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A Comparative Analysis of the Outcome of Malaria Case Surveillance Strategies in Sri Lanka in the Prevention of Re-establishment Phase
KAMINI NIRMALA MENDIS
University of Colombo
Corresponding Author
ORCiD: https://orcid.org/0000-0002-4177-1851
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Sri Lanka sustained its malaria-free status by implementing, among other interventions, three core case detection strategies. The outcomes of these strategies - namely Passive Case Detection (PCD) and, under the overall strategy of Active Case Detection (ACD), Reactive Case Detection (RACD) and Proactive Case Detection (PACD) - were analysed in terms of their effectiveness in detecting malaria infections for the period from 2017-2019.
Methods
Comparisons 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.
Results
A total of 158 malaria cases were reported in 2017-2019, during which between 666,325-725,149 blood smears were examined each year: PCD detected 95.6%, with a yield of 16.1 cases per 100,000 blood smears examined, making it the most effective case detection strategy, while 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.
Conclusions
The PCD arm of case surveillance is the most effective, and therefore, has to continue and be further strengthened as the mainstay in 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.
Keywords
malaria case surveillance, prevention of re-establishment of malaria, passive case detection, active case detection, reactive case detection, proactive case detection, yield, malaria in Sri Lanka, travel cohorts, spatial cohorts
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On 06 Jan, 2021
Reviewer #2 agreed
On 05 Jan, 2021
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Reviewer #1 agreed
On 25 Dec, 2020
Editor invited
On 13 Dec, 2020
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This preprint is under consideration at Malaria Journal. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
A Comparative Analysis of the Outcome of Malaria Case Surveillance Strategies in Sri Lanka in the Prevention of Re-establishment Phase
KAMINI NIRMALA MENDIS
University of Colombo
Corresponding Author
ORCiD: https://orcid.org/0000-0002-4177-1851
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 1
Posted 23 Dec, 2020
No community comments so far
Review #2 received
Received 16 Jan, 2021
Reviewer #3 agreed
On 06 Jan, 2021
Reviewer #2 agreed
On 05 Jan, 2021
Reviewers invited
Invitations sent on 25 Dec, 2020
Reviewer #1 agreed
On 25 Dec, 2020
Editor invited
On 13 Dec, 2020
Editor assigned
On 10 Dec, 2020
Submission checks complete
On 10 Dec, 2020
First submitted
On 09 Dec, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Infectious Diseases
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Sri Lanka sustained its malaria-free status by implementing, among other interventions, three core case detection strategies. The outcomes of these strategies - namely Passive Case Detection (PCD) and, under the overall strategy of Active Case Detection (ACD), Reactive Case Detection (RACD) and Proactive Case Detection (PACD) - were analysed in terms of their effectiveness in detecting malaria infections for the period from 2017-2019.
Methods
Comparisons 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.
Results
A total of 158 malaria cases were reported in 2017-2019, during which between 666,325-725,149 blood smears were examined each year: PCD detected 95.6%, with a yield of 16.1 cases per 100,000 blood smears examined, making it the most effective case detection strategy, while 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.
Conclusions
The PCD arm of case surveillance is the most effective, and therefore, has to continue and be further strengthened as the mainstay in 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.
Figure 1
Figure 2