Aspectos clínicos, epidemiológicos e reprodutivos da infecção natural e experimental em ovinos por Toxoplasma gondii

• Autor(a) principal: MORAES, Érica Paes Barreto Xavier de
• Data de Publicação: 2010
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRPE
• Texto Completo: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5497
• topic: Toxoplasmose; Toxoplasma gondii; Ovino; Infecção natural; Infecção experimental; CIENCIAS AGRARIAS::MEDICINA VETERINARIA

The aim of the present study was to evaluate the clinical, epidemiological, parasitological and reproductive aspects of the T. gondii natural and experimental infection in sheep. Firstly, Toxoplasma gondii venereal transmission via experimental infection was studied 41 seronegative sheep divided in three groups: G1, where 15 females were inseminated with semen containing 6.5 X 104 tachyzoites; G2, where 15 females were inseminated with semen containing 4 X 107 tachyzoites; and G3: 11 females inseminated with tachyzoite-free semen. In order to confirm the T. gondii infection via semen, serological tests were performed as well as the DNA of the parasite was detected in the blood using nested PCR at 0, 7, 14, 21, 28, 49,63 and 123 days post-infection (p.i.). In the G1 only 5/15 (33.3%) of the females seroconverted, while in G2 15/15 (100%)seroconverted. Regarding nested PCR analysis, it was observed that 14/15 (93.3%) of the females in the G1 and 14/15 (93.3%) from G2 were positives for T. gondii. On the other hand, in G3 all samples were negative. In addition, the reproductive disturbances were diagnosed using ultrasound and it was observed that in G1,9/15 (60%) presented embryonic reabsorption and 40% kept gestation, showing normal or dystocic delivery, stillborns and uterine atony. In the G2, embryonic reabsorption was present in 15/15 (100%) of the sheep associated with other pathologies such as 2/24 (8.3%) hydrometra, 2/24 (8.3%) mucometra and 2/24(8.3%) follicular cysts. In the G3, 8/11 of females kept gestation and delivered healthy fetuses. Besides, histopathology showed toxoplasmosis-like lesions in placentas as well as nested PCR was positive for all organs from stillborn and placenta examined. In the next step of the study, 24 non-pregnant sheep (G1 and G2) were submitted to controlled mating season and 15/24 (62.5%) got pregnant while 9/24(37.5%) did not. Those who did not get pregnant presented reproductive pathologies such as anestrous (66.6%), follicular cysts (11.1%), hydrometra and mucometra (22.2%). Next, it was investigated the elimination of Toxoplasma gondii in semen from naturally infected males. In this regard, 65 males were submitted to anti-T. gondii antibody screening using Indirect Immunofluorescence (IFI). Animals serologically positive were submitted to semen collection for parasite DNA detection. In the serological test 6/65 (9.2%) of the animals were positive. In the nested PCR using semen 4/6 (66.6%) of the animals were also positive. In the third series of experiments, 245 organs from stillborns and 28 placentas from sheep with reproductive disturbances were evaluated. Following necropsy, brain, cerebellum, spinal cord, lungs, heart, spleen, liver and placenta were harvest for nested PCR and histopathology. Nested PCR confirmed three fetuses and 2 stillborns (14.3%) positive for T. gondii in fetal organs and placenta, where heart and placenta were the most affected ones. Histopathology evidenced macroscopic damage suggesting T. gondii infection in 2/35 (5.7%) of the placentas, and toxoplasmosis-like damage in placentas with non-supurative infiltration, several necrosis focuses associated to tissue cysts. In conclusion, insemination using fresh semen experimentally contaminated with different doses of tachyzoites from T. gondii is capable of infecting sheep and produce reproductive pathologies, compromising the reproductive life of females. The detection of the proliferative form of the parasite in semen from males naturally infected by nested PCR reinforces the need for intensifying studies about the possibility ofhorizontal transmission of the parasite via semen in sheep. In addition, we reported the involvement of T. gondii in aborted fetuses and placentas of sheep naturally infected in Brazil; these data have not been described earlier in the literature.