title: Regular treatments of praziquantel do not impact on the genetic make-up of Schistosoma mansoni in Northern Senegal.
abstract: The Senegal River Basin (SRB) experienced a major epidemic of intestinal schistosomiasis in the early nineties, after the construction of a dam for irrigation purposes. Exceptionally low cure rates following praziquantel (PZQ) treatment at the onset of the epidemic raised concerns about PZQ resistant strains of Schistosoma mansoni, although they could also be attributed to the intense transmission at that time. A field study in the same region more than 15 years later found cure rates for S. mansoni still to be low, whereas Schistosomahaematobium responded well to treatment. We collected S. mansoni miracidia from children at base-line prior to treatment, six months after two PZQ treatments and two years after the start of the study when they had received a total of five PZQ treatments. In total, 434 miracidia from 12 children were successfully genotyped with at least six out of nine DNA microsatellite loci. We found no significant differences in the genetic diversity of, and genetic differentiation between parasite populations before and after repeated treatment, suggesting that PZQ treatment does not have an impact on the neutral evolution of the parasite. This is in stark contrast with a similar study in Tanzania where a significant decrease in genetic diversity was observed in S. mansoni miracidia after a single round of PZQ treatment. We argue that PZQ resistance might play a role in our study area, although rapid re-infection cannot be excluded. It is important to monitor this situation carefully and conduct larger field studies with short-term follow-up after treatment. Since PZQ is the only general schistosomicide available, the possibility of PZQ resistance is of great concern both for disease control and for curative use in clinical practice.
authors.affiliation: Institute of Tropical Medicine, Department of Biomedical Sciences, Nationalestraat 155, B-2000 Antwerpen, Belgium. Tine.Huyse@bio.kuleuven.be
authors.forename: T
authors.initials: T
authors.lastname: Huyse
authors.forename: F
authors.initials: F
authors.lastname: Van den Broeck
authors.forename: T
authors.initials: T
authors.lastname: Jombart
authors.forename: B L
authors.initials: BL
authors.lastname: Webster
authors.forename: O
authors.initials: O
authors.lastname: Diaw
authors.forename: F A M
authors.initials: FA
authors.lastname: Volckaert
authors.forename: F
authors.initials: F
authors.lastname: Balloux
authors.forename: D
authors.initials: D
authors.lastname: Rollinson
authors.forename: K
authors.initials: K
authors.lastname: Polman
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D016000:Cluster Analysis; D004351:Drug Resistance; D005243:Feces / Q000469:parasitology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D011223:Praziquantel / Q000494:pharmacology*; D012550:Schistosoma mansoni / Q000187:drug effects* / Q000235:genetics*; D012555:Schistosomiasis mansoni / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology*; D012675:Senegal / Q000453:epidemiology
chemical_list: D000871:Anthelmintics; D011223:Praziquantel
keywords: Cure rates; Drug resistance; Molecular epidemiology; Praziquantel; Schistosomiasis; Transmission