engleski

Human tick-borne encephalitis and correlation with rodents and big game in Croatia in the period from 2006 to 2017

Tick-borne encephalitis (TBE) is considered endemic in continental parts of Croatia. Many factors, such as ecological, climatic and social factors, can influence the epidemiology of TBE but are still not sufficiently understood. TBE virus circulates between ticks and their mammal hosts, mostly rodents and deer. There are not enough studies in Croatia that research the correlation between tick hosts and human cases of TBE. The aim of this study was to compare and correlate the numbers of TBE acute patients with tick mammal hosts. For this analysis we used available forest rodent and big game (roe deer, red deer and wild boar) abundance data for the time period from 2006 to 2017. Rodent data is presented as annual rodent damage per hectare, reported annually from forestry offices in continental Croatia. Big game data for each mentioned species is presented as annual number of harvested individuals. In the 12-year period a total of 14154 sera were tested for IgM and IgG anti-TBE. Seropositive were 759 patients, out of whom 588 had acute TBE. For comparison of variables, Pearson’s correlation coefficient (r) was used. There was no correlation found between acute patients and rodent abundance (r= -0.04) as well as wild boar abundance (R= -0.05). Roe deer abundance and acute patient data showed slightly positive correlation (R= 0.22) which was similar but higher for red deer (R= 0.37). In literature, a positive correlation is also described between deer species and tick abundance in forests, which correlated with our findings indicating higher risk for humans in years of higher deer abundance. Our results contribute to other findings described in the literature regarding the relation between deer species, ticks and TBE cases.

TBE ; patients ; rodents ; deer ; wild boar

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