Streptomycin treatment of genital carriers of Leptospira in experimentally infected sheep on different estrous phases.

Leptospirosis in ruminants presents as a chronic disease that causes several reproductive disorders leading to severe economic losses. The current recommended treatment can be efficient to eliminate the renal carrier state, however little is known about the effect of this drug in removing the genital carrier state and the hormonal influence on it. A total of 12 primiparous sheep experimentally infected with a strain of Leptospira santarosai serogroup Sejroe, FV52 strain, were used and distributed as group A (estrus; n = 5), group B (metaestrus; n = 4) and group C (control; n = 3). At D0, groups A and B were treated with streptomycin (25 mg/kg) single dose. Samples of cervicovaginal mucus (CVM) were collected on days 0, 3, and 35 post-treatment, while uterine fragment (UF) samples were collected on days 3 and 35, for PCR. Even after antibiotic treatment, all groups presented infected animals, at D3 and D35, with no significant difference between the treated and control groups. Based on these results, it was conducted a second protocol of treatment with streptomycin, IM (25 mg/kg) for three consecutive days, which was 100% effective to eliminate the genital carrier state; therefore, that protocol should be recommended.

Leptospira noguchii associated to reproductive disease in ruminants.

Leptospirosis is known to determine reproductive disorders on livestock, and Leptospira interrogans and Leptospira borgpetersenii are the most frequently reported species. Leptospira noguchii is an emerging pathogen, but its association with reproductive disease is unclear. We have detected L. noguchii as the agent of an outbreak with reproductive disorders in a Brazilian dairy goat flock. In the kidding season, five out of 10 Saanen had abortions in the final month of pregnancy and two newborn kids had acute clinical signs. After necropsy of three foetuses and one newborn kid, fragments of liver, lung and kidney were submitted to lipL32-PCR. It yielded positive results in at least one fragment from each animal. After, a nested secY-PCR, followed by sequencing, could identify L. noguchii, with 99-100% of identity with sequences obtained from cattle in the same region. For the first time, L. noguchii was detected in goats and, most importantly, the association of this leptospiral species with reproductive failures in ruminants has been demonstrated.

Molecular detection of leptospiral carriers in sheep under tropical field conditions / Detecção molecular de ovinos carreadores de Leptospira em ambiente tropical

The purpose of this study was to analyze the usefulness of PCR for the detection of leptospiral carriers in sheep under tropical field conditions. Two flocks, previously reported as seroreactive (A) and seronegative (B), were selected for this study. From those, the totality of animals of each flock, urine and vaginal fluid (VF)/semen were collected for bacteriological culture and PCR, as well as serum samples for serology. Serology confirmed the previous status of the two flocks. Culture was negative for all the samples. In PCR, animals of Flock A presented 26.7% (VF), 33.3% (semen) and 38.9% (urine) of positivity. Flock B presented 40.0% (VF), 33.3% (semen) and 5.6% (urine) of positivity by PCR. In conclusion, PCR was important to identify carriers of leptospires, including animals from a seronegative flock, what reinforces the advantages of the usage of this tool for the detection of carriers in sheep as part of control programs of leptospirosis under tropical field conditions.

O objetivo do presente estudo foi analisar a aplicabilidade da PCR na detecção de ovinos carreadores de Leptospira em ambiente tropical. Dois rebanhos ovinos, previamente reportados como sororeativo (A) e soronegativo (B) foram selecionados para este estudo. Da totalidade de animais dos rebanhos, amostras de urina e fluido vaginal (FV)/sêmen foram colhidas para cultura bacteriológica e PCR. Além disso, amostras de soro foram colhidas e utilizadas na sorologia (teste da soroaglutinação microscópica). Essa técnica confirmou o estado prévio dos dois rebanhos. Nenhuma amostra pura de leptospiras foi obtida no cultivo. Já na PCR, animais do Rebanho A apresentaram 26,7% (FV), 33,3% (sêmen) e 38,9% (urina) de amostras positivas. O Rebanho B apresentou 40,0% (FV), 33,3% (sêmen) e 5,6% (urina) de positividade pela PCR. Em conclusão, a PCR foi uma importante ferramenta na identificação de carreadores de leptospiras, incluindo animais do rebanho soronegativo, o que reforça as vantagens do uso desta técnica para a detecção de ovinos portadores como parte dos programas de controle da leptospirose em ambiente tropical.