Plasmodium knowlesi Malaria in Children | CDC EID

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Volume 17, Number 5–May 2011
Research
Plasmodium knowlesi Malaria in Children
Bridget E. Barber, Timothy William, Mohammad Jikal, Jenarun Jilip, Prabakaran Dhararaj, Jayaram Menon, Tsin W. Yeo, and Nicholas M. Anstey

Author affiliations: Menzies School of Health Research, Darwin, Northern Territory, Australia (B.E. Barber, T.W. Yeo, N.M. Anstey); Charles Darwin University, Darwin, Northern Territory (B.E. Barber, T.W. Yeo, N.M. Anstey); Queen Elizabeth Hospital, Kota Kinabalu, Sabah, Malaysia (B.E. Barber, T. William, J. Menon); Sabah Department of Health, Kota Kinabalu (T. William, M. Jikal, J. Jilip, J. Menon); Kudat District Hospital, Kudat, Sabah, Malaysia (P. Dhararaj); and Royal Darwin Hospital, Darwin (T.W. Yeo, N.M. Anstey)

Suggested citation for this article


Abstract
Plasmodium knowlesi can cause severe malaria in adults; however, descriptions of clinical disease in children are lacking. We reviewed case records of children (age <15 years) with a malaria diagnosis at Kudat District Hospital, serving a largely deforested area of Sabah, Malaysia, during January–November 2009. Sixteen children with PCR-confirmed P. knowlesi monoinfection were compared with 14 children with P. falciparum monoinfection diagnosed by microscopy or PCR. Four children with knowlesi malaria had a hemoglobin level at admission of <10.0 g/dL (minimum lowest level 6.4 g/dL). Minimum level platelet counts were lower in knowlesi than in falciparum malaria (median 76,500/μL vs. 156,000/mL; p = 0.01). Most (81%) children with P. knowlesi malaria received chloroquine and primaquine; median parasite clearance time was 2 days (range 1–5 days). P. knowlesi is the most common cause of childhood malaria in Kudat. Although infection is generally uncomplicated, anemia is common and thrombocytopenia universal. Transmission dynamics in this region require additional investigation.

The simian malaria parasite Plasmodium knowlesi is increasingly recognized as a frequent cause of potentially fatal human malaria in adults in Malaysian Borneo (1–4). The infection has also been reported in peninsular Malaysia (5) and in other Southeast Asian countries, including Thailand (6,7), Myanmar (8,9), Vietnam (10), the Philippines (11), Indonesian Borneo (12–14), and Singapore (15,16). Until recently, P. knowlesi had been almost uniformly misdiagnosed by microscopy as P. malariae because of its morphologic similarities, leading to underestimations of prevalence (1,17). Accurate diagnosis therefore requires molecular methods.

The clinical and laboratory features of P. knowlesi infections in adults have been described in Kapit, Sarawak, where 107 (70%) of 152 adults with malaria were infected with P. knowlesi (3). Although P. knowlesi malaria was diagnosed in 8 children, the clinical and laboratory features were not described. All previously reported P. knowlesi infections that caused clinical disease have been in adults (1,2,6,8,11–13,15,18–20). In malaria caused by P. falciparum (21) and P. vivax (22), the 2 species that cause the greatest number of human malaria cases, well-described differences exist between adults and children in terms of the clinical epidemiology, disease spectrum, and laboratory manifestations of disease. We report the demographic, clinical, and laboratory features of P. knowlesi infection in children in Kudat, Sabah, a rural coastal farming area with little remaining primary rainforest, an epidemiologic setting that contrasts with the previously described forested areas of Sarawak.

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Plasmodium knowlesi Malaria in Children | CDC EID


Suggested Citation for this Article
Barber BE, William T, Jikal M, Jilip J, Dhararaj P, Menon J, et al. Plasmodium knowlesi malaria in children. Emerg Infect Dis [serial on the Internet]. 2011 May [date cited].
http://www.cdc.gov/EID/content/17/5/814.htm


DOI: 10.3201/eid1705.101489


Comments to the Authors
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Bridget E. Barber, Global Health Division, Menzies School of Health Research, PO Box 41096, Casuarina, Darwin, Northern Territory, Australia; email: bridget.barber@menzies.edu.au