Annals of Tropical Medicine & Parasitology, Vol. 97, No. 1, 37–51 (2003) EYcacy and side-eVects of two praziquantel treatments against Schistosoma haematobium infection, among schoolchildren from Co ˆ te d’Ivoire E. K. N’GORAN*, H. N. GNAKA ² , M. TANNER  and J. UTZINGER § *Unite ´ de Formation et de Recherche: Biosciences, Universite ´ de Cocody, 22 B.P. 770, Abidjan 22, Co ˆte d’Ivoire, and Centre Suisse de Recherches Scientiques, 01 B.P. 1303, Abidjan 01, Co ˆte d’Ivoire ² Grandes Ende ´mies de Tiassale ´, Tiassale ´, Co ˆte d’Ivoire  Swiss Tropical Institute, P.O. Box, CH-4002 Basel, Switzerland § OYce of Population Research, Princeton University, Princeton, NJ 08544, U.S.A. Received 13 August 2002, Revised 10 October 2002, Accepted 14 October 2002 Praziquantel is the current drug of choice for the control of schistosome-attributable morbidity and is likely to remain so for several years. However, as there is concern that schistosomes might develop resistance to the drug, the monitoring of praziquantel’s eYcacy in diVerent epidemiological settings is recommended. Here, the results of an innovative study of the drug’s eVectiveness, in an area in Co ˆ te d’Ivoire that is highly endemic for Schistosoma haematobium, are reported. Each of the subjects (354 schoolchildren aged 5–15 years) was given two oral doses of praziquantel (each of 40 mg/kg ) 4 weeks apart. The numbers of schistosome eggs in urine samples collected over several consecutive days prior to the rst and after the second treatment were then determined. High cure and egg reduction ‘rates’, of 93.0% and 96.6%, respectively, were found. Although mild and transient side-eVects were frequently observed after the rst treatments, no severe systemic complaints were recorded. When the 20 children who remained egg-positive after the second dose were each given a third dose of praziquantel, 16 (80%) of them responded and became egg-negative. Unfortunately, the schistosome strains infecting the remaining four children could not be investigated in detailed laboratory studies, because of the failure of eggs to hatch. There were therefore no unambiguous signs of resistance to praziquantel in this epidemiological setting. The benets and disadvantages, compared with single-dose treatments, of administering praziquantel twice within a few weeks are discussed. It is anticipated that this approach might prove eYcacious in areas of high infection intensity. The integration of such pharmaceutical measures with other readily available control tools is likely to mitigate the current, intolerable burden of schistosomiasis. Praziquantel was synthesised 25 years ago mental hosts, Schistosoma mansoni (Go ¨nnert and Andrews, 1977), S. japonicum ( James (Seubert et al., 1977). It was initially screened et al., 1977; Webbe and James, 1977) and for its properties as a tranquillizer for human S. haematobium ( James et al., 1977; Webbe use, and then underwent veterinary testing and James, 1977). The results of subsequent, (Groll, 1984). In the late 1970s, laboratory clinical trials indicated that the drug was experiments revealed that praziquantel was useful in the treatment of infection with eYcacious against cestodes (Thomas and any of the schistosome species parasitising Go ¨nnert, 1977), including, in various experi- humans, and that it caused no serious side- eVects (Davis and Wegner, 1979; Wegner, 1984; Cioli et al., 1995). At the time of these Reprint requests to: J. Utzinger. E-mail: utzinger@princeton.edu; fax: +1 609 258 1039. trials, the arsenal for the treatment of human © 2003 The Liverpool School of Tropical Medicine DOI: 10.1179/000349803125002553