EXPERIMENTAL INFECTION OF CALVES AND SHEEP WITH <i>LEPTOSPIRA INTERROGANS</i> SEROVAR <i>BALCANICA</i>

Durfee, Philip T.; Presidente, P. J. A.

doi:10.1038/icb.1979.45

Cited by 6 publications

(4 citation statements)

References 6 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%

“…It was unsurprising that the animals that received the highest dose 10 8presented more consistent outcomes. These findings corroborate with similar results of studies conducted in New Zealand [14] and Australia [4].…”

Section: Discussionsupporting

confidence: 92%

“…To detect anti-Leptospira antibodies, a microscopic agglutination test (MAT) was performed using an antigen panel that consisted of 28 reference strains (Institut Pasteur) 4 in accordance with international standards (OIE, 2014). Sera displaying at least 50% agglutinating activity at a 1:100 dilution were considered reactive.…”

Section: Serologymentioning

confidence: 99%

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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: 92%

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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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“…Although WSK are not pathognomonic for leptospirosis (Jeffcott et al 1967;Drolet and Dee 1999), they are frequently observed in natural and experimental infections with Leptospira spp. in cattle (Hadlow and Stoenner 1955;Amatredjo et al 1976), pigs (Cheville et al 1980;Jones et al 1987) and sheep (Marshall 1974;Durfee and Presidente 1979;Hathaway and Marshall 1979;McCaughan et al 1980;Ellis et al 1984;Vermunt et al 1994ab). This association has led meat inspectors and slaughterhouse workers to assume that WSK could be indicators of past or current leptospiral infection, and kidneys were condemned as a consequence (Uzal et al 2002).…”

Section: Introductionmentioning

confidence: 95%