Use of In-Clinic Diagnostic Kits for the Detection of Seropositivity to Leishmania infantum and Other Major Vector-Borne Pathogens in Healthy Dogs

Abstract

Canine Vector-Borne Diseases (CVBDs) are widespread in Europe and enzootic in many other countries. Though severe illnesses may occur, dogs living in enzootic areas often show vague or no clinical signs of CVBDs. Undiagnosed infections/co-infections in subclinically infected animals favor the spread of CVBDs and increase the risk of transmission to other animals and, in some cases, humans. This study has evaluated the exposure of dogs living in key enzootic countries, i.e., Italy and Greece, to major CVBDs via the use of in-clinic diagnostic kits. Overall, 300 privately owned dogs without/with single mild clinical signs living in different regions of Italy (n. 150) and Greece (n. 150) were included in the study. As part of a clinical examination, a blood sample was collected from each dog and subjected to two serological rapid tests, i.e., the SNAP® 4Dx®Plus (IDEXX Laboratories Inc.) for the detection of antibodies against Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi s.l. and Dirofilaria immitis antigen and the SNAP® Leishmania (IDEXX Laboratories Inc.) for the detection of antibodies against Leishmania infantum. In all, 51 dogs (17%; 95% CI 12.9–21.7) were seropositive to at least 1 pathogen, i.e., 4 in Italy (2.7%; 95% CI 1.4–13.1) and 47 in Greece (31.3%; 95% CI 24–39.4). Dirofilaria immitis antigens were found in 39 dogs (13%; 95% CI 9.4–17.3), while antibodies against Ehrlichia, Anaplasma and Leishmania were detected in 25 (8.3%; 95% CI 5.5–12.1), 8 (2.7%; 95% CI 1.2–5.2) and 5 (1.7%; 95% CI 0.5–3.8) dogs, respectively. None of the dogs tested seropositive for B. burgdorferi s.l. Statistical analyses were performed to evaluate associations between exposure to CVBDs and possible risk factors. The present results indicate that dogs living in enzootic areas may be seropositive for one or more CVBDs in absence of clinical signs. Rapid kits are among first line tools for the detection of CVBDs in clinical settings, as they are cost-effective, straightforward and quick to use. Also, in-clinic tests used herein allowed detection of co-exposure to CVBDs investigated.

Beyond Borders: Dirofilaria immitis Infection in Dogs Spreads to Previously Non-Enzootic Areas in Greece—A Serological Survey

“…Interestingly, and confirming once more the hypothesis that infection is enzootic in the northern regions of Greece, Angelou et al [ 13 ] in 2019 examined randomly selected animals from all parts of the country and recorded a 9% prevalence of infected dogs, the vast majority of them distributed only in the preceding regions. In the same context, the most up-to-date survey tested 150 dogs from Northeastern Greece (Macedonia and Thrace) and found a mean prevalence of D. immitis infection of 25.3%, varying from 8% to 68% in an area of Northeastern Greece (Didymoteicho) [ 20 ].…”

“…However, according to the published data originating from different parts of Greece and to the veterinary perception, regions below Thessaly and Epirus and above the northern parts of Central Greece are considered the border between enzootic and non-enzootic areas [ 12 , 13 ]. In particular, epizootiological surveys have recorded prevalence rates ranging from 6.75% up to 68% for D. immitis infection in dogs living in the northern areas of Greece, i.e., Macedonia, Thrace, Epirus, and Thessaly [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Concerning the regions of Greece that were regarded as non-enzootic (Central Greece, Attica, Peloponnese, North Aegean, South Aegean, Crete, and the Ionian islands), the recorded prevalence rates from studies up to 2022 ranged from 0% in Crete up to 10.9% in the Ionian islands [ 12 , 13 , 19 , 21 ].…”