engleski

Fluctuation of seroprevalence in equine population in Croatia

Introduction Leptospirosis is a worldwide zoonosis affecting many animal species and humans. In Croatia it is endemic, with human leptospirosis rates among highest in Europe. Testing of horses is a part of multidisciplinary approach being conducted with purpose of surveillance and control of leptospirosis in Croatia. Materials and Methods In the period of six years (2011-2016) a total of 42965 horse sera were tested, with number of sera ranging from 5000 in 2014 to 10735 in 2016. All sera were tested by microscopic agglutination test (MAT) which was performed following standard procedure (Dikken and Kmety, 1978), using a panel of eight Leptospira serovars: Grippothyphosa, Sejroe, Bratislava, Pomona, Canicola, Icterohaemorrhagiae, Saxkoebing and Bataviae. In accordance with regulations ordered by Veterinary Directory of the Ministry of Agriculture, Republic of Croatia, cut-off value was 1:200 for serovar Bratislava and 1:400 for other serovars. Presumptive infective serogroups were determined according to the highest titres to one or more serovars within certain serogroup. Results and Discussion Overall seroprevalence during six years was 8.8% Continuous decline of seroprevalence was observed from 2011 (14.8%), through 2012 (13.3%) to 2013 (6.2%), with the incidence rising in 2014 (10.8%), and again declining in 2015 (9.4%) and 2016 (8.5%). Decline in seroprevalence during the first three years might be explained by introduction of legally regulated measures for identification and treatment of positive animals. Extreme weather conditions contributed to the rise of seroprevalence in 2014, although even then seroprevalence wasn't as high as before introduction of control measures. In 2015 and 2016 decline in seroprevalence was observed again. Analysis of data by counties revealed that in spite of extreme climate conditions present in the whole country, with precipitation amounts higher than average in the last 30 years, in most Croatian counties rise in seroprevalence in 2014 hasn't occured. Overall rise in seroprevalence in 2014 was a consequence of very significant rise detected in seven counties situated in proximity of big rivers, that were affected by severe floodings occuring as a result of high precipitation amounts and saturation of soil with water. Analysis of presumptive infective serogroups revealed that in 2010 and 2011 the most prevalent presumptive infective serogroup was Australis, in 2012 and 2013 Pomona, in 2014 Grippotyphosa and in 2015 and 2016 Pomona. Conclusion This work once again confirmes endemicity of leptospirosis in Croatia and indicates that flooding, above all other climate conditions, had major impact on leptospirosis incidence in horses.

Leptospira, horse, seroprevalence

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