Severe P. knowlesi Malaria | CDC EID

Severe P. knowlesi Malaria | CDC EID: "EID Journal Home > Volume 17, Number 7–July 2011
Volume 17, Number 7–July 2011
Research
Severe Plasmodium knowlesi Malaria in a Tertiary Care Hospital, Sabah, Malaysia

Timothy William, Jayaram Menon, Giri Rajahram, Leslie Chan, Gordon Ma, Samantha Donaldson, Serena Khoo, Charlie Fredrick, Jenarun Jelip, Nicholas M. Anstey, and Tsin Wen Yeo Comments to Author
Author affiliations: Queen Elizabeth Hospital, Kota Kinabalu, Sabah, Malaysian Borneo (T. William, J. Menon, G. Rajahram, L. Chan, G. Ma, S. Donaldson, S. Khoo, C. Fredrick); Department of Health, Kota Kinabalu, Malaysia (J. Jelip); Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia (N.M. Anstey, T.W. Yeo); and Royal Darwin Hospital, Darwin (N.M. Anstey, T.W. Yeo)

Suggested citation for this article

Abstract
The simian parasite Plasmodium knowlesi causes severe human malaria; the optimal treatment remains unknown. We describe the clinical features, disease spectrum, and response to antimalarial chemotherapy, including artemether-lumefantrine and artesunate, in patients with P. knowlesi malaria diagnosed by PCR during December 2007–November 2009 at a tertiary care hospital in Sabah, Malaysia. Fifty-six patients had PCR-confirmed P. knowlesi monoinfection and clinical records available for review. Twenty-two (39%) had severe malaria; of these, 6 (27%) died. Thirteen (59%) had respiratory distress; 12 (55%), acute renal failure; and 12, shock. None experienced coma. Patients with uncomplicated disease received chloroquine, quinine, or artemether-lumefantrine, and those with severe disease received intravenous quinine or artesunate. Parasite clearance times were 1–2 days shorter with either artemether-lumefantrine or artesunate treatment. P. knowlesi is a major cause of severe and fatal malaria in Sabah. Artemisinin derivatives rapidly clear parasitemia and are efficacious in treating uncomplicated and severe knowlesi malaria.

The simian parasite Plasmodium knowlesi has recently been found to be a major cause of human malaria in Malaysian Borneo (1,2), with the disease also reported from southern and eastern Asia (3). To our knowledge, the only large epidemiologic and clinical studies have been from Sarawak State, Malaysian Borneo, with case series or reports from persons or returning travelers from Myanmar (4), Thailand (5,6), Vietnam (7), Philippines (8,9), Singapore (10), Sarawak (11), western Malaysia (12), and Indonesia (13).

The potential for P. knowlesi to cause severe disease has been suggested by experimental simian and human infections (14–16). The first description of naturally acquired severe human P. knowlesi infection was a retrospective study from Sarawak that detailed 4 fatal cases with multiorgan failure (17). Subsequently, a prospective study from the Kapit District Hospital in Sarawak enrolled 107 persons with P. knowlesi monoinfection and demonstrated that 10 patients had severe disease as defined by World Health Organization (WHO) criteria, resulting in 2 deaths (2).

The disease spectrum and clinical features of large numbers of patients infected with P. knowlesi have not been described outside Sarawak. To reliably differentiate P. malariae from P. knowlesi infections by using only microscopy is difficult (18); such differentiation requires molecular methods (1). In a random survey from several districts in Sabah, the state that borders Sarawak, 44 of 49 cases of microscopy-diagnosed P. malariae infection were confirmed by PCR to be P. knowlesi, indicating that knowlesi malaria was not confined to isolated areas (17). In recent years at Queen Elizabeth Hospital (QEH), a tertiary care referral hospital in Kota Kinabalu, Sabah State, patients with severe malaria by WHO criteria had received a diagnosis by microscopy as P. malariae infection, but P. knowlesi was suspected as the etiologic agent. We conducted a retrospective review of the clinical spectrum of all case-patients with P. malariae malaria who were admitted to QEH during December 2007–November 2009 and confirmed the diagnosis of P. malariae or P. knowlesi infection by molecular methods.

The optimal management of knowlesi malaria is not known. P. knowlesi infection has been successfully treated with chloroquine (2) and quinine (2); however, the therapeutic efficacy of other antimalarial agents is not known. Artemisinin-derivative combination therapy is now the WHO treatment of choice for uncomplicated falciparum malaria (19) and is increasingly recommended for nonfalciparum malaria (20); its efficacy in knowlesi malaria is unknown. Similarly, intravenous artesunate is now the treatment of choice for severe falciparum malaria in adults (19,21), but the therapeutic response to this regimen in severe knowlesi malaria is unknown. As part of our study, we documented the therapeutic responses in uncomplicated and severe knowlesi malaria treated with artemisinin derivatives.

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Suggested Citation for this Article

William T, Menon J, Rajahram G, Chan L, Ma G, Donaldson S, et al. Severe Plasmodium knowlesi malaria in a tertiary care hospital, Sabah, Malaysian Borneo. Emerg Infect Dis [serial on the Internet]. 2011 Jul [date cited]. http://www.cdc.gov/EID/content/17/7/1248.htm

DOI: 3201/eid.1707.101017

Comments to the Authors

Please use the form below to submit correspondence to the authors or contact them at the following address:

Tsin Wen Yeo, Global Health Division, Menzies School of Health Research, PO Box 41096, Casuarina, Darwin, NT 0811, Australia; email: tsin.yeo@menzies.edu.au