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Equine piroplasmosis is a worldwide tick-borne disease caused by the parasites Theileria equi sensu lato and Babesia caballi, with significant economic and sanitary consequences. These two parasites are genetically variable, with a potential impact on diagnostic accuracy. Our study aimed to evaluate the frequency of asymptomatic carriers of these parasites in France and describe the circulating genotypes. We developed a species-specific nested PCR protocol targeting the 18S small sub-unit (SSU) rRNA gene and used it on blood samples collected from 566 asymptomatic horses across four National Veterinary Schools. The carrier frequency varied from 18.7 % around Paris (central-north) to 56.1 % around Lyon (southeast), with an overall prevalence of 38.3 %. Theileria equi carriers were ten times more frequent (91.7 %; 209/228 isolates) compared to B. caballi carriers (8.3 %; 19/228 isolates). Notably, T. equi carrier frequency was significantly lower in the northern region (Ile de France) compared to the southeastern regions. A positive relationship was observed between the frequencies of asymptomatic carriers and the frequency of previous acute piroplasmosis reported from the owner across all four geographic areas. Neither horse gender nor age showed a significant effect on the frequency of asymptomatic carriers. In some areas, a substantial proportion of horses (22.2 % to 37.5 %) carried T. equi before the age of three years, indicating high infection pressure. Genotyping of 201 T. equi isolates revealed a predominance of genotype E (98 %) and few isolates belonging to genotype A (2 %). Notably, two of the four T. equi genotype A isolates were detected in horses originating from Spain. All 19 B. caballi isolates belonged to the genotype A. 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., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024. Published by Elsevier GmbH.)

Cervids are known to be reservoirs of zoonotic bacteria transmitted by ticks. This study aimed to identify the Anaplasma species carried by captive red deer and swamp deer in a wild fauna reserve in France. Blood from 59 red deer and 7 swamp deer was collected and analyzed over a period of two years. A semi-nested PCR targeting the 23S rRNA was performed to detect and characterize Anaplasma spp. and determine the presence of zoonotic species. Anaplasma phagocytophilum was identified in 14/59 red deer (23.7%) but it was not identified in any of the swamp deer (7 animals). Three sequences could not be assigned to any particular species based on the 23S rRNA sequences. Complementary nested PCR targeting 16S rRNA, gltA and groEL genes and sequencing analysis then identified these sequences as a recently reported zoonotic species, Anaplasma capra; this species was found in 2 red deer (Cervus elaphus) and 1 swamp deer (Rucervus duvaucelii). This is the first report of the tick-borne zoonotic bacterium A. capra in France, a species otherwise described only in China, Japan, Malaysia and South Korea in goats, sheep, deer, cattle and Japanese serows (Capricornis crispus). While this bacterium may have been introduced into the reserve by infected imported animals, its local epidemiological cycle via tick transmission seems possible as locally born deer were found infected. Diagnostic methods, especially molecular ones, should take into account the potential infection of animals and humans with this species., Competing Interests: The authors have declared that no competing interests exist.

Background: Anaplasma phagocytophilum is a tick-transmitted Gram-negative obligate intracellular bacterium able to infect a wide variety of wild and domestic animals worldwide. Based on the genetic diversity observed with different molecular markers, several host-specific lineages have been identified. Roe deer is one of the most important reservoirs of this bacterium and hosts different genetic groups sometimes found on domestic animals. We therefore developed an ankA cluster-specific nested PCR (nPCR) to evaluate the prevalence of the three different ankA genetic groups described in roe deer (clusters II, III and IV) at three locations in France and the level of co-infections., Results: The specificity of the three nPCRs was assessed by partially sequencing 35 amplicons of ankA genes obtained from the different nested PCRs. All three genetic lineages were detected in roe deer from all three geographical locations. Of the infected deer population, 60.7% were co-infected by two or three different genetic variants. Co-infections varied from 42.9 to 70.6% of the infected population depending on the local infection prevalences (from 33.3 to 73.9%). All types of mixed infections occurred, suggesting the absence of a strict variant exclusion by another variant., Conclusions: Mixed infections by two or three genetic variants of A. phagocytopilum are a common feature in roe deer. Genetic variants (cluster IV) also found in domestic ruminants (cattle and sheep) were present in all the roe deer populations analyzed, suggesting a shared epidemiological cycle.