Clinical and serological aspects of visceral leishmaniasis in Northeast Brazilian dogs naturally infected with Leishmania chagasi

Escola de Medicina Veterinária, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
Veterinary Parasitology (Impact Factor: 2.46). 03/2005; 127(3-4):227-32. DOI: 10.1016/j.vetpar.2004.10.010
Source: PubMed


Human visceral leishmaniasis is endemic in the northeast of Brazil, where the domestic dog is an important parasite reservoir in the infectious cycle of Leishmania chagasi. In this study, we evaluated the clinical signs of canine visceral leishmaniasis (CVL), serum protein profile and the antileishmanial IgG antibody production in 86 dogs living in northeast endemic areas of leishmaniasis. Thirty dogs from a leishmaniasis-free area were used as a control group. The major clinical signs of CVL seen were emaciation and skin ulcers (80%), followed by onychogryphosis and conjunctivitis (73%). Depilation was observed in 60% of animals while lymphadenomegaly, splenomegaly, liver enlargement or kidney involvement was less frequent (< or =20%). VL seropositive dogs presented with serum hyperproteinemia, hypoalbuminemia, hypergammaglobulinemia and decreased albumin/globulin ratio. A lower sensitivity and higher specificity was observed for promastigote indirect fluorescent antibody test (IFAT) (83 and 100%, respectively) compared with enzyme-linked immunosorbent assay (ELISA) (94 and 90%), which uses a crude extract of Leishmania. There was a positive correlation between IFAT and ELISA titers of antileishmanial IgG antibodies (Spearman test, P < 0.05), which was augmented in CVL dogs. This study found that the determination of serum protein, A/G ratio and the use of two different leishmanial serological tests like IFAT and ELISA are essential in CVL screening.

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    • "It was observed that CS real-time PCR was able to detect infection in dogs independently of the symptomatology degree (p>0.05) while ELISA was more sensitive in SII dogs, demonstrating the CS real-time PCR capacity to identify infected asymptomatic dogs, a drawback frequently reported for the serologic assays. The high frequency of skin disorders observed in CVL-positive animals was compatible with the findings of Almeida et al. (2005) that evaluated the clinical signs in naturally infected dogs living in endemic areas. The major CVL clinical signs seen were emaciation and skin ulcers (80 %), followed by onychogryphosis and conjunctivitis (73 %). "
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    ABSTRACT: The canine visceral leishmaniasis (CVL) diagnosis is an important step of visceral leishmaniasis control program in Brazil once the dog is the main reservoir host of the disease. The aim of this study was to evaluate the conjunctival swab (CS) as a mass-screening tool for CVL molecular diagnosis in an endemic area classified as priority for the Brazilian Ministry of Healthy for surveillance action. A total of 1350 domiciled dogs were screened. The animals were evaluated by serological tests (enzyme-linked immunosorbent assay (ELISA) as screening and immunofluorescence antibody test (IFAT) for confirmation) and by CS associated to real-time PCR, using primers addressed to kinetoplast DNA (kDNA) minicircles and SYBR Green. Canine β-globin gene amplification was used to evaluate the sample DNA integrity. A subgroup of 484 animals was also submitted to clinical evaluation. Among the 1350 dogs screened, 369 (27.3 %) were positive by CS real-time PCR and 126 (9.3 %) tested positive by ELISA. Thirty-one percent (39/126) of the ELISA-positive dogs were confirmed by IFAT. CS real-time PCR was able to detect infection in dogs independently of the symptomatology degree (p > 0.05), while ELISA was more sensitive in the group of dogs that present three or more clinical signs related to CVL. The results demonstrated that CS real-time PCR was able to detect a higher number of infected dogs than ELISA and that the prevalence of canine infections has been underestimated by the serological assays. The use of sensitive molecular diagnostic methods like CS real-time PCR, mainly in endemic areas, could greatly contribute to disease control.
    Full-text · Article · Mar 2015 · Parasitology Research
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    • "Among the methods most applied for the serological diagnosis, the indirect fluorescence assay (IFA) is used quite frequently in epidemiological studies (Alvar et al., 2004). Its sensitivity and specificity range between 60% and 100% (Almeida et al., 2005; da Silva et al., 2013), but cross-reactivity with the antibodies of dogs infected with other diseases has been reported (Zanette et al., 2014). The enzyme-linked immunosorbent assay (ELISA) is also commonly used for the diagnosis of canine visceral leishmaniasis (CVL). "
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    ABSTRACT: We investigated the performance of the DPP® canine visceral leishmaniasis (CVL) rapid test, a novel immunochromatographic assay launched by BioManguinhos (Brazil), which was recently included in the new Brazilian protocol for screening CVL in serological surveys. The present study compared the DPP® with the ELISA and IFA produced by BioManguinhos (Brazil) both with L. major-like antigens and with in-house tests using Leishmania infantum chagasi (in-house ELISA and in-house IFA). We analyzed the sera from clinically symptomatic (n = 47) and asymptomatic (n = 38) infected dogs from an endemic area of CVL, as well as from healthy (n = 18) dogs, in addition to the sera of dogs (n = 81) infected with other pathogens. The DPP® and the in-house ELISA showed a sensitivity of 90.6% and 94.1%, respectively, and specificity of 95.1% and 97.5%, respectively, and both presented cross-reactivity only with the sera of dogs with babesiosis, 44% for the DPP® and 22% for the in-house ELISA. The clinical groups were detected equally by the two assays. The ELISA BioManguinhos, IFA BioManguinhos, and in house-IFA showed a good sensitivity, 90.6% 96.5% and 89.4%, respectively, but very low specificity, 77.8%, 69.1% and 65.8%, respectively, due to the high cross-reactivity with the sera from the animals harboring other pathogens. The in-house ELISA provided the highest accuracy (95.8%), followed by the DPP® (92.7%), ELISA BioManguinhos (84.3%), IFA BioManguinhos (83.1%), and in-house IFA (78.0%). The simultaneous use of the DPP® and ELISA BioManguinhos reached a sensitivity of 99.1% and of 82.1% when used sequentially. In conclusion, the DPP® performed well as serological test for CVL, and detected both asymptomatic and symptomatic dogs in equal proportions. Although its sensitivity is not ideal yet, discarding the IFA and including the DPP® improved the accuracy of the new Brazilian CVL diagnostic protocol, particularly of detecting truly infected dogs. Moreover, considering the higher specificity of DPP® (95.1% vs 77.8%), positive predictive value (95.1% vs 81.1%) and positive likelihood value (18.3% vs 4.1%) in comparison with the ELISA BioManguinhos, the use of DPP® as a confirmatory test instead of a screening test is suggested.
    Full-text · Article · Sep 2014 · Veterinary Parasitology
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    • "In the 35 naturally infected dogs (G1), the most frequent clinical manifestations were increased superficial lymph node size, weight loss, onychogryphosis, skin lesions, conjunctivitis, ulceration of the skin, alopecia, coryza, desquamation of the skin, keratitis, depigmentation of the nose, pale mucous, apathy, hyperkeratosis and edema as found in other study1. "
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    ABSTRACT: In this study, we detected Leishmania spp. infection in R. sanguineus collected from dogs that were naturally infected with L. (L.) infantum. We examined 35 dogs of both sexes and unknown ages. The infected dogs were serologically positive by the immunofluorescence antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA), and Quick Test-DPP (Dual Path Platform), as well as parasitological examination of a positive skin biopsy or sternal bone marrow aspiration. Ten negative dogs were included as controls. The ticks that infested these dogs were collected in pools of 10 adult females per animal. The PCR was performed with specific primers for Leishmania spp., which amplified a 720-bp fragment. Of the 35 analyzed samples, a product was observed in eight samples (8/35; 22.9%). We conclude that the presence of parasite DNA suggests that ticks participate in the zoonotic cycle of canine visceral leishmaniasis, in the city of Teresina, Piauí.
    Full-text · Article · Jul 2014 · Revista do Instituto de Medicina Tropical de São Paulo
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