Comparative analysis of incidence of leptospirosis among farm animals and humans in Ukraine

Abstract

Leptospirosis remains one of the most widespread natural-focal, zoonotic infectious diseases in the world and in Ukraine. Leptospirosis is enzootic in the entire territory of Ukraine. Cases of diseases are registered in all regions of Ukraine. We initiated a study of comparative analysis of territorial distribution of leptospirosis outbreaks among animals and incidence in humans in Ukraine covering the years 2009–2016 inclusive. This study of the incidence of leptospirosis in Ukraine shows a significant circulation of leptospirosis both among humans and animals. Among cattle herds in Ukraine the percentage of positive animals was found to be 4.2% of the surveyed population. The dominant serovars of Leptospira were kabura (12.4%) and polonica (9.5%). Positive reactions with other serovars were observed less frequently: tarassovi – 5.1%, bratislava – 4.9%, copenhageni – 4.1%, grippotyphosa – 2.4%, pomona – 1.1%, canicola – 1.0%. In pigs, the percentage of positive animals amounted to 3.2%, the dominant serovars of Leptospira were bratislava (29.1%) and copenhageni (25.1%). Positive reactions with other serovars were observed less frequently: tarassovi – 4.3%, canicola – 3.0%, pomona – 2.7%, grippotyphosa – 1.3%, polonica – 1.2%, kabura – 0.6%. In horses, the percentage of positive animals amounted to 9.5% of the surveyed population. The serological range of Leptospira in horses was as follows: copenhageni – 14.2%, bratislava – 12.1%, canicola – 6.8%, grippotyphosa – 4.8%, tarassovi – 4.7%, pomona – 2.1%, kabura – 1.4%, polonica – 1.3%. Analysis of the results of research indicates extensive circulation of leptospirosis among humans in Ukraine as evidenced by the percentage of humans positively responding to MAT – 12.1% of the studied samples. The etiological structure of leptospirosis cases includes all the 14 serovars of the diagnostic set. The basis of the etiological spectrum was the serovar copenhageni – 37.3%. The share of other serovars as the etiological factor of leptospirosis in humans was different in different spans of the considered period. Most frequently, those were kabura – 12.3%, grippotyphosa – 11.7%, canicola – 9.5%, pomona – 9.1%. We mapped annual incidence of leptospirosis in animals and humans. Choropleth maps of annual leptospirosis incidence and cluster maps show opposite spatial patterns for animals and humans. The highest human rates were in the western and central parts of the country while the highest animal rates were mainly in the eastern part.