Detection of duo-schistosome infection from filtered urine samples from school children in Zambia after MDA

PLoS One. 2017 Dec 11;12(12):e0189400. doi: 10.1371/journal.pone.0189400. eCollection 2017.

Abstract

Schistosomiasis is one of the major Neglected Tropical Diseases (NTDs) in sub-Saharan Africa. In sub-Saharan Africa, two major human schistosome species namely Schistosoma mansoni and S. haematobium often occur sympatrically largely affecting children. Recognizing the public health impact of Schistosomiasis, the World Health Organization (WHO) is urging member states to regularly treat at least 75% and up to 100%, of all school-aged children at risk of morbidity. For control strategies based on targeted mass drug administration (MDA) to succeed it is essential to have a simple and sensitive test for monitoring the success of these interventions. Current available diagnostic tests, such as egg detection in stool by Kato-Katz (KK) for S. mansoni and detection of eggs or blood (hematuria) in urine for S. haematobium have reduced sensitivity in low intensity settings. The objective of the study was to evaluate active single or duo schistosome infections in school children following MDA using molecular diagnostics (PCR) on filtered urine samples and comparing that against traditional diagnostic tests. This cross-sectional study was conducted among 111 school children aged 7-15 years in Chongwe and Siavonga Districts in Zambia. Species-specific cell-free repeat DNA fragment were amplified from 111 filtered urine samples. Our approach detected eight times more positive cases (total 77) than by KK (9) for S. mansoni and six times more (total 72) than by hematuria (11) for S. haematobium and even more against urine filtration (77 compared to only 6). The same pattern was observed when stratified for age group and sex specific analysis with 100% sensitivity and specificity devoid of any cross amplification. In addition, 69 individuals (62%) were co-infected by both parasites. We have demonstrated a significantly higher prevalence of both species than indicated by the traditional tests and the persistent maintenance of reservoir of infection after MDA. Our approach is an effective means of detecting low intensity infection, which will enhance the effectiveness of surveillance and assess the impact of MDA control programs against schistosomiasis.

MeSH terms

  • Adolescent
  • Child
  • Cross-Sectional Studies
  • Female
  • Humans
  • Male
  • Molecular Diagnostic Techniques
  • Polymerase Chain Reaction
  • Schistosomiasis / diagnosis*
  • Schistosomiasis / urine
  • Zambia

Grants and funding

NL received an Early Career Research award from Thrasher Research Fund. The study was possible because of this funding. The Foundation had no role in designing or conceptualization of the study. https://www.thrasherresearch.org/default.aspx.