THE FIELD SURVEY AND THE UACR THRESHOLDS USED

Using portable ultrasonography, UTP prevalence was assessed on 66 Zanzibari children (9-15

years). Urines were investigated for Schistosoma haematobium eggs using microscopy (Fig 1D),

and albumin and creatinine concentrations using Microalbustix (Bayer,UK)

(Fig. 1A).

Thresholds used: ≥3.4 mg of albumin per mmol of creatinine

as abnormal and ≥33.9 mg of albumin per mmol of

creatinine as severelyabnormal (Fig. 2)

Fig. 1D - S. haematobium egg

Fig. 1B - Ultrasound image of damage bladder due to

chronic infection

Fig. 1A - Microalbustix with reading on creatinine (top) and albumin (bottom)

concentrations

EVALUATION OF THE USE OF URINE ALBUMIN-TO-CREATININE RATIO (UACR) FOR ASSESSMENT OF URINARY SCHISTOSOMIASIS-ASSOCIATED

MORBIDITY ON ZANZIBAR

Sousa-Figueiredo J.C.1, Khamis I.S.2, Garba A. 3, Rollinson D.1, Stothard J.R.1

1 Department of Zoology, Natural History Museum, London, United Kingdom; 2 Helminth Control Laboratory Unguja, Zanzibar, Tanzania

3 Schistosomiasis Control Initiative (SCI) national programme, Niger Evaluation of the use of UACR, calculated from measurements using Microalbustix® reagent strips, as

a rapid diagnostic tool for urinary tract pathologies (UTP) associated with S. haematobium infection

OBJECTIVE

MONITORING CHRONIC PATHOLOGIES OF URINARY SCHISTOSOMIASIS

Monitoring of control programmes for urinary schistosomiasis involves assessing the progression of morbidity indicators, such as haematuria (Fig. 1C) and UTPs (Fig. 1B), as well as infection intensity and prevalence, in the presence of treatment. Lowcost-efficiency and poor field-applicability of ultrasonography demands the development of a rapid diagnostic test for monitoring the chronic manifestations of urinary schistosomiasis (i.e. UTPs).

References: •Vennervald BJ et al (2000). Assessment of morbidity in Schistosoma haematobium infection: current methods and future tools. Acta Tropica; 77:81- 89

•WHO (1991). Meeting on ultrasonography in schistosomiasis. Proposal for a practical guide to the standardized use of ultrasound in the assessment of pathological changes. World Health Organization, Geneva•Eknoyan G, et al (2003). Proteinuria and other markers of chronic kidney disease: a position statement of the National Kidney Foundation (NKF) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

American Journal of Kidney Diseases; 42:617-22

Acknowledgements: Zanzibar MoHSW, Schistosomiasis Control Initiative, Niger, and The Health Foundation, UK; conducted as part of the MSc thesis

• 65.2% of the surveyed schoolchildren were positive for S. haematobium eggs

• 89.4% and 50.0% of schoolchildren had abnormal and severely abnormal UACR, respectively

• 66.1% had one or more ultrasound-identified UTPs, commonest being bladder-related (62.9%)

• UTP prevalence was highly associated with active S. haematobium infection (P<0.001)

• UACR was found to be sensitive, although with poor specificity (Table 1)

• Reason for confounding: active infections cause tissue damage, i.e. haematuria (Fig 1C), increasing albumin in urine resulting in an abnormal UACR.

RESULTS

• The UACR is a field applicable and extremely sensitive methodology for identifying urinary tract morbidity associated with urinary schistosomiasis

• Further evaluation of this protocol should take place during control campaigns, particularly in previously high transmission areas, where UTPs will be common

• Effectiveness is likely to increase as control programmes progress and the prevalence of infection diminishes, as the latter is a major confounder when using UACR for identifying UTPs (Fig. 1)

CONCLUDING REMARKS

Fig. 2 - Graphical representation of albumin and creatinine urine concentration readings using the Microalbustix®, as well as calculated urine albumin-to-creatinine ratios (UACR) (table). Arrows represent potential aetiologies for readings in a urinary schistosomiasis-endemic scenario.

Table 1 – Performance of urine albumin-to-creatinine ratio (UACR) (calculated from measurements using the Microalbustix®) as a rapid diagnostic tools for UTPs (‘gold standard: ultrasonography). PPV = Positive predictive value; NPV = Negative predictive value

Fig. 1C - Red urine (haematuria) due to tissue damage as eggs enter the bladder