THE FIELD SURVEY AND THE UACR THRESHOLDS USED

1
EVALUATION OF THE USE OF URINE ALBUMIN-TO-CREATINI
NE 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
OBJECTIVE
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
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
severely abnormal (Fig. 2)
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. Low cost-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).
Fig. 1A - Microalbustix with reading on
creatinine (top) and albumin (bottom)
concentrations
Fig. 1B - Ultrasound image of damage bladder due
to chronic infection
Fig. 1D - S. haematobium egg
Fig. 1C - Red urine (haematuria) due to tissue
damage as eggs enter the bladder
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-creatini
ne 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
RESULTS
CONCLUDING REMARKS

• 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 (Plt0.001)
• 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.

• 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)

• References
• Vennervald BJ et al (2000). Assessment of
  morbidity in Schistosoma haematobium infection
  current methods and future tools. Acta Tropica
  7781- 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 42617-22
• Acknowledgements Zanzibar MoHSW, Schistosomiasis
  Control Initiative, Niger, and The Health
  Foundation, UK conducted as part of the MSc
  thesis