Spatial distribution of malaria in Peninsular Malaysia from 2000 to 2009
© Alias et al.; licensee BioMed Central Ltd. 2014
Received: 16 January 2014
Accepted: 10 April 2014
Published: 15 April 2014
Malaria is still an endemic disease of public health importance in Malaysia. Populations at risk of contracting malaria includes indigenous people, traditional villagers, mobile ethnic groups and land scheme settlers, immigrants from malaria endemic countries as well as jungle workers and loggers. The predominant species are Plasmodium falciparum and P. vivax. An increasing number of P. knowlesi infections have also been encountered. The principal vectors in Peninsular Malaysia are Anopheles maculatus and An. cracens. This study aims to determine the changes in spatial distribution of malaria in Peninsular Malaysia from year 2000–2009.
Data for the study was collected from Ministry of Health, Malaysia and was analysed using Geographic Information System (GIS).
Changes for a period of 10 years of malaria spatial distribution in 12 states of Peninsular Malaysia were documented and discussed. This is illustrated by digital mapping according to five variables; incidence rate (IR), fatality rate (FR), annual blood examination rate (ABER), annual parasite index (API) and slide positivity rate (SPR).
There is a profound change in the spatial distribution of malaria within a 10-year period. This is evident from the digital mapping of the infection in Peninsular Malaysia.
Worldwide, there are 109 malaria endemic countries with an estimated 3.3 billion people at risk of malaria in 2010, out of which 1.2 billion are at high risk (>1 case/1000 population). Of the 1.2 billion, 37% reside in Southeast Asia . Malaysia was highly endemic with malaria, and in 1892, nearly one third of all deaths in Penang (an island state on the north-west of Malaysia) were attributed to malaria. Introduction of a new drainage system scheme by one of the pioneer antimalaria workers, i.e. Malcolm Watson in Peninsular Malaysia in the early twentieth century, was recognised as an early control measure in the world, leading to great reduction of malaria cases .
The highest number of malaria deaths in Peninsular Malaysia was reported to be 29 in 2001 and this figure decreased to 5 in 2009. The highest malaria incidence was recorded in the 20–39 years old age group (, Unpublished data from Disease Control Division Ministry of Health records). The younger age group who are actively working and highly mobile has increased the risk of being exposed to malaria infection, subsequently affecting the economic productivity due to work absenteeism. There were more males infected with malaria compared to females probably due to the former being involved in outdoor activities ([3, 6], Unpublished data from Disease Control Division Ministry of Health records).
Important vectors involved in malaria transmission in Peninsular Malaysia are Anopheles maculatus and An. cracens. An. maculatus is the vector for human malaria whereas An. cracens is the vector for simian malaria caused by P. knowlesi. With deforestation and environmental changes, new vectors have displaced the established vectors.
The study was conducted using retrospective secondary data of malaria for the period of 2000 to 2009. We obtained all annual reports of malaria for the mentioned period from the Ministry of Health (MOH) Malaysia. Besides that, the data was also obtained from public health centers and local journals. For the updated population numbers, the data was taken from Department of Statistics (DOS) Malaysia which is available online. The approval from Malaysia National Health Institute (NIH) was successfully obtained in order to conduct the research in MOH. A second approval was given by MOH to allow the data collection process. Collected data was then entered in Microsoft Excel computer program. After proper data cleaning, the data was analyzed using Geographic Information System (GIS) to produce digital maps of incidence rate (IR), fatality rate (FR), annual blood examination rate (ABER), annual parasite index (API) and slide positivity rate (SPR).
Results and discussion
Changes for a period of ten years of malaria spatial distribution in 12 states of Peninsular Malaysia are illustrated by digital mapping according to five parameters; IR, FR, ABER, API and SPR.
There is a profound change in the spatial distribution of malaria within a 10-year period. This is evident from the digital mapping of the infection in Peninsular Malaysia. The reduction in the number of malaria indigenous cases has been attributed to a successful Malaria Control Program (1980), which includes the increase in laboratory diagnostic capability, prompt treatment, nationwide implementation of insecticide treated bed nets and regular insecticide spraying.
The authors would like to thank the Director of Health Malaysia for permission to publish this paper. We gratefully acknowledge The Ministry of Health Malaysia for supplying the data as well as the MOH staff who helped to collect the data. The research is funded by HIR grant (E000051-20001), Ministry of Higher Education Malaysia and UMRG grant (222110HTM).
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