Prevalence of antinuclear antibodies and rheumatoid factor titers in dogs with arthritis secondary to leishmaniosis (Leishmania infantum).

Dogs with infectious arthritis may occasionally exhibit positive serum antinuclear antibody (ANA) and rheumatoid factor (RF) titers; however, relevant data are sparse for arthritis secondary to canine leishmaniosis (CanL) caused by Leishmania infantum. We determined the prevalence of positive serum ANA and RF titers in dogs with arthritis secondary to CanL. Blood samples from adult, client-owned dogs with purulent arthritis secondary to CanL, without any comorbidities, were collected for diagnostic purposes. Serum ANA titers were measured by immunoperoxidase test and RF titers by the Rose-Waaler latex test. Twelve of 23 dogs enrolled prospectively in our study had clinical arthritis, and 11 of 23 had subclinical arthritis. Based on LeishVet clinical staging, 7 dogs had clinical stage II disease, 11 had clinical stage III disease, and 5 had stage IV. None of the 23 dogs was seropositive for ANA; 3 of 23 were positive for RF. ANA and/or RF seropositivity, in dogs with CanL-associated arthritis, appears to be weak, if present at all. Based on our results, positive serum ANA and RF titers should not be expected in dogs with arthritis secondary to CanL.

Evaluation of clinicopathological abnormalities in sick cats naturally infected by Leishmania infantum.

Feline infection by Leishmania infantum (syn. L. chagasi) has been described in areas where canine leishmaniosis is endemic. A wide variety of clinicopathological abnormalities have been reported in cats presenting clinical signs of leishmaniosis but there is a paucity of information regarding cats infected by L. infantum that do not suffer from leishmaniosis but from other diseases. The aim of this study was to compare: a) the frequency of clinicopathological abnormalities and b) the values of hematology, serum biochemistry and urinalysis parameters, between non-infected sick cats and sick cats that were infected by L. infantum. A total of 50 cats with cutaneous, ocular and/or systemic clinical signs that lived in an endemic area and had been tested for infection by L. infantum using PCR from four different tissues, were included. Based on the results of PCR, 20/50 cats were found to be infected and 30/50 non-infected. The only difference between the two groups of cats was that the concentration of inorganic phosphorus (P = 0.043) was higher in infected cats. This finding may suggest an association between infection by L. infantum and feline kidney disease.

Evaluation of indirect immunofluorescence antibody test and enzyme-linked immunosorbent assay for the diagnosis of infection by Leishmania infantum in clinically normal and sick cats.

Cats that live in areas where canine and human leishmaniosis due to Leishmania infantum is endemic may become infected and may develop anti-Leishmania antibodies. In this study 50 clinically normal and 50 cats with cutaneous and/or systemic signs that lived in an endemic area and had been previously examined for infection by L. infantum using PCR in four different tissues were serologically tested for the presence of anti-Leishmania IgG (IFAT and ELISA) and IgM (IFAT). The aim was to compare the results of IFAT, ELISA and PCR and to investigate the possible associations between seropositivity to Leishmania spp and signalment, living conditions, season of sampling, health status of the cats, and seropositivity to other infectious agents. Low concentrations of anti-Leishmania IgG were detected by IFAT in 10% of the cats and by ELISA in 1%, whereas anti-Leishmania IgM were detected by IFAT in 1%. There was disagreement between the results of IFAT and ELISA for anti-Leishmania IgG (P = 0.039) and between all serological tests and PCR (P < 0.001). The diagnostic sensitivity of all serological tests, using PCR as the gold standard, was very low, but ELISA and IFAT for anti-Leishmania IgM had 100% specificity. The diagnostic sensitivity of all serological tests could not be improved by changing the cut-off values. Seropositivity for Leishmania spp was not associated with signalment, living conditions, season of sampling and health status of the cats or with seropositivity to feline leukemia virus, feline immunodeficiency virus, feline coronavirus, Toxoplasma gondii and Bartonella henselae. In conclusion, because of their low sensitivity and very high specificity two of the evaluated serological tests (ELISA for anti-Leishmania IgG and IFAT for anti-Leishmania IgM) may be useless as population screening tests but valuable for diagnosing feline infection by L. infantum.

Molecular identification of Bartonella species in dogs with leishmaniosis (leishmania infantum) with or without cytological evidence of arthritis.

Recent evidence suggest that Bartonella species may cause polyarthritis and lameness in dogs. Canine leishmaniosis (CanL) due to Leishmania infantum is a multi-systemic disease often occurring in association with arthritis. We hypothesized that concurrent Bartonella infection may be a contributing factor for the development of arthritis in dogs with CanL. Hence the primary objective of this study was to investigate the molecular prevalence of Bartonella spp. in dogs with naturally occurring CanL, with or without cytologically documented arthritis. Thirty-eight dogs with CanL (31 with neutrophilic arthritis and 7 without arthritis) were retrospectively studied. Seventy-four archived clinical specimens from these 38 dogs, including 33 blood samples, 19 bone marrow (BM) samples and synovial fluid (SF) aspirates from 22 dogs were tested for Bartonella spp. DNA using the Bartonella alpha proteobacteria growth medium (BAPGM) diagnostic platform. Overall, eight (21.1%) dogs were infected with one or two Bartonella species; however, Bartonella spp. infection was not associated with arthritis in dogs with CanL. Further prospective studies are warranted to determine if there is a correlation between Bartonella spp. infection and the development of arthritis in dogs with CanL.

Cytological and molecular detection of Leishmania infantum in different tissues of clinically normal and sick cats.

Natural infection of domestic cats by Leishmania infantum (synonym: L. chagasi) has been demonstrated in several European, Latin American, and Asian countries, and the estimated prevalence of infection, based mainly on blood PCR, ranges from 0.3% up to 60.6%. In this study we aimed to: (a) estimate the prevalence of the infection by L. infantum in clinically normal cats (group A; n=50) and in cats with various clinical signs (group B; n=50), living in an endemic region, by both cytological examination of four different tissues (lymph node, skin, bone marrow, and conjunctiva) and by PCR in four different tissues (blood, skin biopsies, bone marrow, and conjunctiva); (b) compare the diagnostic sensitivity of the above methods and evaluate for possible associations between their results; and (c) investigate the possible associations between infection by L. infantum and signalment, living conditions, season of sampling, and health status of the cats. The prevalence of the infection in the study population was 41% and did not differ (P=0.839) between group A (42%) and B (40%) cats. Lymph node, skin, bone marrow and conjunctiva cytology was always negative. Therefore, the diagnosis of the infection was based only on PCR in blood, skin biopsy, bone marrow and conjunctiva, which was positive in 13%, 18.2%, 16% and 3.1% of the cats, respectively. PCR was positive in only one of the four tissues in 80.5% of the infected cats. The results differed (P=0.014) among the four tissues and were less frequently positive in conjunctiva compared to skin biopsies and bone marrow (P=0.007 for both comparisons), thus highlighting the need for multiple tissue PCR testing in order to minimize false-negative results. More PCR-positive cats were found when sampling was performed during the period of sandfly activity (odds ratio: 2.44; P=0.022). Also, in group B cats, the likelihood of PCR-positivity was higher (odds ratio: 3.93; P=0.042) among those presenting at least one systemic clinical sign that had been previously reported in cats with leishmaniosis.

Comparison of two commercial rapid in-clinic serological tests for detection of antibodies against Leishmania spp. in dogs.

Antibodies against Leishmania spp. are detected in most dogs with clinical signs of leishmaniasis due to Leishmania infantum. Accurate, rapid in-clinic serological tests may permit immediate confirmation of the diagnosis and implementation of therapeutic measures. The aim of the current study was to evaluate the diagnostic accuracy of 2 commercial, rapid in-clinic serological tests for the detection of anti-Leishmania antibodies in sera of dogs, the Snap Canine Leishmania Antibody Test kit (IDEXX Laboratories Inc., Westbrook, Maine) and the ImmunoRun Antibody Detection kit (Biogal Galed Labs, Kibbutz Galed, Israel), using indirect fluorescent antibody test (IFAT) as the reference method. A total of 109 sera collected from 65 seropositive and 44 seronegative dogs were used. The sensitivities of the Snap and ImmunoRun kits were 89.23% (95% confidence interval: 79.05-95.54%) and 86.15% (95% confidence interval: 75.33-93.45%), respectively, and the specificity of both tests was 100%. A good agreement between each of the rapid in-clinic serological tests and IFAT and between the 2 rapid in-clinic serological tests was witnessed. Both rapid in-clinic serological tests showed an adequate diagnostic accuracy and can be used for the fast detection of antibodies against L. infantum in dogs.