A comparative analysis of the outcome of malaria case surveillance strategies in Sri Lanka in the prevention of re\u2010establishment phase

W. M. Kumudunayana T. de A. W. Gunasekera,Muzrif Munaz,Kamini Mendis,Risintha Premaratne,Devika Perera,M. G. Y. Piyasena,K. D. N. Prasad Ranaweera,Rajitha Wickremasinghe,Deepika Fernando

doi:10.1186/s12936-021-03621-5

Abstract

BackgroundSri Lanka sustained its malaria-free status by implementing, among other interventions, three core case detection strategies namely Passive Case Detection (PCD), Reactive Case Detection (RACD) and Proactive Case Detection (PACD). The outcomes of these strategies were analysed in terms of their effectiveness in detecting malaria infections for the period from 2017 to 2019.MethodsComparisons were made between the surveillance methods and between years, based on data obtained from the national malaria database and individual case reports of malaria patients. The number of blood smears examined microscopically was used as the measure of the volume of tests conducted. The yield from each case detection method was calculated as the proportion of blood smears which were positive for malaria. Within RACD and PACD, the yield of sub categories of travel cohorts and spatial cohorts was ascertained for 2019.ResultsA total of 158 malaria cases were reported in 2017–2019. During this period between 666,325 and 725,149 blood smears were examined annually. PCD detected 95.6 %, with a yield of 16.1 cases per 100,000 blood smears examined. RACD and PACD produced a yield of 11.2 and 0.3, respectively. The yield of screening the sub category of travel cohorts was very high for RACD and PACD being 806.5 and 44.9 malaria cases per 100,000 smears, respectively. Despite over half of the blood smears examined being obtained by screening spatial cohorts within RACD and PACD, the yield of both was zero over all three years.ConclusionsThe PCD arm of case surveillance is the most effective and, therefore, has to continue and be further strengthened as the mainstay of malaria surveillance. Focus on travel cohorts within RACD and PACD should be even greater. Screening of spatial cohorts, on a routine basis and solely because people are resident in previously malarious areas, may be wasteful, except in situations where the risk of local transmission is very high, or is imminent. These findings may apply more broadly to most countries in the post-elimination phase.

Highlights

Sri Lanka sustained its malaria-free status by implementing, among other interventions, three core case detection strategies namely Passive Case Detection (PCD), Reactive Case Detection (RACD) and Proactive Case Detection (PACD)
On a routine basis and solely because people are resident in previously malarious areas, may be wasteful, except in situations where the risk of local transmission is very high, or is imminent
Reactive Case Detection (RACD) Case surveillance conducted in response to an index case of malaria

Summary

Introduction

Sri Lanka sustained its malaria-free status by implementing, among other interventions, three core case detection strategies namely Passive Case Detection (PCD), Reactive Case Detection (RACD) and Proactive Case Detection (PACD). The outcomes of these strategies were analysed in terms of their effectiveness in detecting malaria infections for the period from 2017 to 2019. Detection of malaria cases among people who seek health care on their own Patients seeking health care in the public and private health sectors e.g. General usually for fever. 2. Reactive Case Detection (RACD) Case surveillance conducted in response to an index case of malaria. Screening people who were exposed to the same risk of infection as the index case. i.e. travel contacts (identified through contact tracing)

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Conclusion