Evaluation of DPP® and SNAP® Rapid Tests for diagnosis of Leishmania infantum canine infections

Abstract INTRODUCTION: Visceral leishmaniasis is a disease that affects humans, wildlife, and domestic species. Since dogs play a key role in urban Leishmania spp. transmission, the Brazilian government maintains the Monitoring and Control Program of Visceral Leishmaniasis (VLMCP) in endemic regions, which promotes awareness campaigns aiming to enhance the control of the infection. The VLMCP recommends the Dual Path Platform (DPP®) canine visceral leishmaniasis test (Bio-Manguinhos, Brazil) for screening and enzyme-linked immunosorbent assay to confirm the infection. The DPP® test is produced and distributed by the Health Ministry to the Municipal Health Centers responsible for the local VLMCP. The test is not available to all the clinics, forcing some veterinarians to use other rapid tests for screening and diagnosis of this disease in their daily routine. METHODS: The present study was conducted to compare the performance of the DPP® and SNAP® tests using sera from the dogs with confirmed infections of L. infantum and from the dogs with no previous testing, residing in areas with a low Leishmania infection. RESULTS: There was 97.0% agreement between the two tests. Sensitivity and specificity of the SNAP® test were 96.3% and 100%, respectively. Agreement between both the antibody tests and the parasitological detection methods was 96.8%. The DPP® test had 95.8% sensitivity and 100% specificity. CONCLUSIONS: The SNAP® and the DPP® tests were virtually equivalent in terms of detection of canine antibodies against L. infantum, and both the tests demonstrated high and similar levels of sensitivity and specificity.

Natural infection by Trypanosoma cruzi in triatomines and seropositivity for Chagas disease of dogs in rural areas of Rio Grande do Norte, Brazil

Abstract INTRODUCTION: Chagas disease is caused by the protozoa Trypanosoma cruzi. Its main reservoir is the domestic dog, especially in rural areas with favorable characteristics for vector establishment and proliferation. The aims of this study were to collect data, survey and map the fauna, and identify T. cruzi infection in triatomines, as well as to assess the presence of anti-T. cruzi antibodies in dogs in rural areas of the municipality of Mossoró, Brazil. METHODS: An active entomologic research was conducted to identify adult specimens through an external morphology dichotomous key. The analysis of natural infection by T. cruzi in the insects was performed by isolation in culture and polymerase chain reaction. The antibody testing for T. cruzi in dogs was performed by enzyme-linked immunosorbent assay and indirect immunofluorescence assay. RESULTS: A total of 68 triatomines were captured, predominantly the Triatoma brasiliensis brasiliensis (Neiva 1911) species. The vector mapping displayed areas with greater risk for parasite transmission. Of the examined triatomines (51 specimens), 41.2% (21/51) were positive on polymerase chain reaction, and all were negative on culture. In the serum testing, 11% (25/218) of dogs were seropositive, but no association was found between the serologic results and the presence and infection by T. cruzi in triatomines. CONCLUSIONS: This study demonstrated the movement of T. cruzi in the studied area, by the presence of vectors and naturally infected domestic reservoirs. The mapping of the studied rural area demonstrates the risk of disease transmission.

Canine visceral leishmaniosis in an area of fishing tourism, Bonito Municipality, Mato Grosso do Sul, Central-West Brazil / Leishmaniose visceral canina em área de turismo pesqueiro, município de Bonito, Mato Grosso do Sul, Centro-Oeste do Brasil

ABSTRACT: The study aimed to investigate Leishmania infection in a population of dogs (92 animals) in a fishing area of Bonito Municipality, and evaluate comparatively the serological methods used, immunoenzymatic assay (ELISA), indirect immunofluorescence antibody test (IFAT), and rapid Dual Path-Platform test (DPP®). Blood and aspirate of bone marrow samples were used and parasitological investigation was also performed, such as parasite isolation in Neal, Novy, Nicolle (NNN) medium culture, Woo technique, Giemsa stained smears and specific identification by polymerase chain reaction (PCR). IFAT revealed 56/92 seropositive, the ELISA 8/92 and the DPP®41/92. Regarding the agreement between the serological tests by the Kappa index, there was a slight agreement between ELISA/IFAT and ELISA/DPP®, and fair agreement in IFAT/DPP®. The NNN culture was positive in three out of 21 dogs, and identified by PCR as Leishmania infantum chagasi. No samples were positive by the Woo technique. Our results showed low agreements between the serological tests recommended by the Brazilian Ministry of Heath, and it is necessary to associate other diagnostic techniques, such as parasitological tests and PCR, to increase the sensitivity for canine visceral leishmaniosis diagnosis, mainly regarding asymptomatic dogs in endemic areas.

RESUMO: O estudo teve como objetivo verificar a infecção por Leishmania em uma população de cães (n=92 animais) de uma área de turismo de pesca no município de Bonito e avaliar comparativamente os métodos sorológicos utilizados, ensaio imunoenzimático (ELISA), reação de imunofluorescência indireta (RIFI) e teste rápido de plataforma dupla (DPP®). Testes parasitológicos também foram realizados, como o isolamento do parasita em meio de cultura Neal, Novy, Nicolle, técnica de Woo, esfregaços em lâminas coradas com Giemsa e identificação específica pela reação em cadeia da polimerase (PCR). A RIFI revelou sorologia positiva de 56/92, ELISA 8/92 e DPP®41/92. Quanto à concordância entre os testes sorológicos pelo índice Kappa, houve um ligeiro acordo entre ELISA/RIFI e ELISA/DPP®, e uma concordância razoável entre RIFI/DPP®. A cultura NNN foi positiva em três cães, e identificada por PCR como Leishmania infantum chagasi. Nenhuma amostra foi positiva pela técnica de Woo. Nossos resultados mostraram baixas concordâncias entre os testes sorológicos recomendados pelo Ministério da Saúde, sendo necessário associar a outras técnicas de diagnóstico, como testes parasitológicos e PCR, para aumentar a sensibilidade ao diagnóstico de leishmaniose visceral canina, principalmente, com relação aos cães assintomáticos em áreas endêmicas.

N-acetyl-cysteine inhibits liver oxidative stress markers in BALB/c mice infected with Leishmania amazonensis

BACKGROUND Leishmaniasis is a parasitosis caused by several species of the genus Leishmania. These parasites present high resistance against oxidative stress generated by inflammatory cells. OBJECTIVES To investigate oxidative stress and molecular inflammatory markers in BALB/c mice infected with L. amazonensis and the effect of antioxidant treatment on these parameters. METHODS Four months after infection, oxidative and inflammatory parameters of liver, kidneys, spleen, heart and lungs from BALB/c mice were assessed. FINDINGS In liver, L. amazonensis caused thiol oxidation and nitrotyrosine formation; SOD activity and SOD2 protein content were increased while SOD1 protein content decreased. The content of the cytokines IL-1β, IL-6, TNF-α, and the receptor of advanced glycation endproducts (RAGE) increased in liver. Treatment with the antioxidant N-acetyl-cysteine (20 mg/kg b.w) for five days inhibited oxidative stress parameters. MAIN CONCLUSIONS L. amazonensis induces significant alterations in the redox status of liver but not in other organs. Acute antioxidant treatment alleviates oxidative stress in liver, but it had no effect on pro-inflammatory markers. These results indicate that the pathobiology of leishmaniasis is not restricted to the cutaneous manifestations and open perspectives for the development of new therapeutic approaches to the disease, especially for liver function.

Awareness of visceral leishmaniasis and its relationship to canine infection in riverside endemic areas in Northeastern Brazil

Introduction An awareness of visceral leishmaniasis (VL) is necessary to encourage the population to participate in prevention and control in collaboration with more efficient, centrally organized health programs. The aim of this study was to evaluate the awareness of the riverside population regarding VL and the association between awareness and the prevalence of canine visceral leishmaniasis (CVL). Methods In total, 71 people living in riverside areas in the City of Mossoró in State of Rio Grande do Norte participated of the study, and 71 dogs were tested for CVL by polymerase chain reaction (PCR). Association analysis of several variables related to knowledge of the riverside population regarding CVL positivity was performed, yielding odds ratios (OR) and 95% confidence intervals (CI), and significance was determined using chi-square (χ2) and Fisher's exact tests. Results Among individuals whose dogs tested positive for CVL, 60% did not know the cure for CVL, and these subjects were three times more likely to have a dog test positive for CVL than those who were aware the cure for CVL. Knowledge of CVL cure was the only variable that remained in the logistic model after the successive removal of variables, with an adjusted OR of 3.11 (95%CI: 1.1-8,799; p=0.032). Conclusions Insufficient awareness regarding VL in riverside areas with CVL-positive dogs was associated with increased rates of canine infection, which suggests that changes in habits and the adoption of attitudes and preventive practices may contribute to the control and prevention of this disease. This study reinforces the need to invest in better health education programs regarding VL. .

Performance of DPP™ immunochromathographic rapid test (IRT) for canine visceral leishmaniasis:comparison with other serological methods in suspected dogs from Cuiabá, Mato Grosso State, Brazil / Desempenho do teste rápido imunocromatográfico (TRI) para o diagnóstico da leishmaniose visceral canina: comparação com outros métodos sorológicos em cães suspeitos de Cuiabá, Mato Grosso, Brasil

The immunochromathographic rapid test (IRT) for canine visceral leishmaniasis (CVL) was tested in suspected dogs from the urban area of Cuiabá. The performance of IRT was compared with IFT and EIE and the direct parasitological test (DPT) as the gold standard. The sample, comprising 45 dogs, was selected by the Zoonosis Control Center. Twenty (51%) were male and thirty-four (75.5%) were both mongrel and had an estimated age of less than three years old. According to clinical data and lab tests: 10 (26.3%) dogs have been classified as exposed or infected and 18 (47.4%) as sick. IRT has achieved the best result for sensibility, 62%, high specificity, 87% and for positive and negative predictive values: 83.3% and negative 81.48%, respectively, reinforced by a k coefficient equal to 0.50, representing substantial agreement.

O teste rápido imunocromatográfico (TRI) para leishmaniose visceral canina (LVC) foi testado em cães suspeitos da área urbana de Cuiabá. O desempenho do teste foi comparado com RIFI e ELISA e, como padrão ouro, o teste parasi- tológico direto (TPD). A amostra com 45 cães foi selecionada pelo Centro de Controle de Zoonoses, sendo 23 (51,1%) machos, 34 (75,5%) sem raça definida e com idade estimada inferior a três anos. De acordo com os dados clínicos e os exames laboratoriais, 10 (26,3%) cães foram classificados como expostos, outros 10 (26,3%) como infectados e 18 (47,4%) como doentes. O TRI alcançou os melhores resultados quanto à sensibilidade, 62%, elevada especificidade, 87% e para os valores preditivos positivo e negativo: 83,30% e 81,48%, respectivamente, consolidado pelo coeficiente Kappa igual a 0,50, de concordância moderada. Os resultados confirmaram TRI como um bom preditor de doença e infecção para LVC.