Analysis of Enzootic Bovine Leukosis prevalence

Livestock farming in Lithuania is one of the main branches of industry. According to the data of the Department of Statistics (Statistics Lithuania), in 2015 in Lithuania it was considered to be kept 736,000 livestock, including 313,000 dairy breeds of cows (1). In order to obtain a safe production, the prevention of communicable diseases in this sector is very important. The aim of the graduate thesis is to analyze the prevalence of leucosis in cattle population in Lithuanian farms. The tasks of the work have been formulated in order to examine the frequency of testing and prevalence for enzootic bovine leucosis in the counties of Lithuania, compare the study and infection of the disease by the year, and to determine the prevalence of infection carriers by age, breed, and sex. The thesis is composed of 46 pages. The work also contains 15 Figures and 6 Tables. The survey was conducted at the Department of Infectious Diseases of Veterinary Academy of Lithuanian University of Health Sciences, and at the Serology Investigation Section of National Food and Veterinary Risk Assessment Institute (NFVRAI). The seven-year (2008-2014) period data of the surveys have been analyzed. During this period 169,764 samples of bovine blood serum have been examined. After the analysis of the data collected on the tests for enzootic bovine leucosis, it was deduced that 168 (0.1%) individuals out of 169,764 bovine animals examined were infected by the disease during the period from 2008 to 2014. Following an examination of the frequency and prevalence of the disease in the counties, it was found that the majority of the blood serum samples were examined in Vilnius County households (28.85%), while the virus is most prevalent in Marijampolė County cattle holdings (1.34%). After systematizing the data in a year period analysed, it was concluded that the greatest number of blood serum samples were tested in 2011 (29.96%), and the highest number of seropositive cattle was in 2008 (0.86%). Among all the subjects concerned, the highest infection rate was found among animals aged from 0 to 5, i.e., the youngest age group of individuals (58.33%). The largest group of infected cattle consisted of females (89.88%). Among the seropositive animals, mainly Black Pied breeds (64.88%) of Lithuanian cattle suffered from enzootic bovine leucosis. Among all the 168 blood serum samples, positively assessed by ELISA (Enzyme-Linked Immunosorbent Assay) reaction, 151 samples have been investigated for the approval using AGID (Agar Gel Immunodiffusion Test) method. It was ascertained that 151 samples which had been tested using both the ELISA and AGID methods were rated positively