An unknown haemoparasite was detected on blood smears from two wild Leadbeater's possums brought into captivity for the purpose of joining the conservation breeding program. The parasite was identified as a novel apicomplexan using molecular techniques. Phylogenetic analyses grouped this parasite with other apicomplexans identified from Australian marsupials. Opportunistic and retrospective testing (PCR on blood or tissue and microscopic examination of blood smears) was undertaken on a total of 31 captive and wild individuals. Haemoparasites were detected in 44.4 % (95 % confidence interval [CI] 25.5-64.8) of blood smears and in 83.3 % (95 % CI 58.6-96.4) of blood and tissue samples tested by PCR. Duration in captivity at the time of testing was statistically significant, with decreasing odds of being PCR positive (OR = 0.95, 95 % CI 0.90-0.99; p = 0.043) and blood-smear positive (OR = 0.83, 95 % CI 0.69-0.99; p = 0.041) with increasing time (months) in captivity. A subset of animals that died was submitted for necropsy, but there was no histologic evidence of disease attributable to the haemoparasite identified. Given its apparent high prevalence in the population of Leadbeater's possum, without evidence of significant disease, this parasite is presumed to be endemic in this host species.

Cryptosporidium and Giardia are major causes of gastrointestinal illness globally. In Australia, cryptosporidiosis is nationally notifiable, yet molecular characterization is not routinely undertaken, limiting outbreak detection, source attribution, and zoonotic risk assessment. This limitation became apparent in 2024, when Australia experienced a 273% increase in cryptosporidiosis notifications, the third-highest rise globally. We conducted a molecular epidemiological investigation of Cryptosporidium and Giardia in fecal samples from humans with gastroenteritis in Victoria, Australia, between 2020 and 2024. Positive samples were sequenced using SSU and gp60 for Cryptosporidium and tpi for Giardia, and parasite load was estimated. Of the 2,330 samples tested, 225 were positive for Cryptosporidium and nine for Giardia. One Giardia sample was identified as sub-assemblage AI, two as AII, and six as assemblage B. Seven Cryptosporidium species and 24 subtypes were identified, including eight novel subtypes. Cryptosporidium hominis predominated (85%), followed by C. parvum and C. meleagridis. Six C. hominis subtypes were detected, three associated with 11 recreational water-linked outbreaks in 2024. Subtypes IaA12R3 and IeA11G3T3 were most frequent, in line with global trends; concordance analysis indicated that at least 52 additional cases were likely linked to outbreaks. Several C. parvum subtypes were identified, including two linked to childcare and camp outbreaks. Novel human-infective subtypes of C. occultus, C. fayeri, and C. meleagridis were also detected. These findings reveal extensive Cryptosporidium diversity in Victoria and highlight the value of molecular surveillance for resolving transmission pathways and informing public health responses.IMPORTANCECryptosporidium is a nationally notifiable pathogen in Australia, yet routine subtyping is not performed, limiting the detection of both outbreak-related and sporadic transmission and constraining source attribution. This study represents the first large-scale molecular surveillance of human Cryptosporidium and Giardia infections in southern Australia, including the first molecular epidemiological exploration of the marked increase in cryptosporidiosis observed in 2024. By integrating species, subtype, or assemblage information with epidemiological metadata, we demonstrate substantial Cryptosporidium lineage diversity in symptomatic patients, including multiple novel subtypes and zoonotic transmission. These findings demonstrate the critical value of molecular tools for uncovering hidden transmission, resolving pathways contributing to both sporadic disease and outbreak, and informing targeted public health responses. The findings provide a strong foundation for incorporating routine genotyping into national surveillance systems for parasitic eukaryotic enteropathogens, and the accompanying international comparison of case trends suggests broader transmission dynamics of significant public health relevance.

The control of parasitic nematodes of humans and animals remains heavily dependent on a limited number of anthelmintic drug classes, and resistance to major classes is now widespread. Although phenotypic screening readily identifies compounds that impair worm motility or development, the intrinsic biological processes underlying chemical sensitivity in parasitic nematodes remain poorly defined. Here, we identified a hit compound with a pyridyl scaffold from a phenotypic screen against the model parasitic nematode, Haemonchus contortus, and using structure–activity optimisation we generated a potent chemical probe, WEHI-684. To uncover protein networks associated with the mechanism of action, thermal proteome profiling and time-resolved quantitative proteomics interrogated WEHI-684-induced perturbations in H. contortus. Across larval and adult stages of this major parasite of livestock, proteome integral solubility alteration (PISA) profiling revealed reproducible alterations in proteins associated with cytoskeletal organisation and intracellular trafficking, including actin- and motor-related components. Complementary quantitative proteomics identified induction of an aspartyl protease and suppression of secretory CAP family proteins. Integrated analysis of these datasets supports a model in which chemical perturbation of cytoskeletal and trafficking proteins is associated with secondary modulation of proteolytic pathways, coinciding with rapid impairment of motility. These findings indicate that linked structural and proteolytic responses contribute to chemical sensitivity in H. contortus and demonstrate how integrative proteomics can resolve organism-level responses to chemical perturbation beyond single-target paradigms.

We report a case of Cryptosporidium sp. OTUi identified in a tourist from Denmark who recently traveled to Indonesia. Previous detections include a traveler from Australia returning from Bali, a bat from the Philippines, and a patient from Australia. On the basis of those findings, we believe zoonotic transmission is plausible.

Waterborne pathogens, particularly Cryptosporidium, pose a growing public-health risk in Australia and globally. Cryptosporidiosis notifications have increased markedly in recent years across multiple countries, driven by greater recreational water exposure, human mobility and climate variability. Climate change, including rising temperatures and extreme weather events, is expected to intensify transmission. Emerging drug resistance in some parasitic pathogens underscores the need for high-resolution surveillance. Despite its status as a nationally notifiable disease, cryptosporidiosis surveillance in Australia relies largely on conventional diagnostic methods that lack sufficient resolution for outbreak detection and source attribution. This Viewpoint examines the rationale for a national genomics-informatics platform integrating whole-genome sequencing, bioinformatics and analytics to modernise surveillance. Drawing on international experience, we outline how genomics can support outbreak tracking and transmission mapping. While bacterial and viral pathogen surveillance has advanced under national genomic initiatives, eukaryotic pathogens remain underrepresented. The proposed platform would leverage existing infrastructure to strengthen responses.

BACKGROUND:Swimming pool-related cryptosporidiosis outbreaks are a global issue disproportionately affecting young children. This study aimed to (1) quantify swimming pool outbreak detection timelines; (2) identify pathogen prevention and detection strategies from Australia, United Kingdom, United States, and World Health Organization guidelines for public swimming pools; and (3) review oocyst detection methods used in pool-related cryptosporidiosis investigations. METHODS:Literature searches of peer-reviewed databases, public health publications, and relevant government guideline repositories were conducted. The interval between pool contamination, outbreak detection, and disinfection was estimated using an average response scenario. A comparative analysis of pool guidelines was performed based on Cryptosporidium prevention and testing strategies. Efficacy of proactive and reactive testing was estimated using oocyst detection yields from global studies. RESULTS:There was an average delay of 27 days between pool contamination and disinfection, contributing to the persistence of outbreaks in swimming pools. Cryptosporidium prevention strategies varied and were inconsistent across jurisdictions. Proactive surveillance was discouraged in many jurisdictions based on financial cost, methodological gaps, and sampling biases. Oocyst detection data showed a proactive approach provides surveillance and prevalence metrics in aquatic facilities. CONCLUSIONS:Reliance on notification-based outbreak identification and existing contamination prevention guidelines appear insufficient to prevent and reduce outbreaks in public swimming pools. Barriers to proactive surveillance can be addressed by monitoring high-risk settings using existing methods alongside current mandatory microbiological surveillance already occurring in swimming pools. Earlier detection of contamination events would significantly reduce pool-associated cryptosporidiosis outbreaks locally and globally, and reduce the burden of gastroenteric disease in young children.

Freshwater snails play essential roles in the transmission of trematode parasites that affect humans, livestock and wildlife. Australia's freshwater ecosystems are increasingly influenced by non-native and potentially invasive snail species that may pose biosecurity challenges and alter parasite transmission dynamics. This study characterised the complete mitochondrial genomes for four non-native snail taxa established in Australia (Pseudosuccinea columella, Orientogalba viridis, Physa acuta and Planorbella sp.) and for Galba truncatula, a high-priority exotic species considered a potential invader. Using long-read sequencing and comparative analyses, 15 complete mitogenomes were assembled, annotated and compared across three families (Lymnaeidae, Physidae and Planorbidae). Genome sizes ranged from 13.7 to 14.3 kb and exhibited conserved gene organisation and marked A + T bias. Australian populations of P. columella, O. viridis and Ph. acuta showed very limited mitochondrial nucleotide variability, consistent with founder effects, demographic bottlenecks and self-fertilisation, in contrast to the marked divergence observed among lineages within Galba from European laboratory strains. Phylogenetic inference based on concatenated and single-gene (cytochrome c oxidase subunit 1, cox1) datasets confirmed well-resolved family-level relationships and revealed cryptic diversity within Galba. The mitogenomes defined here provide molecular references for future taxonomic studies, diagnostic assay development and environmental (e)DNA monitoring of freshwater snails. These genomic resources establish a basis for biosecurity preparedness and vector surveillance in Australia and contribute to a broader One Health approach by supporting early detection, accurate identification and risk assessment of trematode-transmitting snails in freshwater ecosystems.

Human activities are changing the natural world at an accelerating pace, and as a consequence exerting novel and often strong selection pressures on living organisms. For species with traits conferring huge inherent evolutionary potential, like parasites, the outcome may be rapid adaptive responses spanning multiple phenotypic traits. The rise of drug resistance in parasites of domesticated animals is well documented; however, rapid changes in other key parasite traits may go unnoticed. In this contribution to the Scientists' Warning series, we argue that parasites are capable of evolving quickly to meet the new pressures of the Anthropocene. After summarizing evidence demonstrating their ability to evolve quickly and the magnitude of the anthropogenic selection pressures they now face, we discuss the basic types of adaptive responses we might expect. Next, we propose methods to track rapid parasite evolution in real time, as well as possible approaches to either slow it down or mitigate its impact on animal production systems. Our aim is to raise awareness of this concerning but underappreciated phenomenon and appeal for greater research into rapid parasite evolution in the Anthropocene and its consequences.

The nematode parasites of Australasian macropodoid and vombatoid marsupials (kangaroos, wallabies and wombats) comprise a variety of endemic species, dominated by members of the superfamily Strongyloidea. Thus far, more than 300 species of strongyloid nematodes have been described from the gastrointestinal tracts of macropodoid (kangaroos, wallabies, rat-kangaroos and potoroos) and vombatoid (wombats) marsupials. These nematodes belong to the family Cloacinidae which is subdivided into two subfamilies, the Cloacininae and Phascolostrongylinae. This chapter reviews the historical and current understanding of their morphology, biology, ecology and recent advances in molecular phylogeny. Knowledge gaps in the systematics, phylogenetic relationships and evolutionary origins of the cloacinid nematodes and possible avenues for future research are also discussed.

Parasitic nematodes of the family Onchocercidae (superfamily Filarioidea) have evolved alongside vertebrate hosts for millions of years. While morphological methods have played a central role in identifying species, many taxa remain cryptic and are challenging to differentiate, complicating diagnosis and the understanding of their epidemiology. Among the clinically relevant genera are Onchocerca and Dirofilaria, the latter being responsible for illnesses such as heartworm disease in canines and rare zoonotic infections in humans. Despite advances in our knowledge of the canine heartworm (Dirofilaria immitis), substantial gaps remain regarding other Dirofilaria spp. and genotypes, and their impact on both animal and human health. In this study, we conducted the first known comprehensive morphological and molecular characterisation of a novel Dirofilaria sp., Dirofilaria asiatica sp. nov., from Canis lupus familiaris in Sri Lanka. This new species, genetically consistent with a previously identified novel genotype of Dirofilaria, initially found in humans in Hong Kong, was described using a combined morphological and molecular approach. The findings reveal that D. asiatica sp. nov. differs significantly from other known species, including D. repens and D. immitis, and might be responsible for the majority of zoonotic Dirofilaria infections in southern and southeastern Asia. Furthermore, the identification of cryptic Dirofilaria spp. in both canine and human hosts emphasises the importance of molecular tools for specific identification, particularly when morphological information is inadequate. This study provides insights into the taxonomy and zoonotic potential of D. asiatica sp. nov., as well as its relationship with related species of onchocercids. This combined morphological and molecular approach establishes a framework for future investigations of filarioid nematodes, with implications for improving diagnosis and understanding of their epidemiology in both veterinary and medical contexts.

Fasciola hepatica, the causative agent of fascioliasis in sheep and cattle, requires a compatible snail intermediate host to complete its life cycle. The aquatic larval stage of this parasite is well-adapted for host-finding, with chemotactic abilities that enable it to sense potential host biomolecules. The extent of intermediate host recognition, particularly at the species level, and the downstream correlation with successful attachment has not been explored. This study investigated the ability of F. hepatica miracidia to distinguish between native and invasive host and non-host freshwater snail species during the host-finding and host-attachment phases. Quantitative and qualitative measurements of miracidial behaviour were compared pre- and post-exposure with snail-conditioned water (SCW) from both native and invasive host snails (lymnaeids Austropeplea cf. brazieri and Pseudosuccinea columella) and non-host snails (the lymnaeid Bullastra lessoni and the physid Physa acuta). Miracidia were also exposed to live snails of each representative species to ascertain whether host-finding correlates with successful miracidial host-attachment. Miracidia displayed clear shifts in movement profiles post-exposure to SCW, with no qualitative or quantitative differences observed in the behavioural response to different snail species. When exposed to live snails, miracidia were more likely to attach to both host and non-host native species (A. cf. brazieri and B. lessoni) compared with invasive snail species (P. columella and P. acuta). Among invasive snails, miracidia had a higher rate of successful attachment with P. columella (host) than with P. acuta (non-host). The miracidia of F. hepatica exhibit analogous host-finding responses post-exposure to SCW, regardless of which snail species they are exposed to. Host-finding responses do not correlate with miracidial ability to attach to the snail tissue or with the established host status of the respective snail species. These results provide an insight into host-finding preferences of F. hepatica within the Australian context and lay an important foundation for further exploration into intermediate host–parasite interactions and their mechanisms of action.

In 2024, a 30-year-old female resident of Melbourne, Australia, with no past medical history presented to the Royal Melbourne Hospital. During an acute episode of diarrhoea, the patient passed part of a worm that she collected, placed in a jar, and presented to the emergency department. This occurred on the background of a history of travel to more than 30 countries in Europe, Asia and the Americas between 2013 and 2024 (Supporting Information, figure 1). She reported eating fermented Baltic Sea herring (surströmming) in Sweden and cured salmon (gravlax) in Norway in 2020, in addition to consuming fresh fish and other seafood (ceviche) in South America (2023), Japan (2013) and, potentially, in Australia. At the time of presentation, her symptoms of diarrhoea had resolved. The patient reported a history of intermittent right lower quadrant abdominal pain over a period of about seven years for which a cause had not been established. Laboratory investigations, including eosinophil count, were unremarkable. The macroscopic examination of the worm specimen (40 cm in length) revealed the segmented strobila of a tapeworm that was consistent with a pseudophyllidean cestode (Box 1, A).1 The segments (proglottids) were mature and gravid (ie, contained eggs); no scolex was found. Microscopic examination of operculated eggs expressed from individual segments were ovoid and about 70 μm × 40 μm in size (Box 1, B).1 Based on morphological features and morphometrics, the worm was proposed to be a species of Dibothriocephalus. (A) Worm specimen (40 cm × 1.5 cm) expelled from this patient during a bout of diarrhoea; each segment (proglottid ~3 mm × 15 mm) of this specimen had a centrally located uterus, a dark "zipper-like" pattern under the strobila and a ventrally located uterine pore/opening (arrow), consistent with a pseudophyllidean cestode, most commonly Dibothriocephalus spp. (B) Eggs expelled from a segment (via the uterine pore) were operculated (arrowhead) and ~ 70 × 40 μm in size. (C) Life cycle of Dibothriocephalus latus showing transmission (via the egg) from the piscivorous host (eg, human, dog, cat, seal, birds) to the first intermediate host — a crustacean (including copepod) — in which the first larval stage (procercoid) develops. The infected crustacean is ingested by the second intermediate host — a freshwater fish — in which the second larvae stage (plerocercoid) develops in tissues and can remain alive for the lifespan of the fish. The human and other piscivorous definitive hosts become infected by eating raw or undercooked fish; here, the adult worm can grow to a length of 25 m and produces eggs within four to six weeks.1 To refine the identification, genetic analysis of genomic DNA isolated from this specimen2 was undertaken by polymerase chain reaction-based sequencing of part of the mitochondrial gene cytochrome c oxidase subunit 1 (cox1) (Supporting Information, appendix 1). A phylogenetic analysis of the sequence obtained here (accession No. PP474259) and 31 other representative cox1 sequences revealed that the sequence (PP474259) clustered with, and was identical to, cox1 sequences derived from individual specimens of Dibothriocephalus latus from Chile and Switzerland. These sequences all clustered, with strong nodal support (97–100%), with other cox1 sequences from other D. latus specimens from Europe and South America (Box 2). * GenBank accession numbers indicated on the tree constructed using the neighbour-joining distance method.2 Nodal support is given in bootstrap percentages. Members of the genus Taenia were used as outgroups. Following the diagnosis of diphyllobothriasis, the patient received a single dose (10 mg/kg) of praziquantel, and further tapeworm segments were reported by the patient to have been expelled within two days. Although up to 40% of patients with D. latus infection can develop B12 deficiency,1 no abnormality was seen in this case. Following treatment, the patient experienced clinical improvement. One month after praziquantel treatment, a faecal examination showed no evidence of Dibothriocephalus or other worm eggs. D. latus (fish or broad tapeworm), previously Diphyllobothrium latum, and related species are the largest tapeworms infecting humans and can grow up to 25 m in length.1 Although most people infected are asymptomatic, about 20% experience diarrhoea and abdominal pain.1 Rare complications include intestinal obstruction from massive infection and biliary obstruction caused by migrating proglottids.1 D. latus has an aquatic life cycle (Box 1, C) involving small crustacean copepods as a first intermediate host, subsequently ingested by a freshwater fish as the second intermediate host. The second larval (plerocercoid) stage develops in the tissue of the infected fish; thus, piscivorous animals, including humans, become infected by eating raw or undercooked fish. The parasite does not survive cooking, freezing or curing when adequately performed.1, 3, 4 Infection with this species is usually acquired in endemic countries of the Northern Hemisphere (Asia, Europe and North America).1 Imported cases, which shed large numbers of eggs in stool, pose a risk of introduction into non-endemic regions, especially those with poor sanitary infrastructure.1 This has been demonstrated for D. latus in South America, likely through introduction from Europe.5, 6 D. latus is not known to be endemic in Australian waters, but cases of infection could still occur in Australia through the consumption of fish imported from countries where D. latus is endemic. Autochthonous infection from Australian fish with other pseudophyllidean cestodes remains very rarely reported,7 though potentially underappreciated.4, 8 Accurate identification supports better understanding of geographical distribution, host preferences, and impacts on human health and the fish industry. Phylogenetic determination of whether this patient acquired their infection from Europe or South America was not possible. However, the epidemiological risk, symptomatology, and molecular findings favour acquisition from raw fish consumption infected with tapeworms closely related to those found in Nordic Europe. Timely diagnosis and treatment of human cases is central to preventing the potential for D. latus to become established in a non-endemic country or region. In many high income countries (including Australia), the awareness and diagnostic expertise regarding zoonotic fish parasites are lacking among medical and laboratory practitioners.8, 9 Infection risk of zoonotic fish-borne pathogens, such as D. latus, can be influenced by converging factors, such as changes in climate and water temperatures, potentially leading to alterations in the geographical range of parasites, global demand on diminishing fish stocks, use of aquaculture associated with risk of parasite introduction or spread, and global mobility of infected people and fish worldwide. Dietary habits linked to the consumption of raw and undercooked fish and a lack of standardised food inspection, storage and processes are additional contributing factors.1, 3, 4 The patient gave written consent for publication. The molecular work performed at the laboratory of the University of Melbourne Veterinary School was funded through a grant from the Australian Research Council (LP220200614 to RBG). No specific funding for this study was provided. No relevant disclosures. Not commissioned; externally peer reviewed. Supplementary figure Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Species of Austropeplea are lymnaeid snails endemic to Australia and New Zealand, and most are intermediate hosts of parasitic trematodes. Their taxonomy has long been uncertain due to the high phenotypic plasticity of most species. In this study, we used Oxford Nanopore sequencing technology to characterise the mitogenome and nuclear ribosomal RNA (rRNA) gene cluster of Austropeplea subaquatilis from South Australia to support comparative taxonomic investigations of this species. Then, A. subaquatilis was compared with A. cf. brazieri at both morphological and molecular levels. Morphologically, A. subaquatilis and A. cf. brazieri can be distinguished by shell morphometric indices, mantle edge morphology, pigmentation, and reproductive and neural anatomy. The two taxa differed by 1.9% in both the mitogenome and nuclear rRNA gene cluster. Sequence divergence was pronounced in the internal transcribed spacer (ITS) regions of the latter gene cluster, with nucleotide differences of 13.8% in ITS1 and 8.2% in ITS2. Phylogenetic analyses of sequence data for the mitochondrial 16S gene and ITS2 placed the two taxa in distinct groups. Taken together, the integrative evidence presented herein supported species-level divergence between A. subaquatilis and A. cf. brazieri.

BACKGROUND:Cutaneous myiasis is an ectoparasitic disease caused by fly larvae. In non-endemic regions it is rare, often unfamiliar to clinicians and readily misdiagnosed. CASE PRESENTATION:A 24-year-old Serbian traveller developed painful furuncular lesions on the thigh after returning from Kenya. The lesions were initially treated as insect bites with intramuscular corticosteroid, antihistamines and topical betamethasone-gentamicin. Spontaneous expulsion of a larva led to the recognition of myiasis. METHODS AND RESULTS:Three third-instar (L3) larvae were surgically removed. Morphological features and mitochondrial cox1 sequencing identified Cordylobia anthropophaga. Genetic analysis confirmed 99 % identity with reference sequences. CONCLUSION:This case highlights the challenges associated with diagnosis of furuncular myiasis in travellers. Awareness of travel history, maintenance of clinical suspicion and molecular analysis are essential for accurate diagnosis. Timely larval removal and prophylactic antibiotics minimise complications and improve outcomes.

Dirofilaria asiatica is a recently described filarioid nematode of zoonotic importance whose biology, host interactions and epidemiology are largely unknown. Here, we present the first chromosome-scale nuclear genome for this species, assembled from long-read PacBio and short-read Hi-C (high-throughput chromosome conformation capture) sequence data derived from adult specimens. The resulting 91.9 Mb genome comprises four autosomes and one sex-linked scaffold and encodes 9658 protein-coding genes with a high level of completeness. Comparative genomic analyses with Dirofilaria immitis, Brugia malayi and Onchocerca volvulus revealed both conserved chromosomal synteny and lineage-specific rearrangements. We identified 881 predicted excretory/secretory (ES) proteins, with a marked enrichment in immune-relevant pathways, including proteolysis, lysosomal activity and antigen presentation. Notably, 229 (∼26 %) of these ES proteins were unique to D. asiatica, many of which are implicated in host-parasite interactions, immune evasion and metabolic adaptation in the mammalian host. Proteins such as cystatins, serpins, venom allergen-like (VAL) proteins and cytokine-mimics suggest specialised immunomodulatory capacities distinct from those of other filarioids. The genome of D. asiatica fills a significant gap in filarial genomics and provides a foundational resource for future studies into host adaptation, molecular epidemiology, and the development of improved diagnostics and interventions, with direct relevance to a One Health approach for monitoring and controlling filarioid infections at the human-animal-vector interface.

Cryptosporidium and Giardia are major causes of gastrointestinal illness globally. In Australia, cryptosporidiosis is a nationally notifiable disease, yet molecular characterisation of clinical cases is rarely performed, limiting the capacity to identify outbreaks, trace sources and assess zoonotic risk. During 2024 there was a 273% cases increase in Australia, the third country with the highest increase. We present the first comprehensive molecular investigation of human Cryptosporidium and Giardia infections in the state of Victoria, Australia. We analysed faecal samples collected between 2018 and 2024. Positive samples were subtyped and parasite load was estimated. Of the 2,330 samples tested, 225 were positive for Cryptosporidium and nine for Giardia . Seven Cryptosporidium species and 24 subtypes were identified, including multiple novel or regionally unique subtypes. C. hominis was the predominant species (85%), and three subtypes associated with 11 recreational water outbreaks in 2024. Based on spatiotemporal overlap and subtypes, 52 cases were inferred to represent undetected outbreak-associated infections. Several C. parvum subtypes reflected probable zoonotic transmission, two subtypes were associated with a childcare and camp outbreak. Six C. hominis subtypes and eight subtypes overall were reported for the first time in Australia. Globally novel subtypes of C. occultus , C. fayeri and C. meleagridis in human hosts is reported. The study reveals high diversity of Cryptosporidium subtypes in human infections in Victoria. This study demonstrates the potential for molecular surveillance to inform public health interventions when integrated with epidemiological data. These findings support One Health approaches to outbreak detection and source attribution. IMPORTANCE Cryptosporidium is a nationally notifiable pathogen in Australia, yet routine genotyping is not performed, limiting outbreak detection and source attribution. This study represents the first large-scale molecular surveillance of human Cryptosporidium and Giardia infections in southern Australia. By integrating species- and subtype-level typing with epidemiological metadata, we demonstrate the substantial diversity of infective lineages, including several novel or zoonotic genotypes. Our findings highlight the critical role of molecular tools in tracking transmission pathways, supporting outbreak investigation and informing public health responses. These data provide a foundation for incorporating routine genotyping into national surveillance strategies for parasitic enteropathogens. This study presents the first epidemiological study of the 2024 outbreaks in Australia. The global comparison of cases during this period also highlights potential large-scale disease dynamic of public health importance.

This study presents findings from a 15-year longitudinal surveillance program (2009–2024) monitoring Cryptosporidium and Giardia in protected drinking water catchments in Melbourne and environs in the State of Victoria, Australia. As one of the few major cities worldwide sourcing largely unfiltered water from forested catchments, Melbourne presents a unique opportunity to assess the occurrence and prevalence of protozoan parasites in a minimally disturbed ecosystem. A total of 14,960 animal faecal samples were analysed using polymerase chain reaction (PCR)-based sequencing, including 8695 samples collected over the past 9 years. Cryptosporidium was detected in 3.15

Poor long-term survival (Mean = 2.16 y; 95% CI 1.68-2.65) was identified in a captive population of thorny devils (Moloch horridus) held at the Alice Springs Desert Park in the Northern Territory, Australia, over a period of 27 years. There was no significant difference in survival time (after acquisition) of wild-caught individuals compared captive born animals, or males compared to females. Limited information was available regarding the cause(s) of death for animals found dead or euthanased. Health of the live population at the time of the study (n = 14) was assessed by clinical history review, physical examination, and faecal examination. Large numbers of coccidian oocysts measuring 20-24 mu m in diameter were identified upon faecal examination. Molecular investigation of genomic DNA from these samples identified Isospora amphiboluri based on the sequences of partial regions of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) and the nuclear small subunit of ribosomal RNA gene (SSU). Isospora amphiboluri was originally described from the bearded dragon (Pogona barbata) and has since been recorded in the inland bearded dragon (Pogona vitticeps) and the central netted dragon (Ctenophorus nuchalis). The present case expands the host range for I. amphiboluri. Histological examination of tissues was not available, and therefore the potential role of I. amphiboluri in morbidity and mortality of M. horridus is not clear. Further research is required to understand if colonization with I. amphiboluri is pathogenic in this species.