Experimental infection of sheep and cattle with<i>leptospira interrogans</i>serovar<i>balcanica</i>

Mackintosh, C.G.; Marshall, R.B.; Jc, Thompson

doi:10.1080/00480169.1981.34779

Cited by 9 publications

(3 citation statements)

References 19 publications

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“…It is particularly important to highlight that the age of the animals did not appear to alter their susceptibility to the experimental infection. This finding also contrasts with those of other experimental studies [4,13], which suggested younger animals are more susceptible to acute infection than older ones.…”

Section: Discussioncontrasting

confidence: 99%

“…Despite the lack of clinical signs, serological and molecular results confirmed the experimental infection. Seroconversion was observed only in the animals that received the highest dose of leptospires (Group C), similar to the findings of previous research [11,13,14]. Additionally, in this group, only animals with high titers also presented leptospiruria.…”

Section: Discussionsupporting

confidence: 90%

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Challenges on the Follow-Up Experimental Leptospiral Infection in Sheep

Rosa

Rocha

Correia

et al. 2019

Acta Scientiae. Vet.

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Background: Leptospirosis is currently a source of significant economic losses in the agribusiness; as such, experimental studies on this infection are required to develop a better understanding of the pathogenesis, treatment, and immunoprophylaxis of the disease. Sheep may represent a good model for ruminants in such models. Despite the extent of the studies that has been conducted thus far, researchers have yet to reach a consensus on the experimental practices to apply for leptospirosis in this animal species, and several gaps in understanding remain. To bridge these gaps, the present study aimed to assess the usage of several tools for the monitoring of experimental leptospirosis in sheep.Material, Methods & Results: Twelve Santa Ines sheep of different ages were each allocated to one of four groups (A, B, C, and D). The subjects in groups A, B, and C received different doses of Leptospira interrogans serogroup Icterohemorrhagiae by intraperitoneal route, 1x102, 1x105, and 1x108 respectively. Group D was the control. Hematological, biochemical and clinical parameters were evaluated daily. Serology by microscopic agglutination test (MAT) and PCR were performed to evaluate the infection status. The most remarkable clinical signs were fever (41ºC) and dehydration, and acute pain (cub). Two animals from Group C presented leukocytosis. Only those in Group C exhibited positive results according to serology, while positivity in PCR was observed in animals in groups A and C. The results of the experiment indicated that sheep may be experimentally infected and can, therefore, be used as a model for leptospirosis in ruminants. Clinical signs cannot be considered to represent a reliable parameter for evaluating the development of leptospirosis in experimentally infected sheep. We recommend the use of urine PCR and serology to confirm the infection in experimentally infected animals and daily complete blood count (CBC) as a follow-up tool.Discussion: It was observed that the clinical signs cannot be considered as a reliable parameter to evaluate the pathogenesis in experimentally infected ewes, being important to emphasize that the age of the animals does not seem to alter their susceptibility to the infection. This finding is in agreement with other experimental studies, which report that leptospirosis infection in ruminants occurs asymptomatic and subclinical. Hematological and biochemical tests proved to be adequate tools to monitor the experimental infection. Studies have shown that the complete blood count has been used to monitor the acute phase of leptospirosis and is effective in detecting anemia and leukocytosis with neutrophilia in ruminants. Despite the lack of clinical signs, the serological and molecular results confirmed the experimental infection. PCR has been used as an important tool in the diagnosis of leptospirosis. In addition, the current study is the first of its kind to use PCR to detect the carrier status in experimentally infected ewes. Despite this limitation, PCR was very effective in confirming the infection and should be considered for use in experimental studies. Sheep have been used as a good experimental model in several studies, sheep are relatively small compared to other ruminants and can be easily allocated in smaller pens and pens, facilitating the management of research and minimizing the costs of experimentation. In this context, we suggest that sheep represent a good model for the study of leptospirosis in ruminants and therefore a reliable protocol for experimental infection by leptospirosis is necessary.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 90%

Challenges on the Follow-Up Experimental Leptospiral Infection in Sheep

Rosa

Rocha

Correia

et al. 2019

Acta Scientiae. Vet.

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“…Leptospira interrogans serovar Pomona caused jaundice, haemolysis, haemoglobinuria, hepatic necrosis, interstitial nephritis (Langham et al., ; Hodges, ; Marshall, ) and associated serum biochemical abnormalities, which were attributed to haemolysis and mild impairment of tubular and glomerular kidney function (Millar et al., ). Experimental infection by L. interrogans serovar Balcanica caused only a mild rise in body temperature (Mackintosh, Marshall, & Thompson, ). Leptospira interrogans serovar Hardjo (Director et al., ), L. noguchii serogroup Autumnalis (Silva et al., ) and L. borgpetersenii serovar Hardjo (Arent, Frizzell, Gilmore, Mackie, & Ellis, ) have been isolated from asymptomatic sheep.…”

Section: Introductionmentioning

confidence: 99%

Leptospira interrogansserogroup Pomona serovar Kennewicki infection in two sheep flocks with acute leptospirosis in Uruguay

Hamond

Silveira

Buroni

et al. 2019

Transbound Emerg Dis

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Summary Acute leptospirosis is an infrequent disease in sheep that can cause jaundice, haemolysis, haemoglobinuria, hepatitis and nephritis. In most reports the diagnoses have been made by clinical, pathological or serological evidence without isolation or direct identification of the agent. Here, we report one confirmed and one presumptive outbreak of acute leptospirosis in suckling lambs from two unrelated sheep farms in Uruguay with mortalities of 9/60 (15%) and 9/163 (5.5%) lambs. Both outbreaks occurred in Sep–Oct 2017 after heavy rainfall and flooding events. The main gross and histologic pathological findings in two autopsied lambs, one from each farm, included severe diffuse jaundice, haemoglobinuria, acute necrotizing hepatitis with cholestasis and interstitial nephritis. Leptospira interrogans serogroup Pomona serovar Kennewicki was isolated from sheep in both flocks and the same genotype was identified directly in clinical samples from infected animals, including one of the deceased lambs subjected to autopsy, by amplification and partial sequencing of rrs and secY genes. This serovar has recently been identified in infected cattle and humans in Uruguay. The impact of Leptospira spp. infection in ovine health, and the epidemiologic role of sheep as reservoirs of leptospirosis for humans and animals need further investigation.

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