Seroprevalence of antibodies to Borrelia burgdorferi in wild canids in Spain

Arthropod-Borne Pathogens in Wild Canids

Wild canids, as well as other wild animal species, are largely exposed to bites by ticks and other hematophagous vectors where the features favoring their presence and spread are found in wooded and semi-wooded areas. Much of the information about arthropod-borne infections concerns domestic and companion animals, whereas data about these infections in wild canids are not exhaustive. The present study is a narrative review of the literature concerning vector-borne infections in wild canids, highlighting their role in the epidemiology of arthropod-borne bacteria and protozoa.

Serological evaluation of selected vector-borne pathogens in owned dogs from northern Spain based on a multicenter study using a commercial test

Background

Environmental conditions in northern Spain allow the development of different arthropods involved in the transmission of significant canine vector-borne pathogens. The aim of the study was to systematically assess seroprevalence rates for Leishmania infantum, Ehrlichia canis, Anaplasma spp., Dirofilaria immitis and Borrelia burgdorferi, and risk factors in dogs from all regions of the north of Spain.

Methods

A total of 556 dogs were included in this study between January 2017 and December 2018, belonging to 30 practices covering all regions in northern Spain (Galicia, Asturias, Cantabria, Basque Country, Navarra, Aragon and Catalonia). All practices were located in the north of every region. Blood samples were analyzed using the 4DX SNAP® test (IDEXX Laboratories, Westbrook, Maine, USA) for the detection of D. immitis antigen and E. canis, B. burgdorferi and Anaplasma spp. antibodies. Leishmania SNAP® test (IDEXX Laboratories) was used for detection of L. infantum antibodies. Associations between prevalence of canine vector-borne pathogens, epidemiological and clinical signs data were statistically analyzed.

Results

The overall prevalence rates were 8.99% for L. infantum, 1.26% for Anaplasma spp., 0.9% for E. canis, 0.72% for B. burgdorferi, and 0.18% for D. immitis. Globally, 11.33% of the dogs included in the study were positive to any tested vector-borne pathogen. Leishmania infantum seroprevalence was the highest and the only one detected in all the regions. Leishmania infantum seropositivity was associated with age > 10 years-old, outdoor access, anemia, fever, dermatological signs, lympadenomegaly, muscular atrophy, ocular signs and renal disease. Ehrlichia canis seropositivity was associated with the summer season and living in urban areas. Apathy, weakness, anorexia, weight loss, anemia, fever and gastrointestinal clinical signs were also associated with E. canis antibody detection. Living in a rural area was also a risk factor for Anaplasma spp. and B. burgdorferi seropositivity.

Conclusions

To our knowledge, this is the first multicenter survey performed in northern Spain assessing different canine vector-borne diseases from all regions. Results show the presence of autochthonous cases of these diseases. The vector-borne pathogens found in this study should be included in the differential diagnosis in dogs from some areas previously considered non-endemic for these pathogens.

Vertebrate Ticks Distribution and Their Role as Vectors in Relation to Road Edges and Underpasses

Roads fragment vertebrate populations and affect the dynamics and dispersal patterns of vertebrate parasites. We evaluated how vertebrate ticks distribute near roads and road underpasses in human-caused road-fragmented landscapes in Seville, SW Spain. We sampled 49 stations with 93 individualized sampling points and assessed tick abundance. We explored the relationship between tick presence and abundance and distance to the nearest road and underpass (drainage culverts and other passages used by vertebrates), and landscape features through categorical regression and nonparametric statistics. The presence of the tick-borne pathogens Borrelia sp. and Bartonella sp. was also analyzed by PCR. We found preliminary evidence of high relative tick abundance next to roads and in the vicinity of road underpasses. Plant cover type was related to tick presence in this road context. Implications of road permeability and edge effect in patterns of vertebrate-tick relationships in road fragmentation contexts are discussed. Both Borrelia sp. and Bartonella sp. were detected in the ticks analyzed. This is the first report of these bacteria in ticks from Seville. The results confirm the potential risk of acquiring Lyme disease and bartonellosis in this area.

Antibodies to Rickettsia spp. and Borrelia burgdorferi in Spanish Wild Red Foxes (Vulpes vulpes)

We examined 314 red foxes (Vulpes vulpes) from the province of Soria, Spain, for Rickettsia typhi, Rickettsia slovaca, and Borrelia burgdorferi infection. Immunofluorescence assays showed 1.9% had antibodies to R. typhi, 6.7% had antibodies to R. slovaca, and 8.3% had antibodies to B. burgdorferi. Serostatus was not correlated with sex or age. Because red foxes can be infected by Rickettsiae and B. burgdorferi, presence of red foxes may be and indicator for the presence of these pathogens.

Ecological preferences of exophilic and endophilic ticks (Acari: Ixodidae) parasitizing wild carnivores in the Iberian Peninsula

Ticks parasitizing wild carnivores and the tick-borne pathogens (TBPs) that they transmit may affect domestic carnivores and humans. Thus, investigating the role of wild carnivores as tick hosts is of relevance for understanding the life cycle of ticks in natural foci and the epidemiology of TBPs shared with domestic animals and humans. Therefore, the main objective of this study was to determine the ixodid tick fauna of wild carnivores in Peninsular Spain and the environmental factors driving the risk of wild carnivores to be parasitized by ixodid ticks. We hypothesized that the adaptation of tick species to differing climatic conditions may be reflected in a similar parasitization risk of wild carnivores by ticks between bioclimatic regions in our study area. To test this, we surveyed ixodid ticks in wild carnivores in oceanic, continental-Mediterranean, and thermo-Mediterranean bioclimatic regions of Peninsular Spain. We analyzed the influence of environmental factors on the risk of wild carnivores to be parasitized by ticks by performing logistic regression models. Models were separately performed for exophilic and endophilic ticks under the expected differing influence of environmental conditions on their life cycle. We found differences in the composition of the tick community parasitizing wild carnivores from different bioclimatic regions. Modelling results partially confirmed our null hypothesis because bioclimatic region was not a relevant factor influencing the risk of wild carnivores to be parasitized by exophilic ticks. Bioclimatic region was however a factor driving the risk of wild carnivores to be parasitized by endophilic ticks. Spanish wild carnivores are hosts to a relevant number of tick species, some of them being potential vectors of pathogens causing serious animal and human diseases. Information provided herein can be of help to understand tick ecology in Spanish wildlife, the epidemiology of tick-borne diseases, and to prevent the risks of TBPs for wildlife, domestic animals, and humans.