Introduction

Human schistomiasis remains one of the most important parasitic diseases in the tropics for which there are no vaccines¹. Chemotherapy with praziquantel currently offers the most feasible means of controlling human schistosomiasis, at least in the short term^2,3. There are concerns however that schistosoma haematobium the aetiologic agent of urinary schistosomiasis is developing resistance to praziquantel or at least have the tendency to do so^4,5. Studies conducted elsewhere have associated praziquental with low cure and egg production rates after the administration of a single dose of the drug^6,7,8. Subsequently, communities in a very intense focus of S. mansoni infection in Senegal showed unexpectedly low rate following treatment with praziquantel^9,10. Perhaps the best evidence so far of resistance to praziquantel is the failure of Ismail et al.¹¹ to cure some natural S. mansoni infection in some Egyptian patients with three doses of the drug.

The potential problem of praziquantel resistance led to a search for alternative drug for the treatment and control of schistosomiasis^12,13. Although artemisinin and it derivatives such as artesunate, arteether, artemether and dihydroartemisinin were originally developed for the treatment of malaria, they have antischistosomal activity^13,14. In vitro treatment of adult schistosomes with artemether, for example led to a significant reduction in the glycogen content of the worms and extensive tegumental damage¹⁵.

For more than a decade, evidence has been accumulating of the effect of treating S. japoniucum and S. mansoni infections with one of the artemisinins¹⁶. Artemether appears to exhibit maximum activity against the liver stages and adult worms being less susceptible¹⁵. In human trials, administration of artemisinin derivatives (artesunate, artemeter) at a dose of 6mg/kg every 15 days during the S. japonicum transmission season resulted in the effective control of schistosomiasis in highly endemic areas in China¹⁷. Recently, treatment of schistosomiasis with the combination of artesunate and praziquantel show that more than 80% curative^18,19. Artesunate not only exhibits antimalaria properties, but also possesses strong activities against schistosomes.

The objective of our present research is to determine the efficacy of artesunate in the treatment of urinary schistosomiasis in patients attending the General Hospital, Ogoja in the Cross River State of Nigeria.

Materials And Methods

Sample Collection

Ethical Clearance

Collection of Urine Samples

Urinalysis

Sources of Drug

Treatment of Infected Patients

Adverse effect monitoring

Results

Of the 250 pupils (129 males and 121 females aged 6 – 50 years) initially screened for the presence of Schistosoma haematobium ova in the urine, 25 (10%) pupils were found positive and therefore included in the treatment plan (Table 1).

The frequency of parasitological cure (as estimated two weeks after treatment) is summarized in Table 1. Out of the 25 patients who each received a single dose of artesunate, 16 (64.0%) were cured after treatment. The prevalence of the infection was reduced from 10% pre-treatment to 3.6% post-treatment following the administration of artesunate (P<0.05) (Table 1). There was a drastic and significant (P<0.001) reduction in mean egg count after treatment mean egg count drastically reduced by treatment. The value fell from 17.3% to 3.1% post-treatment. The overall percentage reduction in intensity was 82.1 (range 64.0 – 90.2) (Table 2).

Figure 1

Table 1: Age related, prevalence of infection before and after treatment with artesunate

Figure 2

Table 2: Age related intensity of infection before and after treatment with artesunate

Discussion

This study has assessed the efficacy and tolerability of oral artesunate for the treatment of urinary schistosomiasis.

From the result of the investigation, a single dose of oral artesunate appeared to cure 64% of those treated and also reduced significantly the intensities of infection in those not cured from 17.2 mean ova/10ml urine to 3.1 mean ova/10ml urine. In Senegal, De Clercq et al.²² also found artesunate to be effective against S. haematobium, although the result they obtained with praziquantel were consistently better. Inyang-Etoh et al.²³ found artesunate to be effective against S. haematobium as 70% of those treated were found cured in Admin Community, Nigeria.

In the present study, 36% of the patients treated were not cured probably due to resistance of the patients to artesunate. Borrmann et al.¹⁸ found that only 27% of the subjects they treated with artesunate in Gabon were cured. However, Borrman et al.¹⁸ thought that their disappointing results might be as a result of an inherent resistance to artemisinin or its derivatives in S. haematobium in addition.

Even though 36% of the patients in the present study were not completely cured, there was a drastic reduction in the intensity following the administration of the single doses of artesunate from 17.3 mean ova/10ml to 3.1 mean ova/10ml. There was probably inherent resistance of this individual to artemisinin.

Based on the cure rate of 64% established in the present study, artesunate was said to be effective. Similarly, Ejezie et al.²⁴ recorded a cure rate of 67% using praziquantel. This indicated that there was no significant difference between the two results even though praziquantel is widely recognized as a major drug of choice in the treatment of urinary schistosomiasis. Artesunate was also established as a widely used antimalarial drug in the tropics and thus can similarly treat urinary schistosomiasis. However, the 3.6% that were not cured might be acting as a veritable sources of re-infection, thereby becoming a public health problem.

The use of combination therapy as a safeguard against the rapid development of drug resistance by schistosomes has been advocated by several authors^11,25. The enhanced cure rate obtained by these workers suggest that combination therapy may be an effective strategy of combating drug resistance in schistosomiasis infection. Borrmann et al.¹⁸ recorded that the combination of artesunate and praziquantel gave a cure rate of 81% in Garbon while Inyang-Etoh et al.¹⁹ recorded a cure rate of 88.6% in their study in Nigeria using artesunate and praziquantel combination.

Acknowledgement