{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T03:57:49Z","timestamp":1773287869073,"version":"3.50.1"},"reference-count":59,"publisher":"BMJ","issue":"8","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2014,7,17]]},"published-print":{"date-parts":[[2014,8]]},"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p><jats:italic>Plasmodium knowlesi<\/jats:italic>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<jats:italic>Anopheles leucosphyrus<\/jats:italic>group vectors overlap. The majority of cases are from Eastern Malaysia, with increasing total public health notifications despite a concurrent reduction in<jats:italic>Plasmodium falciparum<\/jats:italic>and<jats:italic>P. vivax<\/jats:italic>malaria. The public health implications are concerning given<jats:italic>P. knowlesi<\/jats:italic>has the highest risk of severe and fatal disease of all<jats:italic>Plasmodium<\/jats:italic>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.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods and analysis<\/jats:title><jats:p>A population-based case\u2013control 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<jats:italic>P. knowlesi<\/jats:italic>malaria. Secondary outcomes will include differences in exposure variables between<jats:italic>P. knowlesi<\/jats:italic>and other<jats:italic>Plasmodium<\/jats:italic>spp, risk of severe<jats:italic>P. knowlesi<\/jats:italic>malaria, and evaluation of<jats:italic>P. knowlesi<\/jats:italic>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.<\/jats:p><\/jats:sec><jats:sec><jats:title>Ethics<\/jats:title><jats:p>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.<\/jats:p><\/jats:sec>","DOI":"10.1136\/bmjopen-2014-006004","type":"journal-article","created":{"date-parts":[[2014,8,23]],"date-time":"2014-08-23T03:53:29Z","timestamp":1408766009000},"page":"e006004","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":27,"title":["Factors that are associated with the risk of acquiring<i>Plasmodium knowlesi<\/i>malaria in Sabah, Malaysia: a case-control study protocol"],"prefix":"10.1136","volume":"4","clinical-trial-number":[{"clinical-trial-number":"nct01708876","registry":"10.18810\/clinical-trials-gov"}],"author":[{"given":"M J","family":"Grigg","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"T","family":"William","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"C J","family":"Drakeley","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J","family":"Jelip","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"L","family":"von Seidlein","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"B E","family":"Barber","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"K M","family":"Fornace","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"N M","family":"Anstey","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"T W","family":"Yeo","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J","family":"Cox","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2014,8,22]]},"reference":[{"key":"2024051512441545000_4.8.e006004.1","doi-asserted-by":"publisher","DOI":"10.1126\/science.149.3686.865"},{"key":"2024051512441545000_4.8.e006004.2","doi-asserted-by":"crossref","first-page":"383","DOI":"10.4269\/ajtmh.1970.19.383","article-title":"Cycles of jungle malaria in West Malaysia","volume":"19","author":"Warren","year":"1970","journal-title":"Am J Trop Med Hyg"},{"key":"2024051512441545000_4.8.e006004.3","first-page":"246","article-title":"A study of monkey-malaria and its experimental transmission to man","volume":"67","author":"Knowles","year":"1932","journal-title":"Indian Med Gazette"},{"key":"2024051512441545000_4.8.e006004.4","doi-asserted-by":"publisher","DOI":"10.1186\/1475-2875-12-8"},{"key":"2024051512441545000_4.8.e006004.5","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(04)15836-4"},{"key":"2024051512441545000_4.8.e006004.6","doi-asserted-by":"publisher","DOI":"10.1128\/CMR.00079-12"},{"key":"2024051512441545000_4.8.e006004.7","doi-asserted-by":"publisher","DOI":"10.1186\/1475-2875-9-344"},{"key":"2024051512441545000_4.8.e006004.8","doi-asserted-by":"publisher","DOI":"10.1016\/j.pt.2008.06.001"},{"key":"2024051512441545000_4.8.e006004.9","doi-asserted-by":"publisher","DOI":"10.1086\/524888"},{"key":"2024051512441545000_4.8.e006004.10","doi-asserted-by":"publisher","DOI":"10.1371\/journal.ppat.1002015"},{"key":"2024051512441545000_4.8.e006004.11","doi-asserted-by":"publisher","DOI":"10.1093\/molbev\/msm277"},{"key":"2024051512441545000_4.8.e006004.12","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijpara.2009.03.003"},{"key":"2024051512441545000_4.8.e006004.13","first-page":"137","article-title":"A. Detection of malaria parasites in Sabah by nested PCR: a focus of naturally acquired P knowlesi infections","volume":"32","author":"Anderios","year":"2008","journal-title":"Sains Malaysiana"},{"key":"2024051512441545000_4.8.e006004.14","first-page":"391","article-title":"Geographic and ethnic distribution of P knowlesi infection in Sabah, Malaysia","volume":"3","author":"Naing","year":"2011","journal-title":"Int J Collab Res Intern Med Public Health"},{"key":"2024051512441545000_4.8.e006004.15","first-page":"166","article-title":"Plasmodium knowlesi malaria in Malaysia","volume":"65","author":"Singh","year":"2010","journal-title":"Med J Malaysia"},{"key":"2024051512441545000_4.8.e006004.16","doi-asserted-by":"crossref","first-page":"104284","DOI":"10.1155\/2011\/104284","article-title":"Incidence of malaria in the interior division of Sabah, Malaysian Borneo, based on nested PCR","volume":"2011","author":"Joveen-Neoh","year":"2011","journal-title":"J Parasitol Res"},{"key":"2024051512441545000_4.8.e006004.17","doi-asserted-by":"publisher","DOI":"10.1093\/cid\/cis902"},{"key":"2024051512441545000_4.8.e006004.18","unstructured":"McArthur J . An account of the work of the Malaria Research Department, North Borneo, 1939\u20131942. London: Library of London School of Hygiene and Tropical Medicine, 1942."},{"key":"2024051512441545000_4.8.e006004.19","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pntd.0002026"},{"key":"2024051512441545000_4.8.e006004.20","unstructured":"Sarawak State Health Department website. http:\/\/jknsarawak.moh.gov.my\/en\/ (accessed 20 Dec 2013)."},{"key":"2024051512441545000_4.8.e006004.21","unstructured":"Ministry of Health Malaysia, V. B. D. C. P. Vector control in Malaysia. Consultative meeting\/workshop on management of vector control programs, 11\u201315 August 2008; Siem Reap, Cambodia. http:\/\/www.actmalaria.net (accessed Feb 21 2014)."},{"key":"2024051512441545000_4.8.e006004.22","doi-asserted-by":"publisher","DOI":"10.3201\/eid1012.040293"},{"key":"2024051512441545000_4.8.e006004.23","doi-asserted-by":"publisher","DOI":"10.3201\/eid1707.101551"},{"key":"2024051512441545000_4.8.e006004.24","doi-asserted-by":"publisher","DOI":"10.3201\/eid1405.070863"},{"key":"2024051512441545000_4.8.e006004.25","doi-asserted-by":"publisher","DOI":"10.3201\/eid1405.071407"},{"key":"2024051512441545000_4.8.e006004.26","first-page":"358","article-title":"Plasmodium knowlesi malaria infection in human","volume":"8","author":"Ninan","year":"2012","journal-title":"Brunei Int Med J"},{"key":"2024051512441545000_4.8.e006004.27","doi-asserted-by":"crossref","first-page":"1476","DOI":"10.3201\/eid1609.100339","article-title":"Co-infections with Plasmodium knowlesi and other malaria parasites, Myanmar","volume":"16","author":"Jiang","year":"2011","journal-title":"Emerg Infect Dis"},{"key":"2024051512441545000_4.8.e006004.28","doi-asserted-by":"publisher","DOI":"10.3201\/eid1710.110355"},{"key":"2024051512441545000_4.8.e006004.29","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dks508"},{"key":"2024051512441545000_4.8.e006004.30","first-page":"70","article-title":"[Human natural infection of Plasmodium knowlesi]","volume":"24","author":"Zhu","year":"2006","journal-title":"Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi"},{"key":"2024051512441545000_4.8.e006004.31","doi-asserted-by":"crossref","first-page":"e2780","DOI":"10.1371\/journal.pntd.0002780","article-title":"Defining the geographical range of the Plasmodium knowlesi reservoir","volume":"8","author":"Moyes","year":"2014","journal-title":"PLoS Negl Trop Dis"},{"key":"2024051512441545000_4.8.e006004.32","doi-asserted-by":"publisher","DOI":"10.3201\/eid1710.110349"},{"key":"2024051512441545000_4.8.e006004.33","doi-asserted-by":"publisher","DOI":"10.1086\/597414"},{"key":"2024051512441545000_4.8.e006004.34","doi-asserted-by":"publisher","DOI":"10.3201\/eid1707.101017"},{"key":"2024051512441545000_4.8.e006004.35","doi-asserted-by":"publisher","DOI":"10.1186\/1475-2875-11-284"},{"key":"2024051512441545000_4.8.e006004.36","doi-asserted-by":"publisher","DOI":"10.2307\/3275712"},{"key":"2024051512441545000_4.8.e006004.37","first-page":"1","article-title":"Plasmodium knowlesi in humans: a review on the role of its vectors in Malaysia","volume":"27","author":"Vythilingam","year":"2010","journal-title":"Trop Biomed"},{"key":"2024051512441545000_4.8.e006004.38","doi-asserted-by":"publisher","DOI":"10.1016\/j.trstmh.2006.02.006"},{"key":"2024051512441545000_4.8.e006004.39","doi-asserted-by":"publisher","DOI":"10.1086\/605439"},{"key":"2024051512441545000_4.8.e006004.40","doi-asserted-by":"crossref","first-page":"355","DOI":"10.4269\/ajtmh.1968.17.355","article-title":"Experimental mosquito-transmission of Plasmodium knowlesi to man and monkey","volume":"17","author":"Chin","year":"1968","journal-title":"Am J Trop Med Hyg"},{"key":"2024051512441545000_4.8.e006004.41","doi-asserted-by":"publisher","DOI":"10.1016\/0035-9203(47)90020-5"},{"key":"2024051512441545000_4.8.e006004.42","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1016\/j.actatropica.2005.06.022","article-title":"The impact of development and malaria control activities on its vectors in the Kinabatangan area of Sabah, East Malaysia","volume":"96","author":"Vythilingam","year":"2005","journal-title":"Acta Trop"},{"key":"2024051512441545000_4.8.e006004.43","doi-asserted-by":"publisher","DOI":"10.1186\/1475-2875-11-401"},{"key":"2024051512441545000_4.8.e006004.44","doi-asserted-by":"publisher","DOI":"10.1186\/1756-3305-1-26"},{"key":"2024051512441545000_4.8.e006004.45","doi-asserted-by":"publisher","DOI":"10.1089\/vbz.2010.0024"},{"key":"2024051512441545000_4.8.e006004.46","doi-asserted-by":"publisher","DOI":"10.3201\/eid1705.101489"},{"key":"2024051512441545000_4.8.e006004.47","doi-asserted-by":"publisher","DOI":"10.1186\/1475-2875-8-249"},{"key":"2024051512441545000_4.8.e006004.48","doi-asserted-by":"publisher","DOI":"10.1086\/519390"},{"key":"2024051512441545000_4.8.e006004.49","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pmed.1000283"},{"key":"2024051512441545000_4.8.e006004.50","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1109621108"},{"key":"2024051512441545000_4.8.e006004.51","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-3156.2009.02370.x"},{"key":"2024051512441545000_4.8.e006004.52","unstructured":"Government M . Malaysian Census 2010\u2014Basic population characteristics by administrative districts and mukim. 2010."},{"key":"2024051512441545000_4.8.e006004.53","doi-asserted-by":"crossref","first-page":"1029","DOI":"10.1093\/oxfordjournals.aje.a116397","article-title":"Selection of controls in case-control studies. II. Types of controls","volume":"135","author":"Wacholder","year":"1992","journal-title":"Am J Epidemiol"},{"key":"2024051512441545000_4.8.e006004.54","doi-asserted-by":"crossref","first-page":"381","DOI":"10.1093\/oxfordjournals.aje.a121625","article-title":"Sample size requirements in cohort and case-control studies of disease","volume":"99","author":"Schlesselman","year":"1973","journal-title":"Am J Epidemiol"},{"key":"2024051512441545000_4.8.e006004.55","doi-asserted-by":"publisher","DOI":"10.1353\/dem.2001.0003"},{"key":"2024051512441545000_4.8.e006004.56","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(03)12515-9"},{"key":"2024051512441545000_4.8.e006004.57","doi-asserted-by":"publisher","DOI":"10.1128\/JCM.00811-09"},{"key":"2024051512441545000_4.8.e006004.58","doi-asserted-by":"publisher","DOI":"10.1179\/000349803125002977"},{"key":"2024051512441545000_4.8.e006004.59","doi-asserted-by":"publisher","DOI":"10.3201\/eid1603.090732"}],"container-title":["BMJ Open"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bmjopen-2014-006004","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,5,15]],"date-time":"2024-05-15T20:01:14Z","timestamp":1715803274000},"score":1,"resource":{"primary":{"URL":"https:\/\/bmjopen.bmj.com\/lookup\/doi\/10.1136\/bmjopen-2014-006004"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2014,8]]},"references-count":59,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2014,8,22]]},"published-print":{"date-parts":[[2014,8]]}},"alternative-id":["10.1136\/bmjopen-2014-006004"],"URL":"https:\/\/doi.org\/10.1136\/bmjopen-2014-006004","relation":{},"ISSN":["2044-6055","2044-6055"],"issn-type":[{"value":"2044-6055","type":"print"},{"value":"2044-6055","type":"electronic"}],"subject":[],"published":{"date-parts":[[2014,8]]}}}