Dr Richmond Loh

Thraustochytrids are heterotrophic protozoa that can be saprophytic, parasitic, or symbiotic. They have become increasingly important as a potential source of polyunsaturated fatty acids. This study describes the isolation and characterisation of a novel thraustochytrid isolate from the abalone Haliotis roei in Western Australia. Isolate W7B6 was propagated in vitro and characterised using optical and electron microscopy as well as phylogenetic analysis. This thraustochytrid exhibits characteristic cell types of the Thraustochytriaceae family, including small sporogenous cells, cysts, encysted amoebosporangia and amoebosporangia. The sequencing and phylogenetic analysis of the 18S rDNA sequence of the W7B6 isolate indicate its classification within the Monorhizochytrium clade, nested within the broader Aurantiochytrium super-clade. This study adds a new thraustochytrid strain that potentially has significance in the bio-production of long-chain fatty acids.

Veterinary fish practice is the newest AVMA-recognised veterinary specialty. This presentation explains the seven steps in veterinary fish disease investigation procedure, using case examples to demonstrate. It will cover aspects of water quality and fish nutrition and also fish euthanasia techniques, necropsy and sampling for laboratory testing (particularly for histology). It concludes with pointing attendees to further aquatic veterinary resources.

Learning objectives of this webinar:
1. Be familiar with the seven steps to investigate fish diseases.
2. Know how to analyse water quality.
3. Learn to assess fish nutrition.
4. Acceptable techniques to euthanase fish.
5. Fish necropsy and laboratory sampling techniques.
6. Fish veterinary resources.

This chapter presents an overview of the clinical signs and major disease syndromes affecting captive and wild invertebrates. This grouping includes all animal groups not in the subphylum Vertebrata. Covered in this chapter are the Porifera (sponges), coelenterates (jellyfish, anemones, corals – wild and in cultivation), mollusks (bivalves), gastropods (abalone), cephalopods, crustaceans, and urochordates.

Parasites such as skin flukes and gill flukes can be a problem for koi carp owners – particularly hobbyists – for a number of reasons. Although they can theoretically be treated with one application of medication, factors such as water quality, drug resistance and degradation of medications can make these parasites more diffcult to eradicate. Acetic acid can be used as a method of killing ectoparasites on fish, though traditionally this is performed by dipping the fish into the acid, not as a prolonged immersion. This case report concerns a hobbyists pond with a long-term skin fluke infestation and the treatment of the infestation by using household vinegar to acidify the water over a prolonged period.

Australia was previously believed to be free of enzootic swine influenza viruses due strict quarantine practices and use of biosecure breeding facilities. The first proven Australian outbreak of swine influenza occurred in Western Australian in 2012, revealing an unrecognized zoonotic risk, and a potential future pandemic threat. A public health investigation was undertaken to determine whether zoonotic infections had occurred and to reduce the risk of further transmission between humans and swine. A program of monitoring, testing, treatment, and vaccination was commenced, and a serosurvey of workers was also undertaken. No acute infections with the swine influenza viruses were detected. Serosurvey results were difficult to interpret due to previous influenza infections and past and current vaccinations. However, several workers had elevated haemagglutination inhibition (HI) antibody levels to the swine influenza viruses that could not be attributed to vaccination or infection with contemporaneous seasonal influenza A viruses. However, we lacked a suitable control population, so this was inconclusive. The experience was valuable in developing better protocols for managing outbreaks at the human–animal interface. Strict adherence to biosecurity practices, and ongoing monitoring of swine and their human contacts is important to mitigate pandemic risk. Strain specific serological assays would greatly assist in identifying zoonotic transmission.

The present study assessed the prevalence and morphology of Leucocytozoon podargii from wild tawny frogmouths (Podargus strigoides) in Western Australia (WA) and genetically characterised the cytochrome b gene (cyt b) of L. podargii in wild tawny frogmouths from WA and Queensland (QLD). The prevalence of L. podargii in wild tawny frogmouths from WA was 93.3% (14/15; 95% CI, 68.1–99.8%). The morphological characters of L. podargii from WA were similar to L. podargii from QLD: the gametocytes were round-oval shape, approximately 8–12 μm in diameter; the macrogametocytes were 12.4 μm in diameter; microgametocytes were 10.4 μm in diameter; and the ratio of macrogametocytes and microgametocytes was 3:2. Sequence analysis of partial cyt b gene fragments revealed that L. podargii sequences isolated from wild tawny frogmouths in WA shared the highest similarity (99.8% at nucleotide level and 100% at protein level) with L. podargii isolated from wild tawny frogmouths in QLD. The mitochondrial 18S rRNA gene of L. podargii gametocytes was quantified using droplet digital PCR (ddPCR), and the highest gametocyte load was detected in the lung. This finding corresponds to the results of the histological study. Based on the morphological and molecular studies, it was concluded that the Leucocytozoon parasite identified from wild tawny frogmouths in WA is consistent with L. podargii from wild tawny frogmouths in QLD, and the present study has genetically characterised two different L. podargii genotypes (QLD and WA) for the first time.

Global swine populations infected with influenza A viruses pose a persistent pandemic risk. With the exception of a few countries, our understanding of the genetic diversity of swine influenza viruses is limited, hampering control measures and pandemic risk assessment. Here we report the genomic characteristics and evolutionary history of influenza A viruses isolated in Australia from 2012 to 2016 from two geographically isolated swine populations in the states of Queensland and Western Australia. Phylogenetic analysis with an expansive human and swine influenza virus data set comprising >40,000 sequences sampled globally revealed evidence of the pervasive introduction and long-term establishment of gene segments derived from several human influenza viruses of past seasons, including the H1N1/1977, H1N1/1995, H3N2/1968, and H3N2/2003, and the H1N1 2009 pandemic (H1N1pdm09) influenza A viruses, and a genotype that contained gene segments derived from the past three pandemics (1968, reemerged 1977, and 2009). Of the six human-derived gene lineages, only one, comprising two viruses isolated in Queensland during 2012, was closely related to swine viruses detected from other regions, indicating a previously undetected circulation of Australian swine lineages for approximately 3 to 44 years. Although the date of introduction of these lineages into Australian swine populations could not be accurately ascertained, we found evidence of sustained transmission of two lineages in swine from 2012 to 2016. The continued detection of human-origin influenza virus lineages in swine over several decades with little or unpredictable antigenic drift indicates that isolated swine populations can act as antigenic archives of human influenza viruses, raising the risk of reemergence in humans when sufficient susceptible populations arise.

This is a study of vertebral deformities in ornamental koi based on computed radiography and skeletons cleaned by dermestid beetles (Dermestes maculatus). All koi developed gradual onset of swimming abnormalities as adults. Extensive intervertebral osteophyte formation correlated with age of fish and was associated with hindquarter paresis in one koi. Vertebral compression and fusion were the most common spinal deformities occurring at multiple sites, similar to findings in other farmed fish. Site-specific spinal deformities were thought to develop due to differences in swimming behaviour and rates of vertebral growth. One koi had offspring with spinal deformities. Spinal deformities are significant problems in both European and Australian food fish hatcheries. The heritability of vertebral deformities in farmed fish is reportedly low unless there is concurrent poor husbandry or nutritional deficiencies. The specific aetiologies for vertebral deformities in koi in this study could not be ascertained. Current knowledge on spinal deformities in the better studied European food fish species suggests multifactorial aetiologies. Future research should include prospective longitudinal studies of larger numbers of koi from hatch and consideration of all potential risk factors such as husbandry, nutrition, temperature, photoperiod and genetics.