Toxoplasma gondii is a protozoan parasite with a complex life cycle and a cosmopolitan host range. The asexual part of its life cycle can be perpetually sustained in a variety of intermediate hosts through a combination of carnivory and vertical transmission. However, T. gondii produces gametes only in felids after the predation of infected intermediate hosts. The parasite changes the behavior of its intermediate hosts by reducing their innate fear to cat odors and thereby plausibly increasing the probability that the definitive host will devour the infected host. Here, we provide a short description of such parasitic behavioral manipulation in laboratory rodents infected with T. gondii, along with a bird’s eye view of underpinning biological changes in the host. We also summarize critical gaps and opportunities for future research in this exciting research area with broad implications in the transdisciplinary study of host–parasite relationships. Graphical abstract

Equine gastrointestinal nematodes (GINs) have been the subject of intermittent studies in Australia over the past few decades. However, comprehensive information on the epidemiology of equine GINs, the efficacy of available anthelmintic drugs and the prevalence of anthelmintic resistance (AR) in Australasia is lacking. Herein, we have systematically reviewed existing knowledge on the horse GINs recorded in Australia, and main aspects of their pathogeneses, epidemiology, diagnoses, treatment and control. Six electronic databases were searched for publications on GINs of Australian horses that met our inclusion criteria for the systematic review. Subsets of publications were subjected to review epidemiology, diagnoses, pathogeneses, treatment and control of GINs of horses from Australia. A total of 51 articles published between 1950 to 2018 were included. The main GINs reported in Australian horses were cyathostomins (at least 28 species), Draschia megastoma, Habronema muscae, H. majus, Oxyuris equi, Parascaris equorum, Strongyloides westeri and Trichostrongylus axei across different climatic regions of Queensland, New South Wales, Victoria, and Western Australia. Nematodes are diagnosed based on the traditional McMaster egg counting technique, though molecular markers to characterise common GINs of equines were characterised in 1990s. The use of anthelmintic drugs remains the most widely-used strategy for controlling equine GIN parasites in Australia; however, the threshold of faecal egg count that should trigger treatment in horses, remains controversial. Furthermore, anthelmintic resistance within GIN population of horses is becoming a common problem in Australia. Although GINs infecting Australian horses have been the subject of occasional studies over the past few decades, the effective control of GIN infections is hampered by a generalised lack of knowledge in various disciplines of equine parasitology. Therefore, coordinated and focused research is required to fill our knowledge gaps in these areas to maximise equine health and minimise economic losses associated with the parasitic infections in Australia.

The contribution of abortions to the overall mortality of lambs born to maiden (primiparous) ewes in Australia remains unclear. This cohort study aimed to quantify abortion and lamb mortality for ewe lambs and maiden Merino two-tooth ewes. Lamb mortality from pregnancy scanning to marking were determined for 19 ewe lamb and 11 Merino two-tooth ewe flocks across southern Australia. Average lamb mortality from scanning to marking was 35.8% (range 14.3–71.1%) for the ewe lambs and 29.4% (range 19.7–52.7%) for the two-tooth ewes. Mid-pregnancy abortion was detected in 5.7% of ewes (range 0–50%) in the ewe lamb flocks and 0.9% of ewes (range 0–4.4%) in the two-tooth ewe flocks. Mid-pregnancy abortion affecting ≥2% of ewes was observed in 6/19 ewe lamb flocks and 2/11 two-tooth ewe flocks. Lamb mortality from birth to marking represented the greatest contributor to foetal and lamb mortality after scanning, but mid-pregnancy abortion was an important contributor to lamb mortality in some ewe lamb flocks. Variability between the flocks indicates scope to improve the overall reproductive performance for maiden ewes by reducing foetal and lamb losses. Addressing mid-pregnancy abortion may improve the reproductive performance in some flocks.

Recent concerns have arisen in Australia regarding detections of the exotic bacteriumEhrlichia caniswhich has resulted in ehrlichiosis outbreaks. In Australia, it is spread by the tropical brown dog tickRhipicephalus linnaei, formerlyRhipicephalus sanguineussensu lato tropical lineage. Previously, the tick has been recorded in South Australia in the Coober Pedy and the Oodnadatta areas. This study, which includes historical specimens data held in historical Australian arthropod collections, along with 10 sampled remote communities, confirms the wide distribution range of this species within the State.E. caniswas detected by PCR in the ticks. The percentage of dogs hosting PCR‐positive ticks increased from 2.8% (95% confidence interval [CI]: 0.3 to 9.7) in November–December 2020 to 62.9% (95% CI: 44.9 to 78.5) end of February 2021, initially in two then in seven Anangu Pitjantjatjara Yankunytjatjara lands communities in the far northern regions of South Australia. Our results suggest a rapid spread of the pathogen. No evidence ofE. caniswas found in nine regional communities. The extended tropical brown dog tick distribution indicates a greater area whereE. canismay occur and may require management to minimise the impacts of ehrlichiosis outbreaks. Without the implementation of effective detection and control programs, this extended distribution ofR. linnaeiis likely to result in the spread of the bacterium to other regions.

Reports of Dirofilaria immitis infection vary by location in the USA and Europe, with an occurrence gradient increasing towards the equator and warmer climates. In Australia, heartworm preventative guidelines are not climate specific, implying homogenous risk of infection across the continent. We systematically reviewed the published literature to assess if the distribution of D. immitis infection varies in Australia. We sourced 41 relevant publications by searching multiple bibliographic databases and the citations of key articles. From those, we extracted the data from a total of 106 individual surveys of variable size and quality. The reported prevalences ranged from 0.0 % to 100.0 % and we meta-analysed the observed heterogeneity using survey location's latitude, climate zone or temperature/humidity zone. Crude heterogeneity between surveys was partly explained (approximately 30 %) by temperature/humidity zone, and the quality of the surveys did not affect the proportional explanation of heterogeneity. There was significantly higher pooled prevalence in humid summer zones (18.7 %, 95 %CI: 10.9-30.1 %) compared to cool winter zones (2.1 %, 95 %CI: 1.0-4.3 %). Historical reports of D. immitis infection in Australia concur with the strong association to warmer climates observed in other continents. The current blanket recommendation for dirofilariosis preventative usage does not reflect the important variability of infection risk to canids across locations of Australia.