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Studies on the kidneys of pregnant hamsters infected with Leptospira canicola.

An electron microscopic study on the histopathological changes in the kidneys of pregnant hamsters resulting from infection with Leptospira canicola was undertaken. The experiment revealed damage to the glomeruli as well as the tubules. The severity of these lesions increased with the progress of the disease and examination of kidney sections showed leptospires in the tissue. It is suggested that the stress of pregnancy has some influence on the severity of the lesions seen in this disease.

Animals↗

Pathogenic leptospira isolates from the Caribbean Islands of Trinidad, Grenada and St. Vincent.

All known isolates of Leptospira interrogans obtained in Trinidad, Grenada and St. Vincent up to the end of 1979 are listed. There were 80 from Trinidad, 20 from Grenada and 2 from St. Vincent, representing at least 20 serotypes from 11 or more serogroups. Six of the serotypes were first reported from Trinidad. The leptospires were isolated from man, domestic animals and wildlife species.

Animals↗

Serum biochemical changes in dogs with experimental Leptospira interrogans serovar icterohaemorrhagiae infection.

Inoculation of 2 groups of dogs with 1 X 10(9) and 4 X 10(9) Leptospira interrogans serovar icterohaemorrhagiae produced disease varying from transient fever to uremia and death. Clinical signs of disease in the severely affected dogs were fever, dehydration, depression, and icterus. Laboratory changes in serum of infected dogs included increased urea nitrogen, creatinine, phosphorus, alkaline phosphatase, total bilirubin, aspartate aminotransferase, and alanine aminotransferase. Chloride concentration decreased in the serum of dogs with severe disease. The icterus in the infected dogs did not appear to be related to hemolytic anemia.

Alanine Transaminase↗

Seroepidemiology of Leptospira interrogans serovar hardjo in Colorado antelope and cattle.

A seroepidemiologic study was conducted to determine the prevalence of Leptospira interrogans serovar hardjo infection in Colorado cattle and antelope. Sera were tested by the microscopic agglutination test, using a standard battery of 12 antigens as well as 4 additional serovars of the Hebdomadis serogroup: hardjo, szwajizak, sejroe, and balcanica. Sera from 1,856 cattle and 544 antelope were tested. In both populations, the predominant serovar detected was hardjo; hardjo titers greater than or equal to 1:400 were found in 3.2% of the cattle and 3.6% of antelope. A positive correlation was found to exist between serologic evidence of infection in cattle and the presence of antelope. In counties with presumably infected antelope, 5.6% of cattle sera reacted to hardjo; in counties with uninfected antelope, 2.6% of cattle tested were seropositive for hardjo; where no antelope existed, titers of greater than or equal to 1:400 were not detected.

Animals↗

A serological survey of Leptospira interrogans serotype pomona in Alberta and Saskatchewan striped skunks and possible transmission between cattle and skunks.

The range of known occurrence of Leptospira interrogans serotype pomona is extended to Alberta in striped skunks (Mephitis mephitis); no evidence of L. sejroe was found. Reacting sera from skunks were confined to the southern portion of Alberta and adjacent Saskatchewan, although a number of reactors were found sufficiently further north in Saskatchewan suggesting that a different mode of infection may be functioning there. Of 95 skunk sera from near a dairy farm infected with serotype pomona 40% were reactors. Of 438 skunk sera from other areas only 5.7% were reactors; that difference was suggestive of transmission from cattle to skunks on the dairy farm. Of 22 skunk sera collected near the dairy farm in summer none were reactors, whereas 52% of skunk sera taken the previous and following winters were. That seasonal difference was not evident among sera from other locations.

Alberta↗

Isolation of revertants from antigenic variants of leptospiras.

The revertants were isolated from the antigenic variants of Leptospira interrogans serovar copenhageni Shibaura by plating the variants on the solid medium containing the homologous immune serum, and by noting the growth of small colonies. The revertants which produced the small colonies were antigenically identical with the parents. The variants which retained their antigenicity for 2 to 3 years produced only a small number of revertants. On the other hand, the variants which phenotypically changed to the parent during the same period of maintenance produced many revertants. The revertant-clones and the variant-clones showed a similar generation time. No revertant was isolated from the variants of hebdomadis Hebdomadis.

Animals↗

Pathogenesis of experimental Leptospira interrogans serotype icterohaemorrhagiae infection in the guinea pigs: possible role of endotoxin of intestinal bacteria in the development of lesions.

Germ-free guinea pigs were infected with a virulent strain of Leptospira interrogans serotype icterohaemorrhagiae to evaluate the possible role of endotoxin of intestinal bacteria in the development of hemorrhages and hepatic and renal failure. Clinical manifestations, necropsy findings and histological lesions were similar to those seen in control animals. In the second part of the experiment, endotoxin was not detected by the Limulus test in the blood of ten guinea pigs during the five day course of leptospirosis.

Animals↗

Two new leptospira serovars belonging to the Hebdomadis serogroup.

Two new serovars in the leptospira Hebdomadis serogroup are described following parallel investigations by the "classical" comparative cross-agglutinin absorption test method and by a method derived from factor analysis. The serovar names nyanza with reference strain Kibos and dikkeni with reference strain Mannuthi are proposed.

Agglutination Tests↗

Sheep as maintenance host for Leptospira interrogans serovar hardjo subtype hardjobovis.

Transmission of Leptospira interrogans serovar hardjo subtype hardjobovis from naturally infected sheep to uninfected sheep and calves was studied. A microscopic agglutination test and ELISA were used to determine specific antibody responses in serum. Polymerase chain reaction was used to detect bacterial shedding in urine. Six sheep were derived from a dairy farm where cows were infected with L hardjobovis. Three of these sheep were seropositive for L hardjobovis, and 1 also shed leptospires in the urine. The other 2 sheep shed leptospires in the urine 7 days after the first observation date. The 6 sheep were placed on an isolated pasture together with a second group of 6 noninfected sheep. During the observation period of 140 days, 1 sheep of the second group became infected with L hardjobovis. On 5 consecutive days, a urine mixture from the 4 infected sheep was sprayed on the heads of 4 noninfected calves. Within 56 days, all calves that had been sprayed with urine shed L hardjobovis in the urine and became seropositive for L hardjobovis.

Animals↗

Titers to Leptospira species in horses in Alberta.

Sera from horses in Alberta, submitted to Agriculture and Agri-Food Canada for routine testing for equine infectious anemia from January 1987 to June 1989, were tested for antibody against 13 serovars of pathogenic Leptospira spp., using the microscopic agglutination test. The purpose of the study was to investigate the prevalence of serum titers to those serovars in horses in Alberta, and to analyze the associated risk factors. Descriptive statistics were compiled and logistic regressions were computed. Titers to L. interrogans serovars icterohaemorrhagiae, bratislava, copenhageni, and autumnalis were common (94.6%, 56.6%, 46.5%, and 43.5%, respectively). The prevalence of titers to other serovars ranged from 0.8% to 27.2%. Age was almost always significantly associated with the presence of titers. In general, the chances of being seropositive rose by approximately 10% with each year of life. Horses managed individually (eg, track horses) were approximately half as likely to be seropositive as were horses managed in groups (eg, rodeo horses).

Alberta↗

[Restriction endonuclease analysis of Pomona serogroup of Leptospira interrogans].

Restriction Endonuclease Analysis (REA) was performed on DNAs from the type strains of the Pomona serogroup of Leptospira interrogans by using EcoRI and HhaI restriction enzyme, and the electrophoretic patterns obtained were compared with patterns obtained from 27 isolates from pig kidneys collected at abattoirs in Victoria, which belong to Pomona serogroup previous identified by MAT. All of the isolates were identified as serovar Pomona.

Animals↗

Factor analysis of Basovizza serogroup of "Leptospira biflexa".

Factor analysis is performed on serotypes of Basovizza serogroup of "Leptospira biflexa". The results show the arrangement of main factors typical for the members of this serogroup as well as the antigens common with serotypes of the heterologous serogroup. The existence of a main haptene-like factor is also hypothesized.

Antigens, Bacterial↗

[Significance of human leptospirosis in Mexico. Detection of Leptospira antibodies in a blood donor population].

The presence of specific serum antibodies has been used as a diagnostic test for human leptospirosis. The presence of these antibodies in humans is indicative of an active natural infection. Its detection after exposure denotes the presence of immunity. Serum samples from 206 adult blood donors were analyzed with a microscopic agglutination assay against 7 serovars of Leptospira interrogans. A total of 7% were positive with the following serovar distribution; shermani 53%, canicola 33%, pyrogens 20%, pomona 13% and icterohaemorrhagiae 6%. The highest frequency of seropositivity was found in the 20 year to 39 age group. These results in asymptomatic individuals show that leptospirosis is a frequent zoonosis in Mexico.

Adolescent↗

[Leptospira infected rat population as probable cause of a fatal case of Weil's disease].

In the summer of 1992 a patient died of a leptospiral infection which he probably had contracted while he was swimming in an artificial lake in the region of Tübingen/Reutlingen. Regarding the epidemiological role of leptospirosis the rodent population was investigated, because rats and mice were often seen in the surrounding area. 11 rats and 20 mice could be trapped. From their urine or kidneys two leptospiral serovars were isolated: Serovar copenhageni from Rattus norvegicus and serovar saxkoebing from Clethrionomys glareolus. Leptospiral antibody titers were not detected in one of these infected animals. It may be supposed that the Leptospira interrogans serovar copenhageni out of the Serogroup Icterohaemorrhagiae had caused the leptospiral infection of the patient.

Animals↗

Preliminary evaluation of antimicrobial agents for treatment of Leptospira interrogans serovar pomona infection in hamsters and swine.

OBJECTIVE: To evaluate antimicrobial agents for treatment of models of acute and persistent leptospirosis caused by Leptospira interrogans serovar pomona. DESIGN: Randomized trials comparing dosages and regimens of various antimicrobial agents for treatment of acute and persistent leptospirosis. ANIMALS: 245 Golden hamsters to model acute leptospirosis and 121 mixed-breed swine to model persistent leptospirosis. PROCEDURE: Hamsters and swine were inoculated with L interrogans serovar pomona. Antimicrobial agents were given to hamsters for 3 or 5 days after inoculation, with necropsy at 14 days after inoculation. Swine were treated for 1, 3, or 5 days beginning at 3 weeks after inoculation, and were necropsied 7 to 10 days after completion of antimicrobial agent treatment. Hamster tissue and swine tissue and urine specimens were examined by culture, fluorescent antibody testing, and histologic examination for presence of leptospires. RESULTS: All untreated control hamsters became infected and manifested clinical signs and lesions of acute leptospirosis. Leptospires were not detected in hamsters treated with dihydrostreptomycin/penicillin G (25 mg/kg of body weight). Administration of ampicillin at all dosages reduced the number of hamsters infected, as confirmed at necropsy; the other agents tested required dosages greater than label recommendations to reduce the number infected. All untreated control swine became infected and shed leptospires in urine through the time of necropsy. Leptospires were not detected in kidneys or urine of swine treated with dihydrostreptomycin/penicillin G (25 mg/kg) for 1, 3, or 5 days, or in swine treated with oxytetracycline (40 mg/kg for 3 or 5 days), tylosin (44 mg/kg for 5 days), or erythromycin (25 mg/kg for 5 days). Treatment with ceftiofur and ampicillin was not effective in elimination of L interrogans serovar pomona in swine. CONCLUSIONS: Dihydrostreptomycin/penicillin G is effective for treatment of acute and persistent leptospirosis. Differences between the effectiveness of antimicrobial agents in the acute and persistent model of leptospirosis emphasize the importance of using the appropriate model for treatment evaluation. Antimicrobial agents evaluated for treatment of persistent leptospirosis in swine required the use of dosages above those recommended by the manufacturer. CLINICAL RELEVANCE: Use of antimicrobial agents at extra-label dosages for treatment of persistent leptospirosis may cause residue problems in food animals; however, these regimens may be useful for treatment of breeding stock or animals destined for import/export.

Animals↗

Experimental immunization of hamsters with an EDTA extract of Leptospira interrogans, serovar icterohaemorrhagiae.

The EDTA extract was prepared from the Leptospira interrogans serovar icterohaemorrhagiae. When inoculated subcutaneously in hamsters it conferred protection from challenge with virulent leptospires with a low dose (10 micrograms/ml) and low agglutinating antibody (40). The protection of animals obtained by the EDTA extract opens up the perspective of its use as a component of a vaccine for the control of leptospirosis.

Agglutinins↗

Leptospira interrogans in the genital tract of sheep. Research on ewes and rams experimentally infected with serovar hardjo (hardjobovis).

To verify if Leptospira hardjo can colonize the male and female genital organs of sheep, 9 animals (6 non pregnant ewes and 3 mature rams) were infected with a strain of L. hardjobovis recently recovered from the kidneys of a seropositive ewe. Postinfection controls (bacteriologic, serologic, immunohistochemistry and electron microscopy) failed to disclose the presence of leptospires in the uterus and oviducts, testicles, epididymis, prostate and bulbourethral glands of animals used for the experiment and slaughtered from 37 to 242 postinfection days. All animals showed a renal localization of L. hardjobovis lasting for the entire period of the study (over 8 months). These results emphasize the important role of sheep as maintenance hosts of the serovar.

Animals↗