Études et publications

De Clercq D, Vercruysse J, Kongs A, Verlé P, Dompnier JP, Faye PC.

Acta tropica, 2002, 82(1):61-6 (PMID : 11904104)

Praziquantel is the current mainstay for morbidity control of schistosomiasis. Artemisinin and its derivatives, widely used for the treatment of malaria, also display antischistosomal properties. The present study is an effort to assess the therapeutic efficacy of artesunate, an artemisinin derivative, in Schistosoma haematobium infections in a human population. The efficacy of artesunate and praziquantel were comparatively studied in primary schoolchildren from two villages, Lampsar (n=180) and Makhana (n=108), located along the Lampsar river in the delta of the Senegal River Basin in Northern Senegal (West Africa). In each village, half of the infected children were treated with a single oral dose of 40 mg/kg praziquantel and half with artesunate following the recommended malaria monotherapy regimen. For both drugs, cure and egg count reduction rates were, without apparent explanation, higher in Makhana than in Lampsar. In both villages, high and nearly comparable egg count reduction rates were obtained with both drugs at each follow-up after treatment (5, 12 and 24 weeks) in the heavy infected group of children (>50 eggs/10 ml of urine). No major adverse effects were observed. The results demonstrate that artesunate is effective against S. haematobium, but the results obtained with praziquantel were consistently better.

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van der Werf MJ, Mbaye A, Sow S, Gryseels B, de Vlas SJ.

Tropical Medicine and International Health, 2002, 7(1):70-9 (PMID : 11851957)

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Capron A, Capron M, Dombrowicz D, Riveau G.

International archives of allergy and immunology, 2001, 124(1-3):9-15 (PMID : 11306914)

Schistosomiasis, the second major parasitic disease in the world after malaria, affects 200 million people. Vaccine strategies represent an essential component of the control of this chronic debilitating disease where the deposition of millions of eggs in the tissues is the main cause of pathology. Research developed in our laboratory over the last 20 years has led to the identification of novel effector mechanisms, pointing for the first time to the protective role of Th2 responses and of IgE antibodies now supported by seven studies in human populations. The identification and molecular cloning of a target antigen, a glutathione S-transferase (GST), has made it possible to demonstrate its vaccine potential in several animal species (rodents, cattle, primates) and to establish consistently the capacity of vaccination to reduce female worm fecundity and egg viability through the production of neutralizing antibodies (IgA and IgG). Following promising preclinical studies, clinical trials (phase I and II) have been undertaken using Schistosoma haematobium GST, Sh28GST. High titers of neutralizing antibodies were produced (IgG3 and IgA) together with Th2 cytokines, consistently with the concepts developed from experimental models. With these results we are on the way towards a feasible approach of vaccine development against a major human parasitic disease.

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Liang YS, Coles GC, Dai JR, Zhu YC, Doenhoff MJ.

Annals of tropical medicine and parasitology, 2001, 95(7):715-23 (PMID : 11784425)

If there is a change in the biological characteristics of schistosomes associated with the development of resistance to praziquantel, this could affect the transmission and pathology of the diseases they cause. To investigate this possibility, the host-parasite relationships of five praziquantel-resistant and five praziquantel-susceptible isolates of Schistosoma mansoni were compared in Biomphalaria glabrata snails and outbred CD(1) albino mice. Whether praziquantel-resistant or -susceptible, all the laboratory-selected isolates gave similar results in B. glabrata. However, the snails infected with any of three field-collected isolates from Senegal, each of which has been shown to be praziquantel-resistant, shed fewer cercariae and survived longer than the snails infected with the drug-susceptible or laboratory-selected, drug-resistant isolates. There were no differences between isolates in terms of their infectivity to mice. However, mice infected with any of four of the five drug-resistant isolates shed more eggs in their faeces than mice carrying the drug-susceptible parasites, and mice infected with any of the resistant isolates also had larger numbers of eggs in their tissues. Although granuloma sizes were generally similar for all isolates, the praziquantel-resistant isolates may be more pathogenic in mice than the susceptible ones because of their relatively high egg productions.

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