Evidence for significant influence of host immunity on changes in differential blood count during malaria.
BACKGROUND
Malaria has been shown to change blood counts. Recently, a few studies have investigated the alteration of the peripheral blood monocyte-to-lymphocyte count ratio (MLCR) and the neutrophil-to-lymphocyte count ratio (NLCR) during infection with Plasmodium falciparum. Based on these findings this study investigates the predictive values of blood count alterations during malaria across different sub-populations.


METHODS
Cases and controls admitted to the Department of Infectious Diseases and Tropical Medicine from January 2000 through December 2010 were included in this comparative analysis. Blood count values and other variables at admission controlled for age, gender and immune status were statistically investigated.


RESULTS
The study population comprised 210 malaria patients, infected with P. falciparum (68%), Plasmodium vivax (21%), Plasmodium ovale (7%) and Plasmodium malariae (4%), and 210 controls. A positive correlation of parasite density with NLCR and neutrophil counts, and a negative correlation of parasite density with thrombocyte, leucocyte and lymphocyte counts were found. An interaction with semi-immunity was observed; ratios were significantly different in semi-immune compared to non-immune patients (P <0.001).The MLCR discriminated best between malaria cases and controls (AUC = 0.691; AUC = 0.741 in non-immune travellers), whereas the NLCR better predicted severe malaria, especially in semi-immune patients (AUC = 0.788).


CONCLUSIONS
Malaria causes typical but non-specific alterations of the differential blood count. The predictive value of the ratios was fair but limited. However, these changes were less pronounced in patients with semi-immunity. The ratios might constitute easily applicable surrogate biomarkers for immunity.
Department of Infectious Diseases and Tropical Medicine, Medical Centre of the University of Munich, Ludwig-Maximilians-Universität (LMU), Leopoldstraße 5, 80802 Munich, Germany. berens@lrz.uni-muenchen.de.
Nicole
N
Berens-Riha
Inge
I
Kroidl
Mirjam
M
Schunk
Martin
M
Alberer
Marcus
M
Beissner
Michael
M
Pritsch
Arne
A
Kroidl
Günter
G
Fröschl
Ingrid
I
Hanus
Gisela
G
Bretzel
Frank
F
von Sonnenburg
Hans Dieter
HD
Nothdurft
Thomas
T
Löscher
Karl-Heinz
KH
Herbinger
D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007958:Leukocyte Count / Q000379:methods*; D008288:Malaria / Q000453:epidemiology* / Q000276:immunology* / Q000469:parasitology; D008297:Male; D008875:Middle Aged; D018512:Parasitemia / Q000453:epidemiology / Q000276:immunology / Q000473:pathology; D010961:Plasmodium / Q000502:physiology*; D011237:Predictive Value of Tests; D014195:Travel; D055815:Young Adult
D015415:Biomarkers