Is There a Risk of Suburban Transmission of Malaria in Selangor, Malaysia?

Kamil A Braima,Wenn-Chyau Lee,Adeeba Kamarulzaman,Mustakiza Muslimin,Jia-Siang Sum,Noraishah M Abdul-Aziz,John Jeffery,Frankie Sitam,Rosnida Mohd-Noh,Amir-Ridhwan M Ghazali,Ibrahim Jamaiah,Mahmud Rohela,Yee-Ling Lau,Mohammed R Shaker,Alaa-Eldeen M Elamin

doi:10.1371/journal.pone.0077924

Kamil A Braima, Wenn-Chyau Lee + Show 13 more

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https://doi.org/10.1371/journal.pone.0077924

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Journal: PLoS ONE	Publication Date: Oct 23, 2013
Citations: 44	License type: CC BY 4.0

Affiliation: University of Malaya, Universiti Teknologi MARA

Abstract

BackgroundThe suburban transmission of malaria in Selangor, Malaysia’s most developed and populous state still remains a concern for public health in this region. Despite much successful control efforts directed at its reduction, sporadic cases, mostly brought in by foreigners have continued to occur. In addition, cases of simian malaria caused by Plasmodium knowlesi, some with fatal outcome have caused grave concern to health workers. The aim of this study was to investigate the possibility of local malaria transmission in suburban regions of Selangor, which are adjacent to secondary rainforests.FindingsA malaria survey spanning 7 years (2006 - 2012) was conducted in Selangor. A total of 1623 laboratory confirmed malaria cases were reported from Selangor’s nine districts. While 72.6% of these cases (1178/1623) were attributed to imported malaria (cases originating from other countries), 25.5% (414/1623) were local cases and 1.9% (31/1623) were considered as relapse and unclassified cases combined. In this study, the most prevalent infection was P. vivax (1239 cases, prevalence 76.3%) followed by P. falciparum (211, 13.0%), P. knowlesi (75, 4.6%), P. malariae (71, 4.4%) and P. ovale (1, 0.06%). Mixed infections comprising of P. vivax and P. falciparum were confirmed (26, 1.6%). Entomological surveys targeting the residences of malaria patients’ showed that the most commonly trapped Anopheles species was An. maculatus. No oocysts or sporozoites were found in the An. maculatus collected. Nevertheless, the possibility of An. maculatus being the malaria vector in the investigated locations was high due to its persistent occurrence in these areas.ConclusionsMalaria cases reported in this study were mostly imported cases. However the co-existence of local cases and potential Plasmodium spp. vectors should be cause for concern. The results of this survey reflect the need of maintaining closely monitored malaria control programs and continuous extensive malaria surveillance in Peninsula Malaysia.

Highlights

Malaria is considered as one of the most important infectious diseases in the world
Of the total 1623 samples, malaria parasite with the highest prevalence was P. vivax, with 1239 cases (76.3%). This was followed by P. falciparum, with 211 cases (13.0%), P. knowlesi, with 75 cases (4.6%), P. malariae, with 71 cases (4.4%), 26 cases (1.6%) of mixed infections of P. vivax and P. falciparum, and 1 (0.06%) P. ovale infection (Figure 3)
In line with the National Malaria Elimination Strategic Plan 2010-2020, vector control strategies consisting of residual spraying, the use of impregnated bed net and larvicidal control activities have to be done in malaria reported areas

Summary

Introduction

Malaria is considered as one of the most important infectious diseases in the world It is caused by the protozoan parasites of the genus Plasmodium [1]. The suburban transmission of malaria in Selangor, Malaysia’s most developed and populous state still remains a concern for public health in this region. Cases of simian malaria caused by Plasmodium knowlesi, some with fatal outcome have caused grave concern to health workers. The co-existence of local cases and potential Plasmodium spp. vectors should be cause for concern.

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