Significantly reduced intensity of infection but persistent prevalence of schistosomiasis in a highly endemic region in Mali after repeated treatment

PLoS Negl Trop Dis. 2012;6(7):e1774. doi: 10.1371/journal.pntd.0001774. Epub 2012 Jul 31.

Abstract

Background: Preventive chemotherapy against schistosomiasis has been implemented since 2005 in Mali, targeting school-age children and adults at high risk. A cross-sectional survey was conducted in 2010 to evaluate the impact of repeated treatment among school-age children in the highly-endemic region of Segou.

Methodology/principal findings: The survey was conducted in six sentinel schools in three highly-endemic districts, and 640 school children aged 7-14 years were examined. Infections with Schistosoma haematobium and S. mansoni were diagnosed with the urine filtration and the Kato-Katz method respectively. Overall prevalence of S. haematobium infection was 61.7%, a significant reduction of 30% from the baseline in 2004 (p<0.01), while overall prevalence of S. mansoni infection was 12.7% which was not significantly different from the baseline. Overall mean intensity of S. haematobium and S. mansoni infection was 180.4 eggs/10 ml of urine and 88.2 epg in 2004 respectively. These were reduced to 33.2 eggs/10 ml of urine and 43.2 epg in 2010 respectively, a significant reduction of 81.6% and 51% (p<0.001). The proportion of heavy S. haematobium infections was reduced from 48.8% in 2004 to 13.8% in 2010, and the proportion of moderate and heavy S. mansoni infection was reduced from 15.6% in 2004 to 9.4% in 2010, both significantly (p<0.01). Mathematical modelling suggests that the observed results were in line with the expected changes.

Conclusions/significance: Significant reduction in intensity of infection on both infections and modest but significant reduction in S. haematobium prevalence were achieved in highly-endemic Segou region after repeated chemotherapy. However, persistent prevalence of both infections and relatively high level of intensity of S. mansoni infection suggest that more intensified control measures be implemented in order to achieve the goal of schistosomiasis elimination. In addition, closer monitoring and evaluation activities are needed in the programme to monitor the drug tolerance and to adjust treatment focus.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Anthelmintics / administration & dosage*
  • Chemoprevention / methods*
  • Child
  • Child, Preschool
  • Cross-Sectional Studies
  • Endemic Diseases*
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Mali / epidemiology
  • Middle Aged
  • Models, Theoretical
  • Parasitology / methods
  • Prevalence
  • Schistosoma haematobium / isolation & purification
  • Schistosoma mansoni / isolation & purification
  • Schistosomiasis haematobia / drug therapy
  • Schistosomiasis haematobia / epidemiology*
  • Schistosomiasis haematobia / pathology*
  • Schistosomiasis mansoni / drug therapy
  • Schistosomiasis mansoni / epidemiology*
  • Schistosomiasis mansoni / pathology*
  • Schools
  • Young Adult

Substances

  • Anthelmintics

Grants and funding

This study was made possible by the generous support of the American people through the USAID. The national integrated NTD control program in Mali is supported by the USAID NTD Control Program managed by RTI International and implemented by Helen Keller International. The baseline survey was supported by the Schistosomiasis Control Initiative, which was funded by the Bill and Melinda Gates Foundation. The contents are the responsibility of the authors and do not necessarily reflect the views of USAID or the United States government. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.