School-based control of urinary schistosomiasis on Zanzibar, Tanzania: Monitoring micro-haematuria with reagent strips as a rapid urological assessment

Abstract 

Objective

To evaluate micro-haematuria, detected by Haemastix^® reagent strips, for diagnosis of urinary schistosomiasis during a 3-year period of school-based control on Zanzibar.

Patients and methods

A sub-set of school children, from a total of 135,000 who were receiving treatment for urinary schistosomiasis and soil-transmitted helminthiasis, were monitored by parasitological and questionnaire methods for Schistosoma haematobium infections: at treatment baseline in 2004 (n=2002), follow up with re-treatment in 2005 (n=3278) and further follow up with re-treatment in 2006 (n=3993). Standard diagnostic scores for micro-haematuria were calculated against parasitological assessment.

Results

Diagnostic scores of Haemastix^® remained strong throughout the 3-year period. In 2006, scores were: sensitivity (SS)=0.86 (95% CI: 0.86–0.88), specificity (SP)=0.99 (0.98–1.00), positive predictive value (PPV)=0.90 (0.88–0.91), negative predictive value (NPV)=0.98 (0.98–0.99) in boys; and SS=0.84 (0.82–0.86), SP=0.98 (0.98–0.99), PPV=0.77 (0.75–0.79) and NPV=0.99 (0.99–1.00) in girls. By comparison, reported blood in urine and pain upon urination were much lower and not as informative.

Conclusion

At a cost of approximately £0.20/test, further use of reagent strips for monitoring of urinary schistosomiasis during ongoing control programmes should be advocated as a rapid, cost-effective and informative disease surveillance tool.

Keywords: Micro-haematuria, Diagnosis, Urinary schistosomiasis, Schistosoma haematobium