Biomedical subjects
Publications and source records attributed to W A Ellis.
Ovine vulvitis was experimentally reproduced by intravaginal inoculation of a mixture of bacterial strains of the histophilus/haemophilus group isolated from field cases. Grossly, the experimental vulvitis was identical to the field condition, and bacteria indistinguishable from the inoculated strains were reisolated.
Four pathogenic strains of leptospires were isolated from the kidneys of toads (Bufo marinus) and seven from frogs (Eleutherodactylus johnstonei). Isolates from two toads and one frog belonged to serovar bim, the causative agent of most cases of severe leptospirosis on Barbados. The other eight strains belonged to a new serovar within the Australis serogroup. The name bajan is proposed for this new serovar of Leptospira interrogans.
Restriction endonuclease analysis was performed on DNAs from the type strains of the Australis serogroup of Leptospira interrogans by using 20 restriction enzymes, and the electrophoretic patterns obtained were compared with patterns obtained from 162 Australis serogroup isolates from pigs. It proved to be a quick and reliable method for typing such strains. All of the pig isolates were identified as either serovar bratislava or muenchen. It also showed differences at the subserovar level which may be important in (i) understanding the epidemiology of the Australis serogroup, (ii) the development of suitable vaccines, and (iii) pathogenesis and pathogenicity studies. Two genotypes (B2b and M2) accounted for 92% of isolates from aborted or stillborn piglets, while a third genotype (B2a) was the only one recovered from the brains of piglets with meningitis.
In a serological examination of 710 serum samples collected from human volunteers in Plateau State, Nigeria, 128 (18.0pc) had leptospiral antibody titres of 1:100 and above. The prevalence of antibodies to individual serovars were: hardjo 28 (21.9pc), pomona 18 (14.1pc), canicola 17 (13.3pc), grippotyphosa 15 (11.7pc), pyrogenes 13 (10.2pc), icterohaemorrhagiae 12 (0.4pc) and autumnalis 8 (6.3pc). There was no statistical difference in the prevalence rate of leptospirosis in the different local government areas (p greater than 0.05; X2). Among the occupational groups examined, the abattoir workers were particularly at risk with a prevalence rate of 29.5pc. A leptospiral variant of strain Hardjoprajitno was also isolated from the midstream urine of an abattoir worker who was apparently healthy. The isolation of Leptospira interrogans serovar hardjo in man is the first such report in Nigeria.
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Evidence of past zoonotic infection was investigated serologically in randomly selected Northern Ireland farmers. The percentage of farmers with antibody was: Brucella abortus (0.7), Leptospira interrogans serovars (8.1), Borrelia burgdorferi (14.3), Toxoplasma gondii (73.5), Coxiella burnetii (28.0), Chlamydia psittaci (11.1) and Hantavirus (1.2). The results show that Northern Ireland farmers have been exposed in the past to zoonotic infections. It is not known if these infections contributed to ill health in farmers but it is now time for the health of farm workers and their medical services to be reassessed.
Five leptospiral strains were isolated from bovine kidneys during a cultural survey for pathogenic leptospires in Nigeria. Preliminary test results indicated that the five strains were identical and serologically heterologous to the other members of the Pyrogenes serogroup. Further examination of the strains by the cross-agglutinin absorption test, factor analysis and restriction endonuclease analysis confirmed that the strains constitute a new serovar. It is therefore proposed that this strain be recognised and designated as serovar nigeria, type strain Vom.
The intramuscular vaccination of pigs with two doses, two weeks apart, of a Leptospira interrogans serovar bratislava bacterin, protected pigs against renal infection when challenged with bratislava strains six weeks later but did not protect pigs challenged after 26 weeks.
The genomes of 253 strains of Leptospira interrogans serovar hardjo were examined by restriction endonuclease analysis of their DNA. The strains had been isolated from cattle at an abattoir (190), milk of agalactic cows (seven) and from aborted bovine fetuses (56). Two distinct genome types, Hardjoprajitno and Hardjobovis, were detected. The majority (91 per cent) of isolates from abattoir cattle were of the Hardjobovis type while most (76 per cent) of the isolates from clinical/pathological material were similar to Hardjoprajitno.
Thirty reference Leptospira strains and twelve leptospire-like cultures were examined for aminopeptidase activity using twenty-two aminoacyl-beta-naphthylamide substrates. Aminopeptidase activity was demonstrated in extracts of each of the cultures and their substrate specificity profiles compared using several computer analysis procedures. The specificity profiles were consistent for each of the strains examined. Leptospira were readily differentiated from non Leptospira strains. This was supported by DNA base ratios calculated for the strains. Of the non Leptospira strains, seven appeared similar to the "L. illini" cultured included. Two of these strains, which included the strain "L. parva" sp. nov., formed a subgroup of this "L. illini" group. Substrate specificity profiles for the L. interrogans and L. biflexa strains examined were also different from each other.
A double blind controlled trial was carried out on four commercial dairy herds, to investigate the effect of one 50 mg injection of selenium, 10 days before parturition, on the incidence of weak calves. Although the treatment marginally increased the selenium status of treated calves it did not decrease the incidence of the weak calf syndrome.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Twenty sows were examined as part of an investigation into the relative importance of the genital and urinary tracts as sites of leptospiral persistence in pigs. The sows had previously either aborted leptospire-infected fetuses or aborted on farms where leptospire infection had been demonstrated in other litters. Leptospires belonging to the Australis serogroup were recovered from the upper genital tract of all the sows. In contrast, leptospires were only recovered from 75 per cent of their kidneys. Isolates from 10 of the sows were identified to serovar level: six were serovar muenchen and four were bratislava. Persistence was observed in renal and genital tissues for up to 147 days after abortion.
During an investigation of pig abortions and stillbirths in Northern Ireland, leptospires were isolated from 55 of the 78 litters examined. Strains belonging to four serogroups (Australis, Icterohaemorrhagiae, Hebdomadis and Autumnalis) were recovered but leptospires of the Australis serogroup accounted for 91 per cent of the isolates. Two serovars of the Australis group bratislava and muenchen, were identified.
In a bacteriological investigation of 60 cows and heifers from an abattoir Leptospira interrogans serovar hardjo was isolated from 39 (65 per cent) animals. The genital tract (57 per cent) appeared to be as important a site of hardjo localisation as the urinary tract (62 per cent). This is believed to be the first report of genital hardjo infection in naturally infected cattle.
Almost the full range of clinical signs observed in pregnant cattle naturally infected with Leptospira interrogans serovar hardjo was observed in this experimental study in which 22 heifers were infected by intraplacentome inoculation with serovar hardjo strains. These features included abortion, mummification, stillbirth, premature and term birth of weak calves and full-term birth of live apparently healthy calves. Leptospires were demonstrated in all but three calves by culture and or immunofluorescence.