Dataset Information

The Rapid Test Based on Leishmania infantum Chimeric rK28 Protein Improves the Diagnosis of Canine Visceral Leishmaniasis by Reducing the Detection of False-Positive Dogs.

ABSTRACT: Visceral Leishmaniasis (VL) has spread to many urban centers worldwide. Dogs are considered the main reservoir of VL, because canine cases often precede the occurrence of human cases. Detection and euthanasia of serologically positive dogs is one of the primary VL control measures utilized in some countries, including Brazil. Using accurate diagnostic tests can minimize one undesirable consequence of this measure, culling false-positive dogs, and reduce the maintenance of false-negative dogs in endemic areas. In December 2011, the Brazilian Ministry of Health replaced the ELISA (EIE CVL) screening method and Indirect Immunofluorescence Test (IFI CVL) confirmatory method with a new protocol using the rapid DPP CVL screening test and EIE CVL confirmatory test. A study of diagnostic accuracy of these two protocols was done by comparing their performance using serum samples collected from a random sample of 780 dogs in an endemic area of VL. All samples were evaluated by culture and real time PCR; 766 out of the 780 dogs were tested using the previous protocol (IFI CVL + EIE CVL) and all 780 were tested using the current protocol (DPP CVL + EIE CVL). Performances of both diagnostic protocols were evaluated using a latent class variable as the gold standard. The current protocol had a higher specificity (0.98 vs. 0.95) and PPV (0.83 vs. 0.70) than the previous protocol, although sensitivity of these two protocols was similar (0.73). When tested using sera from asymptomatic animals, the current protocol had a much higher PPV (0.63 vs. 0.40) than the previous protocol (although the sensitivity of either protocol was the same, 0.71). Considering a range of theoretical CVL prevalences, the projected PPVs were higher for the current protocol than for the previous protocol for each theoretical prevalence value. The findings presented herein show that the current protocol performed better than previous protocol primarily by reducing false-positive results.

SUBMITTER: Fraga DB

PROVIDER: S-EPMC4701173 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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The Rapid Test Based on Leishmania infantum Chimeric rK28 Protein Improves the Diagnosis of Canine Visceral Leishmaniasis by Reducing the Detection of False-Positive Dogs.

Fraga Deborah Bittencourt Mothé DB Pacheco Luciano Vasconcellos LV Borja Lairton Souza LS Tuy Pétala Gardênia da Silva Estrela PG Bastos Leila Andrade LA Solcà Manuela da Silva Mda S Amorim Leila Denise Alves Ferreira LD Veras Patrícia Sampaio Tavares PS

PLoS neglected tropical diseases 20160105 1

Visceral Leishmaniasis (VL) has spread to many urban centers worldwide. Dogs are considered the main reservoir of VL, because canine cases often precede the occurrence of human cases. Detection and euthanasia of serologically positive dogs is one of the primary VL control measures utilized in some countries, including Brazil. Using accurate diagnostic tests can minimize one undesirable consequence of this measure, culling false-positive dogs, and reduce the maintenance of false-negative dogs in ...[more]

PMID: 26731098

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Project description:BACKGROUND:Visceral leishmaniasis (VL) is an infectious disease with a variety of clinical signs. The main form of parasite transmission to humans and other mammalian hosts is through the bite of infected arthropod females with Lutzomyia longipalpis serving as the main vector in the Americas. Dogs are the main urban domestic reservoirs of the parasite and the main source of vector infection due to their high prevalence in endemic areas and the large number of parasites in the skin of infected animals. Although miltefosine has been used in Europe since 2002 for treatment of VL infected dogs, in the Americas the treatment of dogs has not been recommended. Therefore, this study aimed to evaluate efficacy of miltefosine observing a reduction of clinical signs in infected dogs and the infectiveness to the vector by Leishmania (L.) infantum. METHODS:To our knowledge, this is the first controlled study using qPCR and xenodiagnosis to evaluate the efficacy of miltefosine (Milteforan®, Virbac) as a single treatment in Brazil. Thirty-five adult dogs with canine visceral leishmaniasis (CVL), confirmed by clinical and laboratory tests, were included in this study. They received miltefosine at a dose of 2 mg/kg every 24 h for 28 days. The dogs were observed over a three-month period, during which clinical evaluations based on a scoring system were conducted at pre-established times. Parasite load was assessed by cytology and real-time polymerase chain reaction (qPCR). Transmissibility to the vector was evaluated by xenodiagnosis. RESULTS:At the end of the period, the following were observed: (i) the remission of clinical signs with a reduction in clinical scores for 94.2% of the animals; (ii) a statistically significant reduction (98.7%) in parasitic load by qPCR; and (iii) a reduction in infectivity to sand flies. After treatment, 74.2% of the animals remained or had become non-infectious. CONCLUSIONS:Our study indicates that the use of miltefosine administered orally for 4 weeks contributes to a clinical improvement and reduction in infectivity of dogs to L. infantum.

Project description:BackgroundA recombinant cysteine proteinase from Leishmania (Leishmania) infantum chagasi (rLdccys1) was previously shown to induce protective immune responses against murine and canine visceral leishmaniasis. These findings encouraged us to use rLdccys1 in the immunotherapy of naturally infected dogs from Teresina, Piauí, a region of high incidence of visceral leishmaniasis in Brazil.Methodology/principal findingsThirty naturally infected mongrel dogs displaying clinical signs of visceral leishmaniasis were randomly divided in three groups: one group received three doses of rLdccys1 in combination with the adjuvant Propionibacterium acnes at one month interval between each dose; a second group received three doses of P. acnes alone; a third group received saline. The main findings were: 1) dogs that received rLdccys1 with P. acnes did not display increase of the following clinical signs: weight loss, alopecia, onychogryphosis, cachexia, anorexia, apathy, skin lesions, hyperkeratosis, ocular secretion, and enlarged lymph nodes; they also exhibited a significant reduction in the spleen parasite load in comparison to the control dogs; 2) rLdccys1-treated dogs exhibited a significant delayed type cutaneous hypersensitivity elicited by the recombinant antigen, as well as high IgG2 serum titers and low IgG1 serum titers; sera from rLdccys1-treated dogs also contained high IFN-? and low IL-10 concentrations; 3) control dogs exhibited all of the clinical signs of visceral leishmaniasis and had low serum IgG2 and IFN-? levels and high concentrations of IgG1 and IL-10; 4) all of the dogs treated with rLdccys1 were alive 12 months after treatment, whereas dogs which received either saline or P. acnes alone died within 3 to 7 months.Conclusions/significanceThese findings illustrate the potential use of rLdccys1 as an additional tool for the immunotherapy of canine visceral leishmaniasis and support further studies designed to improve the efficacy of this recombinant antigen for the treatment of this neglected disease.

Project description:Wild canids and domestic dogs are the main reservoir of zoonotic visceral leishmaniasis (VL) caused by Leishmania infantum (syn.: Leishmania chagasi). Serological diagnosis of VL is therefore important in both human and dog leishmaniasis from a clinical and epidemiological point of view. Routine diagnosis of VL is traditionally carried out by immunofluorescent antibody test (IFAT), which is laborious and difficult to standardize and to interpret. In the last decade, however, several specific antigens of Leishmania infantum have been characterized, allowing the development of a recombinant-based immunoassay. Among them, the whole open reading frame encoding K9 antigen, the gene fragment encoding the repetitive sequence of K26, and the 3'-terminal gene fragment of the kinesin-related protein (K39sub) were previously evaluated as diagnostic markers for canine leishmaniasis and proved to be independent in their antibody reactivity. Since sensitivity of serological test is usually higher in multiple-epitope format, in this study the relevant epitopes of K9, K26, and K39 antigens were joined by PCR strategy to produce the chimeric recombinant protein. The resulting mosaic antigen was found highly expressed in Escherichia coli and efficiently purified by affinity chromatography. Antigenic properties of this recombinant antigen were evaluated by indirect enzyme-linked immunosorbent assay (ELISA) using a panel of human and dog sera previously characterized by parasitological and/or serological techniques. Chimeric ELISA showed 99% specificity in both human (n = 180) and canine (n = 343) control groups, while sensitivity was higher in canine VL (96%, n = 213) than in human VL (82%, n = 185). Accordingly, concordance between IFAT and canine chimeric ELISA (k = 0.95, 95% confidence interval = 0.93 to 0.98) was higher than between IFAT and human chimeric ELISA (k = 0.81, 95% confidence interval = 0.76 to 0.87). Results suggest the potential use of this new antigen for routine serodiagnosis of VL in both human and canine hosts.

Project description:BackgroundControl strategies adopted by the Brazilian Visceral Leishmaniasis Surveillance and Control Programme (VLSCP) include identifying and culling seropositive infected dogs, early diagnosis and treatment of human cases, chemical control of the vector and population awareness. This study evaluated the effectiveness of the VLSCP on the prevalence and incidence rates of Leishmania infantum in children residing in areas under different VLSCP intervention times.MethodsA quasi-experimental epidemiological study with a panel (two cross-sectional) and a concurrent cohort was performed in three areas of Belo Horizonte, southeast Brazil. The first cross-sectional study (I) was carried out with 1875 children, 478 of which were enrolled in the cohort study. In the second cross-sectional study (II), 413 additional children were included, totalizing 891 children. Laboratory diagnosis was performed by ELISA-rK39. Analyses included multilevel logistic and Poisson regression models.ResultsThe incidence rates of L. infantum infection were: 14.4% in the area where VLSCP intervention was initiated in 2006 (AI2006); 21.1% in the area where intervention was initiated in 2008 (AI2008); and 11.6% in the area where intervention was initiated in 2010 (AI2010 - control area). A follow-up period of 24 months showed that the persons-time incidence rates in AI2006, AI2008, and AI2010 were: 6.2/100, 10/100, and 5.6/100 persons/24 months, respectively. The final prevalence rates of infection (cross-sectional II - in 2012), compared to the initial rates (cross-sectional I - in 2010), increased 83.7% in AI2006, 74.1% in AI2008, and decreased 5% in AI2010. Analysis of the effectiveness revealed that children residing in AI2008 are more likely to be infected (OR = 1.84; 95% CI: 1.06-3.23) and present a higher risk of infection (IRR = 1.76; 95% CI: 1.05-2.95) compared to those in AI2010. No statistically significant differences were observed in asymptomatic infection (OR and IRR) in AI2006 compared to AI2010.ConclusionsThe VLSCP was not effective at controlling L. infantum infection in areas where interventions had respectively been carried out for six and four years. However, it is unclear what the consequences in terms of human infection and diseases would be in the absence of the VLSCP. Efforts to improve the effectiveness of control measures remain a necessary priority.

Dataset Information

The Rapid Test Based on Leishmania infantum Chimeric rK28 Protein Improves the Diagnosis of Canine Visceral Leishmaniasis by Reducing the Detection of False-Positive Dogs.

Publications

The Rapid Test Based on Leishmania infantum Chimeric rK28 Protein Improves the Diagnosis of Canine Visceral Leishmaniasis by Reducing the Detection of False-Positive Dogs.

Similar Datasets

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