Research Article: Evidence of Long Term Benefit of Morbidity Reduction Due to Praziquantel Treatment Against Schistosoma Mansoni in Kigungu Fishing Village in Entebbe, Uganda

Date Published: , 2011

Publisher: African Ethnomedicines Network

Author(s): Emmanuel I Odongo-Aginya, FK Kironde, MI Lyazi, Harman Sempewo, Rodrigo Correa Oliveira.



Praziquantel (PZQ) is efficacious against Schistosoma mansoni. This was prospective cohort study. This study was carried out at Kigungu fishing village, Entebbe, Uganda. The goal of the study was to establish cost effective regiment for mass drug administration (MDA) of Praziquentel in the morbidity reduction of S.mansoni infection. In January 2004, nine hundred and forty five (945) participants were registered in this study. Our analysis was based on examining microscopically three slides prepared from each of 945 stool specimens delivered by each of the participant using modified Kato/Katz method. These included male and female, children and adults living in Kigungu fishing village in Entebbe Uganda. In total 901, cohorts were re-examined for infections clearance six months later in July 2004 and 18 months later in June 2005, 625 cohorts were again re-evaluated for S.mansoni infections after the baseline study. At baseline, (448) of 945 (47.5%) cohorts were S. mansoni positive. All these participants were treatment with a single oral dose of praziquantel at 40mg/kg. At the same time, 495 (52.5%) were S. mansoni negative. Of the 625 (66.3%) cohorts who came back for final review, 80 (12.8%) were still positive for S. mansoni while 210 (33.6%) remained negative after the base line treatment with praziquantel. On the other hand 103 (16.3%) of cohorts who were initially negative at the base line became S.mansoni positive after 18 months and 213(34.1%) remained negative for S.mansoni. The force of re-infection after six months was significant {(P=0.0001), (OR 0.47) CI at 95% (0.31–0.71)}. Nevertheless the force of reinfection was not significant after 18 months {(P=0.766), (OR 0.95) CI at 95% (0.68–1.34)}.The geometric mean eggs excretion of the 80 cohorts who were S.mansoni positive at 18 months was 151.967.This did not reach the geometric mean egg excreted by the same cohorts at baseline which was 285.05. The egg excretion was reduced by 46.8%. Similarly there was marked decrease in clinical symptoms amongst the cohorts. Our study suggests evidence of long-term benefit of praziquantel in Kigungu and that a yearly administration of praziquantel to the community could be a regiment for mass drug administration (MAD) for this community to control schistosomiasis morbidity.

Partial Text

Praziquantel (PZQ) is efficacious against Schistosoma mansoni (Sleigh et al., 1985). Presently in Uganda, one of schistosomiasis endemic countries in sub Saharan Africa, PZQ is the drug of choice in controlling morbidity due to schistosomiasis because the mean cost of treatment per dose per person in Uganda is about $0.3 (Mott, 1982; Doenhoff et al., 2002). In spite of its relative low cost, Uganda Ministry of Health budget is still unable to procure adequate PZQ for short period mass chemotherapy. Previous studies in the seventies showed that in Uganda, the efficacy of PZQ was evaluated after six months to determine the cure proportion (Odongo-Aginya and Mugisha, 1987). Nevertheless in other tropical countries, few studies evaluated the efficacy of PZQ at the interval of one year (Stelma et al., 1995; Correa-Oliveira, et al., 2000; Davis, 1993). At present, studies in different endemic settings using the single oral dose regiment of 40 (mg/kg wt) of PZQ against S. mansoni, and mixed infections, the efficacy of PZQ stands at 60-90 % (Cioli and Pica- Mattoccia, 2000). Extensive use of PZQ in Uganda and elsewhere in the tropics has been linked to the development of parasite resistance to the drug. This is evidenced by reduced cure proportion in humans treated with PZQ in the Richard Toll area of Senegal (Stelma et al., 1995). However, factors like intensity of infections and high transmission of infections have been known to influence schistosomicidal activity of PZQ (Gryseels, 1994). In spite this fact, repeated treatment with PZQ has been shown to improve cure proportion as observed in West Nile districts of Uganda areas of high transmission and intensity (Ongom and Bradley, 1972).

A very small proportion (2.4%) of the 433 patients who were S. mansoni positive at the baseline survey continued to excrete eggs of S. mansoni in their faeces. Meanwhile among the 468 negative patients at the baseline (2.5%) of them were infected (Figure 1). Comparison of eggs intensity excreted by the 80 cohorts who were positive at base line, cleared their infections after six months but got re-infected twelve months later are shone in (Table 1).Meanwhile Comparison of Intensity of S. mansoni amongst 80 patients who were reinfected 18 months later and 102 patients who were S. mansoni negative but became S. mansoni positive 18 months later by Student’s T-test did not find any significant difference This implies that the benefit of treatment with PZQ continues to be felt in the community even after 18 months (Table 2).

Several studies of infections and reinfection with Schistosoma mansoni after treatments with PZQ of residents living in endemic areas in the Tropics have been shown to lead to reduction of prevalence and intensity to re-infection after treatment. The re-infection prevalence and intensity have been shown never to equal before treatment level (Correa-Oliveira, et al., 2000). This study showed that there was reduction in the percentage of infection from {47.4% (448 out of 945) to 25.8% (80 out 310)} and the percentage reduction of the sum of eggs excretion was 50.4% in post PZQ therapy. This was 18 months after the initial treatment with PZQ 40mg/kg/wt. (Stelma et al., 1995; van.Liehout, et al., 1999).