Epidemiological indicators of Chagas disease in the metropolitan region of Salvador, Bahia, Brazil

BACKGROUND

Chagas disease (CD) is caused by Trypanosoma cruzi and transmitted by triatomines. Historical information from the 20th century demonstrates T. cruzi records in the metropolitan region of Salvador (MRS), the third largest urban agglomeration in the Brazilian Northeast and the eighth largest in Brazil, an area with intense migratory activity from CD-endemic regions. Therefore, this study aimed to evaluate CD indicators (prevalence and mortality) in the MRS.

METHODS

A mixed ecological and descriptive study was conducted using secondary data. We analyzed data from 2008 to 2015: deaths due to CD, self-reported cases of CD, and blood donors that were non-negative for T. cruzi infection.

RESULTS

São Francisco do Conde was one of the municipalities with the highest mortality rates due to CD. The seroprevalence rates varied by year and municipality; those with the highest values were 2008: Vera Cruz, 2009: Mata de São João, 2010: Dias D'Ávila, 2011 and 2015: São Francisco do Conde, 2012: São Sebastião do Passé, and 2013 and 2014: Pojuca. Spatial correlations between the municipalities were not detected.

CONCLUSIONS

We conclude that CD is present in the MRS. The indicators analyzed in the MRS are below-state-level data. Given the importance of indicator analysis for the surveillance and control of CD at the state and national levels, it is important to strengthen the surveillance program at the municipal level, including the regions classified as low risk for T. cruzi vector transmission.

Triatomine fauna in the state of Bahia, Brazil: What changed after 40 years of the vector-control program?

Background:

Neglected tropical diseases are a growing threat to global health, and endemic Chagas disease has emerged as one of the most important health problems in America. The main strategy to prevent Trypanosoma cruzi transmission is chemical control of vectors. This study presents a descriptive analysis of synanthropic triatomines before and after the implementation of a vector-control program in Bahia, Brazil.

Methods:

Descriptive analysis and geospatial statistics were performed on triatomine data, (1) the relative abundance and (2) proportional spatial distribution, from Bahia during two periods: (A) 1957 to 1971 and (B) 2006 to 2019.

Results:

We observed a decrease in the relative abundance of Panstrongylus megistus (A: n=22.032, 61.9%; B: n=1.842, 1.0%) and Triatoma infestans (A: n=1.310, 3.7%; B: n=763, 0.43%), as well as an increase in the relative abundance of T. sordida (A: n=8.314, 23.4%, B: n=146.901, 81.6%) and T. pseudomaculata (A: n=894, 2.5%, B: n=16.717, 9.3%).

Conclusions:

Our results indicate a clear reduction in the occurrence of P. megistus and T. infestans (last record in 2015) and an increase in the relative abundance and geographical distribution of T. sordida and T. pseudomaculata after 40 years of the vector-control program. The high frequency of other triatomine species in the municipalities of the state of Bahia and their abundance in recent years highlight the need to reinforce permanent entomological surveillance actions to prevent Chagas disease.

Retrospective Investigation in Horses with Encephalitis Reveals Unnoticed Circulation of West Nile Virus in Brazil

During these past years, several studies have provided serological evidence regarding the circulation of West Nile virus (WNV) in Brazil. Despite some reports, much is still unknown regarding the genomic diversity and transmission dynamics of this virus in the country. Recently, genomic monitoring activities in horses revealed the circulation of WNV in several Brazilian regions. These findings on the paucity of genomic data reinforce the need for prompt investigation of WNV infection in horses, which may precede human cases of encephalitis in Brazil. Thus, in this study, we retrospectively screened 54 suspicious WNV samples collected between 2017 and 2020 from the spinal cord and brain of horses with encephalitis and generated three new WNV genomes from the Ceará and Bahia states, located in the northeastern region of Brazil. The Bayesian reconstruction revealed that at least two independent introduction events occurred in Brazil. The first introduction event appears to be likely related to the North American outbreak, and was estimated to have occurred in March 2013.The second introduction event appears to have occurred in September 2017 and appears to be likely related to the South American outbreak. Together, our results reinforce the importance of increasing the priority of WNV genomic monitoring in equines with encephalitis in order to track the dispersion of this emerging pathogen through the country.

Field and classroom initiatives for portable sequence-based monitoring of dengue virus in Brazil

Brazil experienced a large dengue virus (DENV) epidemic in 2019, highlighting a continuous struggle with effective control and public health preparedness. Using Oxford Nanopore sequencing, we led field and classroom initiatives for the monitoring of DENV in Brazil, generating 227 novel genome sequences of DENV1-2 from 85 municipalities (2015-2019). This equated to an over 50% increase in the number of DENV genomes from Brazil available in public databases. Using both phylogenetic and epidemiological models we retrospectively reconstructed the recent transmission history of DENV1-2. Phylogenetic analysis revealed complex patterns of transmission, with both lineage co-circulation and replacement. We identified two lineages within the DENV2 BR-4 clade, for which we estimated the effective reproduction number and pattern of seasonality. Overall, the surveillance outputs and training initiative described here serve as a proof-of-concept for the utility of real-time portable sequencing for research and local capacity building in the genomic surveillance of emerging viruses.

Early use of alcohol associated with sociodemographic, nutritional and lifestyle factors: survival analysis with Brazilian students

BACKGROUND

To evaluate the early age of onset (AOO) of alcohol consumption and its association with sociodemographic, nutritional and lifestyle characteristics.

METHODS

A national cross-sectional multi-centered study assessed 12-17-year old adolescents from 1247 public and private schools in 124 Brazilian municipalities with more than 100 000 habitants. Our variable of interest was the AOO of alcohol consumption. Covariates comprised sociodemographic status, lifestyle habits and nutritional parameters. We used adapted survival models to investigate the association between covariates and the AOO of alcohol consumption.

RESULTS

From a sample of 67 672 adolescents, 50% were females. The mean AOO of alcohol consumption was 12.9 years. Male adolescents had a lower mean age of alcohol experimentation when compared to females in Northeast and South regions. The difference between private and public school for AOO was observed only for the Northeast Region (12.6 versus 13.1, respectively). Adolescents who reported smoking or mental health problems or from the Southern Region presented earlier alcohol use. Physical activity and overweight were positively associated with earlier use of alcohol.

CONCLUSIONS

There is no homogeneity in the AOO of alcohol consumption among adolescents, which should be considered when formulating public policies and government campaigns directed toward reducing alcohol consumption.

Yellow fever transmission in non-human primates, Bahia, Northeastern Brazil

Yellow fever virus (YFV) causes a clinical syndrome of acute hemorrhagic hepatitis. YFV transmission involves non-human primates (NHP), mosquitoes and humans. By late 2016, Brazil experienced the largest YFV outbreak of the last 100 years, with 2050 human confirmed cases, with 681 cases ending in death and 764 confirmed epizootic cases in NHP. Among affected areas, Bahia state in Northeastern was the only region with no autochthonous human cases. By using next generation sequence approach, we investigated the molecular epidemiology of YFV in NHP in Bahia and discuss what factors might have prevented human cases. We investigated 47 YFV positive tissue samples from NHP cases to generate 8 novel YFV genomes. ML phylogenetic tree reconstructions and automated subtyping tools placed the newly generated genomes within the South American genotype I (SA I). Our analysis revealed that the YFV genomes from Bahia formed two distinct well-supported phylogenetic clusters that emerged most likely of an introduction from Minas Gerais and Espírito Santo states. Vegetation coverage analysis performed shows predominantly low to medium vegetation coverage in Bahia state. Together, our findings support the hypothesis of two independent YFV SA-I introductions. We also highlighted the effectiveness of the actions taken by epidemiological surveillance team of the state to prevented human cases.

MRI estimated changes in visceral adipose tissue and liver fat fraction in patients with obesity during a very low-calorie-ketogenic diet compared to a standard low-calorie diet

AIM

To compare the changes in visceral adipose tissue (VAT), liver fat fraction, and liver stiffness using quantitative magnetic resonance imaging (MRI) during a very-low-calorie ketogenic (VLCK) diet and a standard low-calorie diet (LC).

MATERIALS AND METHODS

The study involved secondary analysis of prospective collected clinical data. Patients undergoing weight loss interventions were randomised to either a LC or a VLCK diet. VAT, liver fat fraction, and stiffness were measured at baseline and after 2 months.

RESULTS

Forty-six patients were included; 39 patients were evaluated at baseline and at 2 months follow-up. Mean weight loss was -9.7±3.8 kg (interquartile range [IQR]: -12.3; -7 kg) in the VLCK group and -1.67±2.2 kg (IQR: -3.3, -0.1 kg) in the LC group (p<0.0001). Mean VAT reductions were -39.3±40 cm² (IQR: -52, -10 cm²) and -12.5±38.3 cm² (IQR: -29, 5 cm²; p=0.0398), and mean liver proton density fat fraction (PDFF) reductions were -4.77±4.2% (IQR: -7.3, -1.7%) and -0.79±1.7%, (IQR: -1.8, -0.4%; p<0.005) in the VLCK group and in the LC group, respectively. No significant changes in liver stiffness occurred from baseline to follow-up.

CONCLUSION

A VLCK diet resulted in greater weight loss than a standard low-calorie diet and in significantly greater reduction in liver PDFF. As anthropometric measurements may not correlate with liver fat changes, it may be advantageous to include quantitative MRI to the monitoring strategies of patients undergoing weight-loss programmes.

Wide distribution of Trypanosoma cruzi-infected triatomines in the State of Bahia, Brazil

Background

The identification of Trypanosoma cruzi and blood-meal sources in synanthropic triatomines is important to assess the potential risk of Chagas disease transmission. We identified T. cruzi infection and blood-meal sources of triatomines caught in and around houses in the state of Bahia, northeastern Brazil, and mapped the occurrence of infected triatomines that fed on humans and domestic animals.

Methods

Triatominae bugs were manually captured by trained agents from the Epidemiologic Surveillance team of Bahia State Health Service between 2013 and 2014. We applied conventional PCR to detect T. cruzi and blood-meal sources (dog, cat, human and bird) in a randomized sample of triatomines. We mapped triatomine distribution and analyzed vector hotspots with kernel density spatial analysis.

Results

In total, 5906 triatomines comprising 15 species were collected from 127 out of 417 municipalities in Bahia. The molecular analyses of 695 triatomines revealed a ~10% T. cruzi infection rate, which was highest in the T. brasiliensis species complex. Most bugs were found to have fed on birds (74.2%), and other blood-meal sources included dogs (6%), cats (0.6%) and humans (1%). Trypanosoma cruzi-infected triatomines that fed on humans were detected inside houses. Spatial analysis showed a wide distribution of T. cruzi-infected triatomines throughout Bahia; triatomines that fed on dogs, humans, and cats were observed mainly in the northeast region.

Conclusions

Synanthropic triatomines have a wide distribution and maintain the potential risk of T. cruzi transmission to humans and domestic animals in Bahia. Ten species were recorded inside houses, mainly Triatoma sordida, T. pseudomaculata, and the T. brasiliensis species complex. Molecular and spatial analysis are useful to reveal T. cruzi infection and blood-meal sources in synanthropic triatomines, identifying areas with ongoing threat for parasite transmission and improving entomological surveillance strategies.

Sedative and anticonvulsant effects of hydroalcoholic extract of Equisetum arvense

The hydroalcoholic extract of Equisetum arvense (HAE) tested at the doses of 200 and 400 mg/kg showed a significant activity on the open-field, enhanced the number of falls in the rota-rod reducing the time of permanence in the bar and increased the sleeping time (46% and 74%) in the barbiturate-induced sleeping time. In the pentylenetetrazole-seizure, it increased the first convulsion latency, diminished the severity of convulsions, reduced the percentage of animals which developed convulsion (50% and 25%) and protected animals from death. On the contrary, in the elevated plus maze, the doses 50, 100 and 150 mg/kg did not affect the evaluated parameters. Thus, HAE presented anticonvulsant and sedative effects. Phytochemical analysis detected the presence of tannins, saponins, sterols and flavonoids.

Genomic characterization of wild-type measles viruses that circulated in different states in Brazil during the 1997 measles epidemic

Despite the marked reduction in the incidence of measles in Brazil, a measles epidemic occurred in this country in 1997. The measles cases observed during this epidemic began to reappear in large numbers in São Paulo, and spread to Rio de Janeiro and other Brazilian states. In the present study molecular biology techniques were used for the detection and genomic characterization of measles viruses from clinical samples such as urine and nasopharyngeal secretions collected in the states of Rio de Janeiro, Minas Gerais and Paraná, during the 1997 epidemic. RT-PCR and nucleotide sequence analysis of part of the carboxyl-terminal region of the nucleoprotein gene of measles viruses obtained directly from clinical samples or from infected cell cultures during this epidemic classified all as wild-type of genotype D6. As the genotype D6 was identified in different Brazilian states, this study demonstrated that this genotype was circulating in Brazil during the 1997 epidemic.

Pentoxifylline improves learning and memory in glutamate-lesioned rats

The present work shows the effects of pentoxifylline (ptx), on learning and memory in rats with hippocampal lesions induced by glutamate (glu). Immediately after stereotaxic procedures and in the absence or presence of glu lesions, animals were treated with ptx (50, 100, or 200 mg/kg, IP) for 6 days. Twenty-four hours after the last injection, behavior and memory tests were performed, animals were sacrificed, and hippocampi dissected for cAMP determination or histopathological studies. Results from the T-maze task showed a less learning ability in the glu-lesioned group compared to other ones. Ptx alone or associated with glu significantly improved memory acquisition, but not memory consolidation compared to glu-lesioned rats. Except for the increased locomotor activity observed in the ptx100+glu-treated group compared to saline, no other difference was detected in the open-field test. A significant impairment in avoidance performance was observed in glu-lesioned group as compared to saline or to other groups in the short as well as in the late phase of memory. All groups showed an improved water-maze performance over time with similar performances on the final day of acquisition. The impairment in memory retention observed in glu-lesioned rats was reversed by the pretreatment with ptx200. Glu induced hippocampal lesion and reduced cAMP levels. Both effects were blocked by ptx, suggesting that its action may be the result of increased cAMP levels and/or inhibition of adenosine A1 receptors.

Nerve growth factor, ganglioside and vitamin E reverse glutamate cytotoxicity in hippocampal cells

The present work showed that glutamate decreased hippocampal cell viability in a dose-dependent manner. While no significant effect was observed after cell exposure to 0.1 mM glutamate, cell incubation for 0.5 h caused a progressive decrease of cell viability, which at 5 mM concentration reached 68% as compared to controls. No further effect was observed in the presence of 10 mM glutamate. While nerve growth factor (NGF) at the dose of 0.5 ng/ml presented no effect, it significantly reduced glutamate cytotoxicity at a higher dose (1 ng/ml) increasing the cell viability to 66%. Similarly, cell viabilities in the presence of the ganglioside GM, (5 and 10 ng/ml) after glutamate exposure were 19 and 73%, respectively. A dose-response relationship was observed after cell incubation with vitamin E (0.5 and 1 mM) which resulted in cell viability of the order of 34 and 70%, respectively. Surprisingly, a potentiation of the effect was observed after the association of NGF (0.5 ng/ml) plus ganglioside GM1 (5 ng/ml) or vitamin E (0.5 mM) plus ganglioside GM1 (5 ng/ml), after pre-incubation with glutamate. In these conditions, significantly higher viabilities were demonstrated (66 and 71% for the two associations, respectively) as compared to each one of the compounds alone (NGF 0.5 ng/ml--29.5%; ganglioside GM1 5 ng/ml--19.4%). However, no potentiation was seen after the association of NGF plus vitamin E on glutamate pre-exposed cells. These results showed a cytoprotective effect of ganglioside GM1, NGF and vitamin E on the glutamate-induced cytotoxicity in rat hippocampal cells.

Effects of gangliosides, ouabain and arachidonic acid on glutamate cytotoxicity in PC12 cells

The present work shows that gangliosides prevent glutamate cytotoxicity in PC12 cells. Similarly, ouabain (1 and 5 micrograms/ml) protected cells against glutamate-induced toxicity in a dose-dependent manner. The cytoprotection observed with ouabain was not maintained after its association with gangliosides and glutamate. Also, the effects of gangliosides in blocking glutamate cytotoxicity did not persist in the presence of arachidonic acid. The results indicate that a higher degree of sodium pump inhibition is necessary for ouabain cytotoxicity to be manifested, and that a partial enzyme inhibition may actually be protective to glutamate and/or arachidonic acid-induced toxicity in PC12 cells.

Taurine modulates chemical nociception in mice

The effect of taurine on nociception was investigated in adult male Swiss mice using the formalin and acetic acid tests. Taurine (50-200 mg/kg) injected sc into the animals (N = 6 per group) 30 min before formalin injection into the right hind paw reduced formalin-induced early phase (0-5 min) licking activity by 30-42%, but had no effect on the late phase (20-25 min) response. Writhing responses induced by acetic acid injected ip were also significantly inhibited by 49% and 56% by doses of 100 and 200 mg/kg taurine, respectively. In both tests taurine demonstrated antinociception which was significantly blocked by naloxone (1 mg/kg, sc, administered simultaneously with taurine). The naloxone-sensitive antinociceptive action of taurine was probably mediated via modulation of endogenous pain-regulatory systems that involve opioid peptides, neuropeptides like substance P and amino acids such as glutamate and aspartate.