A review of laboratory techniques and their use in the diagnosis of Leptospira interrogans serovar hardjo infection in cattle

SUMMARY This paper reviews the laboratory diagnosis of Leptospira hardjo infection in cattle. Two genotypes of L hardjo, Hardjoprajitno and Hardjobovis, have been identified in cattle, but only Hardjobovis has been isolated in Australia. There are problems with diagnosis and control of bovine leptospirosis. Infection is usually subclinical and the serological titres vary greatly in peak and duration. Leptospires may be excreted in urine for up to 18 months. Low microscopic agglutination test titres may be significant in unvaccinated herds as indicators of endemic infection. Vaccines differ in their composition, and their efficacy is difficult to evaluate. The serological response after vaccination is difficult to differentiate from the response after infection. Pregnant cows that become infected may abort, but this is usually after the serological response has peaked. Therefore, paired serum samples are of little use in diagnosing abortion caused by L hardjo. Fluorescent antibody techniques are more sensitive than dark field microscopy for detection of leptospires in urine and tissue samples. Techniques for culture have improved but are still difficult to perform and take 3 months or longer for results to be known. DNA probes and polymerase chain reaction tests are very sensitive and specific, quick to perform, and can be used on fluid and tissue samples.     

Role of Gene Interactions in Hybrid Speciation: Evidence from Ancient and Experimental Hybrids

The origin of a new diploid species by means of hybridization requires the successful merger of differentiated parental species' genomes. To study this process, the genomic composition of three experimentally synthesized hybrid lineages was compared with that of an ancient hybrid species. The genomic composition of the synthesized and ancient hybrids was concordant (rs = 0.68, P < 0.0001), indicating that selection to a large extent governs hybrid species formation. Further, nonrandom rates of introgression and significant associations among unlinked markers in each of the three synthesized hybrid lineages imply that interactions between coadapted parental species' genes constrain the genomic composition of hybrid species.     

Spatial Response of Mammals to Late Quaternary Environmental Fluctuations

Analyses of fossil mammal faunas from 2945 localities in the United States demonstrate that the geographic ranges of individual species shifted at different times, in different directions, and at different rates in response to late Quaternary environmental fluctuations. The geographic pattern of faunal provinces was similar for the late Pleistocene and late Holocene, but differing environmental gradients resulted in dissimilar species composition for these biogeographic regions. Modern community patterns emerged only in the last few thousand years, and many late Pleistocene communities do not have modern analogs. Faunal heterogeneity was greater in the late Pleistocene.     

Pulmonary mycobacteriosis caused by Mycobacterium intracellulare in a Tasmanian devil (Sarcophilus harrisii)

The health of captive Tasmanian devils (Sarcophilus harrisii) is currently of increased interest because wild populations are being decimated by the spread of devil facial tumour disease. This report describes the pathology of an aged captive Tasmanian devil that had a pulmonary mycobacterial infection caused by Mycobacterium intracellulare in addition to multiple neoplastic processes.     

An economic assessment of porcine parvovirus vaccination

SUMMARY A decision analysis model was designed to evaluate the cost effectiveness of a vaccination program for preventing endemic or epidemic porcine parvovirus (PPV) Induced reproductive failure in a 100-sow pig herd. The results showed that the cost of vaccination was less than the cost incurred by continuing endemic PPV infection, or the cost of a severe epidemic. A long term vaccination program is a cost effective method for controlling PPV-induced reproductive failure in pig herds suffering endemic and epidemic PPV infection.