Evaluation of Cytopathological Techniques for the Diagnosis of Canine Visceral Leishmaniosis with Lymph Node Samples

The immune response in canine and human leishmaniasis and how this influences the diagnosis- a review and assessment of recent research

Leishmaniasis is a widespread but still underdiagnosed parasitic disease that affects both humans and animals. There are at least 20 pathogenic species of Leishmania, most of them being zoonotic. The diagnosis of leishmaniasis remains a major challenge, with an important role being played by the species of parasites involved, the genetic background, the immunocompetence of the host. This paper brings to the fore the sensitivity of the balance in canine and human leishmaniasis and addresses the importance of the host's immune response in establishing a correct diagnosis, especially in certain cases of asymptomatic leishmaniasis, or in the situation the host is immunosuppressed or acquired leishmaniasis through vertical transmission. The methods considered as a reference in the diagnosis of leishmaniasis no longer present certainty, the diagnosis being influenced mostly by the immune response of the host, which differs according to the presence of other associated diseases or even according to the breed in dogs. Consequently, the diagnosis and surveillance of leishmaniasis cases remains an open topic, requiring new diagnostic methods adapted to the immunological state of the host.

Development of Immunological Assays Based on Leishmania donovani Antigen for Diagnosis of Canine Visceral Leishmaniasis and Their Multicenter Evaluation in Brazil and Italy

Canine visceral leishmaniasis (CVL) due to Leishmania infantum infection is a zoonotic disease prevalent in the areas of South America and the Mediterranean. Infected dogs as reservoirs can contribute to disease transmission and can be a scourge to public health. Therefore, early diagnosis of infected dogs may play a pivotal role in circumscribing disease progression. Invasive tissue aspiration and insufficient serological methods impair a single assay for prompt CVL diagnosis. In the present study, we aimed to evaluate the potential of Leishmania donovani isolated membrane protein, LAg, for the diagnosis of CVL through immunological assays. Initially, enzyme-linked immunosorbent assay was done with Brazilian dog sera to evaluate the performance of LAg in diagnosing CVL and found sensitivity and specificity of 92.50% and 95%, respectively. The study further confirmed the diagnostic efficacy of LAg in a dipstick format. The dipstick test of canine sera from three centers in Brazil and one center in Italy collectively showed sensitivity values in the range of 53.33% to 100% in recognizing symptomatic dogs and specificity values between 75% and 100% to rule out healthy dogs. Moreover, a rapid immunochromatographic test was developed and optimized using LAg. This test was able to identify 94.73% of CVL of Brazilian origin with specificity of 97.29%. The current results highlight the reactive potential of the L. donovani antigen, LAg, for L. infantum CVL diagnosis and support our previous findings, which suggest the utility of LAg for the diagnosis of both L. donovani and L. infantum human VL in a variety of endemic regions. LAg as a diagnostic candidate may be employed to identify comprehensive CVL cases in epidemiological areas.

Retrospective study of canine peripheral lymphadenopathy in a Mediterranean region: 130 cases

Lymphadenopathy is a common clinical concern in dogs. Causes of lymphadenopathy include neoplasia, infection, and immune-mediated diseases. Seasonal infectious diseases should be considered as a potential cause of lymphadenopathy in endemic regions, such as the Mediterranean region. Therefore, the purpose of this study was to evaluate the causes of peripheral lymph node enlargement in dogs in a Mediterranean region (north‑eastern Spain). In addition, we aimed to assess the relationship between peripheral lymphadenopathy and other clinical data. Medical records of dogs admitted to two referral hospitals in Barcelona (Spain) with peripheral lymphadenopathy and cytological evaluation of lymph nodes, during a 4-year period (2015 to 2019) were included. One hundred and thirty dogs met the inclusion criteria. The most common final clinical diagnoses were lymphoproliferative neoplasia (36%) and dermatological disease (18.4%), followed by vector borne infectious disease (VBID; 16.5%). In the VBID group, 19 dogs were positive for Leishmania infantum and two dogs were positive for heartworm antigen. The presence of lymphadenopathy as the only clinical sign, generalized peripheral lymphadenopathy and internal lymphadenopathy was more frequent in dogs with lymphoma. The patients with metastatic neoplasms had significantly more localized lymphadenopathy compared to the other diagnosis groups. Twenty percent of the dogs had fever and this was more frequent in the immunemediated disease group. Our findings suggest that lymphoma is the most likely cause of lymphadenopathy in dogs. Clinicians should consider lymphoproliferative neoplasia in dogs with general peripheral lymphadenopathy concurrent with internal (abdominal or thoracic) lymphadenopathy and without other clinical signs. A higher incidence of immune-mediated disease was found in the population of febrile dogs included in this study.