Prevalence of visceral leishmaniasis in A population of free-roaming dogs as determined by multiple sampling efforts: A longitudinal study analyzing the effectiveness of euthanasia.

Free-roaming dogs affected by visceral leishmaniasis (VL) contribute to the geographical expansion of the disease and require special attention from health authorities. The objectives of the present study were to determine the prevalences of VL in a population of free-roaming dogs in an endemic region of Brazil, to establish the spatial distribution of infected dogs, and to examine the effectiveness of euthanasia of infected dogs in controlling the disease in this particular population. Dogs were captured every two months during seven sampling efforts. Capture locations were georeferenced and captured dogs were assessed for the presence of anti-Leishmania antibodies using an enzyme-linked immunosorbent assay (ELISA) as a screening test and the indirect fluorescent antibody test (IFAT) as the confirmatory procedure. Dogs that were seropositive by both assays were considered infected and were submitted to immediate euthanasia. After the end of the collection period, stored sera were evaluated with the Dual-Path Platform test (DPP). Animals positive by this method and by ELISA were also considered infected as currently recommended by the Brazilian Ministry of Health. Spatial analysis was performed using the Kernel technique. A total of 328 dogs were captured at least once during the sampling period, 25 (7.6%) of them were seropositive by ELISA and IFAT and 27 (8.2%) by DPP and ELISA. The prevalence of VL showed an overall decreasing trend. However, even with periodical euthanasia, it was not possible to eliminate the infection and increased prevalences were observed in the fourth and seventh samplings. There was a high overall agreement between the two criteria for defining infection. None of the dogs that tested negative by IFAT at the first capture seroconverted in the subsequent captures but a number of dogs exhibited changes in serological status over time. From the three dogs initially tested negative by ELISA and IFAT, but tested positive by the protocol currently adopted in Brazil, two became negative in subsequent recaptures. Spatial analysis revealed that infected animals concentrated in areas with a high density of free-roaming dogs. The existence of VL among homeless dogs may contribute significantly in the persistence of the disease among the human population, despite the practice of periodical euthanasia. The operational and ethical implications associated with euthanasia of free-roaming dogs, and the failure to control the transmission of VL among this particular population, led us to conclude that interventions promoting responsible ownership of pets may be a more effective strategy.

Autochthonous case of Canine Visceral Leishmaniasis in a non-endemic area in Minas Gerais, Brazil / Caso autóctone de Leishmaniose Visceral Canina em área indene em Minas Gerais

Visceral Leishmaniasis by Leishmania infantum chagasi is an endemic zoonosis present in many areas of Brazil. This parasite needs reservoirs for maintenance of the infection and the presence of dogs in urban areas is a key factor for the spread of canine visceral leishmaniasis (CVL). The aim of this study was to report the first autochthonous case of CVL in the municipality of Iguatama, in west central region of Minas Gerais State. Dog infection by Leishmania infantum chagasi was confirmed in the municipality, previously considered as non-endemic area to CVL. The canine infection by Leishmania was confirmed by three immunological tests for antibodies: indirect immunofluorescence assay (IFA), rapid Dual Path Platform (DPP®) CVL immunochromatographic test, enzyme-linked immunosorbent assay (ELISA), and microscopic demonstration of Leishmania amastigotes in imprints of spleen and bone marrow stained by Giemsa. The species Leishmania infantum chagasi was confirmed by molecular diagnosis (PCR). Studies are being carried out, aiming to describe the importance and the prevalence of this disease in the region and factors associated with its transmission.(AU)

Leishmaniose visceral causada por Leishmania infantum chagasi é uma zoonose endêmica em algumas regiões do Brasil. Este parasito necessita de reservatórios para a manutenção da infecção e a presença de cães em áreas urbanas é um fator importante para a manutenção e expansão da leishmaniose visceral canina (LVC). O objetivo deste estudo foi relatar o primeiro caso autóctone de LVC no município de Iguatama, na região Centro Oeste de Minas Gerais, cidade onde a LVC era tida como não existente. A infecção canina por Leishmania foi confirmada por três testes imunológicos para pesquisa de anticorpos: reação de imunofluorescência indireta (RIFI), teste rápido de imunocromatografia com plataforma dupla (DPP® LVC) e ensaio imunoenzimático (ELISA), e demonstração microscópica de amastigotas de Leishmania a partir de aposições de amostras de baço e de medula óssea corados pelo Giemsa. A espécie Leishmania infantum chagasi foi confirmada por diagnóstico molecular (PCR). Estudos estão sendo realizados com o objetivo de descrever a importância e a prevalência desta parasitose na região e os fatores associados com a transmissão.(AU)

IgG avidity in differential serodiagnosis of human strongyloidiasis active infection.

IgG avidity assays have been developed for several parasitic diseases although there are no researches focused in strongyloidiasis diagnosis. Definitive diagnosis of strongyloidiasis is based on the presence of Strongyloides larvae in stool, but majority of cases involve low and irregular larval output. While limitations of serological assays for strongyloidiasis are well known, characteristics of persons who are misdiagnosed based on negative coproparasitological tests have been little explored. The aim of the present study was to evaluate the use of IgG avidity to detect patients with active strongyloidiasis and to characterize sources of disagreement between serology and coproparasitology. A total of 80 serum samples was analyzed, 40 from patients with Strongyloides larvae in stool (G1) and 40 from individuals with negative coproparasitology, but positive serology (G2). Serum samples were analyzed in an indirect IgG avidity ELISA using urea 6M in serial double dilutions from 1:80 to 1:2560. Avidity index (AI) was calculated to each serum dilution and analyzed as screening AI (serum dilution of 1:160) or mean AI of different serum dilutions that had a positive result. Statistical analyzes were performed by Mann-Whitney's (U) and Fisher's exact tests. At screening dilution, median of AI was 68% in G1 and 88% in G2 (P<0.0001), whereas median of mean AI in G1 was 72% and in G2 94% (P<0.0001), but there was no significant differences between both AI in each patient group. A cut off value established at AI of 75% demonstrated a significant difference between groups, with G1 sera showing AI<75% and G2 sera with AI>75% (P<0.0001). In conclusion, IgG avidity assays may distinguish active infection with Strongyloides stercoralis from suspect or serologically false positive cases.

IgA detection in human neurocysticercosis using different preparations of heterologous antigen.

Neurocysticercosis (NC) is the most important neurological disease of parasitic origin in humans. IgA and IgG detection in serum from neurocysticercosis patients was tested using some antigenic preparations of total saline extract from Taenia saginata: detergent (D) and aqueous (A) phases extracted with Triton X-114 and the jacalin bound (JBF) and unbound fractions (JUF) obtained by affinity chromatography using jacalin column. Samples were obtained from 45 patients with definitive NC, who were subdivided into active-NC group and inactive-NC group; 35 patients with other parasitoses; and 30 apparently healthy individuals. Sensitivity and specificity were calculated. Specificity to detect IgA and IgG for D phase, respectively, were 89.8% and 86.9% and for IgG detection 91.3% and 76.8% when using D phase and JUF, respectively. D phase and JBF proved to be specific and efficient and could be efficiently utilized as an alternative antigen for IgA detection in NC, with comparable results with IgG.