Granulocytic anaplasmosis is a zoonotic disease that affects various domestic mammals (dogs, horses, and, more rarely, cats). In ruminants, it is better known as tick-borne fever (TBF) and is responsible for significant economic losses on European livestock farms, mainly due to a drop in milk production, abortions, and immunosuppression, which can lead to secondary infections. The disease is caused by the strictly intracellular bacterium Anaplasma phagocytophilum, whose biological vectors are ticks of the genus Ixodes. Other blood-feeding arthropods may be involved in transmitting this bacterium, notably Stomoxys calcitrans, a major ectoparasite of livestock that is implicated in transmitting other pathogens, including bacteria of the genus Anaplasma. This study aimed to evaluate the potential of S. calcitrans to act as a mechanical vector of A. phagocytophilum under laboratory conditions. Two experimental models were employed: one mimicking immediate transmission, and the other delayed transmission. In both models, A. phagocytophilum DNA and RNA were detected in S. calcitrans for the first time, but no traces of the bacterium’s DNA or RNA were found in the glass feeder’s blood. Further research is needed to confirm these findings through field studies investigating the presence of the bacterium in flies under natural conditions. This study also describes two original infection models of stable flies designed to reproduce their ex vivo blood-feeding, promoting alternative experimental approaches in accordance with animal welfare regulations and 4R principles.
Anaplasma phagocytophilum is an obligate intracellular tick-borne bacterium widely distributed across the northern hemisphere. It is the causative agent of tick-borne fever in ruminants and human granulocytic anaplasmosis. The epidemiology of A. phagocytophilum infection differs markedly between the USA and Europe. In the USA, human granulocytic anaplasmosis represents an increasing public health concern, whereas infections in ruminants are rarely reported. In contrast, in Europe only sporadic human cases have been described, while infections in ruminants cause significant economic losses. Previous genomic studies based on limited datasets suggested genetic divergence between USA and European strains, but the small number of available genomes, particularly from Europe, limited robust conclusions. In this study, we report 12 new European A. phagocytophilum genomes, including four human-derived genomes and eight genomes from cattle. Using a capture-based short-read sequencing approach, we doubled the number of publicly available European genomes. In addition, systematic quality assessment of these public assemblies revealed variable genome completeness and the presence of contamination in several genomes. After curation of these datasets and inclusion of our 12 new sequenced genomes, comparative genomic analyses were performed using phylogenetic and population genetic approaches. Our results confirm a marked genetic divergence between European and USA strains. Hence, the capture-based short-read sequencing can be performed on samples from naturally infected humans and ruminants to increase the representation of European genomes, particularly human isolates, confirming A. phagocytophilum population structure patterns previously inferred from limited gene-based and provide new potential genomic markers that may help identify lineages associated with zoonotic transmission.
Toxoplasma gondii is a cosmopolitan zoonotic parasite for which free-range poultry can act as sentinels of oocyst contamination. Romanian avian data on toxoplasmosis are limited to extensive systems and wildlife, while poultry seropositivity in intensive systems has not been previously characterized. In this study, 1940 domestic birds from intensive and extensive production systems were tested for T. gondii IgG antibodies by the Modified Agglutination Test (MAT). The descriptive dataset included data on 813 intensive broiler chickens and 1127 backyard birds. Backyard chickens had roughly twice the MAT seroprevalence of intensive broilers (31.2% vs. 14.1%, p < 0.001), rising to more than a tenfold difference at ≥1:48 (18.7% vs. 1.7%, p < 0.001). Seroprevalence varied among counties and farms, but intensive broilers were sampled in a very delimited area, so geographic and production-system patterns partly overlapped and should not be interpreted independently. In models adjusting for county and age, intensive production remained associated with lower odds of infection. These findings establish the first Romanian seroprevalence baseline for intensive poultry and support risk-based surveillance focused on backyard flocks and counties with high extensive-system prevalence.
Understanding the patterns and drivers of infectious disease dynamics at different levels of life organization is a fundamental disease ecology challenge. In this study, we performed a multi-infectious agents (IA) screening of 1,983 individuals belonging to 18 seabird species, sampled between 2017 and 2022 across five sub-Antarctic islands in the Southern Indian and Atlantic Oceans. Our aim was to identify the drivers of IA community in these seabirds by considering intrinsic and extrinsic factors on three dimensions: distance between seabird metapopulations and within-island sites, macro-community (host functional traits based on feeding and breeding features) and intra-host IA community composition. Samples were screened for 24 DNA-based IAs using a high-throughput real-time PCR method, followed by subsequent hierarchical modelling of species communities. Campylobacter lari , Escherichia coli, Pasteurella multocida, Chlamydiaceae and Mycobacterium spp. were found to be present on all islands in some, but not all, species. However, only E. coli was detected in all species. According to our modelling results, the influence of year and within-island site had limited influence on IA presence/absence, accounting respectively for an average of 1.0% and 1.8% of the variation in IA community. Including host species as a response variable produced a better model fit than including host species’ functional traits, highlighting the difficulty in simplifying systems by focusing on high-level functional categories. Model outputs show how each species influences IA distribution depending on IA traits, but no clear trend has emerged. Interestingly, burrowing species were less frequently infected with directly transmitted IAs, probably due to the low frequency of transmission events associated with their breeding features and limited social contacts. Our findings pave the way for further multi-dimension studies that would combine complementary approaches to disentangle the complex processes at play in the dynamics of hosts and IAs interactions.
Asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) are endogenous methylated arginine derivatives associated with endothelial dysfunction and tumour progression in humans. Their relevance in canine oncology remains unclear. This prospective study aimed to assess plasma concentrations of ADMA and SDMA in dogs newly diagnosed with large cell lymphoma or non-cutaneous hemangiosarcoma (HSA); dogs with benign splenic lesions were also enrolled. Renal function was assessed at the time of inclusion to exclude overt kidney disease. Plasma ADMA and SDMA concentrations were measured at diagnosis, and clinical staging data were collected. A total of 31 dogs were enrolled: 11 with lymphoma, 15 with HSA and 5 with benign splenic lesions. SDMA concentrations exceeded the reference interval in 47%, 36% and 0% of dogs with HSA, lymphoma and benign lesions, respectively. Dogs with lymphoma (p = 0.003) and HSA (p = 0.013) had significantly higher SDMA concentrations than dogs with benign splenic lesions. Moreover, dogs with presumed disseminated HSA had significantly higher SDMA concentrations than those without metastatic disease (median: 21.5 vs. 12 μg/dL; p = 0.012). In contrast, plasma ADMA concentrations did not differ significantly among groups (p = 0.39). These findings suggest that lymphoma and HSA may represent extra-renal causes of SDMA elevation in dogs, and that SDMA could have value as a biomarker of tumour burden or progression. The potential clinical utility of ADMA in canine cancer warrants further investigation.
