Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Jul 18;67(3):350-359.
doi: 10.1093/cid/ciy065.

Age-Related Clinical Spectrum of Plasmodium knowlesi Malaria and Predictors of Severity

Matthew J Grigg  1   2 , Timothy William  2   3   4 , Bridget E Barber  1   2 , Giri S Rajahram  2   4   5 , Jayaram Menon  4   5 , Emma Schimann  1   2 , Kim Piera  1   2 , Christopher S Wilkes  1   2 , Kaajal Patel  1   2 , Arjun Chandna  1   2 , Christopher J Drakeley  6 , Tsin W Yeo  1   2   7   8 , Nicholas M Anstey  1   2
Affiliations

Age-Related Clinical Spectrum of Plasmodium knowlesi Malaria and Predictors of Severity

Matthew J Grigg et al. Clin Infect Dis. .

Abstract

Background: Plasmodium knowlesi is increasingly reported in Southeast Asia, but prospective studies of its clinical spectrum in children and comparison with autochthonous human-only Plasmodium species are lacking.

Methods: Over 3.5 years, we prospectively assessed patients of any age with molecularly-confirmed Plasmodium monoinfection presenting to 3 district hospitals in Sabah, Malaysia.

Results: Of 481 knowlesi, 172 vivax, and 96 falciparum malaria cases enrolled, 44 (9%), 71 (41%), and 31 (32%) children aged ≤12 years. Median parasitemia was lower in knowlesi malaria (2480/μL [interquartile range, 538-8481/μL]) than in falciparum (9600/μL; P < .001) and vivax malaria. In P. knowlesi, World Health Organization-defined anemia was present in 82% (95% confidence interval [CI], 67%-92%) of children vs 36% (95% CI, 31%-41%) of adults. Severe knowlesi malaria occurred in 6.4% (95% CI, 3.9%-8.3%) of adults but not in children; the commenst severity criterion was acute kideny injury. No patient had coma. Age, parasitemia, schizont proportion, abdominal pain, and dyspnea were independently associated with severe knowlesi malaria, with parasitemia >15000/μL the best predictor (adjusted odds ratio, 16.1; negative predictive value, 98.5%; P < .001). Two knowlesi-related adult deaths occurred (fatality rate: 4.2/1000 adults).

Conclusions: Age distribution and parasitemia differed markedly in knowlesi malaria compared to human-only species, with both uncomplicated and severe disease occurring at low parasitemia. Severe knowlesi malaria occurred only in adults; however, anemia was more common in children despite lower parasitemia. Parasitemia independently predicted knowlesi disease severity: Intravenous artesunate is warranted initially for those with parasitemia >15000/μL.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Enrollment flowchart. Abbreviations: PCR, polymerase chain reaction; Pf, Plasmodium falciparum; Pk, Plasmodium knowlesi; Pv, Plasmodium vivax.
Figure 2.
Figure 2.
Proportion of cases and median parasite count by age-group and Plasmodium spp.
See this image and copyright information in PMC

References

    1. Singh B, Kim Sung L, Matusop A et al. . A large focus of naturally acquired Plasmodium knowlesi infections in human beings. Lancet 2004; 363:1017–24. - PubMed
    1. Singh B, Daneshvar C. Human infections and detection of Plasmodium knowlesi. Clin Microbiol Rev 2013; 26:165–84. - PMC - PubMed
    1. Shearer FM, Huang Z, Weiss DJ et al. . Estimating geographical variation in the risk of zoonotic Plasmodium knowlesi infection in countries eliminating malaria. PLoS Negl Trop Dis 2016; 10:e0004915. - PMC - PubMed
    1. World Health Organization. World malaria report 2017 Available at: http://www.who.int/malaria/publications/world-malaria-report-2017/report.... Accessed 28 December 2017.
    1. World Health Organization Malaria Policy Advisory Committee. Outcomes from the Evidence Review Group on Plasmodium knowlesi. 2017. Available at: http://www.who.int/malaria/mpac/mpac-mar2017-plasmodium-knowlesi-present.... Accessed 15 December 2017.

Publication types

MeSH terms