Background: Plasmodium knowlesi commonly causes severe malaria in
Malaysian Borneo, with high case-fatality rates reported. We compared risk,
spectrum, and outcome of severe disease from P. knowlesi, Plasmodium falciparum, and Plasmodium vivax and outcomes following introduction of protocols for early
referral and intravenous artesunate for all severe malaria.
From September 2010 to
October 2011 we prospectively assessed nonpregnant patients aged ≥12 years
admitted to Queen Elizabeth Hospital (QEH), Sabah, with polymerase chain reaction–confirmed Plasmodiummonoinfection. Standardized referral and
prereferral intravenous artesunate were instituted at district hospitals.
Results: Severe malaria occurred in 38 of 130
(29%) patients with P. knowlesi,
13 of 122 (11%) with P. falciparum,
and 7 of 43 (16%) with P. vivax.
The commonest severity criteria in knowlesi malaria included parasitemia
>100 000/µL (n = 18), jaundice (n = 20), respiratory distress (n = 14),
hypotension (n = 13), and acute kidney injury (n = 9). On multivariate analysis, P.
associated with a 2.96-fold (95% confidence interval, 1.19–7.38-fold) greater
risk of severity than P. falciparum (P = .020); only parasitemia and
schizontemia >10% independently predicted knowlesi severity. Risk of severe
knowlesi malaria increased 11-fold with parasitemia >20 000/µL, and 28-fold
with parasitemia >100 000/µL. Nearly all (92%) knowlesi malaria patients
received oral artemisinin therapy; 36 of 38 (95%) and 39 of 92 (42%) with
severe and nonsevere disease, respectively, also received ≥1 dose of
intravenous artesunate. No deaths occurred from any species.
Plasmodium knowlesi is the commonest cause of severe malaria at QEH, with
parasitemia the major risk factor for severity. Early referral and treatment
with artesunate was highly effective for severe malaria from all species and
associated with zero mortality.