Mapping of Schistosoma mansoni in the Nile Delta, Egypt: Assessment of the prevalence by the circulating cathodic antigen urine assay

Acta Trop. 2017 Mar:167:9-17. doi: 10.1016/j.actatropica.2016.11.038. Epub 2016 Dec 11.

Abstract

In line with WHO recommendations on elimination of schistosomiasis, accurate identification of all areas of residual transmission is a key step to design and implement measures aimed at interrupting transmission in low-endemic settings. To this purpose, we assessed the prevalence of active S. mansoni infection in five pilot governorates in the Nile Delta of Egypt by examining schoolchildren (6-15 years) using the Urine-Circulating Cathodic Antigen (Urine-CCA) cassette test; we also carried out the standard Kato-Katz (KK) thick smear, the monitoring and evaluation tool employed by Egypt's national schistosomiasis control programme. Prevalence rates determined by the Urine-CCA test for all governorates were higher than those determined by KK (p<0.01). Of 35 districts surveyed in the five governorates, S. mansoni infection was detected in 19 districts (54.3%) using KK, and in 31 districts (88.6%) by Urine-CCA (χ2=9.94; P=0.0016). S. mansoni infections were detected by Urine-CCA, but not by KK in 12 districts (34.3%), and infection was not detected by either of the two diagnostic methods in four districts in Qalyubia governorate. Males and higher age-groups have significantly higher Urine-CCA prevalence rates. Based on the findings of the current S. mansoni mapping exercise, authorities of the Ministry of Health and Population (MoHP) adopted a new elimination strategy by readjusting thresholds for mass treatment with praziquantel and targeting all transmission areas. MoHP is now planning to remap in all other endemic governorates using Urine-CCA with the aim of identifying all areas of transmission where the elimination strategy should be applied.

Keywords: Egypt; Elimination; Kato-Katz; Mapping; S. mansoni; Urine-CCA.

MeSH terms

  • Adult
  • Animals
  • Anthelmintics / therapeutic use
  • Antigens, Helminth / urine*
  • Child
  • Egypt / epidemiology
  • Female
  • Geographic Mapping*
  • Humans
  • Male
  • Pilot Projects
  • Praziquantel / therapeutic use
  • Prevalence
  • Schistosoma mansoni / immunology*
  • Schistosomiasis mansoni / drug therapy
  • Schistosomiasis mansoni / epidemiology*
  • Schistosomiasis mansoni / urine
  • Sensitivity and Specificity
  • Surveys and Questionnaires

Substances

  • Anthelmintics
  • Antigens, Helminth
  • Praziquantel