Clinical and laboratory prognostic factors in patients with mixed infection of erythema form of ixodic tick-borne borreliosis and tick-borne encephalitis

Abstract

Background. Early diagnosis of the mixed infection of ixodic tick-borne borreliosis and tick-borne encephalitis can be difficult without laboratory confirmation of the diagnosis.The aim. To assess clinical and laboratory predictors in patients for building the models of early differential diagnosis between mixed infection of erythema form of ixodic tick-borne borreliosis and febrile form of tick-borne encephalitis and monoinfection of erythema form of ixodic tick-borne borreliosis.Materials and methods. The clinical study included 26 patients with mixed infection of the erythema form of ixodic tick-borne borreliosis with tick-borne encephalitis (mean age – 46.7 years) and 30 patients with monoinfection of the erythema form of ixodic tick-borne borreliosis (mean age – 48.5 years). 59 clinical, epidemiological and laboratory parameters, including 6 leukocyte blood indices, standard and extended hemogram profiles were studied in these patients the first week of the disease. For statistical analysis, we used Pearson and Mann – Whitney goodness-of-fit tests, ROC analysis with calculation of the area under curve (AUC) and logistic regression. Results. Patients with mixed infection, compared to the patients with monoinfection, had increased odds of having febrile fever, weakness, headache and orbital pain; meningism symptoms occurred only in patients with mixed infection. Early predictors of a preliminary diagnosis of mixed infection were elevated values of fever (AUC = 0.87), intoxication syndrome score (AUC = 0.71), leukocyte count (AUC = 0.64) and neutrophils (AUC = 0.71) in the hemogram, levels of leukocyte intoxication index according to V.K. Ostrovsky (AUC = 0.67) and neutrophil-leukocyte index (AUC = 0.65), as well as a decrease in the number of platelets (AUC = 0.77), eosinophils (AUC = 0.72) and basophils (AUC = 0.79) in peripheral blood. Two prognostic models which included clinical and laboratory parameters demonstrated excellent prediction of mixed infection (AUC = 0.90 and AUC = 0.91).Conclusion. Early clinical and laboratory predictors have been established and models have been developed that make it possible, with excellent prognosis quality, to calculate in patients the probability of a preliminary diagnosis of mixed infection of the erythema form of ixodic tick-borne borreliosis with tick-borne encephalitis in comparison with borreliosis monoinfection.

Keywords

• mixed infection
• erythema form
• ixodic tick-borne borreliosis
• tick-borne encephalitis
• fever syndrome
• leukocyte blood indices
• hemogram
• logistic regression model