Is the Prevalence of Leishmania infantum Linked to Breeds in Dogs? Characterization of Seropositive Dogs in Ibiza

Abstract

Leishmaniosis is an important zoonotic protozoan disease primarily spread to the Mediterranean region by Leishmania infantum, the predominant protozoan species, which accounts for the majority of cases. Development of disease depends on the immune response of the definitive host and, predictably, their genetic background. Recent studies have revealed breed-typical haplotypes that are susceptible to the spread of the protozoan parasite. The objective of this study was to analyze the prevalence of leishmaniosis on a Mediterranean island and determine the relationship between disease prevalence and breed. In addition, information on seropositive animals was recorded to characterize animals affected by the disease. To study the prevalence, a total of 3141 dogs were analyzed. Of these, the 149 infected animals were examined for age, sex, antibody titer, and disease stage. We observed a prevalence of 4.74%, which varied between breeds (p < 0.05). The Doberman Pinscher and Boxer breeds had the highest prevalence of leishmaniosis. Significant differences were observed between breeds with common ancestors, emphasizing the important genetic component. Finally, regarding the characterization of seropositive animals, the distribution is similar to other studies. We discovered a relationship (p < 0.05) between the number of antibody titers and the clinical disease stage, which was also present in Leishmania infantum, suggesting that the development of the disease depends on the humoral or Th2 immune response with ineffective antibodies.

Canine Cytokines Profile in an Endemic Region of L. infantum: Related Factors

“…Out of the animals examined, 14.10% were positive to L. infantum infection, in accordance with data observed in other reported studies on Mediterranean areas, where prevalence was estimated between 5 and 57.1% [38]. Previous studies in indoor animals estimated this prevalence in 4.74% in other Mediterranean areas [31], and these higher levels were found probably because the animals used in this study were all outdoor. Of the positive animals, 81.82% presented values above 1:100 of parasitic burden and had at least one clinical feature.…”

“…These results could indicate an immunological protection mainly in the Ibizan hound, and to a lesser extent in crossbred dogs. Our results show that different immune responses occur depending on the dog's breed, mainly in Ibizan hound and boxer, according to several studies [31,34,35].…”

“…However, one of the most relevant factors that seems to affect the immune response in Leishmania infection is the canine breed. In fact, the prevalence of infection differs between canine breeds in endemic regions of L. infantum [31], which could indicate immunological protection of some canine breeds compared to others against infection by the parasite and, mainly, the development of leishmaniosis. Several studies show that the activation of Th1 immune response depends on the canine breed such that some breeds present different serum levels of cytokines [22,32,33].…”

“…In fact, different studies suggest a certain resistance and/or susceptibility to clinical diseases in dogs related to breed. In this sense, our research group recently published a study where a clear difference was observed in the prevalence of leishmaniosis according to the canine breed, presenting a higher prevalence in breeds such as boxer or Doberman (evolutionarily related) in which the prevalence of clinical signs reaches up to around 50% [31]. This difference in the prevalence of leishmaniosis could be indicating an underlying cause of genetic origin that could be related to different immune responses, or with the activation of different immunity pathways.…”

Leishmania infantum infection serosurveillance in stray dogs inhabiting the Madrid community: 2007–2018

“…However, few studies have been conducted in stray dogs and these are not always comparable in terms of the different diagnostic techniques used, size and origin of samples, and study duration, among other factors. For example, reports exist of seroprevalences in owned dogs of 34.6% in Malaga, 33.1% in Lleida, 24.6% in Huesca, 22% in Alicante province, and 4.74 to 31% in the Balearic Islands [ 23 , 37 ]. In contrast, in the north and northwest of Spain, respectively, seroprevalences of 0–5% and 3.7–10.8% have been reported [ 32 , 38 , 39 ].…”