Evaluation of isotype-based serology for diagnosis of Schistosoma mansoni infection in individuals living in endemic areas with low parasite burden.

Intestinal schistosomiasis is a chronic and debilitating disease that affects public health systems worldwide. Control interventions to reduce morbidity primarily involve the diagnosis and treatment of infected individuals. However, the recommended Kato-Katz (KK) parasitological method shows low sensitivity in individuals with low parasite loads and is not useful for monitoring elimination of parasite transmission at later stages. In the current study, we evaluated the accuracy of serum reactivity levels of different immunoglobulin isotypes in an enzyme-linked immunosorbent assay (ELISA), utilizing Schistosoma mansoni crude extracts, with the aim to improve the diagnosis of infected individuals with low parasite loads. The serum reactivity of IgM and IgG subclass antibodies (IgG1, IgG3, and IgG4) against soluble adult worm and egg antigen preparations was evaluated in residents from a schistosomiasis-endemic area in northern Minas Gerais, Brazil. The parasitological status of the study population was determined through fecal examination with multiple parasitological tests to create a consolidated reference standard (CRS) plus a fecal DNA detection test (q-PCR). Twelve months after praziquantel treatment, a second serum sample was obtained from the population for reexamination. A two-graph receiver operating characteristic curve (TG-ROC) analysis was performed using the serum reactivity of non-infected endemic controls and egg-positive individuals, and the cut-off value was established based on the intersection point of the sensibility and specificity curves in TG-ROC analyses. The diagnostic accuracy of each serological test was evaluated in relation to the parasitological CRS and to the combination of CRS plus qPCR results. The data revealed that serum reactivity of IgM and IgG3 against S. mansoni antigens did not allow identification of infected individuals from the endemic area. In contrast, serum IgG1 and IgG4-reactivity against schistosome antigens could distinguish between infected and non-infected individuals, with AUC values ranging between 0.728-0.925. The reactivity of IgG4 anti-soluble egg antigen - SEA (sensitivity 79 %, specificity 69 %, kappa = 0.49) had the best diagnostic accuracy, showing positive reactivity in more than 75 % of the infected individuals who eliminated less than 12 eggs per gram of feces. Moreover, serum IgG4 reactivity against SEA and against soluble worm antigen preparation (SWAP) was significantly reduced in the serum of infected individuals after 12 months of confirmed parasitological cure and in the absence of re-infection. These results reinforce that the described IgG4 anti-SEA ELISA assay is a sensitive alternative for the diagnosis of active intestinal schistosomiasis in individuals from endemic areas, including in those with a very low parasite load.

Epidemiological profile, spatial patterns and priority areas for surveillance and control of leishmaniasis in Brazilian border strip, 2009-2017.

Leishmaniasis represents a major neglected public health problem and the control measures have not been successful in Brazil. Recent studies have shown leishmaniasis importance to Brazilian border zones which reinforces the need to investigate its spread in those regions. This study aimed to analyze epidemiologic profile and its spatial distribution or aggregation process in both tegumentary and visceral leishmaniasis in the Brazilian border strip from 2009 to 2017. This is an ecological study of the epidemiological profile and spatial patterns encompassing municipalities in the Brazilian border strip. The presence of spatial autocorrelation and determination of priority areas for disease control were performed using global (Moran I) and local (LISA) Moran spatial techniques. The annual mean coefficients of tegumentary and visceral leishmaniasis were 29.8 and 0.6 by 100,000 inhabitants in the border strip, respectively. The indigenous population rates of leishmaniasis in the border zone appears to be higher than in the rest of the country (cutaneous changed from 33.2% to 6.6% and visceral rising from 1.0% to 17.5%) in the period. The most affected municipalities were located in the North and Central arches of the border zone. The results can subsidize the development of more targeted and effective strategies that can contribute to the surveillance and control of leishmaniasis in border zones, as the provision of epidemiological and spatial data on the disease. For better control of the disease, we recommend and emphasize the need to integrate public health policies of neighboring countries.

Prevalence of tungiasis in humans in Brazil and in its federative units: a systematic review

Tungiasis is a neglected parasitic disease caused by penetration of female Tunga penetrans under the skin, causing important health outcomes in humans. Therefore, the aim of this study was to describe the prevalence of tungiasis in Brazil and in its federative units. In November 2019, an investigation was carried out to find studies published from 1980 onwards in MEDLINE, LILACS, Cochrane, CINAHL, Scopus, Web of Science and Embase databases, and in the gray literature, using descriptors related to the prevalence of tungiasis caused by T. penetrans in Brazil. Of the 542 studies found, only 16 published between 2002 and 2010 met the eligibility criteria to be included in this systematic review. Of the 16 selected publications, 14 addressed the prevalence of tungiasis in communities in the Northeast region of the country, one in the South and one in the Southeast. The general prevalence of the parasitosis in the studies ranged from 1.6% to 54.8%, predominantly in the five to nine age group. Eight studies considered the prevalence by gender, ranging from 2.2% to 62.2% for females and 1.1% to 62.5% for males. This systematic review presents an unprecedented survey of the prevalence of tungiasis, a parasitic disease whose dissemination is facilitated by several factors, occuring mainly in low-income communities. Considering the regionalization of the findings, the scarcity of publications, as well as disease neglect, more studies are required.

Spatiotemporal dynamics and risk estimates of COVID-19 epidemic in Minas Gerais State: analysis of an expanding process.

COVID-19 is an infectious disease caused by the recently discovered coronavirus SARS-Cov-2. The disease became pandemic affecting many countries globally, including Brazil. Considering the expansion process and particularities during the initial stages of the epidemic, we aimed to analyze the spatial and spatiotemporal patterns of COVID-19 occurrence and to identify priority risk areas in Minas Gerais State, Southeast Brazil. An ecological study was performed considering all data from human cases of COVID-19 confirmed from the epidemiological week (EW) 11 (March 08, 2020) to EW 26 (June 27, 2020). Crude and smoothed incidence rates were used to analyze the distribution of disease patterns based on global and local indicators of spatial association and space-time risk assessment. Positive spatial autocorrelation and spatial dependence were found. Our results suggest that the metropolitan region of the State capital Belo Horizonte (MRBH) and Vale do Rio Doce mesoregions, as major epidemic foci in the beginning of the expansion process, have had important influence on the dispersion of SARS-CoV-2 in Minas Gerais State. Triangulo Mineiro/Alto Paranaiba region presented the highest risk of infection. In addition, six statistically significant spatiotemporal clusters were identified in the State, three at high risk and three at low risk. Our findings contribute to a greater understanding of the space-time disease dynamic and discuss strategies for identification of priority areas for COVID-19 surveillance and control.

Accuracy of real-time polymerase chain reaction to detect Schistosoma mansoni - infected individuals from an endemic area with low parasite loads.

Due to the efforts to control schistosomiasis transmission in tropical countries, a large proportion of individuals from endemic areas present low parasite loads, which hinders diagnosis of intestinal schistosomiasis by the Kato-Katz (KK) method. Therefore, the development of more sensitive diagnostic methods is essential for efficient control measures. The aim was to evaluate the accuracy of a real-time polymerase chain reaction (RT-PCR) to detect Schistosoma mansoni DNA in fecal samples of individuals with low parasite loads. A cross-sectional population-based study was conducted in a rural community (n = 257) in Brazil. POC-CCA® was performed in urine and feces were used for RT-PCR. In addition, fecal exams were completed by 18 KK slides, saline gradient and Helmintex techniques. The combined results of the three parasitological tests detected schistosome eggs in 118 participants (45.9%) and composed the consolidated reference standard (CRS). By RT-PCR, 117 out of 215 tested samples were positive, showing 91.4% sensitivity, 80.2% specificity and good concordance with the CRS (kappa = 0.71). RT-PCR identified 86.9% of the individuals eliminating less than 12 eggs/g of feces, demonstrating much better performance than POC-CCA® (50.8%). Our results showed that RT-PCR is a valuable alternative for the diagnosis of intestinal schistosomiasis in individuals with very low parasite loads.

Prospection of immunological biomarkers for characterization and monitoring of asymptomatic Leishmania (Leishmania) infantum infection.

In areas endemic for Leishmania infantum, an asymptomatic infection may be an indicator of the extent of transmission. The main goal of this study was to evaluate the applicability of measuring circulating immunological biomarkers as an alternative strategy to characterize and monitor L. infantum asymptomatic infections in combination with serological methods. To this end, 179 children from a region endemic for visceral leishmaniasis (VL), aged 1-10 years old, selected from a cross-sectional study, were identified as asymptomatic (n = 81) or uninfected (n = 98) by qPCR and/or serological tests (ELISA using L. infantum soluble antigen and rK39), and, together with serum samples of children diagnosed with VL (n = 43), were subjected to avidity tests and cytokine levels measurement. Avidity rates (AR) ranging from 41 to 70% were found in 29 children (66%) from the asymptomatic group. On the other hand, high AR (above 70%) were observed in 27 children (64%) from the VL group. Logistic Regression and Classification and Regression Tree (CART) analyses demonstrated that lower AR and IFN-γ production associated with higher IL-17A levels were hallmarks in asymptomatic L. infantum infections. Therefore, this study proposes an association of immunological biomarkers that can be used as a complementary strategy for the characterization and monitoring of asymptomatic VL infections in children living in endemic areas.

Prognostic factors associated with death from visceral leishmaniasis: a case-control study in Brazil.

BACKGROUND: The aim of this study was to identify the prognostic factors associated with death from visceral leishmaniasis (VL) considering the clinical evolution of patients through a case-control study. METHODS: We randomly selected 180 cases (death caused by VL) and 180 controls (cured) from Belo Horizonte's hospitals in Brazil, according to data found in the patients' medical records. Five models of multivariate logistic regression were performed following the chronological order of the variables between the onset of the symptoms and evolution of the VL cases. RESULTS: Considering the multivariate models and the stages of clinical evolution of VL, the prognostic factors associated with death are: age >60 y, minor hemorrhagic phenomena, increased abdominal volume, jaundice, dyspnea, malnutrition, TB, billirubin >2 mg/dL, Aspartate Aminotransferase (AST) or Alanine Aminotransferase (ALT) >100 U/L, leukocytes >7000/mm3, hemoglobin <7 g/dL, platelets <50 000/mm3 and infection without defined focus and bleeding. CONCLUSIONS: Knowledge regarding the prognostic factors associated with death from VL in different stages of the disease in large Brazilian urban centers such as Belo Horizonte may help optimize patient management strategies and contribute to reduce the high fatality rates in these cities.

Effectiveness of the Brazilian Visceral Leishmaniasis Surveillance and Control Programme in reducing the prevalence and incidence of Leishmania infantum infection.

BACKGROUND: Control 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. METHODS: A 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. RESULTS: The 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. CONCLUSIONS: The 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.

Evaluation of diagnostic methods for the detection of intestinal schistosomiasis in endemic areas with low parasite loads: Saline gradient, Helmintex, Kato-Katz and rapid urine test.

BACKGROUND: In some tropical countries, such as Brazil, schistosomiasis control programs have led to a significant reduction in the prevalence and parasite burden of endemic populations. In this setting, the Kato-Katz technique, as the standard diagnostic method for the diagnosis of Schistosoma mansoni infections, which involves the analysis of two slides from one fecal sample, loses its sensitivity. As a result, a significant number of infected individuals are not detected. The objective of this study was to perform extensive parasitological testing of up to three fecal samples and include a rapid urine test (POC-CCA) in a moderate prevalence area in Northern Minas Gerais, Brazil, and evaluate the performance of each test separately and in combination. METHODS AND FINDINGS: A total of 254 individuals were examined with variants of the standard Kato-Katz technique (up to18 Kato-Katz slides prepared from three fecal samples), a modified Helmintex (30 g of feces), the saline gradient (500 mg of feces), and the POC-CCA methods. We established a reference standard taking into consideration all the positive results in any of the parasitological exams. Evaluation of the parasite burden by two Kato-Katz slides confirmed that most of the individuals harbored a light infection. When additional slides and different parasitological methods were included, the estimated prevalence rose 2.3 times, from 20.4% to 45.9%. The best sensitivity was obtained with the Helmintex method (84%). All parasitological methods readily detected a high or moderate intensity of infection; however, all lost their high sensitivity in the case of low or very low intensity infections. The overall sensitivity of POC-CCA (64.9%) was similar to the six Kato-Katz slides from three fecal samples. However, POC-CCA showed low concordance (κ = 0.34) when compared with the reference standard. CONCLUSIONS: The recommended Kato-Katz method largely underestimated the prevalence of S. mansoni infection. Because the best performance was achieved with a modified Helmintex method, this technique might serve as a more precise reference standard. An extended number of Kato-Katz slides in combination with other parasitological methods or with POC-CCA was able to detect more than 80% of egg-positive individuals; however, the rapid urine test (POC-CCA) produced a considerable percentage of false positive results.

Clinical Profiles and Factors Associated with Death in Adults with Dengue Admitted to Intensive Care Units, Minas Gerais, Brazil.

The purpose of our study was to describe the clinical profile of dengue-infected patients admitted to Brazilian intensive care units (ICU) and evaluate factors associated with death. A longitudinal, multicenter case series study was conducted with laboratory-confirmed dengue patients admitted to nine Brazilian ICUs situated in Minas Gerais state, southeastern Brazil from January 1, 2008, to December 31, 2013. Demographic, clinical and laboratory data; disease severity scores; and mortality were evaluated. A total of 97 patients were studied. The in-ICU and in-hospital mortality rates were 18.6% and 19.6%, respectively. Patients classified as having severe dengue according to current World Health Organization classifications showed an increased risk of death in a univariate analysis. Nonsurvivors were older, exhibited lower serum albumin concentrations and higher total leukocyte counts and serum creatinine levels. Other risk factors (vomiting, lethargy/restlessness, dyspnea/respiratory distress) were also associated with death in a univariate analysis. Multivariate analysis indicated that in-hospital mortality was significantly associated with Acute Physiology and Chronic Health Evaluation II and the Sequential Organ Failure Assessment score. The ICU and in-hospital mortality observed in this study were higher than values reported in similar studies. An increased frequency of ICU admission due to severe organ dysfunction, higher severity indices and scarcity of ICU beds may partially explain the higher mortality.

[Bone histomorphometry of lactating and no lactating hyperthyroid rats]. / Histomorfometria óssea de ratas hipertireóideas lactantes e não-lactantes.

The objective of this study was to verify if hyperthyroidism potentiates the osteopenia lactational. 24 adult female rats were distributed in four groups: euthyroid no lactating (control), euthyroid lactating, hyperthyroid no lactating and hyperthyroid lactating. 20 days after gestation, all the animals were necropsied. The thoracic and lumbar vertebrae, the femur and tibia were decalcified and processed for histomorphometric analysis. The euthyroid lactating group presented intense osteopenia in the studied bones. In the hyperthyroid no lactating group, there was not any change in trabecular bone percentage in none of the analyzed bone. In the hyperthyroid lactating group, there was osteopenia in the tibia and femur, similar to the one in the euthyroid lactating group. But the trabecular bone percentage in all the vertebral bodies was significantly larger in comparison with the euthyroid lactating group. It was concluded that the hyperthyroidism does not potentiate the osteopenia lactational in female rats, but it minimizes the vertebral osteopenia once it stimulates the osteoblastic activity.

Histomorfometria óssea de ratas hipertireóideas lactantes e não-lactantes / Bone histomorphometry of lactating and no lactating hyperthyroid rats

O objetivo deste estudo foi verificar se o hipertireoidismo potencializa a osteopenia causada pela lactação. Foram utilizadas 24 ratas adultas distribuídas em quatro grupos: eutireóideo não lactante (controle), eutireóideo lactante, hipertireóideo não-lactante e hipertireóideo lactante. Todos os animais foram necropsiados, 20 dias após a gestação. As vértebras torácicas e lombares, o fêmur e a tíbia foram colhidos, descalcificados e submetidos à análise histomorfométrica. O grupo eutireóideo lactante apresentou osteopenia intensa em todos os sítios ósseos estudados. No grupo hipertireóideo não-lactante, não houve alteração da porcentagem de tecido ósseo trabecular nos sítios analisados. No grupo hipertireóideo lactante, havia osteopenia na tíbia e no fêmur, semelhante à do grupo eutireóideo lactante. Mas a porcentagem de tecido ósseo trabecular em todos os corpos vertebrais foi significativamente maior em comparação ao grupo eutireóideo lactante. Conclui-se que o hipertireoidismo não agrava a osteopenia lactacional em ratas, mas minimiza a osteopenia vertebral por estimular a atividade osteoblástica.

The objective of this study was to verify if hyperthyroidism potentiates the osteopenia lactational. 24 adult female rats were distributed in four groups: euthyroid no lactating (control), euthyroid lactating, hyperthyroid no lactating and hyperthyroid lactating. 20 days after gestation, all the animals were necropsied. The thoracic and lumbar vertebrae, the femur and tibia were decalcified and processed for histomorphometric analysis. The euthyroid lactating group presented intense osteopenia in the studied bones. In the hyperthyroid no lactating group, there was not any change in trabecular bone percentage in none of the analyzed bone. In the hyperthyroid lactating group, there was osteopenia in the tibia and femur, similar to the one in the euthyroid lactating group. But the trabecular bone percentage in all the vertebral bodies was significantly larger in comparison with the euthyroid lactating group. It was concluded that the hyperthyroidism does not potentiate the osteopenia lactational in female rats, but it minimizes the vertebral osteopenia once it stimulates the osteoblastic activity.