Epizootiologic background of dissimilar distribution of human cases of Lyme borreliosis and tick-borne encephalitis in a joint endemic area.
Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are co-endemic in some parts of Europe, however, their distribution differs despite a common tick vector and comparable animal hosts. A serosurvey of game and small mammals was made in a highly endemic area and compared with historical data in human cases; the epidemiologic risk and the population density of game were modelled using a geographic information system. While LB-risk corresponded with an overall population density of game (red deer, roe deer, mouflon, wild boar) regardless of mouse abundance, TBE-risk suggested a dependence on the abundance of mice on the one hand, and game, particularly roe deer, on the other. While the prevalence of TBE-antibodies generally grew with the game's age, it was virtually constant at about 65% in LB irrespective of species. It implies a cumulation of scarce TBE-infection histories during the game's lifetime, and thus a limited size of TBE-foci relative to the living space of these animals, as well as omnipresent LB-foci, in which the animals became continuously re-infected. More ecological prerequisites seem necessary to keep TBE circulating in nature which may be responsible for its confined distribution.
Zeman
P
P
Regional Center of Hygiene, Prague, Czech Republic. zemanp@bbs.szu.cz
Januska
J
J
D000367:Age Factors; D000820:Animal Diseases / Q000453:epidemiology / Q000821:virology; D000818:Animals; D003670:Deer; D004197:Disease Reservoirs; D004675:Encephalitis, Tick-Borne / Q000453:epidemiology*; D019353:Endemic Diseases; D005060:Europe; D006801:Humans; D008193:Lyme Disease / Q000453:epidemiology*; D051379:Mice; D012377:Rodentia; D013552:Swine