Detection and localization of Leptospira spp. by real-time PCR and culture in the genital tract and fetal tissues in the beginning and late pregnancy of slaughtered deer.

Abstract

Leptospirosis is an economically important bacterial infection of livestock that causes reproductive losses due to abortions, stillbirths and infertility and non-reproductive losses due to septicaemia and nephritis. In addition, leptospirosis is presumed to be the most widespread zoonotic disease in the world. Earlier studies in red deer in New Zealand show reproductive effects, mainly lower weaning rates. No effect has been proved yet on calving rate per se. Abortion due to leptospirosis has been demonstrated only experimentally in (white tailed) deer. The economic consequence of reproductive effects in rising-two-yearold deer in NZ averaged 15.5$ per hind. This study attempts to find evidence for detection and localization of Leptospira spp. by PCR and culture in the genital tract and fetal tissues in the beginning and late pregnancy of slaughtered deer. From July to October 2011, 57 mixed age hinds, phenotypically Cervus elaphus, but possibly containing some Wapiti genes, from 7 commercial deer farms were sampled at a deer slaughter premises in Feilding, New Zealand. From each deer farm 3 to 23 hinds were randomly sampled at the slaughterhouse. In total, 57 kidneys, 57 blood samples, 57 uteri and 23 fetuses were collected at a deer slaughter premises. Serum reactivity was tested for serovars Hardjo-bovis, Pomona and Ballum. A titre of ≥1:48 was considered as positive. Bacterial culture and real-time PCR were performed on the kidney, uteri and fetus (kidneys) samples. For the 57 blood samples, 29 (50.1%) were positive for serovar Hardjo-bovis, 41 (71.9%) were positive for serovar Pomona and 2 (3.5%) were positive for serovar Ballum. Eight of 43 (18.6% ) kidneys from 2 farms were culture positive. . Three of 48 kidney samples were PCR positive all of which were culture positive. One of the culture positive kidney samples was not positive by real-time PCR. From 4 culture positive kidney samples it was not possible to perform real-time PCR. This research failed to isolate Leptospira spp. from the uterus or fetus of deer by bacterial culture and real time PCR.