Exposure of Owned Dogs and Feeding Ticks to Spotted Fever Group Rickettsioses in Central Italy

Retrospective Longitudinal Survey on Canine Vector-Borne Pathogens: Trends and Challenges of 10 Years of Activities of a Veterinary Blood Bank

Canine vector-borne pathogens (CVBPs) represent a challenge for veterinary transfusion medicine, since some can be transmitted by blood transfusion and are of zoonotic concern. Epidemiological data on CVBPs, obtained during 10 years of pre-donor screening (2012−2021) by a veterinary blood bank in central Italy, were used to conduct a retrospective epidemiological longitudinal survey. The results were obtained using the Immunofluorescent Antibody Test (IFAT) conducted on sera in order to assess IgG antibodies against Leishmania infantum, Ehrlichia canis, Anaplasma phagocythophilum, Babesia canis, and Rickettsia conorii; the modified Knott’s test and an ELISA kit were used to detect Dirofilaria immitis and Dirofilaria repens. In total, 324 out of the 1260 canine blood donors (25.71%) tested seropositive for at least one pathogen. The highest overall positive rate was detected for L. infantum (12.22%), followed by E. canis (2.30%), A. phagocytophilum (1.19%), D. repens (0.95%), D. immitis (0.32%), and B. canis (0.16%). From 2012 to 2014, a prevalence of 20.12% was recorded for R. conorii. Mixed infections were recorded in 21 dogs. For all the CVBPs investigated, significant differences (p < 0.05) were not observed over the period studied. The results evidenced a non-negligible prevalence of CVBPs in canine donors, which were selected based on strict criteria concerning regular endo- and ectoparasite controls. The results confirmed that the blood bank could be a reliable local epidemiological observatory. The need for implemented screening is discussed.

Looking for Dog Blood Donors in an Endemic Area for Vector-Borne Infections of Central Italy

Simple Summary

Dogs have proved to be competent reservoir hosts for several vector-borne pathogens, whose prevalence varies according to the area and over time due to the increased movement of people and their pets, climate changes, and vector adaptation strategies. The purpose of this study was to determine the prevalence of some vector-borne pathogens in dog blood donors, living in central Italy. Blood samples of 126 donors included were tested for a broad screening panel for infectious pathogens. The differences in pathogens prevalence according to age, sex, and breeds were tested. Overall, 50 animals tested positive for at least one pathogen. A tendency of hemoplasmas to be more prevalent in older dogs (41.2%) was noted. We highlight the difficulties of selecting healthy blood donor dogs in an endemic area for vector-borne infections. Close collaboration between specialists is important in the interpretation of positive test results. Finally, we underline the important role of blood donors as an epidemiological tool for active surveillance against canine infectious diseases.

Abstract

Dogs are proved to be competent reservoir hosts for several vector-borne pathogens. Their prevalence varies according to the geographical area. Many vector-borne pathogens may be transmitted by blood transfusion. The purpose of this study was to determine the serological and molecular prevalence of some vector-borne pathogens in dog blood donors, living in central Italy. Blood samples of 126 donors (19 breeds) included were tested for a broad serological and DNA-base tests panel. The differences in pathogen prevalence according to age, sex, and breeds were tested (chi-square test, Fisher’s exact test). Overall, 50 animals (39.7%) tested positive at PCR (polymerase chain reaction) and/or serology (IFAT, indirect fluorescent antibody test) for at least one pathogen. Three dogs were positive at both serology and PCR. A tendency of hemoplasmas to be more prevalent in older dogs (41.2%) compared to the younger ones (25.7%) was noted. We highlight the difficulties of selecting healthy blood donor dogs in an endemic area for vector-borne infections. It is important to choose the serological and biomolecular investigations panel that is most suited to the donor’s environment. Close collaboration between clinician and parasitologists is important in the interpretation of IFAT and PCR results. Finally, we underline the important role of blood donors as an epidemiological tool for active surveillance against canine vector-borne diseases.

Rickettsiales in Italy

There is no updated information on the spread of Rickettsiales in Italy. The purpose of our study is to take stock of the situation on Rickettsiales in Italy by focusing attention on the species identified by molecular methods in humans, in bloodsucking arthropods that could potentially attack humans, and in animals, possible hosts of these Rickettsiales. A computerized search without language restriction was conducted using PubMed updated as of December 31, 2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was followed. Overall, 36 species of microorganisms belonging to Rickettsiales were found. The only species identified in human tissues were Anaplasma phagocytophilum,Rickettsia conorii, R. conorii subsp. israelensis, R. monacensis, R. massiliae, and R. slovaca. Microorganisms transmissible by bloodsucking arthropods could cause humans pathologies not yet well characterized. It should become routine to study the pathogens present in ticks that have bitten a man and at the same time that molecular studies for the search for Rickettsiales can be performed routinely in people who have suffered bites from bloodsucking arthropods.

Detection of potentially pathogenic bacteria from Ixodes ricinus carried by pets in Tuscany, Italy

Background

Ticks are vectors of disease-causing pathogens that pose a serious threat to animals and people. Dogs and cats are exposed to tick infestation in multiple ways and can easily transport infected ticks into domestic environments and potentially transfer them to people. Pet owners are at increased risk of picking up ticks from their pets and developing tickborne diseases. This study aims to detect the presence of pathogens of potential public health interest in ticks removed from cats and dogs in Tuscany, Italy.

Methods

The collected ticks were screened for the presence of protozoan (Theileria species and Babesia species) and bacterial (Rickettsia species, Anaplasma species, Ehrlichia species, Chlamydia species, Bartonella species and Coxiella burnetii) pathogens using PCR.

Results

PCR and sequencing analysis revealed that 3 per cent of the ticks were PCR-positive for the presence of Rickettsia helvetica DNA, 5 per cent of ticks were PCR-positive for Bartonella henselae DNA, and 46 per cent of ticks were PCR-positive for Chlamydia psittaci and Chlamydia abortus DNA. None of the examined ticks was PCR-positive for Theileria species, Babesia species, Anaplasma species, Ehrlichia canis or Coxiella burnetii DNA.

Conclusion

The results of this preliminary study highlight the importance of monitoring companion animals as indicators to evaluate the health status of their owners. Preventive measures are necessary to limit the spread of zoonotic pathogens from companion animals to people within the home environment.

Emerging feline vector-borne pathogens in Italy

Background

The epidemiology of feline vector-borne pathogens (FeVBPs) has been less investigated in cats than in dogs. The present study assessed the prevalence of Rickettsia spp., Babesia spp., Cytauxzoon spp. and Leishmania infantum infections in cat populations living in central Italy, by molecular and serological tools.

Results

A total of 286 healthy cats were randomly selected from catteries and colonies in central Italy. Peripheral blood and conjunctival swab (CS) samples were collected during surgical procedures for regional neutering projects. Sera were analysed by IFAT to detect anti-Rickettsia felis, R. conorii, Babesia microti and Leishmania IgG antibodies using commercial and home-made antigens. DNA extracted from buffy coats (BCs) was tested for Rickettsia spp., and Piroplasmida species, including Cytauxzoon spp. and Babesia spp. by PCR. Buffy coats and CS samples were assayed by a nested (n)-PCR for Leishmania spp. Sixty-two cats (21.67%) were seropositive to at least one of the tested pathogens. The serological assay revealed 23 (8.04%) and 18 (6.29%) positive cats for R. felis and R. conorii, respectively, with low titers (1/64–1/128). No antibodies against B. microti were detected. Neither Rickettsia nor Piroplasmida DNA were amplified using the specific PCR assays. Thirty-one cats (10.83%) tested positive to anti-Leishmania IgG, with titers ranging from 1:40 to 1:160 and 45 animals (15.73%) tested positive to Leishmania CS n-PCR, whereas none of the animals tested positive to BC n-PCR. Considering the results obtained by IFAT and CS n-PCR, a moderate agreement between the two tests was detected (κ = 0.27).

Conclusions

The results of the serological and molecular surveys showed a moderate exposure to Leishmania in the investigated cats and highlighted the limited molecular diagnostic value of BC versus CS samples for this pathogen. Conversely no evidence supported the circulation of Cytauxzoon spp. in domestic cats, in contrast with previous detections in European wild cats in the same areas monitored. The low positive titres for R. felis in association with no DNA BC amplification prevent speculation on the exposure of feline populations to this FeVBP due to the cross-reactivity existing within spotted fever group rickettsiosis (SFGR).