Leptospiral antibodies in cattle in alberta and evidence of an emerging serovar

Antibodies to Leptospira interrogans serovars hardjo and pomona were present in 8.3% and 0.5% of sera respectively, from adult female cattle in Alberta surveyed in 1984-85. Criterion for a positive serum sample was 50% agglutination at 1/100 dilution in the microscopic agglutination test. A positive herd contained one or more cows with positive serum. Prevalences were calculated on sample sizes that would give 80-95% reliability. Hardjo antibody prevalences and hardjo-positive herd prevalences were 0-53.9% and 0-83.3%, respectively, among 65 municipalities surveyed. Pomona prevalences by comparison were 0-3.4% and 0-11.7% respectively. Hardjo had increased significantly since 1980-82, and antibodies were found throughout the province. Pomona occurred mainly in southeastern Alberta, where it was isolated from cattle, swine and skunks. Hardjo was isolated only from cattle and it was found in many areas. Antibodies to icterohaemorrhagiae were present in 0.4% of sera from parts of Alberta surveyed in 1980; evidence of the presence of leptospires related to this serovar in bovine and porcine urinary tracts was obtained by immunofluorescence.     

Is canine leptospirosis underdiagnosed in southern Ontario? A case report and serological survey

An eight-year-old city-dwelling Cairn Terrier was presented to a veterinary hospital in acute renal failure with evidence of hepatic insufficiency. The dog was treated symptomatically over three days, during which time vomiting was largely controlled, but it became jaundiced as hepatic insufficiency worsened. Leptospira pomona was demonstrated in large numbers by immunofluorescent staining of urinary sediment. It was isolated and its identity confirmed as L. pomona genotype kennewicki. The source of the infection was thought to be raccoons.

Sera from 474 blood samples submitted for diagnostic purposes to two clinical pathology laboratories in southern Ontario were examined with the microscopic agglutination test for antibodies to selected leptospiral serovars. Of the sera tested, 39.2% reacted at titers ≥1:100 with one or more serovars, the majority of all sera (26.2%) reacting at low titers to canicola or icterohaemorrhagiae, or both. These reactions likely resulted from vaccination. A smaller proportion reacted to other serovars tested: autumnalis (3.8%), bratislava (8.2%), grippotyphosa (1.9%), hardjo (3.0%), and pomona (3.2%). Among dogs reacting to these latter serovars (other than bratislava), many had broadly cross-reacting and relatively high titers. One dog with a titer of 1:800 to pomona had had a disease typical of leptospirosis two years previously. Three other dogs with high titers to autumnalis, bratislava, or mixed serovars had clinical histories compatible with leptospirosis.

We suggest that leptospiral bacterins for dogs in Ontario be broadened to include at least serovars autumnalis and pomona.

     

The epidemiological interpretation of serological responses to leptospiral serovars in sheep.

Serum samples were examined for evidence of leptospiral agglutinins from 928 sheep from 45 lines and kidneys from 12 of these lines for evidence of leptospiral infection. All sheep had been submitted for slaughter at meat works in the Manawatu.

Serological results were analysed using the results at a minimum serum dilution in the microscopic agglutination test (MAT) of 1:24 and at a minimum dilution of 1:48. It was shown that a minimum dilution of 1:24 resulted in many non-specific or cross-reactions. A minimum dilution of 1:48 was more accurate for detecting the serological prevalence of specific agglutinins to leptospires in ovine sera. Twenty percent of the sheep had titres of 1:48 or greater to hardjo, 3.8% to pomona, 2.6% to tarassovi, 2.3% to copenhageni and 2.7% to ballum. No titres of 1:48 or greater to australis were detected. Serovar hardjo was isolated from the kidneys of three animals in one line.

Eighteen months later 291 serum samples and 95 urine samples were collected from live animals on the property from which the three hardjo infected animals originated. No titres to hardjo were detected in the sera of lambs, but a serological prevalence of 44% and 84% to this serovar was demonstrated in the hoggets and ewes respectively. No leptospires were demonstrated in any of the urine samples.

These results show that sporadic infection of sheep with hardjo can occur but they also indicate that infection with this serovar is not endemic and that sheep are unlikely to act as maintenance hosts for hardjo in New Zealand.     

Prevalence of leptospiral titres in normal horses

SUMMARY Serum samples were collected from 479 clinically normal horses from 11 different locations in Queensland. Using a microscopic agglutination test, 157 serums (33%) reacted to one or more serovars of Leptospira interrogans at a minimum serum dilution of 1/30. The prevalences of reactors among all horses to the serovars tested were pomona 30.5%icterohaemorrhagiae 23.9%, tarassovi 18.8%, hardjo 12.2%, canicola 8.6%, grippotyphosa 3.6%, and australis 2%. There was a significantly higher prevalence of reactors in tropical areas than in sub-tropical areas, but no difference in prevalence between coastal and non-coastal areas.     

Structure of the canine oesophagus

The hardjo component of a bivalent pomona/hardjo vaccine was evaluated, using sheep. Nine sheep were vaccinated and 10 remained unvaccinated. All sheep were challenged with an intraperitoneal and intramuscular injection of a hardjo culture. After 13 weeks, the sheep were slaughtered and their kidneys cultured for leptospires.

There was a highly significant difference between the culture results from the two groups (p<0.001); 10/10 (100%) of the unvaccinated animals gave positive cultures compared with 2/9 (22%)of the vaccinates.     

Transmission and control of leptospiral infection in a beef cattle herd in southern alberta

Leptospiral antibodies were detected in unvaccinated cattle on a 17 000 hectare ranch in the arid southeast region of Alberta. Antibody to serovar hardjo was present before the breeding season in 7% of 42 yearling bulls, 86% of 29 two year old bulls and 5% of 519 cows. Pomona antibody was confined to 3.7% of the cows. Bulls were treated once with dihydrostreptomycin, 25 mg/kg. Bulls and cows were vaccinated twice at a six week interval, with pomona-hardjo-gripptotyphosa bacterin before breeding and cows were revaccinated the next year. Leptospires were demonstrated in urine, kidney and spinal fluid of vaccinated and treated cattle. New infections occurred on range in vaccinates. Eighteen months after the last vaccination, hardjo and pomona antibody prevalences in cows were 3.6 and 3.2% respectively. A group of 250 seronegative cows on the same ranch were not vaccinated. They remained seronegative throughout the 2.5 years of the study. These cows, in contrast to infected groups, were excluded from pastures adjacent to perimeter herds and grazing leases, and they were bred by artificial inseminstion. Rotation through pastures in common with infected groups, and exposure to seropositive heat detector bulls, did not result in seroconversion in these cows. The study showed the potential of range bulls to amplify and transmit hardjo infection, limitations to the value of treatment and vaccination with available agents, and the potential of management practices to maintain an uninfected herd in close proximity to cattle carrying hardjo infection.     

Seroprevalence of and Risk Factors for Leptospiral Antibodies among Cattle in the State of Yucatan,Mexico

Sera obtained from cattle in the state of Yucatan, Mexico, were screened using the microscopic agglutination test against 13 serovars of Leptospira interrogans. A total of 62.8% (461/734) cows were positive for one or more serovars. This seroprevalence probably reflects infection because vaccination against leptospirosis has not been practised in Yucatan. The most common antibodies detected were those against antigens of serovars hardjo (54.1%) and tarassovi (53.3%). Region was the only risk factor associated with the seroprevalence of leptospirosis (p < 0.05). This revised version was published online in July 2006 with corrections to the Cover Date.     

Prevalence of Antibodies to Leptospira Serovars in Sheep and Goats in Alto Adige–South Tyrol

Serum samples from 313 sheep and 95 goats were collected during November 1993 in 26 localities in Alto Adige–SouthTyrol and tested by microscopic agglutination test for antibodies to 28 serovars of the genus Leptospira. At the time of blood collection all the animals appeared healthy with no clinical sign suggestive of leptospirosis. The observed seroprevalence in sheep was 6.1 %, whereas the seropositivity rate for goat serum samples was 2.1 %. The highest serological prevalence in sheep was recorded for serovar castellonis, followed by poi, sejroe, hardjo subtype hardjobovis, copenhageni, and cynopteri. Titres to poi were the only ones found in goats. These findings, which are proof of Leptospira infection in Alto Adige–South Tyrol, indicate that foci of several serovars exist in this region.     

Serological titers to various leptospiral serovars before and after vaccinating gilts with three commercial vaccines

The antibody response to various leptospiral serovars was evaluated in six-month-old gilts vaccinated with three commercial vaccines, each containing five leptospiral serovars.

All three vaccines elicited a significant postvaccinal antibody response to Leptospira canicola, grippotyphosa and icterohaemorrhagiae (copenhageni). The antibody response to the other leptospiral antigens in the vaccines varied among the vaccinates. None of the vaccinated groups developed significant titers to L. hardjo. Two of the three vaccines elicited a significant postvaccinal response to L. pomona, but in each case the titer mean of the vaccinated group was <1/100. Although not among the antigens in the vaccines, titers to L. bratislava increased in all vaccinated groups, except one, and in one control group.

     

A Serological Study on The Prevalence of Toxoplasma Gondii in Meat-Producing Animals in Sweden

Sera from 200 sheep, swine and cattle, respectively, collected at slaughter at each of 3 abattoirs situated in the north, middle and south of Sweden were examined for the presence of antibodies to Toxoplasma gondii by the indirect fluorescent antibody test. Seropositive animals (titre ≥ 1:20) were found at the following rates from north to south: sheep 60%, 66% and 68.5%, swine 9%, 2.5% and 37%, and cattle 10%, 6 % and 35%. The significance of the serological findings is discussed, and it is concluded that T. gondii infection is common in Swedish farm animals. Thus the meat from particularly swine and sheep may provide a potential source of human toxoplasmosis.     

A serological and bacteriological survey of leptospiral infection in dogs in Edinburgh and Glasgow

Sera collected from 511 unvaccinated urban dogs were examined for antibodies to serovars of Leptospira interrogans representing nine serogroups found in the United Kingdom. The point estimates of the seroprevalence of leptospiral titres in Edinburgh and Glasgow at a minimum serum dilution of 1:10 were 23-5 per cent and 27-5 per cent, respectively, and, in Glasgow, the seroprevalence was significantly higher in males than females, for both crude and age-adjusted values. Serovar canicola was the dominant strain identified, followed by serovars icterohaemorrhagiae, bratislava and ballum. Antibodies against serovars javanica and hardjo also were detected. Urine samples were collected from 84 of the male blood-sampled dogs, and cultured. Serovars canicola and bratislava were isolated from three and four samples, respectively.     

Leptospiral agglutinins among cattle in the Republic of Guyana

Summary Cattle sera collected in the Republic of Guyana during 1981 to 1982 were examined for serologic evidence of leptospirosis. Significant leptospiral agglutinins (1∶100 or higher) were disclosed in 49·1% of 2,935 apparently normal cattle from 734 farms in the three major cattle-raising regions of the country. Seroreactions principally involvedhardjo andwolffi of the Sejroe serogroup,icterohaemorrhagiae, pomona, tarassovi, canicola andgrippotyphosa. A high proportion of reactions to one or more of different leptospiral serovars were observed in each of the three regions. These variations were attributed to differences in environmental conditions and farming practices. The findings provided evidence for the first time of the widespread occurrence of leptospirosis in cattle in Guyana caused by multiple leptospiral serovars.

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Resumen Se examinaron sueros bovinos colectados durante 1981 y 1982, con el propósito de detectar aglutininas de leptospirosis. Mediante los análisis, se evidenció la enfermedad (titulos 1∶100 o superiores) en el 49,1% de 2.935 bovinos aparentemente sanos, en las tres principales regiones ganaderas del país. Las seroreacciones involucraron principalmente a lahardjo ywolffi del serogrupo Sejroe, lo mismo que a laicterohaemorrhagiae, pomona, tarassovi, canicola ygrippotyphosa. Se observó una alta proporción de reacciones a una o más serovars en cada una de las tres regiones estudiadas; estas se atribuyeron a prácticas de manejo diferentes, asi como a condiciones ambientales. El estudio, se concluye, proporcionó evidencia de la amplia distribición de la leptospirosis en Guyana.

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Résumé On a recherché l'existence sérologique de la leptospirose dans des sérums de bovins de la République de Guyana récoltés en 1981 et 1982. Des agglutinines à un taux significatif (1∶100 et plus) ont été détectées chez 49,1% de 2935 animaux apparemment normaux répartis dans 734 fermes des trois grandes régions d'élevage du pays. Les réactions sérologiques touchent principalement les sérotypeshardio etwolfii du sérogroupe Sejroe,icterohaemorrhagiae pomona, tarassovi, canicola etgrippotyphosa. On note une importante proportion de réaction à un ou plusieurs des sérovars leptospiriens dans chacune des trois régions. Ces variations sont attribuées aux différences de conditions d'environnement et aux pratiques d'élevage. Pour la première fois, ces résultats apportent la preuve d'une répartition étendue de la leptospirose bovine en Guyana causée par plusieurs sérovars.

     

The prevalence of antibodies to serovars of Leptospira interrogans in horses

SUMMARY Serum samples from 272 horses, some III, were tested by the microscopic agglutination test for the presence of antibody to 12 serovars of Leptospira interrogans. Serums from 41.5% of horses reacted to one or more of the serovars tested; the most common reactions were to L. interrogans serovar ballum (15.1%), L. interrogans serovar autumnalis (11.8%), L. interrogans serovar icterohaemorrhagiae (9.9%), L. interrogans serovar pomona (8.1%) and L. interrogans serovar hardjo (7.7%).     

Serological investigation of granulocytic Ehrlichia infection in sheep in Norway

Serum samples of 749 sheep from 75 sheep flocks in Norway, i.e. 361 lambs (6 to 7 months old) and 388 adults (>1.5 year), were analysed for antibodies to Ehrlichia equi. Ten animals from each flock were examined. Seropositive animals were found along the coast of southern Norway from Vestfold to Sør-Trøndelag (as far north as 63°38''N). Seropositive sheep were not found in southeast, east or northern Norway. Thirty-two flocks were seropositive, although tick-borne fever had only been diagnosed earlier in half of these. In 78% of the seropositive flocks, more than 80% of the sheep were seropositive. A total of 35.7 % and 36.3 % of lambs and adults were found seropositive, respectively. However, the overall seroprevalence among animals that had been grazing on Ixodes pastures were 0.80 for the lambs and 0.84 for the adults. Mean antibody titres (± SD) (log₁₀) in seropositive lambs and adults were 2.59 (± 0.449) and 2.70 (± 0.481), respectively. No significant differences in either seroprevalence or mean antibody titre between sheep of different ages were obtained in this study. Based on antibodies 94% of sheep flocks on Ixodes pastures were infected with a granulocytic Ehrlichia infection. The association between seropositive flocks and Ixodes infested pasture shows a very high degree of agreement (p < 0.00001). The present study indicates that granulocytic Ehrlichia infection in sheep is underdiagnosed in Norway.     

Salmonella and on-farm risk factors in healthy slaughter-age cattle and sheep in eastern Australia

OBJECTIVE: To examine healthy slaughter-age cattle and sheep on-farm for the excretion of Salmonella serovars in faeces and to identify possible risk factors using a questionnaire. PROCEDURE: The study involved 215 herds and flocks in the four eastern states of Australia, 56 with prior history of salmonellosis. Production systems examined included pasture beef cattle, feedlot beef cattle, dairy cattle, prime lambs and mutton sheep and animals were all at slaughter age. From each herd or flock, 25 animals were sampled and the samples pooled for Salmonella culture. All Salmonella isolated were serotyped and any Salmonella Typhimurium isolates were phage typed. Questionnaires on each production system, prepared in Epi Info 6.04, were designed to identify risk factors associated with Salmonella spp excretion, with separate questionnaires designed for each production system. RESULTS: Salmonellae were identified in all production systems and were more commonly isolated from dairies and beef feedlots than other systems. Statistical analysis revealed that dairy cattle were significantly more likely to shed Salmonella in faeces than pasture beef cattle, mutton sheep and prime lambs (P<0.05). A wide diversity of Salmonella serovars, all of which have been isolated from humans in Australia, was identified in both cattle and sheep. Analysis of the questionnaires showed access to new arrivals was a significant risk factor for Salmonella excretion on dairy properties. For beef feedlots, the presence of large numbers of flies in the feedlot pens or around stored manure were significant risk factors for Salmonella excretion. CONCLUSION: Dairy cattle pose the highest risk of all the slaughter-age animals tested. Some of the identified risk factors can be overcome by improved management practices, especially in relation to hygiene.     

Diagnosis of Leptospira serovar hardjo Infection in Cattle in Canada

The investigations described were designed to identify the cause of serological reactions to Leptospira interrogans serovars hardjo and sejroe in Canadian cattle, and to confirm by culture a diagnosis of leptospirosis in cases of reproductive failure and atypical mastitis.     

An unusual serological response in cattle after use of a commercial leptospiral combined hardjo-pomona vaccine

Vaccination of four calves with Leptavoid (Wellcome New Zealand Limited) gave rise to Leptospira interrogans serovars hardjo and pomona microscopic agglutination test titres that could not be distinguished in magnitude from post-infection titres. Vaccination of four calves with Lepto-3 (ICI Tasman Limited) gave rise to much lower titres.

Revaccination of cows with Leptavoid caused a rise in hardjo titres which was significantly greater than after use of Lepto-3.

The possibility that titres were due to the simultaneous infection with serovars pomona and hardjo of only the animals vaccinated with Leptavoid must he discounted.     

Effect of feeding olive-pulp ensiled with additives on feedlot performance and carcass attributes of fat-tailed lambs

Feed cost has a significant effect on the economic efficiency of feedlot lambs; therefore, the use of low-cost non-conventional feedstuffs, such as olive pulp (OP), has the potential to decrease the production costs. Because optimum inclusion of OP-treated silages has not been determined in feedlot lambs, an experiment was conducted to determine the effect of inclusion of OP ensiled with additives in the diet on the feedlot performance and carcass attributes of feedlot lambs. Ram lambs of Mehraban and Ghezel breeds (n?=?50 lambs per breed) were randomly allotted to 10 groups and fed with one of the nine diets containing OP silage or a control diet. Silage treatments were: (1) OP silage without additives (OPS), (2) OP ensiled with 8 % beet molasses and 0.4 % formic acid (OP-MF), and (3) OP ensiled with 8 % beet molasses, 0.4 % formic acid and 0.5 % urea (OP-MFU). The control diet contained 50 % alfalfa hay and 50 % barley grain. Three levels from each silage were chosen to replace the barley grain (10, 20, or 30 % dry matter basis). The lambs were slaughtered after 92 days, and the average daily gain (ADG), feed conversion ratio (FCR), and carcass characteristics were determined. Feeding OPS to fat-tailed lambs, at an inclusion level of 30 %, decreased the carcass dressing percentage, mainly as a result of decreased brisket percentage, but the ADG and FCR values were not adversely affected. Ghezel lambs had higher ADG than Mehraban lambs, but the visceral fat weight percentage, flap weight percentage, and back fat depth were higher in Mehraban. The crude protein content in the longissimus dorsi (LD) muscle was higher in Ghezel, but the dry matter percentage was higher in Mehraban (P?<?0.05). Other attributes were not significantly affected by breed (P?>?0.05). Most carcass characteristics, including major cuts, were not affected by OPS feeding; therefore, feeding OPS (up to 30 %) can be economical for feedlot lambs. Most carcass characteristics, including major cuts, were not affected by OPS levels used in this experiment; therefore, inclusion of OPS (up to 30 %) in the diet may reduce the cost of raising feedlot lambs. This also could help alleviate the problem of storage of OP in oil factories.     

Prevalence of Anaplasma phagocytophilum infection and effect on lamb growth

Background

A major challenge in sheep farming during the grazing season along the coast of south-western Norway is tick-borne fever (TBF) caused by the bacteria Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus.

Methods

A study was carried out in 2007 and 2008 to examine the prevalence of A. phagocytophilum infection and effect on weaning weight in lambs. The study included 1208 lambs from farms in Sunndal Ram Circle in Møre and Romsdal County in Mid-Norway, where ticks are frequently observed. All lambs were blood sampled and serum was analyzed by an indirect fluorescent antibody assay (IFA) to determine an antibody status (positive or negative) to A. phagocytophilum infection. Weight and weight gain and possible effect of infection were analyzed using ANOVA and the MIXED procedure in SAS.

Results

The overall prevalence of infection with A. phagocytophilum was 55%. A lower weaning weight of 3% (1.34 kg, p < 0.01) was estimated in lambs seropositive to an A. phagocytophilum infection compared to seronegative lambs at an average age of 137 days.

Conclusions

The results show that A. phagocytophilum infection has an effect on lamb weight gain. The study also support previous findings that A. phagocytophilum infection is widespread in areas where ticks are prevalent, even in flocks treated prophylactic with acaricides.