BackgroundThe so-called canine vector-borne diseases (CVBD) are caused by a wide range of pathogens transmitted by arthropods. In addition to their veterinary importance, many of these canine vector-borne pathogens can also affect the human population due to their zoonotic potential, a situation that requires a One Health approach. As the prevalence of vector-borne pathogens in cats from southern Portugal has been recently evaluated, the aim of the present study was to assess if the same agents were present in dogs living in the same area, and to assess positivity-associated risk factors.MethodsOne thousand and ten dogs (521 domestic and 489 stray) from veterinary medical centres and animal shelters in southern Portugal were enrolled. Anaplasma spp./Ehrlichia spp., Bartonella spp., Borrelia burgdorferi sensu lato, Babesia spp., Hepatozoon spp. and Leishmania infantum infections were evaluated by polymerase chain reaction (PCR) assays in blood samples.ResultsSixty-eight (6.7%) dogs were PCR-positive to at least one of the tested CVBD agent species, genera or complex, including one dog found positive to two different genera. Nineteen (1.9%) dogs were positive to Anaplasma spp./Ehrlichia spp., eight (0.8%) to B. burgdorferi s.l., 31 (3.1%) to Hepatozoon spp. and 11 (1.1%) to L. infantum. Anaplasma platys, Ehrlichia canis, B. burgdorferis.l. and Hepatozoon canis were identified by DNA sequencing, including one animal confirmed with both A. platys and H. canis. Furthermore, Wolbachia spp. was amplified in blood from four dogs. None of the tested dogs was positive by PCR for Bartonella spp. or Babesia spp.ConclusionsThe molecular identification of CVBD agents in southern Portugal, some of them with zoonotic concern, reinforces the importance to alert the veterinary community, owners and public health authorities to prevent the risk of transmission of vector-borne pathogens among dogs and to other vertebrate hosts including humans. The prevalence of the selected pathogens was lower than that previously found in cats from the same region, probably because veterinarians and owners are more aware of them in the canine population and control measures are used more often.

Approximately 20% of hepatitis C virus (HCV) infected individuals clear the virus. Host factors that influence the course of HCV infection are still under investigation, and the data on the association of human leukocyte antigen (HLA) alleles and HCV clearance are scarce and controversial. The aims of this study were to investigate whether HLA alleles are associated with clearance of HCV infection in a highly admixed Brazilian population and whether these associations could be influenced by ethnicity and route of infection. HLA-A, -B, -C, -DRB1 and -DQB1 genotyping were performed in 135 HCV-infected Brazilian patients among which 45 cleared HCV infection (cases) and 90 had persistent viral infection (controls). Controls were matched by sex, ethnicity (withes and non-whites) and route of infection (high infectious dose or low infectious dose). No significant association was identified between HLA alleles and the outcome of HCV infection when analyzing the sample as a single group. However, a new protective association of HLA-DQB1*04 (P = 0.006; P(c) = 0.030) and a rarely described association of HLA-DRB1*08 (P = 0.004; P(c) = 0.048) were found only among white patients. The DRB1*11 allele, previously reported in homogeneous population, was associated with HCV clearance (P = 0.020) only among patients with expected high-dose exposure. These findings confirm the influence of ethnicity on the associations of HLA with spontaneous viral clearance of HCV infection and emphasize the possible influence of route of infection in this process.

Lymphoma is the most common haematological malignancy in dogs and its aetiology is largely unknown. The presence of canine vector‐borne agents (CVBD) in lymphoma tissues has been described and its causative effects questioned. We intended to evaluate the presence and extent of Leishmania infantum, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae infection in dogs with lymphoma. Sixty‐one dogs, living in the Lisbon metropolitan area, with a diagnosis of lymphoma were enrolled. Immunofluorescence assays were used to detect serum IgG's. The presence of DNA from CVBD agents in tumour tissue was assessed by PCR. All dogs tested negative for B. henselae, A. phagocytophilum and E. canis by both serology and PCR. Regarding L. infantum, 8.2% (n = 5) of the dogs had a positive serologic result. L. infantum DNA was detected in two samples of diffuse large B‐cell lymphoma (DLBCL). These results show an increased, but not significant, seropositivity (8.2% vs 7.9%) and molecular detection (3.3% vs 1.2%) for L. infantum in dogs with lymphoma, when compared to the reported canine population in the same geographical area. We could not identify an association between lymphoma and E. canis, A. phagocytophilum, B. henselae or Leishmania infantum infection in the studied population. Nevertheless, further studies, following dogs trough their CVBD disease evolution, are worthwhile and may help clarify a possible role of CVBD agents in lymphomagenesis.

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