A preliminary report on the awareness and knowledge of seafood-borne parasitic diseases among medical doctors in Australia

Despite the increasing popularity of seafood in Australia and various reports of infection with transmissible parasites in Australian edible aquatic animals such as fish, the number of reported cases of human infections in the country is low. This raised the question that Australian medical doctors may not be fully aware of the presence of these parasites in Australia, which in turn can lead to misdiagnosis of infections. This also may lead to an underestimation of the risk seafood-borne parasites may pose to public health. This preliminary study was conducted to determine the awareness and level of knowledge among Australian medical practitioners in New South Wales, the most populated and multicultural state in Australia, about seafood-borne parasitic diseases. Medical doctors, both general practitioners and gastroenterologists, were surveyed through an anonymous questionnaire (n = 376). Although the response rate was low at 11%, participants represented a diverse group in terms of gender, age, nationality and expertise. Despite several publications on occurrence of zoonotic parasites in Australian fish and other edible aquatic animals, and also in humans in the country, all respondents said no seafood-borne parasite had been reported as being seen within Australian or overseas practice. Although, due to low response rate, we are unable to confidently comment on the level of awareness, the findings of this study clearly suggest that further research is needed to investigate the extent of unawareness among Australian medical doctors about these highly important parasites and understanding the underlying issues in medical education that lead to the unawareness

Seafood-Borne Parasitic Diseases: A “One-Health” Approach Is Needed

Global consumption of seafood is steadily increasing, as is the variety of seafood, including dishes with raw or undercooked fish, leading to an increased risk of seafood-borne parasitic diseases. To address today’s challenges to understand the biology and ecology of these parasites in an ever-changing environment and to tackle their pathogenicity, multidisciplinary research is needed. In addition, the gap between research and stakeholders must be bridged to decrease the risk these parasites pose to public health. A “One-Health„ approach to research is necessary to ensure that consumers, aquatic animals, and environmental health questions are assessed in an integrated and holistic manner, resulting in a more comprehensive understanding of the issues associated with seafood-borne parasitic diseases and potential solutions. However, when it comes to seafood-borne parasitic diseases, there is limited guidance available for a “One-Health„ approach since these diseases can be less known. In this article, the focus is on parasitic diseases caused by seafood, which have been less studied even in some developed countries where seafood is popular. A brief overview of some of the seafood-borne parasitic diseases is provided followed by the significance of the awareness among various stakeholders in a country. In this article, it is argued that researchers and stakeholders are closely connected and a knowledge gap in one can result in a gap in knowledge and awareness in the other, causing an inability to accurately estimate the issues caused by these parasites. It is suggested that raising awareness, supporting research and training of all stakeholders are crucial for the prevention of seafood-borne parasitic diseases and the protection of the health of seafood consumers

Occurrence of Terranova larval types (Nematoda: Anisakidae) in Australian marine fish with comments on their specific identities

Pseudoterranovosis is a well-known human disease caused by anisakid larvae belonging to the genus Pseudoterranova. Human infection occurs after consuming infected fish. Hence the presence of Pseudoterranova larvae in the flesh of the fish can cause serious losses and problems for the seafood, fishing and fisheries industries. The accurate identification of Pseudoterranova larvae in fish is important, but challenging because the larval stages of a number of different genera, including Pseudoterranova, Terranova and Pulchrascaris, look similar and cannot be differentiated from each other using morphological criteria, hence they are all referred to as Terranova larval type. Given that Terranova larval types in seafood are not necessarily Pseudoterranova and may not be dangerous, the aim of the present study was to investigate the occurrence of Terranova larval types in Australian marine fish and to determine their specific identity. A total of 137 fish belonging to 45 species were examined. Terranova larval types were found in 13 species, some of which were popular edible fish in Australia. The sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2 respectively) of the Terranova larvae in the present study showed a high degree of similarity suggesting that they all belong to the same species. Due to the lack of a comparable sequence data of a well identified adult in the GenBank database the specific identity of Terranova larval type in the present study remains unknown. The sequence of the ITS regions of the Terranova larval type in the present study and those of Pseudoterranova spp. available in GenBank are significantly different, suggesting that larvae found in the present study do not belong to the genus Pseudoterranova, which is zoonotic. This study does not rule out the presence of Pseudoterranova larvae in Australian fish as Pseudoterranova decipiens E has been reported in adult form from seals in Antarctica and it is known that they have seasonal presence in Australian southern coasts. The genetic distinction of Terranova larval type in the present study from Pseudoterranova spp. along with the presence of more species of elasmobranchs in Australian waters (definitive hosts of Terranova spp. and Pulchrascaris spp.) than seals (definitive hosts of Pseudoterranova spp.) suggest that Terranova larval type in the present study belong to either genus Terranova or Pulchrascaris, which are not known to cause disease in humans. The present study provides essential information that could be helpful to identify Australian Terranova larval types in future studies. Examination and characterisation of further specimens, especially adults of Terranova and Pulchrascaris, is necessary to fully elucidate the identity of these larvae

A Critical Appraisal of Global Testing Protocols for Zoonotic Parasites in Imported Seafood Applied to Seafood Safety in Australia

It is not suggested that any country is intentionally exporting seafood which does not comply with Codex seafood-safety guidelines/codes/standards. However, with an open access resource such as fisheries, there is vast potential for errors to occur along convoluted supply chains, spanning multiple countries, which may negatively impact the safety of edible seafood products imported into Australia. Australian importation policy and inspection procedures are founded upon a bedrock of trust in the integrity, reliability and safety of the global seafood supply chain. In order for seafood imported to Australia to be considered safe the non-mandatory international health standards, governed by Codex Alimentarius, for seafood must be predicated upon the most efficacious methods and stringently governed by each exporting provenance. Currently, tests for zoonotic parasites are not applied to imported edible seafood products on arrival into Australia. Therefore, this critical analysis is aimed at discussing the effectiveness of current testing protocols for zoonotic parasites in edible seafood advised by Codex Alimentarius which may impact the safety of the product imported into Australia

Occurrence of Anisakis (Nematoda: Anisakidae) larvae in unusual hosts in Southern hemisphere

International audienc

Parasites in Imported Edible Fish and a Systematic Review of the Pathophysiology of Infection and the Potential Threat to Australian Native Aquatic Species

Previous research has shown that certain types of edible fish imported into Australia are infected with Euclinostomum/Isoparorchis digenetic trematodes. In the present study, imported Channa fish were examined for parasites which were then morphologically identified to the lowest taxonomic unit possible. Here we provide the first Australian report of Pallisentis sp. Van Cleave, 1928 (Prevalence (P) 35.9%) of family Quadrigyridae; Genarchopsis sp. Ozaki, 1925 (P. 16.5%), family Derogenidae and Senga sp. Dollfus, 1934 (P. 4.8%) in edible imported Channa fish (n = 103). Pallisentis sp. and Senga sp. have invasive hold fast organs which cause significant mechanical damage to fish intestinal structures and Euclinostomum/Isoparorchis cause severe pathology and loss of marketability in infected fish. These exotic parasites, if introduced into Australia, have the potential to negatively impact the health, fecundity, resilience and marketability of native and commercial fish species. Biosecurity is a constant ontogenesis of novel hypothesis based on current scientific discoveries. To further increase understanding of how parasitism impacts fish health, a systematic literature review was conducted and the pathophysiology of infection described. Potential exposure pathways and parasite host associations in Australia are discussed

Some adult and larval nematodes from fishes off New Caledonia

International audienceA collection of nematodes from the Muséum National d’Histoire Naturelle (National Museum of Natural History), Paris, France, was studied. The nematodes had previously been collected from a range of marine fish hosts. The aim of this study was to investigate the identity of these nematodes. Detailed body measurements of the nematodes were taken via light microscopy and where possible first and second internal transcribed spacers (ITS-1 and ITS-2) of ribosomal DNA were subjected to PCR, purified and sequenced. Six species and three larval types were found from a range of fish species and included 13 new host records and two new geographical records. Of the taxa found, Hysterothylacium kajikiae is the only species which may have zoonotic potential. The majority of host fish in this study are edible species, commercially and recreationally fished and frequently incorporated into the cuisine of New Caledonia as raw fish dishes. This study will allow better understanding of the diversity, life cycles, distribution and host-parasite relationships in the New Caledonia area

Occurrence of Anisakis spp. (Nematoda: Anisakidae) in a pygmy sperm whale Kogia breviceps (Cetacea: Kogiidae) in Australian waters

Little is known about parasitism in the pygmy sperm whale Kogia breviceps. Here, the occurrence of 3 anisakid species in a female pygmy sperm whale found stranded at Baxter's Beach, Australia, is reported, along with histopathological findings from this whale. Thirty-nine nematodes were submitted to the Parasitology Laboratory of Charles Sturt University for identification, where 37 of them were identified to species level as Anisakis berlandi (n = 13), A. brevi spiculata (n = 19), and A. paggiae (n = 5), using a combined molecular and morphological approach. This is the first report of A. paggiae in Australian waters. The other 2 specimens were Anisakis spp. females but could not be identified to species level due to a lack of taxonomically important features. ITS sequence data for these 2 specimens were considerably different from one another and from previously known Anisakis spp. The nomenclatures of the new species remain pending until male adults are found and described. The histopathological findings in the present study suggest that despite occurring in large numbers, Anisakis spp. do not have an adverse impact on the host's stomach; however, the damaged intestinal mucosa and floating eggs found during histopathological examination of the intestinal tissue suggest that these parasites can have an adverse impact on the host's intestine, which may lead to malnutrition and stress

Description of two new species of Diplectanum Diesing, 1858 (Monogenea: Diplectanidae) collected from Protonibea diacanthus (Lacepède, 1802) (Teleostei: Sciaenidae) from waters off northern Australia

Two new species of the family Diplectanidae Monticelli, 1903 from the gills of Protonibea diacanthus (Lacepède, 1802) (Teleostei: Sciaenidae) off the northern Australian coast are described. Previous studies have either morphological or genetic results, whereas this study combines morphological and advanced molecular methods to provide the first detailed descriptions for species of Diplectanum Diesing, 1858 from Australia utilising both methodologies. Two new species, Diplectanum timorcanthus n. sp. and Diplectanum diacanthi n. sp., are morphologically described and genetically characterised using the partial nuclear 28S ribosomal RNA gene (28S rRNA) and the internal transcribed spacer 1 (ITS1) partial sequence

Occurrence of tongue worm, Linguatula cf. serrata (Pentastomida: Linguatulidae) in wild canids and livestock in south-eastern Australia

Pentastomids are obligate zoonotic arthropod parasites utilising canids and vulpids as their definitive hosts and several herbivorous species as their intermediate hosts. Reported only 10 times in Australia over the last 150 years as incidental findings, adult Pentastomids referred to as Linguatula serrata have been encountered in nasal cavities of domestic and wild dogs, and foxes. Nymphs have been reported in cattle and rabbits. In the present study, a number of potential definitive hosts, including red foxes (Vulpes vulpes), wild dogs (Canis lupus dingo and C.l. dingo x C. familiaris) and feral cats (Felis catus), and intermediate hosts cattle (Bos taurus), sheep (Ovis aries), feral pigs (Sus scrofa), rabbits (Oryctolagus cuniculus), goats (Capra hircus) and a European hare (Lepus europaeus), from the highlands of south-eastern Australia were examined. Of the animals examined 67.6% of wild dogs (n = 37), 14.5% of red foxes (n = 55) and 4.3% of cattle (n = 164) were found to be infected with Pentastomids, herein identified as Linguatula cf. serrata. The common occurrence of the parasite in wild dogs and less frequently in foxes suggests these wild canids have potential to act as a reservoir for infection of livestock, wildlife, domestic dogs and possibly humans. The unexpected high frequency of the parasite in wild dogs and foxes in south-eastern Australia suggests the parasite is more common than previously realised. Of the potential intermediate hosts in the region, only 4.3% of cattle were found to be infected with pentastomid nymphs which suggest the search for the host(s) acting as the main intermediate host in the region should continue. Future studies should investigate transmission patterns, health impacts on hosts and whether the parasite has zoonotic significance in Australia. Keywords: Tongue worm, Australia, Linguatulidae, Pentastomid