Prognostic significance of plasma lactate levels on admission in non-immune travellers with various species of imported malaria

Abstract

Objective. To study the prognostic significance of plasma lactate levels as a functional marker for tissue hypoxia on admission in non-immune travellers with imported Plasmodium falciparum malaria and non-P. falciparum malaria. Design. Cross-sectional, prospective, observational study. Setting. Harbour Hospital, Institute for Tropical Diseases, a national referral centre for tropical diseases. Patients. One hundred and twenty-two non-immune travellers with imported malaria (one patient with P. malariae, four with P. ovale, 20 with P. vivax, 83 with uncomplicated P. falciparum and 14 patients with severe, complicated P. falciparum infection). Measurements. Plasma lactate levels and standard laboratory evaluations on admission in relation to malaria species and criteria for severe malaria. Results. The plasma lactate levels on admission of those travellers who acquired a severe P. falciparum infection were higher than those with either uncomplicated P. falciparum malaria or travellers with non-P. falciparum infections. In the group of travellers with P. falciparum infection, an increased plasma lactate level >2.2 mmol/l had a sensitivity of 64%, a specificity of 89%, a positive predictive value of 50% and a negative predictive value of 94% for severe disease. Conclusions. A timely determination of plasma lactate on admission may assist in the clinical decision making of travellers with malaria who should be candidates for intensified monitoring and parenteral treatment.