Evaluation of plasma lactate as a parameter for disease severity on admission in travelers with Plasmodium falciparum malaria.

Background: Rapid immunochromatographic dipstick assays are used increasingly in many tropical and Western countries as a tool to diagnose Plasmodium falciparum malaria. However, these tests do not provide any information about the severity of the infection. We evaluated the usefulness of plasma lactate as a parameter for disease severity on admission in imported P. falciparum malaria.

Methods: In a cohort of 61 nonimmune travelers with imported P. falciparum malaria, plasma lactate levels on admission were related to the severity of the infection. Results from 12 of 61 patients fulfilled the criteria of severe malaria.

Results: Logistic regression analysis showed that a plasma lactate level above the upper range of normal was associated with an odds ratio of 31 (95% CI 6-164) for severe malaria. As a continuous variable, a 1 mmol/L increase in plasma lactate level was associated with an odds ratio of 12 (95% CI 3-50) for severe malaria. The sensitivity of an increased plasma lactate level on admission for severe malaria was 67% with a specificity of 94%.

Conclusions: A timely determination of plasma lactate on admission may be helpful in the assessment of disease severity in travelers with imported P. falciparum malaria. An increased plasma lactate level should raise suspicion of a severe P. falciparum malaria infection, in particular when concomitant infections are not considered likely.