Diagnostic Value of Platelet and Leukocyte Counts in the Differential Diagnosis of Fever in the Returning Traveler

Abstract

Malaria, arbovirus infection and travelers' diarrhea are among the most common etiologies of fever after a stay in the tropics. Because the initial symptoms of these diseases often overlap, the differential diagnostic remains a challenge. The aim of this study was to establish the effectiveness of platelet and leukocyte counts in the differential diagnosis of fever in the returning traveler. Between 2013 and 2016, patients with a clinical suspicion of malaria, who had thick blood smears performed were retrospectively included. The microbiological etiology of each episode was established based on molecular detection in the case of arbovirus infection, the detection of pathogens in stool samples for diarrhea and other gastrointestinal symptoms and the thick and thin blood smear results for malaria. A total of 1,218 episodes were included. Malaria, arbovirus infection, and diarrhea and other gastrointestinal symptoms caused 102 (8.4%), 68 (5.6%), and 72 (5.9%) episodes, respectively. The median platelet counts in malaria episodes were 89 × 10 9 /L and thrombocytopenia (< 150,000 × 10 9 platelets/L) yielded a 98% negative predictive value to predict malaria. The median leukocyte counts in arbovirus infection episodes were 3.19 × 10 9 /L and leucopenia (< 4 × 10 9 leukocytes/L) yielded a 97.9% negative predictive value to predict arbovirus infections. Platelet and leukocyte counts were not significantly altered in episodes caused by diarrhea and other gastrointestinal symptoms. Initial platelet and leukocyte counts might be useful for the clinical differential diagnosis of fever in the returning traveler. Although these results are insufficient to establish a diagnosis, they should be considered in the initial clinical assessment.

High prevalence of malaria in a non-endemic setting among febrile episodes in travellers and migrants coming from endemic areas: a retrospective analysis of a 2013–2018 cohort

“…Furthermore, laboratory results such as thrombocytopenia and higher levels of bilirubin are highly suggestive of Plasmodium spp. infection and, if absent, they have been proposed as biomarkers with negative predictive value [ 19 , 20 , 36 ].…”

A High Index of Malaria Suspicion is Necessary for Febrile Episodes in Travellers and Migrants Coming from Endemic Areas

“…Furthermore, laboratory results such as thrombocytopenia and higher levels of bilirubin are highly suggestive of Plasmodium spp. infection and, if absent, they have been proposed as biomarkers with negative predictive value 23,24,37 .…”

Increased platelet distribution width and reduced IL-2 and IL-12 are associated with thrombocytopenia in Plasmodium vivax malaria

“…Another limitation to the study was the semi-quantification of parasites which is carried out in the Brazilian Amazon, and which made it impossible to assess further correlations, as also observed by a few other studies. (18,30) A further limitation to this study was that documentation of mega platelets was not done at the time of blood collection, however, the aim of the study was to assess changes in the immune response associated with thrombocytopenia. It is likely that the changes in MPV and PDW observed here may be due the release of the larger platelets also called as mega platelets or giant platelets.…”