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Changing epidemiology of malaria in Sabah, Malaysia: increasing incidence of Plasmodium knowlesi.

William T, Jelip J, Menon J, Anderios F, Mohammad R, Awang Mohammad TA, Grigg MJ, Yeo TW, Anstey NM, Barber BE - Malar. J. (2014)

Bottom Line: Notifications of P. vivax and P. falciparum decreased from 605 and 628, respectively, in 2011, to 297 and 263 in 2013.Among 1,082 P. malariae/P. knowlesi blood slides referred for PCR testing during 2011-2013, there were 924 (85%) P. knowlesi mono-infections, 30 (2.8%) P. falciparum, 43 (4.0%) P. vivax, seven (0.6%) P. malariae, six (0.6%) mixed infections, 31 (2.9%) positive only for Plasmodium genus, and 41 (3.8%) Plasmodium-negative.With the decline of P. falciparum and P. vivax, control programmes need to incorporate measures to protect against P. knowlesi, with further research required to determine effective interventions.

View Article: PubMed Central - PubMed

Affiliation: Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu 88560, Sabah, Malaysia. bridget.barber@menzies.edu.au.

ABSTRACT

Background: While Malaysia has had great success in controlling Plasmodium falciparum and Plasmodium vivax, notifications of Plasmodium malariae and the microscopically near-identical Plasmodium knowlesi increased substantially over the past decade. However, whether this represents microscopic misdiagnosis or increased recognition of P. knowlesi has remained uncertain.

Methods: To describe the changing epidemiology of malaria in Sabah, in particular the increasing incidence of P. knowlesi, a retrospective descriptive study was undertaken involving a review of Department of Health malaria notification data from 2012-2013, extending a previous review of these data from 1992-2011. In addition, malaria PCR and microscopy data from the State Public Health Laboratory were reviewed to estimate the accuracy of the microscopy-based notification data.

Results: Notifications of P. malariae/P. knowlesi increased from 703 in 2011 to 815 in 2012 and 996 in 2013. Notifications of P. vivax and P. falciparum decreased from 605 and 628, respectively, in 2011, to 297 and 263 in 2013. In 2013, P. malariae/P. knowlesi accounted for 62% of all malaria notifications compared to 35% in 2011. Among 1,082 P. malariae/P. knowlesi blood slides referred for PCR testing during 2011-2013, there were 924 (85%) P. knowlesi mono-infections, 30 (2.8%) P. falciparum, 43 (4.0%) P. vivax, seven (0.6%) P. malariae, six (0.6%) mixed infections, 31 (2.9%) positive only for Plasmodium genus, and 41 (3.8%) Plasmodium-negative. Plasmodium knowlesi mono-infection accounted for 32/156 (21%) and 33/87 (38%) blood slides diagnosed by microscopy as P. falciparum and P. vivax, respectively. Twenty-six malaria deaths were reported during 2010-2013, including 12 with 'P. malariae/P. knowlesi' (all adults), 12 with P. falciparum (seven adults), and two adults with P. vivax.

Conclusions: Notifications of P. malariae/P. knowlesi in Sabah are increasing, with this trend likely reflecting a true increase in incidence of P. knowlesi and presenting a major threat to malaria control and elimination in Malaysia. With the decline of P. falciparum and P. vivax, control programmes need to incorporate measures to protect against P. knowlesi, with further research required to determine effective interventions.

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Plasmodiumincidence by district, per 1,000 persons.
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Fig4: Plasmodiumincidence by district, per 1,000 persons.

Mentions: Sixteen of 23 districts in Sabah have experienced a continued increase in notifications of P. malariae/P. knowlesi (Figures 2 and 3). In the past two years this increase has been particularly marked in the districts located along the Crocker Range, including Sipitang, Tenom, Keningau, Tambunan, and Ranau (Figures 3 and 4). In these five districts alone notifications of P. malariae/P. knowlesi have nearly doubled from 274 in 2011 to 523 in 2013, with these districts now accounting for 53% of all P. malariae/P. knowlesi notifications in Sabah despite comprising only 12.5% of Sabah’s population.Figure 2


Changing epidemiology of malaria in Sabah, Malaysia: increasing incidence of Plasmodium knowlesi.

William T, Jelip J, Menon J, Anderios F, Mohammad R, Awang Mohammad TA, Grigg MJ, Yeo TW, Anstey NM, Barber BE - Malar. J. (2014)

Plasmodiumincidence by district, per 1,000 persons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4195888&req=5

Fig4: Plasmodiumincidence by district, per 1,000 persons.
Mentions: Sixteen of 23 districts in Sabah have experienced a continued increase in notifications of P. malariae/P. knowlesi (Figures 2 and 3). In the past two years this increase has been particularly marked in the districts located along the Crocker Range, including Sipitang, Tenom, Keningau, Tambunan, and Ranau (Figures 3 and 4). In these five districts alone notifications of P. malariae/P. knowlesi have nearly doubled from 274 in 2011 to 523 in 2013, with these districts now accounting for 53% of all P. malariae/P. knowlesi notifications in Sabah despite comprising only 12.5% of Sabah’s population.Figure 2

Bottom Line: Notifications of P. vivax and P. falciparum decreased from 605 and 628, respectively, in 2011, to 297 and 263 in 2013.Among 1,082 P. malariae/P. knowlesi blood slides referred for PCR testing during 2011-2013, there were 924 (85%) P. knowlesi mono-infections, 30 (2.8%) P. falciparum, 43 (4.0%) P. vivax, seven (0.6%) P. malariae, six (0.6%) mixed infections, 31 (2.9%) positive only for Plasmodium genus, and 41 (3.8%) Plasmodium-negative.With the decline of P. falciparum and P. vivax, control programmes need to incorporate measures to protect against P. knowlesi, with further research required to determine effective interventions.

View Article: PubMed Central - PubMed

Affiliation: Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu 88560, Sabah, Malaysia. bridget.barber@menzies.edu.au.

ABSTRACT

Background: While Malaysia has had great success in controlling Plasmodium falciparum and Plasmodium vivax, notifications of Plasmodium malariae and the microscopically near-identical Plasmodium knowlesi increased substantially over the past decade. However, whether this represents microscopic misdiagnosis or increased recognition of P. knowlesi has remained uncertain.

Methods: To describe the changing epidemiology of malaria in Sabah, in particular the increasing incidence of P. knowlesi, a retrospective descriptive study was undertaken involving a review of Department of Health malaria notification data from 2012-2013, extending a previous review of these data from 1992-2011. In addition, malaria PCR and microscopy data from the State Public Health Laboratory were reviewed to estimate the accuracy of the microscopy-based notification data.

Results: Notifications of P. malariae/P. knowlesi increased from 703 in 2011 to 815 in 2012 and 996 in 2013. Notifications of P. vivax and P. falciparum decreased from 605 and 628, respectively, in 2011, to 297 and 263 in 2013. In 2013, P. malariae/P. knowlesi accounted for 62% of all malaria notifications compared to 35% in 2011. Among 1,082 P. malariae/P. knowlesi blood slides referred for PCR testing during 2011-2013, there were 924 (85%) P. knowlesi mono-infections, 30 (2.8%) P. falciparum, 43 (4.0%) P. vivax, seven (0.6%) P. malariae, six (0.6%) mixed infections, 31 (2.9%) positive only for Plasmodium genus, and 41 (3.8%) Plasmodium-negative. Plasmodium knowlesi mono-infection accounted for 32/156 (21%) and 33/87 (38%) blood slides diagnosed by microscopy as P. falciparum and P. vivax, respectively. Twenty-six malaria deaths were reported during 2010-2013, including 12 with 'P. malariae/P. knowlesi' (all adults), 12 with P. falciparum (seven adults), and two adults with P. vivax.

Conclusions: Notifications of P. malariae/P. knowlesi in Sabah are increasing, with this trend likely reflecting a true increase in incidence of P. knowlesi and presenting a major threat to malaria control and elimination in Malaysia. With the decline of P. falciparum and P. vivax, control programmes need to incorporate measures to protect against P. knowlesi, with further research required to determine effective interventions.

Show MeSH
Related in: MedlinePlus