An algorithm for visceral leishmaniasis diagnosis in Brazil from a 10-year analysis of National Reference Laboratory data.

Visceral leishmaniasis (VL) requires diagnostic assays to complement clinical suspicion. However, there is no standardization of a diagnostic flow using available assays. This study aimed to evaluate the performance of parasitological, molecular, and serological assays for diagnosing VL and propose a diagnostic flow based on performance, practicality, and invasiveness. We conducted a study of 10-year (2010-2020) routine diagnoses of VL at the Brazilian National Reference Laboratory. We propose a diagnostic flow where individuals suspected of VL are initially screened for antibodies using an immunochromatographic test (ICT) with rK39 antigen on the nitrocellulose membrane. This is followed by a blood polymerase chain reaction (PCR) for Leishmania sp. kDNA and direct parasitological exam and/or PCR in bone marrow aspirate. A positive result in any of these assays can define a VL case. If clinical suspicion persists in negative individuals, the diagnostic flow should be repeated. The proposed flow has the potential to standardize and improve the diagnosis of VL. It reduces the need for invasive tests without compromising diagnostic accuracy.

A multicenter comparative study of the performance of four rapid immunochromatographic tests for the detection of anti-Trypanosoma cruzi antibodies in Brazil.

Diagnosis of Trypanosoma cruzi (T. cruzi) infection in the chronic phase of Chagas disease (CD) is performed by serologic testing. Conventional tests are currently used with very good results but require time, laboratory infrastructure, and expertise. Rapid diagnostic tests (RDTs) are an alternative as the results are immediate and do not require specialized knowledge, making them suitable for epidemiologic studies and promising as a screening tool. Nevertheless, few studies conducted comparative evaluations of RDTs to validate the results and assess their performance. In this study, we analyzed four trades of rapid tests (OnSite Chagas Ab Combo Rapid Test-United States, SD Bioline Chagas AB-United States, WL Check Chagas-Argentina, and TR Chagas Bio-Manguinhos-Brazil) using a panel of 190 samples, including sera from 111 infected individuals, most of whom had low T. cruzi antibody levels. An additional 59 samples from uninfected individuals and 20 sera from individuals with other diseases, mainly visceral leishmaniasis, were included. All tests were performed by three independent laboratories in a blinded manner. Results showed differences in sensitivity from 92.8 to 100%, specificity from 78.5 to 92.4%, and accuracy from 90.5 to 95.3% among the four assays. The results presented here show that all four RDTs have high overall diagnostic ability. However, WL Check Chagas and TR Chagas Bio-Manguinhos were considered most suitable for use in screening studies due to their high sensitivity combined with good performance. Although these two RDTs have high sensitivity, a positive result should be confirmed with other tests to confirm or rule out reactivity/positivity, especially considering possible cross-reactivity with individuals with leishmaniasis or toxoplasmosis.

Phase II validation study of the rK39 ELISA prototype for the diagnosis of canine visceral leishmaniasis in Brazil.

Dogs are the main reservoirs in the domestic transmission cycle of visceral leishmaniasis, and the diagnosis is essential for the effectiveness of the control measures recommended by the Brazilian Ministry of Health. We assessed the diagnostic performance of the ELISA-Vetlisa/BIOCLIN prototype with serum samples from 200 dogs, in triplicate, including symptomatic, oligosymptomatic, asymptomatic, and healthy dogs, originated by two distinct panels (A and B) characterized by parasitological tests as the reference standard. In this study, the prototype kit showed a 99% sensitivity (95%CI: 94.5-100.0) and a 100% specificity (95%CI: 96.4-100.0). The sensitivity of the prototype kit did not vary significantly with the clinical status of the dogs. Considering the final result classification (positive or negative), agreement between the results of repeated tests was almost perfect (kappa = 0.99; 95%CI: 0.98-1.00). ELISA-Vetlisa/BIOCLIN is a promising option for the serological diagnosis of canine visceral leishmaniasis in Brazil.

Phase II validation study of the rK39 ELISA prototype for the diagnosis of canine visceral leishmaniasis in Brazil / Estudo de validação da fase II do teste ELISA rK39 para o diagnóstico da leishmaniose visceral canina no Brasil / Estudio de validación de la fase II del test ELISA rK39 para el diagnóstico de la leishmaniasis visceral canina en Brasil

Abstract: Dogs are the main reservoirs in the domestic transmission cycle of visceral leishmaniasis, and the diagnosis is essential for the effectiveness of the control measures recommended by the Brazilian Ministry of Health. We assessed the diagnostic performance of the ELISA-Vetlisa/BIOCLIN prototype with serum samples from 200 dogs, in triplicate, including symptomatic, oligosymptomatic, asymptomatic, and healthy dogs, originated by two distinct panels (A and B) characterized by parasitological tests as the reference standard. In this study, the prototype kit showed a 99% sensitivity (95%CI: 94.5-100.0) and a 100% specificity (95%CI: 96.4-100.0). The sensitivity of the prototype kit did not vary significantly with the clinical status of the dogs. Considering the final result classification (positive or negative), agreement between the results of repeated tests was almost perfect (kappa = 0.99; 95%CI: 0.98-1.00). ELISA-Vetlisa/BIOCLIN is a promising option for the serological diagnosis of canine visceral leishmaniasis in Brazil.

Resumo: Os cães são os principais reservatórios do ciclo de transmissão domiciliar da leishmaniose visceral, e o diagnóstico é essencial para a efetividade das medidas de controle recomendadas pelo Ministério da Saúde. Os autores avaliam o desempenho diagnóstico do protótipo da ELISA-Vetlisa/BIOCLIN em amostras sorológicas de 200 cães, em triplicata, incluindo cães sintomáticos, oligossintomáticos e saudáveis, com dois painéis distintos (A e B) caracterizados por testes parasitológicos enquanto referência. No estudo, o kit-protótipo mostrou sensibilidade de 99% (IC95%: 94,5-100,0) e especificidade de 100% (IC95%: 96,4-100,0). A sensibilidade do kit-protótipo não variou de maneira significativa de acordo com o estado clínico dos cães. Considerando a classificação final dos resultados (positivo ou negativo), a concordância entre os resultados dos testes em triplicata foi quase perfeita (kappa = 0,99; IC95%: 0,98-1,00). O protótipo ELISA-Vetlisa/BIOCLIN tem o potencial de ser utilizada para o diagnóstico sorológico da leishmaniose visceral canina no Brasil.

Resumen: Los perros son los principales reservorios en el ciclo de transmisión doméstica de la leishmaniasis visceral, por ello el diagnóstico es esencial para la efectividad de las medidas de control recomendadas por el Ministerio de Salud de Brasil. Evaluamos el desempeño diagnóstico de ELISA-Vetlisa/BIOCLIN prototipo con muestras de sérum de 200 perros, en triplicado, incluyendo sintomático, oligosintomático, asintomático y perros sanos, originadas por dos paneles distintos (A y B), caracterizados por test parasitológicos como referencia estándar. En este estudio, el kit prototipo mostró un 99% de sensibilidad (IC95%: 94,5-100,0) y un 100% de especificidad (IC95%: 96,4-100,0). La sensibilidad del kit prototipo no varió significativamente con el estatus clínico de los perros. Considerando la clasificación final del resultado (positiva o negativa), el acuerdo entre los resultados de los tests repetidos fue casi perfecto (kappa = 0,99; IC95%: 0,98-1,00). ELISA-Vetlisa/BIOCLIN tiene potencial para ser usado para el diagnóstico serológico de la leishmaniasis visceral canina en Brasil.

Evidence of a sylvatic enzootic cycle of Leishmania infantum in the State of Amapá, Brazil

Abstract INTRODUCTION: Leishmania infantum was considered to be absent from Amapá until 2017 when canine infection was detected. However, there is a lack of knowledge about which reservoir species are involved in transmission in this region. METHODS: Between 2014 and 2016, 86 samples from wild mammals and 74 from domestic dogs were collected in Wajãpi Indigenous Territory and were tested for the presence of deoxyribonucleic acid (DNA) of Leishmania. RESULTS: The DNA of Le. infantum was detected in two rodent samples, Dasyprocta sp. and Proechimys cuvieri. CONCLUSIONS: This is the first evidence characterizing a sylvatic transmission cycle of Le. infantum in the State of Amapá.

Evidence of a sylvatic enzootic cycle of Leishmania infantum in the State of Amapá, Brazil.

INTRODUCTION: Leishmania infantum was considered to be absent from Amapá until 2017 when canine infection was detected. However, there is a lack of knowledge about which reservoir species are involved in transmission in this region. METHODS: Between 2014 and 2016, 86 samples from wild mammals and 74 from domestic dogs were collected in Wajãpi Indigenous Territory and were tested for the presence of deoxyribonucleic acid (DNA) of Leishmania. RESULTS: The DNA of Le. infantum was detected in two rodent samples, Dasyprocta sp. and Proechimys cuvieri. CONCLUSIONS: This is the first evidence characterizing a sylvatic transmission cycle of Le. infantum in the State of Amapá.

Hepatitis Delta Prevalence in South America: A Systematic Review and Meta-Analysis.

Hepatitis delta virus (HDV) has been associated with acute or chronic hepatitis in Latin America, but there is no prevalence study covering South American countries. This meta-analysis aimed to estimate anti-HDV prevalence through a systematic review of published articles in English, Portuguese and Spanish until December 2017. Searches were conducted in Health Virtual Library, Capes, Lilacs, PubMed, and SciELO, according to defined criteria regarding participant selection and geographical setting. Study quality was assessed using the GRADE guidelines. Pooled anti-HDV prevalence was calculated using the DerSimonian-Laird random-effects model with Freeman-Tukey double arcsine transformation. Out of the 405 identified articles, only 31 met the eligibility criteria for inclusion in the meta-analysis. In South America, pooled anti-HDV prevalence among hepatitis B virus carriers was 22.37% (95% confidence interval: 13.72-32.26), though it appeared less frequently in some countries and populations, according to the data collection date. The findings indicated significant successive reductions in anti-HDV prevalence over thirty years. However, there was a scarcity of HDV epidemiological studies outside the Amazon Basin, notably in the Southwest continent and absence of target population standardization. There was a high HDV prevalence in South American countries, despite differences in methodological characteristics and outcomes, highlighting a drastic decline in the last decades. Future studies should identify HDV prevalence estimates in other regions of the continent and identify risk factors.

Hepatitis delta prevalence in South America: a systematic review and meta-analysis

Abstract Hepatitis delta virus (HDV) has been associated with acute or chronic hepatitis in Latin America, but there is no prevalence study covering South American countries. This meta-analysis aimed to estimate anti-HDV prevalence through a systematic review of published articles in English, Portuguese and Spanish until December 2017. Searches were conducted in Health Virtual Library, Capes, Lilacs, PubMed, and SciELO, according to defined criteria regarding participant selection and geographical setting. Study quality was assessed using the GRADE guidelines. Pooled anti-HDV prevalence was calculated using the DerSimonian-Laird random-effects model with Freeman-Tukey double arcsine transformation. Out of the 405 identified articles, only 31 met the eligibility criteria for inclusion in the meta-analysis. In South America, pooled anti-HDV prevalence among hepatitis B virus carriers was 22.37% (95% confidence interval: 13.72-32.26), though it appeared less frequently in some countries and populations, according to the data collection date. The findings indicated significant successive reductions in anti-HDV prevalence over thirty years. However, there was a scarcity of HDV epidemiological studies outside the Amazon Basin, notably in the Southwest continent and absence of target population standardization. There was a high HDV prevalence in South American countries, despite differences in methodological characteristics and outcomes, highlighting a drastic decline in the last decades. Future studies should identify HDV prevalence estimates in other regions of the continent and identify risk factors.

Performance of Alere™ immunochromathographic test for the diagnosis of canine visceral leishmaniasis.

The diagnosis and control of canine visceral leishmaniasis (CVL) has fundamental importance in the control of human visceral leishmaniasis. In this context, the immunochromathographic test (ICT) has emerged as a valuable diagnostic tool. Currently, in Brazil, the algorithm for the diagnosis of CVL uses Dual Path Platform (DPP) ICT as a screening test and ELISA as a confirmatory test. However, the DPP(®) ICT has been facing a problem of insufficient production to meet the national demand. Here, the Alere™ canine visceral leishmaniasis ICT was tested with serum samples from 159 dogs, including symptomatic, asymptomatic and healthy dogs, characterized by DPP(®) ICT and ELISA (panel A), or ELISA and Indirect Immunofluorescence Assay (IFA) (panel B), and parasitological examination as gold standard. In this study, the Alere™ ICT obtained 0.974 sensitivity for panel A and 0.854 sensitivity for panel B. The specificity was 1.0 for both panels. Thus, the Alere™ ICT has potential to be used for the serological diagnosis of CVL.

Mutant Brucella abortus membrane fusogenic protein induces protection against challenge infection in mice.

Brucella species can cause brucellosis, a zoonotic disease that causes serious livestock economic losses and represents a public health threat. The mechanism of virulence of Brucella spp. is not yet fully understood. Therefore, it is crucial to identify new molecules that serve as virulence factors to better understand this host-pathogen interplay. Here, we evaluated the role of the Brucella membrane fusogenic protein (Mfp) and outer membrane protein 19 (Omp19) in bacterial pathogenesis. In this study, we showed that B. abortus Δmfp::kan and Δomp19::kan deletion mutant strains have reduced persistence in vivo in C57BL/6 and interferon regulatory factor 1 (IRF-1) knockout (KO) mice. Additionally, 24 h after macrophage infection with a Δmfp::kan or Δomp19::kan strain expressing green fluorescent protein (GFP) approximately 80% or 65% of Brucella-containing vacuoles (BCVs) retained the late endosomal/lysosomal marker LAMP-1, respectively, whereas around 60% of BCVs containing wild-type S2308 were found in LAMP-1-negative compartments. B. abortus Δomp19::kan was attenuated in vivo but had a residual virulence in C57BL/6 and IRF-1 KO mice, whereas the Δmfp::kan strain had a lower virulence in these same mouse models. Furthermore, Δmfp::kan and Δomp19::kan strains were used as live vaccines. Challenge experiments revealed that in C57BL/6 and IRF-1 KO mice, the Δmfp::kan strain induced greater protection than the vaccine RB51 and protection similar that of vaccine S19. However, a Δomp19::kan strain induced protection similar to that of RB51. Thus, these results demonstrate that Brucella Mfp and Omp19 are critical for full bacterial virulence and that the Δmfp::kan mutant may serve as a potential vaccine candidate in future studies.

Brucella cyclic ß-1,2-glucan plays a critical role in the induction of splenomegaly in mice.

Brucella, the etiological agent of animal and human brucellosis, is a bacterium with the capacity to modulate the inflammatory response. Cyclic ß-1,2-glucan (CßG) is a virulence factor key for the pathogenesis of Brucella as it is involved in the intracellular life cycle of the bacteria. Using comparative studies with different CßG mutants of Brucella, cgs (CßG synthase), cgt (CßG transporter) and cgm (CßG modifier), we have identified different roles for this polysaccharide in Brucella. While anionic CßG is required for bacterial growth in low osmolarity conditions, the sole requirement for a successful Brucella interaction with mammalian host is its transport to periplasmic space. Our results uncover a new role for CßG in promoting splenomegaly in mice. We showed that CßG-dependent spleen inflammation is the consequence of massive cell recruitment (monocytes, dendritics cells and neutrophils) due to the induction of pro-inflammatory cytokines such as IL-12 and TNF-α and also that the reduced splenomegaly response observed with the cgs mutant is not the consequence of changes in expression levels of the characterized Brucella PAMPs LPS, flagellin or OMP16/19. Complementation of cgs mutant with purified CßG increased significantly spleen inflammation response suggesting a direct role for this polysaccharide.

Morphological, biochemical, physiological and molecular aspects of the response of Fusobacterium nucleatum exposed to subinhibitory concentrations of antimicrobials.

Subinhibitory concentrations (SICs) of antimicrobials may result in alterations in bacterial biology with implications for its potential aggression. This has considerable importance for the resident microbiota. Our aim was to analyze the effects of SICs of antimicrobials on the morphological, biochemical, physiological and molecular characteristics of the resident anaerobic Fusobacterium nucleatum. Fourteen strains were obtained from F. nucleatum ATCC 25586, selected by culturing on SICs of ampicillin, ampicillin/sulbactam, clindamycin, chloramphenicol, levofloxacin, metronidazole and piperacillin/tazobactam and subsequent culturing in the absence of drugs. Antimicrobial susceptibility, bacterial morphology, biochemical profiles and biofilm formation were evaluated. Genotyping and analysis of protein profiles were also performed. The antimicrobial susceptibility patterns showed that most of the derived strains were less sensitive to the antimicrobials, even after culturing them without drugs. Morphological and cell complexity alterations were observed, mainly in strains grown in SICs of ß-lactam; these strains also expressed a reduced ability for biofilm formation. The other strains showed an increase in biofilm formation but no apparent morphological changes. Alterations were observed in the carbohydrate metabolism patterns and in the activity of microbial enzymes. Several proteins were positively or negatively regulated and there was polymorphism in the DNA from all derived strains. Therefore, SICs of antimicrobials induce alterations in F. nucleatum, which directly impact its biology. These results emphasize the risk of inadequate antibioticotherapy, which may have serious implications for clinical microbiology and infectious diseases and also may interfere with the host-bacteria relationship.

Multidrug-resistance and toxic metal tolerance of medically important bacteria isolated from an aquaculture system.

The use of antimicrobials and toxic metals should be considered carefully in aquaculture and surrounding environments. We aimed to evaluate medically relevant bacteria in an aquaculture system and their susceptibility to antimicrobials and toxic metals. Selective cultures for enterobacteria (ENT), non-fermenting Gram-negative rods (NFR) and Gram-positive cocci (GPC) were obtained from water samples collected in two different year seasons. The isolated bacteria were biochemically identified and antimicrobial and toxic metal susceptibility patterns were determined. Overall, 407 representative strains were recovered. In general, bacteria isolated from fish ponds showed higher multiple antibiotic resistance indices when compared to those isolated from a water-fed canal. Resistance to penicillin and azithromycin was observed more frequently in the GPC group, whereas resistance to ampicillin and ampicillin/sulbactam or gentamicin was observed more frequently in the ENT and NFR groups, respectively. All the isolated bacteria were tolerant to nickel, zinc, chromium and copper at high levels (≥1,024 µg mL(-1)), whereas tolerance to cadmium and mercury varied among the isolated bacteria (2-1,024 µg mL(-1)). Multidrug-resistant bacteria were more frequent and diverse in fish ponds than in the water-fed canal. A positive correlation was observed between antimicrobial resistance and metal tolerance. The data point out the need for water treatment associated with the aquaculture system.