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Plague, a zoonosis caused by Yersinia pestis, is endemic in Madagascar but knowledge on the epidemiological situation in the northern focus remains unclear. The aim of this study was to investigate the circulation of Y. pestis in terrestrial small mammals in north eastern Madagascar, where suspected plague outbreaks have been reported. Sampling of terrestrial small mammals and their fleas was carried out in 22 trapping sites within 9 localities of the two sectors (1 and 3) of Makira Natural Park (MNP) and surroundings, from 2020 to 2022. Yersinia pestis was investigated in terrestrial small mammal spleen samples and their fleas using bacteriological, serological and molecular methods. A total of 614 terrestrial small mammals composed of eight species and 1,754 individual fleas were collected following 4,880 trap-nights. The black rat (Rattus rattus) represented the majority (87.8%) of the small mammal species caught. Flea infestation rate was higher in sector 3 compared to sector 1. In sector 3, Xenopsylla brasiliensis, a plague vector, represented 66.4% of fleas identified. Further, one plague seropositive R. rattus individual, captured inside a house, and one Ctenocephalides felis specimen, collected on another R. rattus, was positive on PCR in this sector. Despite low detection rates, we confirmed the circulation of Y. pestis in our study area (one rat seropositive and one flea PCR positive) and highlight the risk of potential human transmission. Our results also suggest that R. rattus contributes to the maintenance and transmission of plague in MNP, as described for other areas in Madagascar. Further, these findings contribute to documentation of the known geographic distribution of the endemic plague vector S. fonquerniei and X. brasiliensis. The confirmation of the circulation of the Y. pestis through serological and molecular diagnostics in small mammals and fleas underscores the urgent need to assess awareness levels of risk factors and symptoms to monitor among local communities and health workers and ensure that trained rapid response teams are prepared to intervene promptly upon suspect case detection. The risk and epidemiology of plague circulation in remote rural areas of Madagascar remains insufficiently studied. Addressing this gap is crucial, as a more comprehensive understanding of the distribution and dynamics of the wild animal hosts, their vectors and host-vector interactions will enhance risk assessment and prevention for plague emergence and improve mitigation and early control of potential outbreaks.

The origin of Yersinia pestis and the early stages of its evolution are fundamental subjects of investigation given its high virulence and mortality that resulted from past pandemics. Although the earliest evidence of Y. pestis infections in humans has been identified in Late Neolithic/Bronze Age Eurasia (LNBA 5000–3500y BP), these strains lack key genetic components required for flea adaptation, thus making their mode of transmission and disease presentation in humans unclear. Here, we reconstruct ancient Y. pestis genomes from individuals associated with the Late Bronze Age period (~3800 BP) in the Samara region of modern-day Russia. We show clear distinctions between our new strains and the LNBA lineage, and suggest that the full ability for flea-mediated transmission causing bubonic plague evolved more than 1000 years earlier than previously suggested. Finally, we propose that several Y. pestis lineages were established during the Bronze Age, some of which persist to the present day. Yersinia pestis has caused infections (plague) in humans since the Early Bronze Age (5000 years ago). Here, Spyrou et al. reconstruct Y. pestis genomes from Late Bronze Age individuals, and find genomic evidence compatible with flea-mediated transmission causing bubonic plague.

The functional diversity structure of a community can be represented as a combination of three additive components (species dominance D, functional redundancy R, and functional diversity Q) (DRQ approach in which different facets of functional differences between species are considered simultaneously). We applied this concept to assemblages of fleas and gamasid mites parasitic on small mammals at continental (across regions of the Palearctic) and regional (across sampling sites in Slovakia) scales and asked: What are the relative effects of host species, biome/habitat type, and geographic locality on the DRQ composition of a parasite assemblage? At the continental scale, regions were partitioned according to predominant biome or geographic position in a continental section. At the regional scale, sampling sites were partitioned according to habitat type or geographic locality. We tested for differences in the functional diversity structure (measured as the DRQ composition) of an ectoparasite assemblage (a) within a host species between biomes/habitat types or continental sections/localities and (b) between host species within a biome/habitat type or a continental section/locality. At both scales, the functional diversity structure of both flea and mite assemblages differed mainly between host species within a biome/habitat or geographic regions/locations, whereas differences in the DRQ composition between biomes/habitats or geographic regions/locations were only detected in a few host species. We compare our results with the results of earlier studies and conclude that the DRQ approach has an advantage over a single diversity metric and allows a better understanding of spatial variation in different facets of ectoparasite diversity.

Murine typhus, a fleaborne bacterial disease caused by Rickettsia typhi, has reemerged and spread in the United States. We tested spinosad, an oral flea preventive, in opossum flea reservoirs. Spinosad killed 98% of fleas infesting opossums. Oral preventives could control fleas in host species and curb murine typhus spread to humans.

Parasite species interactions, host biology traits, and external environmental factors can drive co-occurrence patterns between parasite species. We investigated co-occurrence patterns between three ectoparasite species (mite ( Neotrombicula harperi ), and fleas ( Orchopeas caedens and Ceratophyllus vison )) of North American red squirrels ( Tamiasciurus hudsonicus ). We evaluated (1) whether ectoparasites of red squirrels exhibit non-random co-occurrence patterns, and (2) the contribution of host and external environmental factors to parasite co-occurrence. Bayesian ordination and regression analysis (boral) revealed random associations between parasite species pairs when accounting for host and external environmental factors. However, the mite N. harperi exhibited a negative association with the flea O. caedens and positive association with the flea C. vison linked to temporal patterns of occurrence. Our data suggests that parasites of the investigated population of red squirrels tend to form associations based on temporal trends in infestation rather than species interactions. Further experimentation should investigate the role of additional factors on parasite co-occurrence patterns, such as temperature, precipitation, and humidity.

Ticks and fleas are vectors of medically important infectious diseases globally, such as Rickettsiae. These pathogens are frequently reported in Southeast Asia, including Laos; however, there are very few comprehensive reports on their prevalence and vector diversity in urban areas. This study collected ectoparasites from companion animals to assess pathogen prevalence and exposure risk. In five veterinary clinics across Vientiane capital, ectoparasites were collected from dogs and cats and identified to the species level using both morphological and molecular methods. Ectoparasite DNA samples were screened for bacteria ( 17-kDa and 16S rRNA gene). Ticks were submitted to evaluate the potential of MALDI-TOF mass spectrometry for species identification. A total of 3,771 arthropod vectors (3,658 ticks, 105 fleas, 8 lice) were removed from dogs and cats. Ticks were morphologically identified as Rhipicephalus sanguineus sensu lato (s.l.) tropical lineage (currently recognised as Rhipicephalus linnaei ), whilst fleas were classified as either Ctenocephalides felis felis (57.1%) or C. f. orientis (42.9%) and lice were Heterodoxus spiniger . The MALDI-TOF spectra in this study revealed similar mass-to-charge (m/z) peak profiles to those reported in previous studies for Rhipicephalus sanguineus . Rickettsia spp. ( Rickettsia asembonensis and Rickettsia felis ) were detected in 44.4% of pooled flea samples collected from 12 dogs and 4 cats, as well as 3.5% of tick pools collected from 142 dogs and 50% of lice pools collected from 2 dogs. In addition, Anaplasmataceae ( Ehrlichia canis and Anaplasma platys ) were detected in 22.5% of ticks collected from dogs. This study highlights the diversity of ectoparasite species collected from dogs and cats and provide preliminary insights into the use of MALDI-TOF MS for tick species identification. While promising, further research is needed to enhance the reliability and efficacy of this approach. The findings also reveal a high prevalence of pathogens in ectoparasites, emphasizing the need for increased awareness among pet owners, veterinarians, and addressing public health concerns.

Background Flea infestations remain a major issue in veterinary medicine. Highly effective flea control for dogs and cats remains the foundation for eliminating infestations from homes and improving skin conditions associated with flea-feeding. Methods Homes with pet cats were screened by flea-history questionnaire. Qualifying homes were subselected into “high” (≥ 5 fleas on ≥ 1 cat, and ≥ 5 fleas collected in environmental flea traps over a 16–24 h period), “low” (< 5 fleas on all cats, < 5 in traps), and “no” homes (no evidence of fleas on cats or traps). All cats and dogs in a household were treated with a lotilaner oral tablet (Credelio ® CAT and Credelio ® , respectively) in weeks 0, 4, and 8. On-animal and trap counts were performed for: “high” at weeks 0, 1, 2, 4, 6, 8, and 11–12; “low” at week 0 and at approximately 2-week intervals through week 11–12; and “no” only at week 0. During each visit, one owner completed a pruritus assessment (PVAS) and a veterinary dermatologist assessed dermatologic lesions using the feline allergic dermatitis (SCORFAD) scale. Results A total of 46 homes met inclusion criteria and completed the study: 19 “high” (35 cats); 17 “low” (27); and 10 “no” (14). By week 1, relative to pretreatment, there was a 99.3% reduction in flea counts on “high” cats, with 31 of 34 cats (91.2%) flea-free. By week 11–12, flea counts across all study cats and traps were zero. Prior to the first treatment, mean PVAS scores were: “high” 6.6; “low” 5.5; and “no” 1.9. By week 1 there was a significant decrease in mean PVAS score of cats from “high” homes to 2.9 ( P  < 0.0001), and mean week 11–12 scores were 0.5 and 0.8 for “high” and “low” homes, respectively. For SCORFAD, by week 11–12, relative to week 0, there was a significant decline in mean scores of cats from both “high” (8.0 to 1.7) ( P  < 0.0001) and “low” homes (3.3 to 0.9) ( P  < 0.0001). Conclusions Lotilaner was 100% efficacious in eliminating flea infestations from animals and their homes. The monthly lotilaner treatments of cats and dogs in flea-infested homes resulted in clinical resolution of pruritus and dermatologic lesions. Graphical abstract

Rickettsia felis is an obligate intracellular bacterium that is being increasingly recognized as an etiological agent of human rickettsial disease globally. The agent is transmitted through the bite of an infected vector, the cat flea, Ctenocephalides felis , however there is to date, no consensus on the pathogen’s vertebrate reservoir, required for the maintenance of this agent in nature. This study for the first time, demonstrates the role of the domestic dog ( Canis familiaris ) as a vertebrate reservoir of R. felis . The ability of dogs to sustain prolonged periods of rickettsemia, ability to remain asymptomatically infected with normal haematological parameters and ability to act as biological vehicles for the horizontal transmission of R. felis between infected and uninfected fleas provides indication of their status as a mammalian reservoir of this emerging zoonosis.

Background Vector-borne pathogens are the subject of several investigations due to the zoonotic concern of some of them. However, limited data are available about the simultaneous presence of these pathogens in cats and their ectoparasites. The aim of the present study was to define the species of ectoparasites found on cats as well as to investigate vector-borne pathogens in cats and their ectoparasites in southern Italy. Methods Blood from 42 cats and fleas or flea pools ( n  = 28) and ticks ( n  = 73) collected from them were investigated by quantitative PCR for the detection of vector-borne pathogens. Feline serum samples were tested by IFAT to detect IgG antibodies against Leishmania infantum, Bartonella henselae , Rickettsia conorii, Rickettsia felis, Rickettsia typhi , Babesia microti , Ehrlichia canis and Anaplasma phagocytophilum antigens. Results Only one flea species ( Ctenocephalides felis ) and four tick species belonging to the genera Rhipicephalus and Ixodes were identified on cats from southern Italy. Molecular evidence of Bartonella spp., Rickettsia spp., hemoplasmas, Babesia vogeli and L. infantum was found in ectoparasites (fleas and/or ticks) while DNA from Hepatozoon felis and Ehrlichia/Anaplasma spp. was not detected. Likewise, DNAs from Bartonella, hemoplasma and Leishmania were the only pathogens amplified from feline blood samples. Cats had also antibodies against all the investigated pathogens with the exception of Rickettsia typhi . Agreement between serological and molecular results in individual cats and their ectoparasites was not found. The only exception was for Bartonella with a fair to moderate agreement between individual cats and their ectoparasites. Bartonella clarridgeiae was the species most frequently found in cats and their fleas followed by B. henselae . Conclusions In conclusion, cats harboring ticks and fleas are frequently exposed to vector-borne pathogens. Furthermore, ticks and fleas harbored by cats frequently carry pathogens of zoonotic concern therefore appropriate feline ectoparasiticide preventative treatments should be used in cats.

Background Fleas are major ectoparasites of dogs and cats, with significant veterinary and public health implications. This study aimed to estimate the prevalence of flea infestation in dogs and cats in mainland Portugal, identify associated risk factors and perform morphological and molecular characterisation of flea specimens. Methods A cross-sectional study was conducted from March 2022 to February 2023 in mainland Portugal. Dogs and cats were screened for flea infestations at veterinary clinics and shelters following World Association for the Advancement of Veterinary Parasitology guidelines. Fleas were morphologically identified to species level, and a subset was characterised molecularly via phylogenetic analysis of the cytochrome c oxidase subunit II gene ( cox2 ) sequences. Epidemiological data were analysed through multivariate logistic regression models to identify possible risk factors associated with flea infestation. Results A total of 1052 dogs and 1039 cats were examined, and flea infestation prevalence was determined to be 33.6% and 36.5%, respectively. Ctenocephalides felis was the predominant flea species in both hosts, accounting for 85.7% of fleas in dogs and 98.8% in cats, with molecular data confirming the subspecies C. felis felis . Other species identified included Ctenocephalides canis (9.6% in dogs; 1.8% in cats), Pulex irritans (4.2% in dogs) and Archaeopsylla erinacei maura (0.8% in dogs). The absence of insecticide use was the strongest predictor of flea infestation in both hosts (dogs: adjusted odds ratio [aOR] 4.87; cats: aOR 4.02). In dogs, the risk of infestation was higher in spring, summer and autumn compared to winter (aOR 2.08–3.72), and lower in the Lisbon Metropolitan Area, Alentejo and Algarve compared to the North region (aOR 0.14–0.45). In cats, risk was reduced in non-northern regions (Lisbon, Alentejo, Centro; aOR 0.10–0.45) and in those cats with non-domestic outdoor lifestyles (aOR 0.19). Conclusions Flea infestations are highly prevalent in dogs and cats across mainland Portugal, with C. felis felis as the dominant species. These findings provide valuable insights for the development of integrated, evidence-based strategies for flea control.