Efficacy and Side Effects of Praziquantel in an Epidemic Focus of Schistosoma mansoni

Abstract

keywords Schistosoma mansoni, praziquantel, resistance correspondence Y.S. Liang, Jiangsu Institute of Parasitic Diseases, Meiyuan, Wuxi, Jiangsu 214064, P. R.China.The tolerance of Schistosoma mansoni to praziquantel has been reported in some endemic regions (Fallon et al. 1995;Stelma et al. 1995;Ismail et al. 1996;Guisse et al. 1997). To establish the reasons for clinical failures of praziquantel, a simple, quick and economic assay is required to detect resistance. Ideally this will involve the use of eggs or miracidia since these are the stages of the parasite life cycle which can easily be obtained from the faecal material of infected humans. As praziquantel causes changes in the shape of miracidia (Coles 1979), this was used as the basis for designing a test for resistance.In 24-well flat bottom microplates we observed the effect of praziquantel on miracidia hatched from eggs obtained from the faeces of mice infected with six isolates of S. mansoni. Two isolates were praziquantel-susceptible (one from Puerto Rico and one a mixture of isolates from Puerto Rico, Brazil, Egypt and Kenya), and four isolates were praziquantelinsusceptible, including a laboratory-selected praziquantelresistant population (Fallon & Doenhoff 1994) and three Senegalese isolates. The cessation of swimming of miracidia was observed in different concentrations of praziquantel at various times and then the morphological changes were checked by adding a drop of Lugol's iodine.When the miracidia of both the susceptible and insusceptible isolates were exposed to 10 -3 and 10 -4 M praziquantel, they immediately contracted in the middle part of their bodies, giving the shapes of an unequal dumbbell or calabash, with the greater mass at the anterior end. In 5 ϫ 10 -6 M praziquantel 100% of miracidia from the susceptible isolates immediately changed shape, whereas only 11-15% of those from the insusceptible isolates did. Thus by addition of Lugol's iodine immediately after administering praziquantel, an objective measure of susceptibility could be obtained. After 1 minute in 10 Ϫ6 M praziquantel 52% to 100% of susceptible miracidia had changed shape, and after 5 min 100% had done so compared with 3% to 15% and 9% to 18% of the insusceptible miracidia. Susceptibility could also be detected by determining whether miracidia had stopped swimming but this was less easy to read as a test than change in shape.By exposing freshly hatched miracidia to 10 Ϫ6 M praziquantel and observing change in shape over one minute it should be possible to determine whether failed therapy is due to the presence of praziquantel-tolerant worms. It is planned to investigate this in field trials in China. The work was supported by the UNDP/World Bank/WHO Special Programmme for Research and Training in Tropical Diseases. ReferencesColes GC (1979) The effect of praziquantel on Schistoma mansoni. Journal of Helminthology 53, 31-33. Fallon PG, Sturrock RF, Niang AC, Doenhoff MJ (1995) Short report: diminished susceptibility to praziquantel in a Senegal isolate of Schistosoma ...

Efficacy and side effects of praziquantel in the treatment of Schistosomiasis mansoni in schoolchildren in Shesha Kekele Elementary School, Wondo Genet, Southern Ethiopia

“…These values are in general within the usual cure rate ranges (63-95%) of PZQ against S. mansoni reported in different epidemiological settings [4,[26][27][28] . Some previous studies have reported efficacy higher than 85% for PZQ [29][30][31][32][33][34] , while others have reported lower (<63%) efficacy for the drug [13][14][15][16][17][18][19][20][21]35,36] . Such variations might be attributable to differences in the number of treatment, factors related to the host, parasite, and drugs or to the methodology.…”

“…Asian Pacific Journal of Tropical Biomedicine journal homepage:www.elsevier.com/locate/apjtb efficacy [13][14][15][16][17][18][19][20][21] . In addition, the expiry of patent protection for the major anthelminthic drugs [10,22] and international competition that has substantially reduced the price of the drug [23] have made several low-cost brands and generic formats of PZQ available on the market.…”

“…The mean age of the study population was 11.4 (age range: 6 to 22 years) with the highest proportion of individuals lying in the [10][11][12][13][14] Most of the S. mansoni infected children were either cured or the intensity of infection became significantly reduced.…”

Schistosomes—proteomics studies for potential novel vaccines and drug targets

“…Reports of treatment failure in Senegal and Egypt [6,7], where isolates with reduced susceptibility to Praziquantel were obtained, have raised concerns about development of drug resistance. Further in vitro experiments confirmed the development of parasite resistance to Praziquantel compared with susceptible isolates [8][9][10][11].…”

Ultrastructural study of morphological changes in Schistosoma mansoni after in vitro exposure to the monoterpene rotundifolone

“…At present, praziquantel (PZQ) is the drug of choice for the treatment of all forms of schistosomiasis 3 . However, dependence on a single drug is a concern because of the possible development of resistance in some strains 4,5 . A second drug, oxamniquine (OXA), acts against Schistosoma mansoni, which is found in Africa, and against Schistosoma haematobium in South America, where it is the only species of this genus present.…”