OBSERVATIONS ON THE ABORTION CAUSED BY LE PTOSPIRAS IN DOMESTIC FARM-ANIMALS

Pathological, bacteriological and histological investigations of 50 ho rse fetuses, 1141 bovine fetuses, 709 swine fetuses and 247 sheep fetu ses have been carried out at the Mammalian Diagnostic Department of th e Veterinary Institute of Debrecen during the past 7 years since 1990. Of them abortion caused by leptospiras was diagnosed by the histologi cal investigation in 21 bovine and 41 swine fetuses (Table 1). Serolog ical examination of the blood of dams served valuable data to clarify the etiology of abortions. Of the blood samples collected from 843 abo rted cows, as well as from 644 aborted sows and investigated at the Ba cteriological Department of the institute 210 and 16s samples were pos itive for one of the leptospira serotypes, respectively (Table 2). To clarify the role of different serotypes in the damage caused in Hungar ian cattle stocks, 23,867 blood samples were investigated for 12 lepto spira strains which occurred also in Europe according to the literatur e data and caused diseases or seroconversion in cattle and might play a role in human diseases also (Tables 3 and 4). According to the data obtained, the Hungarian cattle stocks were most frequently infected by L.bardjo, L.grippotyphosa and L.pomona. The incidence of other seroty pes was less frequent (Tables 5 and 6). Considering that cattle is the main reservoir of L.bardjo, this serotype persists in cattle stocks f or a long time, its high incidence is comprehensible. The role played of L.grippotyphosa and L.pomona in the infections of cattle stocks is essentially determined by the environmental factors and by the vicinit y of most important natural hosts (rodents, pigs). I.e. the role of na tural hosts - in case of leptospiras sensitive for the environmental e ffects - is important for maintaining the infections in different terr itories. Laboratory investigations are needed to clarify the etiology of abortions caused by leptospiras. Owing to the frequent subclinical seroconversion, the serological investigation in itself is not enough to clarify their role. The pathological findings - due to the existing differences among serotypes, as well as depending on the time of infe ction and pathogenicity of the strain - can be variable. Only a positi ve histological finding can be consider pathognostic for leptospirosis . The negative histological findings do not exclude the role of leptos piras in an abortion. Anamnestic data, as well as complex evaluation o f the results of laboratory investigations of the samples originating from the same place can be very useful to achieve an accurate diagnosi s.