Efficacy of Praziquantel in Treating Schistosoma Mansoni Infected School Children in Tumuga and Waja , North Ethiopia

Praziquantel (PZQ) is a drug of choice for treating schistosomiasis mansoni. Praziquantel was effectively used to treat schistosomiasis, but there are reports that indicate the appearance of Praziquantel resistance. The objective of this study was to determine the rate of S. mansoni infection before and after single treatment, thus to measure the efficacy of Praziquantel in treating Schistosoma mansoni infected individuals in the study area. The study utilized microscopic examination of two Kato–Katz slides for each individual sample before and after treatment. The cure rate of S. mansoni infection by Praziquantel in the two study areas remains high and with no significant difference. In Timuga cure rate was 93.44% and in Waja 88.99% (χ= 3.644 and P= 0.16). Efficacy of Praziquantel in treating infections due to S. mansoni is still high and there is no evidence for resistance S. mansoni against Praziquantel in Tumuga and Waja.

As reduction of schistosomiasis is still beyond human and financial resources, the aim of most control programs remains the reduction of morbidity by treating infected people on an individual or population basis by using chemotherapy agents such as Praziquantel (WHO, 1993).Praziquantel was effectively used to treat schistosomiasis since the last two decades (WHO, 1993;Magnussen, 2003).The treatment of schistosomiasis by Praziquantel requires administration of a single dose 40mg/ kg of body weight (Engels et al., 2000).As the drug is supplied by a reasonable price in hospitals, still now in Ethiopia, especially in the study area, Praziquantel is the drug of choice in treating schistosome infected individuals.
Praziquantel is a drug of choice for treating schistosomiasis mansoni (Day et al., 1992, Redman et al., 1995).Besides, it has been reported that Praziquantel has shown a remarkable impact in reducing morbidity due to schistosomiasis (WHO, 2000).But there are reports, Tadesse, D., Tsehaye, A and Mahmud, A (MEJS) Volume 2 (2):3 -11, 2010 © CNCS Mekelle University 4 which indicate the occurrence of Praziquantel resistant schistosome strains, which makes the problem of schistosomiasis worse.Low efficacy of Praziquantel in treating human schistosomiasis mansoni was reported in Senegal (Stelma et al., 1995) andBrazil (Katz et al., 1991).Similarly, Follon and Doenhoff (1994) also demonstrated drug resistance of S. mansoni for Praziquantel.Similar observation of Praziquantel resistance was also reported by Cioli et al., (1993) and Kasel and Hagan (1999).In vitro, sensitivity test of adult schistosomes showed low response Praziquantel including calcium influx, tegument disruption and muscle contraction (William et al. 2001;Ismail et al., 1999;William and Botros, 2004).Interestingly, there is no report of resistance to multiple treatments by Praziquantel and oxamniquine (Follon and Doenhoff, 1994).
The occurrence of Praziquantel resistant schistosomes is a potential problem to control schistosomiasis.Thus, such survey was designed to test whether there are Praziquantel resistant schistosomes in Tigray or not.In this study, determination of the rate of S. mansoni infection before and after single treatment was performed to measure the efficacy of Praziquantel in the treatment of S. mansoni infected individuals.
The outcome of the study will have important implications for schistosomiasis control.
Therefore, from the outcome of the study a clear recommendation in treatment of schistosomiasis will be given, that is by praziquantel alone or by mixed treatment with that of oxamniquine.But treating individuals by mixed treatment without having the information of resistance history costs unnecessary expense.The information that will be gained might provide baseline data for designing suitable and cost effective control scheme against schistosomiasis mansoni in our country.Besides, the study may be helpful to the understanding of the current status efficacy status of praziquantel in Ethiopia.

MATERIALS AND METHODS
The study was done in two towns in the southern tip of Tigray Regional State (northern Ethiopia); Timuga and Waja,190km and 195km, respectively far to the south from the capital city of the region, Mekelle.The two cities were selected purposely based on previous schistosomiasis mansoni prevalence rate of 87% in Timuga (Tadesse and Beyene, 2009) and 36.4% in Waja (Tadesse et al., 2009).In this study, schoolchildren were used to index the assessment of community prevalence (Guyatt et al., 1999).
The overall prevalence rate (p) of S. mansoni in the study area was determined to be 61.7% from the previous studies in the same study area; p was taken to be 61.7%(Tadesse et al., Tadesse, D., Tsehaye, A and Mahmud, A (MEJS) Volume 2 (2):3 -11, 2010 © CNCS Mekelle University 5 2009; Tadesse and Beyene 2009).For the calculation, a 95% confidence interval (z) and a 5% margin of error (d) were used.This gave a sample size of 364.Besides, to minimize errors arising from the likelihood of non compliance, seven percent of the sample size was added to the normal sample (364 + 26= 390).Thus, a total of 390 schoolchildren (152 females and 238 males) were selected from Waja (172) and Tumuga (218) Primary schools.The subjects were selected randomly from their grade categories.The study utilized examination of Kato-Katz slides (42.7 mg stool/slide) for each individual (Peters et al., 1980).Four weeks after the first treatment, the treated patients were tested again, using two Kato-Katz slides for each The data collected was entered in to SPSS program version 12 and were analyzed by using appropriate statistical packages (percentile and Chi-square test).

Prevalence of S. mansoni
The prevalence of Schistosoma mansoni in both study areas Tumuga and Waja was 63.3% and 73.84%, respectively (Table 1).The average prevalence of schistosomiasis mansoni in both study areas was 67.95%.This average is done because the old town Waja on the south direction and the new town Tumuga on the north direction are divided by A Waja Wuha River.When compared with previous studies in Tumuga (Author, 2009), the prevalence of S. mansoni infection was 87%, thus in this report the infection reduces by 27.7% (Tadesse and Beyene, 2009).On the other hand 31.95% increase in prevalence was recorded in Waja in the current survey (Tadesse et al., 2009).We have no evidence for showing neither environmental modification nor educational programs that could show behavioral changes of school children of Tumuga to water contact.Similarly, we cannot demonstrate for the increase in prevalence of S. mansoni infection prevalence in Waja.For this reason, it is Tadesse, D., Tsehaye, A and Mahmud, A (MEJS) Volume 2 (2):3 -11, 2010 © CNCS Mekelle University 6 difficult to say infection decrease or increase because children share the same water source (Waja Wuha) that acts as a source of S. mansoni infection.

Pretreatment Results
Similar proportion of the age dependent prevalence of S. mansoni infection was demonstrated in both before and after infection (Fig. 1).The highly affected age groups were 10-14 and 15-19 year old and the least affected age groups were 5-9 and 20-24 (χ 2 =12.3,P< 0.05).Similar findings were reported in the same study sites and elsewhere in Ethiopia (Berhanu, 1988;Hailu et al., 1997;Alemayehu et al., 1998;Tadesse and Beyene, 2009)

Post treatment results
The cure rate after one treatment with the standard dose of 40 mg/kg PZQ was 84.5%, ranging from 73.8 to 92.3% in the individual primary schools (Table 2).Infection before and after treatment was highly significant (Fig. 2) (χ 2 = 15.66 and P= 0.000) but cure rate among sexes remains in similar proportion (p>0.05).The results of the present study indicated that there is no sex difference in S. mansoni infection in both pre-and post-treatment tests.This findings agree with previous works by the same authors in the study sites (Tadesse and Tadesse, D., Tsehaye, A and Mahmud, A (MEJS) Volume 2 (2):3 -11, 2010 © CNCS Mekelle University 7 Beyene, 2009) Such findings indicate that there is no S. mansoni infection difference between male and female sexes, and also confirmed the efficacy of PZQ has no sex bias.The cure rate of S. mansoni infection by Praziquantel in the two study areas remains the same, in Timuga cure rate was 93.44% and with that of Waja it was 88.99% (Fig. 3) (χ 2 = 3.644 and P> 0.15).
In the current study, intensity of medium and heavy infection after single treatment reduced from 38.49% to 30% and from 10.57% to 5%, respectively (see Table 3).Infections after Praziquantel treatment remain light infection (Botrosa et al., 2005).
Cure rate after single treatment with Praziquantel reported in this study (88.99-93.44%)was found to be similar and in a range of previously reported efficacy of Praziquantel against Schistosoma infection (70-95%) in Ethiopia (Getnet et al., 2002) and outside Ethiopia (Barakat, 2000;Botrosa et al., 2005).

CONCLUSION
Prevalence of S. mansoni infection was not reduced in Waja and Timuga.Efficacy of Praziquantel in treating infections due to S. mansoni is still high and there is no evidence for resistance S. mansoni against Praziquantel in Tumuga and Waja.Thus, authors recommend that treating schistosomiasis patents with Praziquantel in the study aria is still efficient and coast effective.

ACKNOWLEDGEMENT
This study was financially supported by the Mekelle University Inter University Cooperation project (MU-IUC).We would also like to acknowledge Dawit Gebre-egziabher, Getachew Mengistu and Selam Negussie,, who actively participated in data collection and microscopic examination.Our thanks also goes to Timuga and Waja Primary School directors, teachers and students.This study would not be materialized without the assent and willingness of the study participants.
individual.First samples (before treatment) data was collected in March 2009, while the second samples (after treatment) was undertaken in February 2009.Those individuals who do not pass ova were subsequently excluded.Here, the state of no cure was determined by the presence of ova of S. mansoni in the stool specimen.All patients with positive fecal smears were treated with the standard dose of Praziquantel (40 mg/kg body weight, single dose) under the supervision of the authors.Specimens were collected on-the-spot and transported to Parasitology laboratory of the Department of Biology at Mekelle University for microscopic examination.For each stool sample, two slides were prepared and microscopically examined by well trained expertise to detect S. mansoni eggs.

Figure 1 .
Figure 1.Percentage of S. mansoni infection before and after treatment with Praziquantel in Tumuga and Waja Primary Schools, examined in February and March 2009.

Figure 2
Figure 2 Percentage of infection among sexes before and after treatment in Tumuga and Waja Primary Schools, in February and March 2009.

Table 1 .
Prevalence of S. mansoni infection in Tumuga and Waja Primary Schools, examined in February 2009

Table 2 .
Single dose Praziquantel treatment result of S. mansoni infected School Children in Tumuga and Waja, examined in March 2009.

Table 3 .
Intensity of S. mansoni infection before and after Praziquantel single treatment in Timuga and Waja School Children, 2009.Figure 3. Percentage of infection (before treatment) and cure rate after treatment with Praziquantel in Tumuga and Waja, in February and March 2009.