Are viruses associated with disc herniation? A clinical case series.

BACKGROUND: There is some limited evidence for the presence of viruses in herniated disc material including a previous case series that claimed to provide "unequivocal evidence of the presence of herpes virus DNA in intervertebral disc specimens of patients with lumbar disc herniation suggesting the potential role of herpes viruses as a contributing factor to the pathogenesis of degenerative disc disease". This study has not been replicated. The objective of our study was to determine if viruses were present in herniated disc fragments in participants with a prior history of back pain. METHODS: We recruited fifteen participants with a history of prior low-back pain prior to undergoing disc herniation surgery in the lumbar spine. Harvested disc samples were subject to next generation sequencing for detection of both RNA and DNA viral pathogens. Additionally, samples were analysed by a broadly reactive PCR targeting herpesviral DNA. Ethics approval was granted by the Human Research Ethics Committees of both Murdoch University, and St John of God Hospital, Western Australia. RESULTS: Of the fifteen research participants, 8 were female. Mean age was 49.4 years (SD 14.5 yrs) with a range of 24-70 years. All participants had prior back pain with mean time since first ever attack being 8.8 years (SD 8.8 yrs). No samples contained significant DNA sequences relating to known human viral agents. Inconsequential retroviral sequences were commonly found and were a mixture of putative animal and human retroviral protein coding segments. All samples were negative for herpesvirus DNA when analysed by pan-herpesvirus PCR. CONCLUSIONS: This study found no viral pathogens in any intervertebral disc fragments of patients who had previous back pain and underwent discectomy for disc herniation and thus it is unlikely that viruses are associated with disc herniation, however given the contradiction between key studies enhanced replication of this experiment is recommended.

Alphaherpesvirus-associated disease in greater bilbies (Macrotis lagotis).

CASE REPORT: A captive breeding colony of 9 greater bilbies (Macrotis lagotis) exhibited mild upper respiratory signs and sudden deaths with 100% mortality over a 2-week period. Histologically, acute necrotising and erosive epithelial lesions throughout the upper respiratory system and bronchi were associated with eosinophilic intranuclear inclusion bodies. Inclusions were also present in hepatocytes and adrenocortical cells, but were not always associated with necrosis. Transmission electron microscopy of lung sections revealed nucleocapsids forming arrays within some nuclei. A pan-herpesvirus PCR yielded a 440-bp product, with sequencing confirming homology with the alphaherpesviruses. Viral culture in a marsupial cell line resulted in cytopathic effect consistent with an alphaherpesvirus. CONCLUSION: This is the first report of a herpesvirus-associated disease in greater bilbies.

Avian influenza in Australia: a summary of 5 years of wild bird surveillance.

BACKGROUND: Avian influenza viruses (AIVs) are found worldwide in numerous bird species, causing significant disease in gallinaceous poultry and occasionally other species. Surveillance of wild bird reservoirs provides an opportunity to add to the understanding of the epidemiology of AIVs. METHODS: This study examined key findings from the National Avian Influenza Wild Bird Surveillance Program over a 5-year period (July 2007-June 2012), the main source of information on AIVs circulating in Australia. RESULTS: The overall proportion of birds that tested positive for influenza A via PCR was 1.9 ± 0.1%, with evidence of widespread exposure of Australian wild birds to most low pathogenic avian influenza (LPAI) subtypes (H1-13, H16). LPAI H5 subtypes were found to be dominant and widespread during this 5-year period. CONCLUSION: Given Australia's isolation, both geographically and ecologically, it is important for Australia not to assume that the epidemiology of AIV from other geographic regions applies here. Despite all previous highly pathogenic avian influenza outbreaks in Australian poultry being attributed to H7 subtypes, widespread detection of H5 subtypes in wild birds may represent an ongoing risk to the Australian poultry industry.

Porcine circovirus-associated disease in weaner pigs in Western Australia.

OBJECTIVE: To report the occurrence and pathology of porcine circovirus type 2 (PCV2)-associated disease (PCVAD) of postweaning pigs in two Australian pig herds. METHODS: Mortality data from two commercial piggeries that experienced higher than normal postweaning illthrift and mortalities were examined. Gross and histopathological examinations were performed on the index cases, and at weekly intervals thereafter for a period of 10 weeks. Specimens were submitted to the laboratory for routine diagnostic testing and for exclusion of porcine reproductive and respiratory syndrome virus (PRRSV). The genomes of two strains of PCV2 isolated during testing were sequenced. RESULTS: Mortality rates in weaned, 5-12-week-old pigs spiked significantly during mid to late 2007. This increase in the mortalities was mainly attributed to salmonella-associated diarrhoea and illthrift. Salmonellosis was diagnosed in 73/110 cases inclusive of both piggeries. Many pigs also had chronic granulomatous lymphadenitis and diffuse histiocytic interstitial pneumonia consistent with PCVAD and associated with varying amounts of PCV2 antigen and inclusion bodies. All samples tested for PRRSV were negative. Sequence analysis of the PCV2 isolates showed strain differences between piggeries. CONCLUSION: This report describes the first outbreaks of PCVAD in growing pigs in Western Australia (WA) and describes lesions not previously seen in this laboratory. It also describes the first isolation of a PCV2 group 1 virus in WA associated with PCVAD. Although the outbreaks of PCVAD occurred with concurrent salmonellosis, the two diseases were unrelated. Neither of the outbreaks met the Australian case definition for the diagnosis of postweaning multisystemic wasting syndrome.