COSTA, D. F.; http://lattes.cnpq.br/6706552587856413; COSTA, Diego Figueiredo da.
Resumo:
Most of the information on leptospirosis was obtained from experimental rodent infections,
which, while relevant, do not provide all the answers about the pathogenesis of the disease in
animals and humans. It is known that to advance in the control and prevention of leptospirosis
it is necessary to know better on the interaction between the agent and each animal host. Thus,
we sought to contribute to the understanding of host-parasite interaction, disease transmission
and the carrier role of Santa Inês and crossbred sheep experimentally infected with Leptospira
sp., as well as to register clinical and hemato-biochemical changes that may help in the
previous diagnosis of the disease in this species. For this purpose, this Thesis is composed of
three chapters. In Chapter I an experimental infection with Leptospira interrogans serogroup
Pomona serovar Kennewicki was carried out in sheep, seeking to analyze a natural model of
infection and the behavior of the agent-host interaction according to the breed of challenged
sheep. In total, 12 sheep were used, six crossbred and six Santa Inês breed. The ewes were
compared on the basis of serology, molecular and microbiological diagnosis. In Chapter II,
the objective of the study was to reproduce the acute disease in Santa Inês sheep and
crossbred ewes by intraperitoneal inoculation of L. interrogans serogroup Pomona serovar
Kennewicki, verifying possible differences in response to infection in challenged ewes. In
total, 10 ewes were used, five crossbred and five Santa Ines. The ewes were compared on the
basis of serology, molecular and microbiological diagnosis. In Chapter III, the influence of
infection by L. interrogans serogroup Pomona serovar Kennewicki on clinical and haematobiochemical
parameters was determined according to the route of inoculation and the breed of
experimentally infected sheep. Twenty-four sheep were used to carry out this experiment,
which were divided into two groups: crossbred (group A) and Santa Inês (group B). In both
groups the animals were challenged intraperitoneally and conjunctivally. The ewes were
compared on the basis of clinical signs, blood count, serum biochemistry and urinalysis. Both
the conjunctival and intraperitoneal routes were efficient in reproducing the infection in the
infected sheep, but the intraperitoneal route presented more strong alterations in
hematological and biochemical parameters. Santa Inês sheep presented higher concentration
and duration of the antibody titers. No sheep presented clinical signs compatible with
Leptospira sp. infection, so clinical evaluation was insufficient to reliably determine infected
animals. The findings emphasize the importance of the genital tract as an extra urinary
infection site and indicate the possibility of venereal transmission in the species. It is possible
that both Santa Inês and crossbred sheep can exercise a resistance relationship and be able to
participate in the transmission of strains of the Pomona serogroup, with the crossbred sheep
seeming to be more resistant to infection.