Biology subjects

Bonsergent, C.

Publications and source records attributed to Bonsergent, C..

5 recordsLinked to original sources

bioRxiv2025

Highly prevalent co-infections and genetic diversity of Anaplasma species in asymptomatic small ruminants in a Mediterranean context revealed by a gltA-based nested multiplex PCR assay

Anaplasmosis is a widespread tick-borne disease affecting various host species. Small ruminants (sheep and goats) can be infected by multiple Anaplasma species:. To evaluate the circulation and co-infection rates of five Anaplasma species (A. ovis, A. capra, A. bovis, A. marginale and A. phagocytophilum) in asymptomatic small ruminants in Corsica--a Mediterranean island of France--we designed a singleplex, duplex, and multiplex nested PCR (nPCR) scheme based on the gltA gene. Anaplasmosis was found to be highly endemic on the island, with 85.2% of the tested small ruminants infected by one or more Anaplasma species (82.8% of sheep and 89.5% of goats). We confirmed the presence of A. ovis and A. capra, and, for the first time in Corsica, detected A. bovis and A. phagocytophilum in both sheep (respective infection rates: 64.3%, 34.3%, 4.3%, and 7.1%) and goats (respective rates: 84.2%, 13.2%, 18.4%, and 5.3%). A. marginale was not detected. Approximately one-third of the infected animals were co-infected (35.1% of infected sheep and 32.4% of infected goats). A. ovis was always involved in co-infections, most often associated with A. capra (54.8% of co-infections). Importantly, A. bovis was never detected as a mono-infection in asymptomatic animals, but was always found associated with A. ovis (32.3% of co-infections). Sequence analysis of the gltA and 16S rRNA genes confirmed the species identification of all detected Anaplasma species. A probably new Anaplasma species was detected for the first time in Corsica using the 16S rRNA nPCR. Furthermore, we found several circulating A. phagocytophilum genetic variants. Sequence analysis of A. ovis 16S rRNA revealed a single SNP that delineates two sequence groups (Ao1goat and Ao2sheep), which were significantly linked to the host of origin. Additionally, two groups of A. bovis gltA sequences were identified (Ab1 and Ab2, with 87.4% sequence homology), forming two novel clades. While the Ab1 clade is closely related to the six previously described clades, the Ab2 clade formed a separate phylogenetic group that also contained isolates from Corsican symptomatic goats. In conclusion, Anaplasma species are highly prevalent in the small ruminant population of Corsica, confronted with a great diversity of co-infecting species and genetic variants.

microbiology↗

bioRxiv2025

Effects of host sex, age and behaviour on co-infection patterns in a wild ungulate

Recent zoonotic disease emergences reveal the importance of studying wildlife parasite communities. As wild hosts frequently harbour diverse parasite species, understanding the drivers of multiple infection patterns in free-ranging hosts is critical for elucidating the ecological and epidemiological dynamics of parasite communities. In this study, we analysed co-infection patterns in European roe deer (Capreolus capreolus) inhabiting a fragmented rural landscape in southwestern France. Using data from 130 GPS-tracked roe deer, we examined the influence of proximity to livestock, host activity levels, age, sex, and between-parasite interactions on the presence of 11 parasitic taxa. Hierarchical modelling of species communities (HMSC) revealed that proximity to livestock significantly increased the likelihood of infection with orofecally transmitted parasites (Toxoplasma gondii, gastrointestinal parasites). Sex and age were other key predictors, with males and juveniles exhibiting a higher frequency of parasite presence, likely influenced by hormonal and immune system differences. Activity levels showed distinct age-related effects, with higher activity levels being positively associated with increased parasite prevalence in yearlings, but not in adults. In contrast, parasite association patterns within individual hosts were weak, suggesting minimal interactions between parasite species. Our findings highlight the interplay between exposure and susceptibility in shaping co-infection patterns and underscore the value of hierarchical modelling approaches in multi-parasite systems. Key FindingsO_LIParasite communities, studied in 130 GPS monitored roe deer, revealed frequent co-infection. C_LIO_LIProximity to livestock increased the risk of infection by parasite taxa shared with domestic animals. C_LIO_LIFor several parasitic taxa, males and younger roe deer had a higher probability of infection. C_LIO_LIThe effect of host activity on parasite infection was dependent on roe deer age. C_LIO_LIOnly slight between-parasite interactions were detected within individual hosts. C_LI

ecology↗

bioRxiv2024

Equine piroplasmosis in different geographical areas in France: prevalence heterogeneity of asymptomatic carriers and low genetic diversity of Theileria equi and Babesia caballi

Equine piroplasmosis is a worldwide tick-borne disease caused by the protozoan parasites Theileria equi and Babesia caballi, with significant economic and sanitary consequences. It can also limit the export of infected horses to piroplasmosis-free countries. These two parasites are genetically variable, with greater diversity observed in T. equi. This variability can potentially impact diagnostic accuracy. Our study aimed to evaluate the frequency of asymptomatic carriers of these parasites in France and describe the circulating genotypes. We used a species-specific nested PCR protocol targeting the 18S small subunit (SSU) rRNA gene and subsequent amplicon sequencing on blood samples collected from 566 asymptomatic horses across four National Veterinary Schools. The carrier frequency varied considerably, ranging from 18.7% around Paris (central-north) to 56.1% around Lyon (southeast), with an overall prevalence of 38.3%. T. equi carriers were ten times more frequent (91.7%, 209/228 isolates) compared to B. caballi carriers (8.8%, 19/228 isolates). Notably, T. equi carrier frequency was significantly lower in the northern region (Ile de France) compared to the southeastern regions. Interestingly, a strong correlation was observed between the frequencies of asymptomatic carriers and reported cases of acute piroplasmosis across all four geographic areas. Neither gender (female, gelding, or stallion) nor horse age showed a significant effect on the frequency of asymptomatic carriers. In areas with the highest carrier frequency, a substantial proportion of horses (22.2% to 37.5%) carried T. equi before the age of three, indicating high infection pressure. Genotyping of 201 T. equi isolates revealed a predominance of genotype E (98%), with only a few isolates belonging to genotype A (2%). Notably, two of the four genotype A isolates were detected in horses originating from Spain. All 19 B. caballi isolates belonged to the most common genotype A of this species. The discussion section explores the link between these results, the tick distribution and abundance, and the frequency of detection of T. equi and B. caballi in febrile cases attributed to piroplasmosis.

microbiology↗

bioRxiv2023

Ornithodoros maritimus as a vector of Babesia sp. YLG in Yellow-legged gull (Larus michahellis) nests

Babesia sp. YLG has recently been described in Yellow-legged gull (Larus michahellis) chicks and belongs to the Peircei clade in the new classification of Piroplasms. Here, we studied Babesia sp. YLG vectorial transmission by ticks in the simplified environment of a single seabird breeding colony where the Yellow-legged gull is the sole vertebrate host, Ornithodoros maritimus (syn. Alectorobius maritimus) the sole tick species, and Babesia sp. YLG is the only blood parasite species detected in chicks of the colony. We collected ticks over four years, maintained certain individuals through moulting or oviposition, and dissected fresh ticks to isolate different organs and test for the presence of the parasite using molecular assays. We report the first strong evidence of a Piroplasmidae transmitted by a soft tick. Indeed, Babesia sp. YLG DNA was detected in the salivary glands of nymphs, females and males, a necessary organ to infect for transmission to a new vertebrate host. Parasite DNA was also found in tick ovaries, which could indicate possible transovarial transmission. Our detection of Babesia sp. YLG DNA in several male testes and in endospermatophores, and notably in a parasite-free female (uninfected ovaries and salivary glands), raise the interesting possibility of sexual transmission from infected males to uninfected females. Future work in this system will now need to focus on the degree to which the parasite can be maintained locally by ticks and the epidemiological consequences of infection for both O. maritimus and its avian host.

microbiology↗

bioRxiv2019

Invasive in the North: New latitudinal record for Argentine ants in Europe

Environmental niche models predict the presence of the invasive Argentine ant in north-western Europe, especially along all the French Atlantic coast. Yet, the species has never been observed North from the 45th parallel in Europe, suggesting either that current models are wrong or that Argentine ants are already spreading north inconspicuously. Here, we report a three-hectare wide colony of Argentine ants, detected in 2016 in Nantes, France, which is 300 km north of the former northern-most outdoor population of this species in Europe. COI sequencing revealed that the haplotype of this new colony is the same as the one found in the so-called Catalonian supercolony, which is distinct from the haplotype found over most of the species range in Europe. Our discovery confirms models predictions that Argentine ants can colonize north-western Europe and suggests that they might have already reached several other locations along the French Atlantic coast. Detection surveys should be conducted in order to assess Argentine ants invasion patterns in Western France, particularly in high introduction risk areas such as major cities and maritime ports.

ecology↗