilicatus, whose adult worms parasitize bovine, caprine, and ovine ungulates in Niger, is of a circadian type with a mean emission time at 0855 hr 1 hr 6 min, characteristic of the schistosome species parasitizing domestic or wild cattle. The comparison of this cercarial emergence pattern with those of the other 3 sympatric species of schistosomes (Schistosoma haematobium, Schistosoma bovis, and Schistosoma mansoni) shows a significant difference between the chronobiology of the cercariae infective for human and those infective for bovine hosts. This difference may improve epidemiological surveys based on snail prevalences by allowing the distinction between bulinids infected with human and bovine parasites.
TL;DR: Cercarial emergence patterns were used to analyse the intraspecific variability within and between nine populations of Schistosoma haematobium collected along a transect line from the north to the South of the Ivory Coast using Bulinus truncatus or Bulinus globosus as intermediate snail hosts.
Abstract: Cercarial emergence patterns were used to analyse the intraspecific variability within and between nine populations of Schistosoma haematobium collected along a transect line from the north to the South of the Ivory Coast (Africa) and using Bulinus truncatus or Bulinus globosus as intermediate snail hosts. Statistical comparison demonstrated the existence of a chronobiological polymorphism and the existence of three homogeneous groups of S. haematobium isolates with mean shedding times of the cercariae decreasing from the North to the South. The chronobiological variability observed was not correlated with the species of Bulinus (B. truncatus vs. B. globosus) implicated in the parasite transmission but with the climatic and vegetal features of the transmission area. S. haematobium from shaded sites of the forest zone (South) showed cercarial emergence patterns significantly earliest than that of S. haematobium from open sites of the savanna zone (North). Differences in sensitivity to light intensity could characterize the existence of eco-geographical races of S. haematobium one of the forest, the other from the savanna.
TL;DR: Dip-sticks and macroscopic exams could be duly considered for the detection of new high endemic regions because of their specificity and because they become good indicators of clinical improvement.
Abstract: In this study, dip-stick examination for the detection of hematuria and proteinuria, and macroscopic examination of the urine as diagnostic methods for mass screening for urinary schistosomiasis, were compared with the technique of urinary filtration for Schistosoma haematobium eggs. Dip-sticks and macroscopic examination were proved to be simple and rapid. Before treatment, the revealing of hematuria by dip-stick was shown to be a sensitive method by comparison with filtration, but it is not specific. The tests for proteinuria, and macroscopic examination are more specific, but less sensitive. Nevertheless, all these methods give similar prevalences as distributed by age groups. Dip-sticks and macroscopic exams could therefore be duly considered for the detection of new high endemic regions. After treatment, these methods result in less valid prevalences than those obtained by filtration, but their specificity increases; they become good indicators of clinical improvement.
TL;DR: The authors recommend against the combined treatment of oltipraz and niridazole in Niger because of the heavy endemic level and high egg-loads, and the fact that the 30 mg/kg dosage was probably insufficient.
Abstract: PUGH (1978) and TEEDSALE et al. (1980) showed that an associated single dose of metrifonate (12.5 mg/kg) plus niridazole (25 mg/kg) gave good results on Schistosoma haematobium: the egg-reduction percentage ranged between 84.7 and 91.2. In Niger, we compared the effects of this medication to oltipraz in a single dose (30 mg/kg). We selected a dosage of 10 mg/kg of metrifonate and 25 mg/kg of niridazole. This trial was carried out during the minimal transmission period. --109 adults (greater than 15 years) received oltipraz and 159 this combined treatment. They were examined twice: 11/2 month and 6 months after treatment. At the first control, the cure rate was 26.7% for oltipraz and 23.3% for the combined treatment, the egg-reduction was respectively 77.1% and 41.3%. Six months after treatment, the cure rate was 43.5% for oltipraz and 27.7% for the combined treatment and the egg-reduction was 66.5% and 2.0% respectively. Following these results, the authors recommend against the combined treatment in Niger. They note that if, in some particular conditions, this medication can give good results (PUGH, 1978, TEESDALE et al., 1980) it is however necessary to include its test in future control projects. Also, they note the weak result obtained with oltipraz; but, in this case, the heavy endemic level and high egg-loads might explain it, as well as the fact that the 30 mg/kg dosage was probably insufficient.
TL;DR: The case for the control of schistosomiasis has been strengthened by research by SCI teams and the principle that a national programme using ‘preventive chemotherapy’ can be successfully implemented in sub-Saharan Africa, whenever the resources are available.
Abstract: Schistosomiasis remains one of the most prevalent parasitic diseases in developing countries. After malaria, schistosomiasis is the most important tropical disease in terms of human morbidity with significant economic and public health consequences. Although schistosomiasis has recently attracted increased focus and funding for control, it has been estimated that less than 20% of the funding needed to control the disease in Africa is currently available. In this article the following issues are discussed: the rationale, development and objectives of the Schistosomiasis Control Initiative (SCI)-supported programmes; the management approaches followed to achieve implementation by each country; mapping, monitoring and evaluation activities with quantifiable impact of control programmes; monitoring for any potential drug resistance; and finally exit strategies within each country. The results have demonstrated that morbidity due to schistosomiasis has been reduced by the control programmes. While challenges remain, the case for the control of schistosomiasis has been strengthened by research by SCI teams and the principle that a national programme using 'preventive chemotherapy' can be successfully implemented in sub-Saharan Africa, whenever the resources are available. SCI and partners are now actively striving to raise further funds to expand the coverage of integrated control of neglected tropical diseases (NTDs) in sub-Saharan Africa.
01 Jan 2003
TL;DR: The available evidence is summarized to support the recommendation that pre-school children should be included in regular deworming programmes, and country-based evidence to demonstrate improved health outcomes after STH treatment is provided.
Abstract: 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.
TL;DR: African trypanosomiasis, and other NTDs have not fared so well in terms of coverage, and the single largest gap in mass drug administration for a serious NTD has to be the almost nonexistent global coverage for schistosOMiasis.
Abstract: African trypanosomiasis, are also being targeted for elimination. Unfortunately, other NTDs have not fared so well in terms of coverage. Today it is believed that fewer than 10% of eligible populations living in endemic regions of Africa, Asia, and the Americas are receiving annual treatments for their schistosomiasis, intestinal helminth infections, and/or trachoma . The World Health Organization (WHO) and several leading public private partnerships and non-governmental development organizations are actively working to correct this situation and to steadily increase global coverage to the levels of LF and onchocerciasis. Of these, we believe that the single largest gap in mass drug administration for a serious NTD has to be the almost nonexistent global coverage for schistosomiasis.
TL;DR: Cercariae, like miracidia, are non-parasitic larval stages implicated in the life cycle of all trematodes for the host-to-host parasite transmission.
Abstract: Cercariae, like miracidia, are non-parasitic larval stages implicated in the life cycle of all trematodes for the host-to-host parasite transmission. Almost all cercariae are free-living in the external environment. With a few exceptions (cercariae of Halipegus occidualis (Halipegidae) can live several months, Shostak & Esch, 1990a), cercariae have a short active life during which they do not feed, living on accumulated reserves. Most cercariae encyst as metacercariae in second intermediate hosts which are prey of the definitive host; in certain species, the interruption of the active life is achieved by an encystment in the external environment (or a simple immobile waiting strategy in a few species). In some two-host life cycles, the cercariae develop into adults after penetration (this is the case for various species causing human schistosomiasis). Some cercariae do not leave the mollusc which must then be ingested by the definitive host.