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Results for “LEPTOSPIRA INFECTIONS”

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At least 73 records · Page 4Linked to original sources
PubMed1987

The effects of gamma-irradiation on haemopoiesis and red blood cell destruction in hamsters infected with Leptospira interrogans serovar ballum.

Irradiated hamsters were infected with Leptospira interrogans serovar ballum in order to study the effects of impairment of the reticulo-macrophage system on the progression of the disease and the development of haemoglobinaemia. Infected and irradiated hamsters were compared with infected controls, irradiated controls and untreated controls. Red blood cells (RBCs) from untreated controls were biconcave disks while those from irradiated controls were echinocytes. Red blood cells from animals of both infected groups which were severely affected and moribund were in the form of pitted spherocytes and were associated with increased icteric indices and haemoglobinaemia. Red blood cells from less severely affected animals were echinocytic. Pitted spherocytes, however, were seen in some irradiated-infected hamsters before increased icteric indices and haemoglobinaemia were present. Both irradiated-infected and irradiated hamsters showed severe depletion of haemopoietic cells and lymphoid cells, with regeneration occurring in those animals which survived for longer. Red cell sequestration and erythrophagocytosis were present in infected-only hamsters. In irradiated-infected animals, severe anaemia was caused by both persistence of fixed macrophages, RBC sequestration and erythrophagocytosis, and haemorrhage due to vascular damage and renal papillary necrosis. A severe leucopaenia affected the irradiated hamsters' ability to suppress leptospiral multiplication resulting in the presence of larger numbers of organisms.

Animals↗
PubMed1976

Susceptibility of mice treated with cyclophosphamide to lethal infection with Leptospira interrogans Serovar pomona.

Mice not normally susceptible to infection with Leptospira interrogans serovar pomona were rendered susceptible to lethal infections by treatment with a single dose of 300 mg of cyclophosphamide (Cy) per kg administered optimally from 4 days before to 1 day after infection. Cy-treated mice with either passively or actively acquired antibody were protected from death. Blood levels of leptospires in infected untreated and in Cy-treated mice remained similar until 2 days after infection, when untreated mice cleared the leptospires. Soon afterwards, opsonizing and agglutinating antibody appeared. Cy-treated mice given spleen cells from other normal or specifically immune mice were protected from infection. An important factor in the natural resistance of mice to leptospiral infection appears to be their capacity to produce circulating antibody within 48 to 72 h. Applications are suggested for this animal model in vaccination and protection studies.

Animals↗
PubMed2006

NF-kB activation and p38 phosphorilation in microglial cells infected with Leptospira or exposed to partially purified leptospiral lipoproteins.

Recently, we have shown a differential susceptibility of non-pathogenic vs. pathogenic leptospires to phagocytosis and killing by microglial cells. Although all ingested to some extent, only the pathogenic strains survived intracellularly while the non-pathogenic ones were killed in a time-dependent manner. By the same infection model, here we demonstrate that microglial cells respond to Leptospira infection with a time- and dose-dependent induction of molecular signals (p38 phosphorilation and NF-kB activation) and the production of soluble factors (cytokines and nitric oxide). Such bio-molecular response is predominantly observed against the pathogenic Leptospira; the phenomenon is reproduced by leptospiral lipoproteins and, to a lower extent, by leptospiral-derived LPS. These data provide initial evidence that Leptospira affects microglial cell response in a different manner depending upon the virulence of the infecting strain; specific bacterial components happen to be involved in the induction of such pathogen-induced immune response.

Animals↗
PubMed1988

Antigens recognised by the human immune response to infection with Leptospira interrogans serovar hardjo.

Serum samples from patients infected with Leptospira interrogans serovar hardjo were tested by the microscopic agglutination test (MAT), enzyme immunoassay (EIA) and immunoblotting. There was no apparent correlation between MAT titre and EIA optical density (OD) for individual serum samples, but sequential serum samples produced similar profiles in both tests during the course of an infection. Immunoblotting of hardjo sonicate with patients' sera revealed reactions with a number of bands, in the mol. wt (10(3] range 14.4-95. However, all serum samples reacted with the major 28 x 10(3)-mol. wt sub-unit of hardjo lipopolysaccharide (LPS) and most reacted with a (34.5-35) x 10(3)-mol. wt flagella doublet. Examination of sequential serum samples obtained over a period of about 3 months after infection revealed little change in the antigens detected after the second to third week of infection. Absorption of patients' sera with whole viable leptospires revealed that antibodies to several exposed antigens, including LPS, were produced. Sera which reacted with hardjo flagella also reacted with bands of similar mol. wts in preparations from other serovars.

Agglutination Tests↗
PubMed1992

Renal dysfunction associated with infection of Leptospira interrogans in a horse.

Renal failure associated with infection of Leptospira interrogans was detected in a horse. Fever, leukocytosis, pyuria, isosthenuria, and azotemia were suggestive of an inflammatory urinary tract disease. Despite persistent pyuria, no bacteria were found during routine microscopic examinations or bacteriologic culturing of urine. A fluorescent antibody examination of the urine was positive for L interrogans. Serologic testing during a 6-month period, supported an acute infection with L interrogans serovar pomona. Treatment with intravenously administered fluids and antimicrobials resulted in clinical recovery. Leptospira interrogans serovar pomona has been reported as causing fever, uveitis, or abortion in horses.

Acute Kidney Injury↗
PubMed1991

Experimental lethal infection of Leptospira interrogans in mice treated with cyclophosphamide.

After preadministration of cyclophosphamide (300 mg/kg), BALB/c mice were lethally infected with Leptospira interrogans serovar lai and a virulent strain of Leptospira interrogans serovar copenhageni, and leptospiral cells were detected in both kidneys of infected mice by indirect immunofluorescent assay. Nonpathogenic leptospirae, Leptospira biflexa serovar patoc, Leptonema illini, and an avirulent strain of L. interrogans serovar copenhageni, were not parasitic to the mice treated with cyclophosphamide. The cyclophosphamide-treated mice were protected from the homologous leptospiral infection by passive immunization with anti-leptospiral monoclonal antibody or with rabbit antiserum and by active immunization with lyophilized organisms or with protective antigen. The results of active immunization in mice treated with cyclophosphamide agreed well with those in nontreated hamsters, which were sensitive to the organisms. Furthermore, these experiments were reproducible with any lot of cyclophosphamide used. These results indicated that cyclophosphamide-treated mice can be used in the experimental infection of Leptospira in place of hamsters or guinea pigs.

Animals↗
PubMed1984

The immunoglobulin response of swine following experimental infection with Leptospira interrogans serovar pomona.

The antibody response of pigs following experimental infection with Leptospira interrogans serovar pomona was examined using enzyme immunoassay (EIA) and the microscopic agglutination test (MAT). Leptospires elicited the production of both IgM and IgG classes of antibody, with IgG levels persisting for much longer than IgM. A comparison of MAT and EIA indicated that the detection of specific IgM by EIA was potentially useful in distinguishing between past and recent infection in pigs. Agglutinins were also detected in the urine of infected animals but these antibodies could not be detected by EIA.

Animals↗
PubMed1996

Reproductive performance of dairy herds infected with Leptospira interrogans serovar hardjo relative to the year of diagnosis.

To assess the impact of Leptospira interrogans serovar hardjo infection on the reproductive performance of nine dairy herds with evidence of infection, forty years' fertility data were analysed relative to the year of first diagnosis. Fifty per cent of various fertility variables had their lowest values only in the year of diagnosis. Culling rates were highest during the year of diagnosis in five of the herds, and were above 22 per cent in five of nine (55-6 per cent) of the diagnosis years considered compared with seven (22-6 per cent) of the 31 non-diagnosis years. An assessment of the fertility status of the herds by means of a formula with incorporated the first service conception rate, the number of services per conception for cows conceiving, the calving to conception interval and the culling rate, revealed low reproductive performance during the year of diagnosis in six of the nine herds. Abortion rates were highest in four of the herds during the year of diagnosis, and these included the herds in which the fertility status was not lowest. It was concluded that L. interrogans serovar hardjo affected reproductive adversely by causing both abortions and low fertility, but that the effect was temporary.

Abortion, Veterinary↗
PubMed1997

Superoxide dismutase activity and lipid peroxidation in the liver of guinea pig infected with Leptospira interrogans.

Superoxide dismutase (SOD) activity and the degree of lipid peroxidation were studied over a two week period in guinea pigs infected with Leptospira interrogans derived from wild mice. The total SOD activity in infected host liver increased by four-fold two days after infection; this was followed by a 20% decrease resulting in levels comparable to normal, uninfected liver. During the period of decreasing SOD activity after day two, the levels of TBA-reactive material (TBARS) are increased by three-fold in infected guinea pig, liver, compared to uninfected liver. The results indicate that SOD attenuates intracellular superoxide-mediated toxic effects in guinea pigs infected with L. interrogans. In addition, electron microscopy structure demonstrates correlated pathogenic shrinkage of mitochondrial and Kupffer cell structures.

Animals↗
PubMed1992

Control of Leptospira hardjo infection in beef cattle by whole-herd vaccination.

A whole-herd vaccination programme to control Leptospira hardjo infection was applied to a closed herd of approximately 800 beef cattle on the island of Luing in Scotland. An experimental vaccine was produced and the herd was vaccinated annually for five years. Progress was monitored by means of a catalytic model using data for age-specific serological prevalences and geometric mean titres. Any cattle introduced to the herd were subject to antibiotic treatment and quarantine, and at the end of the trial the whole herd was treated prophylactically with antibiotics to minimise the risk of residual infection. There was a progressive right shift in age-specific serological prevalences, and by the end of the trial all young stock entering the breeding herd were seronegative. The age-specific geometric mean titres demonstrated the cessation of an endemic cycle of hardjo infection in the herd. Birth cohort analysis supported the serological evidence of a high level of control, and bacteriological monitoring at the end of the trial indicated that hardjo had been eliminated from the herd.

Age Factors↗
PubMed1997

Amoxycillin as an alternative to dihydrostreptomycin sulphate for treating cattle infected with Leptospira borgpetersenii serovar hardjo.

OBJECTIVE: To assess the effect of amoxycillin treatment on urinary excretion of leptospires from cattle infected with Leptospira borgpetersenii serovar hardjo. DESIGN: A chemotherapy trial with controls. PROCEDURE: Fourteen heifers serologically negative to L hardjo were inoculated with L hardjo via the conjunctival route and assessed for evidence of infection by serological, fluorescent antibody and microbiological tests. Two injections (48 h apart) of amoxycillin at a dose of 15 mg/kg were administered intramuscularly to seven heifers 6.5 weeks after infection; the remaining heifers acted as untreated controls. Later, these seven control group heifers were treated with a single dose of amoxycillin (15 mg/kg). Samples of urine were collected before and after amoxycillin treatments; kidneys were collected at slaughter, and examined by fluorescent antibody test and microbiological culture. RESULTS: Leptospires were isolated from the urine of 11 of 14 heifers inoculated with L hardjo. After treatment of six of these with two injections of amoxycillin, leptospires were not isolated. Of the controls, four of the five initially leptospiruric heifers continued to shed leptospires; after a single injection of amoxycillin, no leptospires were detected in the kidneys of these four. CONCLUSION: Amoxycillin may be an acceptable alternative to dihydrostreptomycin sulphate for the treatment of cattle infected with L hardjo.

Amoxicillin↗