Changes in the epidemiology of human leptospirosis in the Slovak Republic

BACKGROUND: The epidemiologic patterns of infectious diseases are liable to change in the course of time. References to such changes in leptospirosis are very rare and of low systematic value. OBJECTIVES: The study is aimed at the detection of changes in the epidemiology of leptospirosis within the 20 years in Slovakia. METHODS: Basic epidemiologic characteristics of leptoospirosis were compared within two chronological periods. 598 registered cases were analyzed during the first period (1970-1976), and 200 cases of leptospirosis were analysed during the second period (1986-1991). MAIN RESULTS: The second period yielded a decrease in total incidence to approximately 50% (yearly average was 0.9/10(5) of the population). At the same time the cyclic character of morbidity has almost entirely disappeared. The incidence of leptospirosis has significantly decreased in the group of population between 40 and 59 years of age, thus causing a particular shift in morbidity towards the younger population. Cases of leptospirosis caused by L. tarassovi and L. canicola ceased to occur, however one case of infection caused by L. hardjo has been registered in the Slovak population. A significant decrease in the incidence of diseases caused by the Sejroe group serovars was detected, especially in housewives, retired people, industrial and agricultural workers. In contrast to the latter, the proportion of leptospirosis cases caused by L. icterohaemorrhagiae/copenhageni increased particularly in pupils and students, as well as those caused by L. pomona in slaughter-house workers. Consequently, the most dominating disease is represented by field fever (L. gripotyphosa), the second highest incidence is ascribed to Weil disease (L. icterohaemorrhagiae/copenhageni), while the incidence of infections caused by the group of Sejroe serovars dropped from the first to the fourth place. The possible reasons of these changes are presented. No changes in the incidence of leptospirosis according to sex and seasonal occurrence were registered. CONCLUSION: The results of this study are in accordance with the current knowledge of the development of epidemiologic signs of infectious diseases, including leptospirosis. The results provide a pattern of the current situation in the field of leptospirosis epidemiology in the territory of Slovakia and emphasize the importance of systematic surveillance enabling the assessment of appropriate measures suppressing these infections. (Fig. 7, Ref. 7.).