The role of human activities in the transmission of stomach flukes Paramphistomum microbothrium (Fishoeder, 1901) (Trematoda: Paramphistomatidae) in Tessaout amont irrigation scheme, Central Morocco

Une prospection menée au niveau des différentes structures du réseau d’irrigation dans la région de Tessaout Amont a montré l’existence de neuf espèces de mollusques d’eau douce appartenant à cinq familles. Les canaux d’irrigation traditionnels sont des sites de transmission de la schistosomose à Schistosoma haematobium à l'homme et de la distomatose à Fasciola hepatica chez les ovins et les caprins du Haouz. Plus récemment, la transmission de la paramphistomose a été également rapportée pour la première fois dans le Haouz au Maroc. La présente étude montre que l’infestation de Bulinus truncatus hôte intermédiaire de Paramphistomum microbotrium s’effectue dans des siphons inaccessibles au bétail qui en constitue l’hôte définitif. Il s’est avéré que les oeufs du parasite sont mis en contact du mollusque suite au rinçage des viscères de ruminants abattus par les bouchers et par les riverains dans l’eau des canaux et des siphons. Les implications de ce résultat sur les possibilités de lutte contre cette maladie sont discutées

Estimation of changes in the force of infection for intestinal and urogenital schistosomiasis in countries with Schistosomiasis Control Initiative-assisted programmes

The last decade has seen an expansion of national schistosomiasis control programmes in Africa based on large-scale preventative chemotherapy. In many areas this has resulted in considerable reductions in infection and morbidity levels in treated individuals. In this paper, we quantify changes in the force of infection (FOI), defined here as the per (human) host parasite establishment rate, to ascertain the impact on transmission of some of these programmes under the umbrella of the Schistosomiasis Control Initiative (SCI)

Snail control in Africa: towards a community-based environmental control

In Madsen H.; Appleton, C. C.; Chimbari, M. (Eds.) Proceedings of "Workshop on Medical and Veterinary Malacology in Africa, Harare, Zimbabwe, 8-12 November 1999. Charlottenlund, Denmark: Danish Bilharziasis LaboratoryDisease control programme managers are becoming increasingly aware of the need to Promote community participation in all aspects of interventions. In the present paper, community participation in snail control is discussed from three standpoints: feasibility, effectiveness as well as long-term sustainability, based on field experience in Zimbabwe, Tanzania and Morocco. The process leading to the involvement of the community appears to be a crucial factor in the success of any community based approach to control snails. In the successful experiences of environmental control of intermediate hosts, the community is mobilized at the design stage and not only at implementation and evaluation. The authors stress the relevance of ecological studies in providing information on environmental factors to be modified in order to make the habitat hostile to the snail hosts

Micro-distribution of freshwater snails before and after water flow events in hydraulic structures in Tessaout Amont Irrigation System, Morocco

Bulinus truncatus, the intermediate host of Schistosoma haematobium, is widely distributed in modern irrigation schemes in Morocco. These schemes have intermittent irrigation and canals dry out in between irrigation periods. The snail species is therefore associated with the 'siphon boxes' connecting canal segments, as these contain water that stagnates between irrigation cycles. The micro-distribution of snails in siphon boxes, was studied before and after one irrigation period, to identify factors that could be manipulated in order to control this snail species. Density of B. truncatus, Ancylus fluviatilis, Lymnaea peregra and Melanopsis praemorsa varied significantly with water depth before and after irrigation. The pulmonate snail species had the highest densities at depths ranging between 20 and 80 cm. After an irrigation period of 10 to 12 hours B. truncatus, A. fluviatilis and L. peregra were relatively more abundant at the bottom of the siphon boxes than in the upper sections. Aggregation at the corners of the boxes could be among the factors that enable snail species to avoid the detrimental effect of turbulent water flow during irrigation. The relevance of changes in density and micro-distribution following an irrigation cycle in the control of B. truncatus is discussed

Schistosoma haematobium in Morocco: moving from control to elimination

In this article, Hammou Laamrani and colleagues summarize the Moroccan schistosomiasis control programme and discuss the challenges ahead for schistosomiasis elimination. In 1994, a programme was initiated by the Moroccan Ministry of Health to eliminate schistosomiasis from Morocco by the year 2004. In 1997, this objective had been achieved in three out of 20 affected provinces. This article discusses the background and strategies of this programme, as well as the achievements, the problems encountered and the challenges ahead, along with suggestions as to how to reach the goal of elimination of urinary schistosomiasis in Morocco, and possibly elsewhere in Africa

New challenges in schistosomiasis control in Morocco

Cases of schistosomiasis were first detected in 1914. However, there is strong evidence that it was prevailing in the southern part of Morocco long before then. As reported from different African countries, over the last three decades, the development of irrigation has led to the spread of the disease to the north and centre of the country. Thereafter, a national programme of schistosomiasis control was launched by the Ministry of Health in 1983. The programme was based on case detection and treatment, snail control using chemicals, and health education. It has succeeded in reducing the prevalence and intensity of infection to a level low enough to allow an elimination programme to be launched in 1994. The aim is to reach a complete elimination of the disease by the year 2004 in all provinces affected. Though substantial progress was made since the programme started, there is a potential risk of outbreaks in many affected provinces. Therefore, an integrated approach including measures against the intermediate host is needed to reach the goal of elimination. The present paper sheds some light on the features of schistosomiasis in Morocco and presents an evaluation of environmental methods of control of Bulinus truncatus in Tessaout Amont and Akka oasis irrigation schemes. The role of community involvement in planning and implementing environmental measures against the snail intermediate host in modern and traditional irrigation schemes is also discussed