Haemoprotozoan surveillance in peri-urban native and introduced wildlife from Australia

Tick-borne piroplasms and trypanosomes incidentally detected in eastern grey kangaroos (Macropus giganteus) during a mortality and morbidity event in southern New South Wales, Australia

Tick-borne haemoparasites, including piroplasms and trypanosomes, are almost ubiquitous in Australian wildlife, with some associated with health impacts to individual animals and declining wildlife populations. An array of ecologically distinct piroplasm and trypanosome species occur throughout Australia although many of these species and their sylvatic ecologies are poorly characterised. Between May 2022 and October 2023, an anecdotally reported localised eastern grey kangaroo (Macropus giganteus) morbidity/mortality event occurred in coastal southern New South Wales, Australia, characterised by animals presenting with blindness, emaciation, lethargy, ataxia, and astasia. Here we used molecular techniques to identify tick-borne piroplasms (Babesia and Theileria) and trypanosomes in affected animals. Blood (n = 89) and liver (n = 19) samples were collected after the humane euthanasia of wild animals due to welfare concerns, and brief notes on the animal's health were recorded. In total, 20 (22.5%) animals were infected with tick-borne haemoparasites, including a novel Theileria sp. nov. (14, 15.7%), Babesia macropus (2, 2.2%), Trypanosoma gilletti (5, 5.6%), and Trypanosoma vegrandis (1, 1.1%). Liver samples were also screened for Wallal and Warego viruses due to animals' blindness, but were negative. This is the first report of T. gilletti and T. vegrandis in eastern grey kangaroos, although they have been previously reported in high numbers in ticks which commonly parasites this host. The novel Theileria sp. was previously reported in questing Ixodes holocyclus and in ticks from an opportunistically collected eastern grey kangaroo and red-necked wallaby (Notamacropus rufogriseus). However, we show for the first time this Theileria sp. can occur widely in eastern grey kangaroos. Ultimately, this small study did not intend, and is not able to draw inference regarding the pathogenicity of these haemoparasites to eastern grey kangaroos and it is likely that other factors, such as chronic Phalaris grass toxicity, had a role in this localised mortality/morbidity event.

First report of Hepatozoon and Lankesterella spp. infections in wild rodents from Pakistan, and their potential impact on blood parameters and oxidative stress markers in vital organs

Pakistan is home to a rich rodent fauna, yet no investigations have been conducted on the presence of Haemogregarines in these animals, leaving their epidemiology and genetic diversity in this subtropical region unexplored. In this study, blood samples from four wild rodent species, Rattus (R.) rattus (n = 122), Mus (M.) musculus (n = 64), Rattus norvegicus (n = 57), and Dryomys nitedula (n = 1), were collected between May 2022 and July 2023 from three districts in Punjab and three in Khyber Pakhtunkhwa. PCR targeting a fragment of 600 base pairs from the 18 S rDNA gene revealed a 2.86% (7/244) prevalence of Haemogregarines in the rodents. DNA sequencing and BLAST analysis confirmed the presence of Hepatozoon spp. and Lankesterella spp. in the blood samples. Phylogenetic analysis indicated genetic diversity in the Pakistani sequences, which clustered with sequences found in reptiles, amphibians, birds, and mammals from various countries. The prevalence of the parasite varied among rodent species, with R. rattus showing the highest infection rate, followed by R. norvegicus and M. musculus. Female rodents were more frequently infected than males. Infected R. rattus exhibited significant disruptions in white blood cells, red blood cells, and platelet counts. Oxidative stress markers indicated elevated superoxide dismutase in the kidney, catalase in the heart, and malondialdehyde in the liver and lungs of infected rodents compared to uninfected ones. This study is an important contribution towards science as it the first report of Haemogregarines and Lankesterella spp. infections among Pakistani rodents.

Current Status of Trypanosoma grosi and Babesia microti in Small Mammals in the Republic of Korea

Small mammals, such as rodents and shrews, are natural reservoir hosts of zoonotic diseases, including parasitic protozoa. To assess the risk of rodent-borne parasitic protozoa in the Republic of Korea (ROK), this study investigated the status of parasitic protozoa, namely Trypanosoma, Babesia, and Theileria, in small mammals. In total, 331 blood samples from small mammals were analyzed for parasites using PCR and sequenced. Samples were positive for Trypanosoma grosi (23.9%; n = 79) and Babesia microti (10%; n = 33) but not Theileria. Small mammals from Seogwipo-si showed the highest infection rate of T. grosi (48.4%), while the highest B. microti infection rate was observed in those from Gangneung-si (25.6%). Sequence data revealed T. grosi to be of the AKHA strain. Phylogenetic analysis of B. microti revealed the US and Kobe genotypes. B. microti US-type-infected small mammals were detected throughout the country, but the Kobe type was only detected in Seogwipo-si. To our knowledge, this is the first nationwide survey that confirmed T. grosi and B. microti infections at the species level in small mammals in the ROK and identified the Kobe type of B. microti. These results provide valuable information for further molecular epidemiological studies on these parasites.

An invasive human commensal and a native marsupial maintain tick populations at the urban fringe

Ticks (Acari: Ixodidae) are major disease vectors globally making it increasingly important to understand how altered vertebrate communities in urban areas shape tick population dynamics. In urban landscapes of Australia, little is known about which native and introduced small mammals maintain tick populations preventing host-targeted tick management and leading to human-wildlife conflict. Here, we determined (1) larval, nymphal, and adult tick burdens on host species and potential drivers, (2) the number of ticks supported by the different host populations, and (3) the proportion of medically significant tick species feeding on the different host species in Northern Sydney. We counted 3551 ticks on 241 mammals at 15 sites and found that long-nosed bandicoots (Perameles nasuta) hosted more ticks of all life stages than other small mammals but introduced black rats (Rattus rattus) were more abundant at most sites (33%-100%) and therefore important in supporting larval and nymphal ticks in our study areas. Black rats and bandicoots hosted a greater proportion of medically significant tick species including Ixodes holocyclus than other hosts. Our results show that an introduced human commensal contributes to maintaining urban tick populations and suggests ticks could be managed by controlling rat populations on urban fringes.

Diagnostic Accuracy of an Indirect Enzyme Linked Immunosorbent Assay (iELISA) for Screening of Babesia bovis in Cattle from West Africa

The epidemiology of corresponding tick-borne diseases has changed as a result of the recent introduction of Rhipicephalus (Boophilus) microplus to West Africa. The current study aimed to assess the diagnostic performance of an indirect ELISA for the detection of Babesia bovis infection in cattle. In a cross-section study, using a Bayesian Latent Class Model and iELISA diagnostic test for cattle babesiosis due to Babesia bovis, accuracy has been assessed with RT-PCR as an imperfect reference test. A total of 766 cattle were tested. The optimal diagnostic performances were obtained with 5% percentage of positivity. Sensitivity and specificity were, respectively, 0.94 [Cr. I.: 0.85−0.99] and 0.89 [Cr. I.: 0.87−0.92]. Additional diagnostic characteristics revealed that the Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were 96.6% [Cr. I.: 92.7−100%] and 82.2% [Cr. I.: 72−93%]. Overall, this test well discriminates an infected status from an uninfected status considering the area under the ROC curve (AUC) which was 0.78 [Cr. I: 0.72−0.85] and a Diagnostic Odds Ratio (DOR) of 127.8 [Cr. I.: 10.43−1562.27]. The AUC was significantly higher than 0.5 (p < 10−5). In consequence, this serologic assay could be suitable in moderate to high prevalence assessments.

The Troublesome Ticks Research Protocol: Developing a Comprehensive, Multidiscipline Research Plan for Investigating Human Tick-Associated Disease in Australia

In Australia, there is a paucity of data about the extent and impact of zoonotic tick-related illnesses. Even less is understood about a multifaceted illness referred to as Debilitating Symptom Complexes Attributed to Ticks (DSCATT). Here, we describe a research plan for investigating the aetiology, pathophysiology, and clinical outcomes of human tick-associated disease in Australia. Our approach focuses on the transmission of potential pathogens and the immunological responses of the patient after a tick bite. The protocol is strengthened by prospective data collection, the recruitment of two external matched control groups, and sophisticated integrative data analysis which, collectively, will allow the robust demonstration of associations between a tick bite and the development of clinical and pathological abnormalities. Various laboratory analyses are performed including metagenomics to investigate the potential transmission of bacteria, protozoa and/or viruses during tick bite. In addition, multi-omics technology is applied to investigate links between host immune responses and potential infectious and non-infectious disease causations. Psychometric profiling is also used to investigate whether psychological attributes influence symptom development. This research will fill important knowledge gaps about tick-borne diseases. Ultimately, we hope the results will promote improved diagnostic outcomes, and inform the safe management and treatment of patients bitten by ticks in Australia.

Metatranscriptomic profiling reveals diverse tick-borne bacteria, protozoans and viruses in ticks and wildlife from Australia

Tick-borne zoonoses are emerging globally due to changes in climate and land use. While the zoonotic threats associated with ticks are well studied elsewhere, in Australia, the diversity of potentially zoonotic agents carried by ticks and their significance to human and animal health is not sufficiently understood. To this end, we used untargeted metatranscriptomics to audit the prokaryotic, eukaryotic and viral biomes of questing ticks and wildlife blood samples from two urban and rural sites in New South Wales, Australia. Ixodes holocyclus and Haemaphysalis bancrofti were the main tick species collected, and blood samples from Rattus rattus, Rattus fuscipes, Perameles nasuta and Trichosurus vulpecula were also collected and screened for tick-borne microorganisms using metatranscriptomics followed by conventional targeted PCR to identify important microbial taxa to the species level. Our analyses identified 32 unique tick-borne taxa, including 10 novel putative species. Overall, a wide range of tick-borne microorganisms were found in questing ticks including haemoprotozoa such as Babesia, Theileria, Hepatozoon and Trypanosoma spp., bacteria such as Borrelia, Rickettsia, Ehrlichia, Neoehrlichia and Anaplasma spp., and numerous viral taxa including Reoviridiae (including two coltiviruses) and a novel Flaviviridae-like jingmenvirus. Of note, a novel hard tick-borne relapsing fever Borrelia sp. was identified in questing H. bancrofti ticks which is closely related to, but distinct from, cervid-associated Borrelia spp. found throughout Asia. Notably, all tick-borne microorganisms were phylogenetically unique compared to their relatives found outside Australia, and no foreign tick-borne human pathogens such as Borrelia burgdorferi s.l. or Babesia microti were found. This work adds to the growing literature demonstrating that Australian ticks harbour a unique and endemic microbial fauna, including potentially zoonotic agents which should be further studied to determine their relative risk to human and animal health.