Increased detection of Plasmodium knowlesi in Sandakan division, Sabah as revealed by PlasmoNex™

Abstract

BackgroundPlasmodium knowlesi is a simian malaria parasite that is widespread in humans in Malaysian Borneo. However, little is known about the incidence and distribution of this parasite in the Sandakan division, Malaysian Borneo. Therefore, the aim of the present epidemiological study was to investigate the incidence and distribution of P. knowlesi as well as other Plasmodium species in this division based on a most recent developed hexaplex PCR system (PlasmoNex™).MethodsA total of 189 whole blood samples were collected from Telupid Health Clinic, Sabah, Malaysia, from 2008 to 2011. All patients who participated in the study were microscopically malaria positive before recruitment. Complete demographic details and haematological profiles were obtained from 85 patients (13 females and 72 males). Identification of Plasmodium species was conducted using PlasmoNex™ targeting the 18S ssu rRNA gene.ResultsA total of 178 samples were positive for Plasmodium species by using PlasmoNex™. Plasmodium falciparum was identified in 68 samples (38.2%) followed by 64 cases (36.0%) of Plasmodium vivax, 42 (23.6%) cases of P. knowlesi, two (1.1%) cases of Plasmodium malariae and two (1.1%) mixed-species infections (i e, P. vivax/P. falciparum). Thirty-five PlasmoNex™ positive P. knowlesi samples were misdiagnosed as P. malariae by microscopy. Plasmodium knowlesi was detected in all four districts of Sandakan division with the highest incidence in the Kinabatangan district. Thrombocytopaenia and anaemia showed to be the most frequent malaria-associated haematological complications in this study.ConclusionsThe discovery of P. knowlesi in Sandakan division showed that prospective studies on the epidemiological risk factors and transmission dynamics of P. knowlesi in these areas are crucial in order to develop strategies for effective malaria control. The availability of advanced diagnostic tool PlasmoNex™ enhanced the accuracy and accelerated the speed in the diagnosis of malaria.

Accurate identification of the six human Plasmodium spp. causing imported malaria, including Plasmodium ovale wallikeri and Plasmodium knowlesi

“…Plasmodium knowlesi is widespread in humans in Malaysian Borneo [13-16] and the detection of P. knowlesi infections in travellers from Southeast Asia has been increasing [17] due to the availability of specific molecular assays able to reveal them. In particular, in Europe a few cases were described in Sweden [18], in The Netherlands [19], in Spain [20], and in Finland [21], but until now no data are available about imported P. knowlesi malaria cases in Italy.…”

Plasmodium knowlesi malaria: Overview Focussing on Travel-Associated Infections

“…Very sensitive real-time multiplex PCR assays offer a more rapid diagnostic approach but also require more sophisticated laboratory equipment. A single-step hexaplex PCR system targeting the 18S ssu-rRNA of all five human Plasmodium species that overcomes some of the obstacles of the previous two methods has recently been described [34].…”

„Affenmalaria“ nach Thailandreise

“…Der Malaria-Schnelltest zum Nachweis zirkulierender Plasmodienantigene im Blut (Binax Now Malaria, Alere, Scarborough, USA) ist sowohl für HRP2 als auch für die PanAldolase negativ. [10][11][12]. Diese regionalen Unterschiede hängen möglicherweise mit Polymorphismen der Erythrozyten-Invasionsgene des Erregers zusammen [19].…”

“…In einigen Gebieten Malaysias wurden mittels PCR-Diagnostik hohe und in den letzten Jahren zunehmende Prävalenzen beim Menschen gefunden. So waren im Nordosten von Borneo (SabahRegion) zuletzt über 80 % der Malaria-positiven Patienten mit P. knowlesi infiziert [11][12][13]. In anderen Ländern wird P. knowlesi relativ selten als Ursache einer Malaria angegeben, in Thailand in weniger als 1 % [14][15][16].…”