Factors that are associated with the risk of acquiring Plasmodium knowlesi malaria in Sabah, Malaysia

a case-control study protocol

Matthew Grigg, Timothy Williams, Chris Drakeley, Jenarun Jelip, Lorenz Von Seidlein, Bridget Barber, K Fornace, Nicholas Anstey, Tsin Yeo, J Cox

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Abstract

Introduction: Plasmodium knowlesi has long been present in Malaysia, and is now an emerging cause of zoonotic human malaria. Cases have been confirmed throughout South-East Asia where the ranges of its natural macaque hosts and Anopheles leucosphyrus group vectors overlap. The majority of cases are from Eastern Malaysia, with increasing total public health notifications despite a concurrent reduction in Plasmodium falciparum and P. vivax malaria. The public health implications are concerning given P. knowlesi has the highest risk of severe and fatal disease of all Plasmodium spp in Malaysia. Current patterns of risk and disease vary based on vector type and competence, with individual exposure risks related to forest and forest-edge activities still poorly defined. Clustering of cases has not yet been systematically evaluated despite reports of peri-domestic transmission and known vector competence for human-to-human transmission.

Methods and analysis: A population-based case-control study will be conducted over a 2-year period at two adjacent districts in north-west Sabah, Malaysia. Confirmed malaria cases presenting to the district hospital sites meeting relevant inclusion criteria will be requested to enrol. Three community controls matched to the same village as the case will be selected randomly. Study procedures will include blood sampling and administration of household and individual questionnaires to evaluate potential exposure risks associated with acquisition of P. knowlesi malaria. Secondary outcomes will include differences in exposure variables between P. knowlesi and other Plasmodium spp, risk of severe P. knowlesi malaria, and evaluation of P. knowlesi case clustering. Primary analysis will be per protocol, with adjusted ORs for exposure risks between cases and controls calculated using conditional multiple logistic regression models.

Ethics: This study has been approved by the human research ethics committees of Malaysia, the Menzies School of Health Research, Australia, and the London School of Hygiene and Tropical Medicine, UK.
Original languageEnglish
Article numbere006004
Pages (from-to)1-10
Number of pages10
JournalBMJ Open
Volume4
DOIs
Publication statusPublished - 2014

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Plasmodium knowlesi
Plasmodium malariae
Malaysia
Case-Control Studies
Plasmodium
Mental Competency
Malaria
Cluster Analysis
Public Health
Logistic Models
Vivax Malaria
Tropical Medicine
Anopheles
School Health Services
Far East
District Hospitals
Research Ethics Committees
Zoonoses
Macaca
Plasmodium falciparum

Cite this

Grigg, Matthew ; Williams, Timothy ; Drakeley, Chris ; Jelip, Jenarun ; Von Seidlein, Lorenz ; Barber, Bridget ; Fornace, K ; Anstey, Nicholas ; Yeo, Tsin ; Cox, J. / Factors that are associated with the risk of acquiring Plasmodium knowlesi malaria in Sabah, Malaysia : a case-control study protocol. In: BMJ Open. 2014 ; Vol. 4. pp. 1-10.
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abstract = "Introduction: Plasmodium knowlesi has long been present in Malaysia, and is now an emerging cause of zoonotic human malaria. Cases have been confirmed throughout South-East Asia where the ranges of its natural macaque hosts and Anopheles leucosphyrus group vectors overlap. The majority of cases are from Eastern Malaysia, with increasing total public health notifications despite a concurrent reduction in Plasmodium falciparum and P. vivax malaria. The public health implications are concerning given P. knowlesi has the highest risk of severe and fatal disease of all Plasmodium spp in Malaysia. Current patterns of risk and disease vary based on vector type and competence, with individual exposure risks related to forest and forest-edge activities still poorly defined. Clustering of cases has not yet been systematically evaluated despite reports of peri-domestic transmission and known vector competence for human-to-human transmission. Methods and analysis: A population-based case-control study will be conducted over a 2-year period at two adjacent districts in north-west Sabah, Malaysia. Confirmed malaria cases presenting to the district hospital sites meeting relevant inclusion criteria will be requested to enrol. Three community controls matched to the same village as the case will be selected randomly. Study procedures will include blood sampling and administration of household and individual questionnaires to evaluate potential exposure risks associated with acquisition of P. knowlesi malaria. Secondary outcomes will include differences in exposure variables between P. knowlesi and other Plasmodium spp, risk of severe P. knowlesi malaria, and evaluation of P. knowlesi case clustering. Primary analysis will be per protocol, with adjusted ORs for exposure risks between cases and controls calculated using conditional multiple logistic regression models. Ethics: This study has been approved by the human research ethics committees of Malaysia, the Menzies School of Health Research, Australia, and the London School of Hygiene and Tropical Medicine, UK.",
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Factors that are associated with the risk of acquiring Plasmodium knowlesi malaria in Sabah, Malaysia : a case-control study protocol. / Grigg, Matthew; Williams, Timothy; Drakeley, Chris; Jelip, Jenarun; Von Seidlein, Lorenz; Barber, Bridget; Fornace, K; Anstey, Nicholas; Yeo, Tsin; Cox, J.

In: BMJ Open, Vol. 4, e006004 , 2014, p. 1-10.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Factors that are associated with the risk of acquiring Plasmodium knowlesi malaria in Sabah, Malaysia

T2 - a case-control study protocol

AU - Grigg, Matthew

AU - Williams, Timothy

AU - Drakeley, Chris

AU - Jelip, Jenarun

AU - Von Seidlein, Lorenz

AU - Barber, Bridget

AU - Fornace, K

AU - Anstey, Nicholas

AU - Yeo, Tsin

AU - Cox, J

N1 - NHMRC Grant No. 1037304 1045156

PY - 2014

Y1 - 2014

N2 - Introduction: Plasmodium knowlesi has long been present in Malaysia, and is now an emerging cause of zoonotic human malaria. Cases have been confirmed throughout South-East Asia where the ranges of its natural macaque hosts and Anopheles leucosphyrus group vectors overlap. The majority of cases are from Eastern Malaysia, with increasing total public health notifications despite a concurrent reduction in Plasmodium falciparum and P. vivax malaria. The public health implications are concerning given P. knowlesi has the highest risk of severe and fatal disease of all Plasmodium spp in Malaysia. Current patterns of risk and disease vary based on vector type and competence, with individual exposure risks related to forest and forest-edge activities still poorly defined. Clustering of cases has not yet been systematically evaluated despite reports of peri-domestic transmission and known vector competence for human-to-human transmission. Methods and analysis: A population-based case-control study will be conducted over a 2-year period at two adjacent districts in north-west Sabah, Malaysia. Confirmed malaria cases presenting to the district hospital sites meeting relevant inclusion criteria will be requested to enrol. Three community controls matched to the same village as the case will be selected randomly. Study procedures will include blood sampling and administration of household and individual questionnaires to evaluate potential exposure risks associated with acquisition of P. knowlesi malaria. Secondary outcomes will include differences in exposure variables between P. knowlesi and other Plasmodium spp, risk of severe P. knowlesi malaria, and evaluation of P. knowlesi case clustering. Primary analysis will be per protocol, with adjusted ORs for exposure risks between cases and controls calculated using conditional multiple logistic regression models. Ethics: This study has been approved by the human research ethics committees of Malaysia, the Menzies School of Health Research, Australia, and the London School of Hygiene and Tropical Medicine, UK.

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