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Post-MDA surveillance ( including xeno -monitoring)

Post-MDA surveillance ( including xeno -monitoring). Krishnamoorthy K. Vector Control Research Centre Pondicherry India. Rationale. Development of an appropriate and feasible surveillance strategy to monitor the post-MDA epidemiological situation is necessary to:

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Post-MDA surveillance ( including xeno -monitoring)

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  1. Post-MDA surveillance (including xeno-monitoring) Krishnamoorthy K. Vector Control Research Centre Pondicherry India

  2. Rationale • Development of an appropriate and feasible surveillance strategy to monitor the post-MDA epidemiological situation is necessary to: • declare the areas/intervention units are free from LF transmission or • take steps to prevent resurgence of infection, if any. • Antigenaemia prevalence has been recommended to monitor post MDA situation. However, the change in this parameter during the post MDA period (five years) is not known to understand the usefulness of this indicator and also to decide on the frequency of post MDA survey.

  3. Study area Intervention = Mass annual single dose DEC + albendazole Six rounds – supervised administration (2001-2007) Coverage = above 70% Post 6 rounds of MDA = <1% mf Ag prevalence (3-6 years) = 0/93 Stopped MDA in 2008

  4. Objectives • To understand the post-MDA changes in antigenaemia prevalence in children (6-10 years) • To relate the post-MDA changes in antigenaemia prevalence in children with the antigenaemia prevalence in adult groups (16-45 years) • To evaluate the value of xenomonitoring as a tool for post-MDA surveillance • To determine the required duration of post-MDA surveillance period

  5. Evaluation Unit Evaluation Unit - four villages

  6. Overall 7.76 % n=580 Overall 0.05% n=585

  7. Indicators and tools • Antigenemia (mass) survey in : • Diagnostic tool – ICT • Target age class • 6-10 years (children) • 16-45 years (adults) • Entomological survey: • 5000 vector mosquitoes • Gravid traps • Dissection to assess the vector infection • These surveys were repeated after two years. The first survey was done in 2011 and the second in 2013

  8. Coverage for ICT survey

  9. Ag prevalence during post MDA

  10. 2011 2013

  11. TAS exercise (6-7 years)

  12. Ag survey Longitudinal (cohort) folllow-up Total = 1053 Positive in 2011 = 23 Loss in 2013 = 19 (82.6%) Negative in 2011 = 1030 Gain in 2013 = 15 (1.46%)

  13. Conclusion • Absence of recent transmission in two consecutive post-MDA surveys indicate that 1% Mf prevalence was safe to discontinue MDA. • Prevalence of antigenemia prevalence among children (6-10 years) is less than 1% during post MDA period. • Post-MDA Ag-prevalence between children and adult age class is not related, and therefore adult age class cannot be targeted for evaluation. There was reduction in antigenemiaprevalence in both children (28%) and adult age classes (33%). The relative change in Ag prevalence between the age classes was also not significant. • Loss of infection was about 83%. • Xenomonitoringafter two years of stopping MDA did not show evidence for vector infection implying absence of potential mf carriers in the study community.

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