Associations between COVID-19 and Glucose-6-Phosphate Dehydrogenase Activity in Brazil

Glucose-6 phosphate dehydrogenase deficiency (G6PDd) was suggested as a risk factor for severe disease in patients with COVID-19. We evaluated clinical outcomes and glucose-6 phosphate dehydrogenase (G6PD) activity during and after illness in patients with COVID-19. This prospective cohort study included adult participants (≥ 18 years old) who had clinical and/or radiological COVID-19 findings or positive reverse transcription-polymerase chain reaction results. Epidemiological and clinical data were extracted from electronic medical records. Glucose-6 phosphate dehydrogenase activity was measured using SD Biosensor STANDARD G6PD® equipment on admission and 1 year after discharge. Samples were genotyped for the three most common single nucleotide polymorphisms for G6PDd in the Brazilian Amazon. Seven hundred fifty-three patients were included, of whom 123 (16.3%) were G6PD deficient. There was no difference between groups regarding the risks of hospitalization (P = 0.740) or invasive mechanical ventilation (P = 0.31), but the risk of death was greater in patients with normal G6PD levels (P = 0.022). Only 29 of 116 participants (25%) carried the African G6PDd genotype. Of 30 participants tested as G6PD deficient during disease, only 11 (36.7%) results agreed 1 year after discharge. In conclusion, this study does not demonstrate an association of G6PDd with severity of COVID-19. Limitations of the test for detecting enzyme levels during COVID-19 illness were demonstrated by genotyping and retesting after the disease period. Care must be taken when screening for G6PDd in patients with acute COVID-19.

Temporal and spatial analysis of over 7,000 measles cases outbreak from 2018 to 2019 in the Brazilian Amazon

OBJECTIVE

This study aimed to present a temporal and spatial analysis of the 2018 measles outbreak in Brazil, particularly in the metropolitan city of Manaus in the Amazon region, and further introduce a new tool for spatial analysis.

METHODS

We analyzed the geographical data of the residences of over 7,000 individuals with measles in Manaus during 2018 and 2019. Spatial and temporal analyses were conducted to characterize various aspects of the outbreak, including the onset and prevalence of symptoms, demographics, and vaccination status. A visualization tool was also constructed to display the geographical and temporal distribution of the reported measles cases.

RESULTS

Approximately 95% of the included participants had not received vaccination within the past decade. Heterogeneity was observed across all facets of the outbreak, including variations in the incubation period and symptom presentation. Age distribution exhibited two peaks, occurring at one year and 18 years of age, and the potential implications of this distribution on predictive analysis were discussed. Additionally, spatial analysis revealed that areas with the highest case densities tended to have the lowest standard of living.

CONCLUSION

Understanding the spatial and temporal spread of measles outbreaks provides insights for decision-making regarding measures to mitigate future epidemics.

Photobiomodulation Therapy to Treat Snakebites Caused by Bothrops atrox: A Randomized Clinical Trial

Importance

Bothrops venom acts almost immediately at the bite site and causes tissue damage.

Objective

To investigate the feasibility and explore the safety and efficacy of low-level laser therapy (LLLT) in reducing the local manifestations of B atrox envenomations.

Design, Setting, and Participants

This was a double-blind randomized clinical trial conducted at Fundação de Medicina Tropical Doutor Heitor Vieira Dourado, in Manaus, Brazil. A total of 60 adult participants were included from November 2020 to March 2022, with 30 in each group. Baseline characteristics on admission were similarly distributed between groups. Data analysis was performed from August to December 2022.

Intervention

The intervention group received LLLT combined with regular antivenom treatment. The laser used was a gallium arsenide laser with 4 infrared laser emitters and 4 red laser emitters, 4 J/cm2 for 40 seconds at each application point.

Main Outcomes and Measures

Feasibility was assessed by eligibility, recruitment, and retention rates; protocol fidelity; and patients' acceptability. The primary efficacy outcome of this study was myolysis estimated by the value of creatine kinase (U/L) on the third day of follow-up. Secondary efficacy outcomes were (1) pain intensity, (2) circumference measurement ratio, (3) extent of edema, (4) difference between the bite site temperature and that of the contralateral limb, (5) need for the use of analgesics, (6) frequency of secondary infections, and (7) necrosis. These outcomes were measured 48 hours after admission. Disability assessment was carried out from 4 to 6 months after patients' discharge. P values for outcomes were adjusted with Bonferroni correction.

Results

A total of 60 patients (mean [SD] age, 43.2 [15.3] years; 8 female individuals [13%] and 52 male individuals [87%]) were included. The study was feasible, and patient retention and acceptability were high. Creatine kinase was significantly lower in the LLLT group (mean [SD], 163.7 [160.0] U/L) 48 hours after admission in relation to the comparator (412.4 [441.3] U/L) (P = .03). Mean (SD) pain intensity (2.9 [2.7] vs 5.0 [2.4]; P = .004), circumference measurement ratio (6.6% [6.6%] vs 17.1% [11.6%]; P < .001), and edema extent (25.8 [15.0] vs 40.1 [22.7] cm; P = .002) were significantly lower in the LLLT group in relation to the comparator. No difference was observed between the groups regarding the mean difference between the bite site temperature and the contralateral limb. Secondary infections, necrosis, disability outcomes, and the frequency of need for analgesics were similar in both groups. No adverse event was observed.

Conclusions and Relevance

The data from this randomized clinical trial suggest that the use of LLLT was feasible and safe in a hospital setting and effective in reducing muscle damage and the local inflammatory process caused by B atrox envenomations.

Trial Registration

Brazilian Registry of Clinical Trials Identifier: RBR-4qw4vf.

Pediatric central nervous system infections in the Amazon: clinical and laboratory profiles

Background

Central nervous system (CNS) infections are important causes of mortality and morbidity in children, and they are related to severe problems such as hearing loss, neurological sequelae, and death. The objective was to describe clinical and laboratory exam profiles of children who were diagnosed with CNS infections.

Methods

We conducted a cross-sectional study based on medical records, which included pediatric patients aged from 3 months to 15 years, with a clinical suspicion of CNS infection between January 2014 to December 2019. The pathogens were confirmed in cerebrospinal fluid (CSF) samples using Gram staining, cell culture, molecular diagnostics (PCR and qPCR), and serology.

Results

Out of the 689 enrolled patients, 108 (15.6%) had laboratory-confirmed infections in CSF. The most common bacterial pathogens isolated from the culture were Neisseria meningitidis serogroup C in 19, Streptococcus pneumoniae in 11, and Haemophilus influenzae in seven samples. The viruses identified were Enterovirus, Cytomegalovirus, Varicella-zoster virus, Epstein-Barr virus, and arbovirus. No patient was found to be positive for Herpes simplex virus 1 and 2. Patients with viral infections showed altered levels of consciousness (p = 0.001) when compared to bacterial infections.

Conclusion

This study shows the presence of important vaccine-preventable pathogens, and different families of viruses causing CNS infections in the pediatric patients of Manaus.

Effect of fluralaner on the biology, survival, and reproductive fitness of the neotropical malaria vector Anopheles aquasalis

BACKGROUND

Reducing mosquito abundance or interfering with its ability to support the parasite cycle can help to interrupt malaria in areas of significant risk of malaria transmission. Fluralaner is a safe and effective drug for veterinary use indicated for the treatment against fleas and ticks which acts as an antagonist of chloride ion channels mediated by γ-aminobutyric acid (GABA), preventing the entry of these ions into the postsynaptic neuron, leading to hyperexcitability of the postsynaptic neuron of the central nervous system of arthropods. Fluralaner demonstrated insecticidal activity against different insect species.

METHODS

The study aimed to evaluate the effects of fluralaner on the biology, survival, and reproductive fitness of Anopheles aquasalis. The following lethal concentrations (LC) were determined for An. aquasalis: LC5 = 0.511 µM; LC25 = 1.625 µM; LC50 = 3.237 µM.

RESULTS

A significant decrease (P < 0.001) was evident in the number of eggs, larvae, and pupae in the group exposed to a sublethal dose of fluralaner when compared to a control group (without the drug). Using blood from dogs after administration of fluralaner, it was observed that the drug causes 100% mortality in An. aquasalis in less than 24 h after feeding; this effect remains even after 90 days in all samples.

DISCUSSION

Fluralaner showed the same result for up to 60 days, and after that, there was a slight reduction in its effect, evidenced by a decrease in the percentage of dead females; however, still significant when compared to the control group.

CONCLUSION

Fluralaner affects the biology and reduction of survival in An. aquasalis in a lasting and prolonged period, and its fecundity with lower dosages, is a strong candidate for controlling disease vectors.

Indeed, Correlation Does Not Indicate Causation!

Author response to the JOSPT Letter to the Editor-in-Chief "Lower-Limb Kinematics and Clinical Outcomes: Correlation Does not Imply Causality" J Orthop Sports Phys Ther 2023;53(11):723-725. doi:10.2519/jospt.2023.0203-R.

Inflammatory Profile Associated with Secondary Infection from Bothrops atrox Snakebites in the Brazilian Amazon

Bothrops snakebite envenomation (SBE) is consider an important health problem in Brazil, where Bothrops atrox is mainly responsible in the Brazilian Amazon. Local effects represent a relevant clinical issue, in which inflammatory signs and symptoms in the bite site represent a potential risk for short and long-term disabilities. Among local complications, secondary infections (SIs) are a common clinical finding during Bothrops atrox SBE and are described by the appearance of signs such as abscess, cellulitis or necrotizing fasciitis in the affected site. However, the influence of SI in the local events is still poorly understood. Therefore, the present study describes for the first time the impact of SBE wound infection on local manifestations and inflammatory response from patients of Bothrops atrox SBE in the Brazilian Amazon. This was an observational study carried out at the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus (Brazil), involving victims of Bothrops SBE. Clinical and laboratorial data were collected along with blood samples for the quantification of circulating cytokines and chemokines before antivenom administrations (T0) and 24 h (T1), 48 h (T2), 72 h (T3) and 7 days after (T4). From the 94 patients included in this study, 42 presented SI (44.7%) and 52 were without SI (NSI, 55.3%). Patients classified as moderate envenoming presented an increased risk of developing SI (OR = 2.69; CI 95% = 1.08-6.66, p = 0.033), while patients with bites in hands showed a lower risk (OR = 0.20; CI 95% = 0.04-0.96, p = 0.045). During follow-up, SI patients presented a worsening of local temperature along with a sustained profile of edema and pain, while NSI patients showed a tendency to restore and were highlighted in patients where SI was diagnosed at T2. As for laboratorial parameters, leukocytes, erythrocyte sedimentation ratio, fibrinogen and C-reactive protein were found increased in patients with SI and more frequently in patients diagnosed with SI at T3. Higher levels of circulating IL-2, IL-10, IL-6, TNF, INF-γ and CXCL-10 were observed in SI patients along with marked correlations between these mediators and IL-4 and IL-17, showing a plurality in the profile with a mix of Th1/Th2/Th17 response. The present study reports for the first time the synergistic effects of local infection and envenoming on the inflammatory response represented by local manifestations, which reflected on laboratorial parameters and inflammatory mediators and thus help improve the clinical management of SI associated to Bothrops SBE.

Temporal patterns of cytokine and injury biomarkers in hospitalized COVID-19 patients treated with methylprednisolone

Background

The novel coronavirus disease 2019 (COVID-19) presents with complex pathophysiological effects in various organ systems. Following the COVID-19, there are shifts in biomarker and cytokine equilibrium associated with altered physiological processes arising from viral damage or aggressive immunological response. We hypothesized that high daily dose methylprednisolone improved the injury biomarkers and serum cytokine profiles in COVID-19 patients.

Methods

Injury biomarker and cytokine analysis was performed on 50 SARS-Cov-2 negative controls and 101 hospitalized severe COVID-19 patients: 49 methylprednisolone-treated (MP group) and 52 placebo-treated serum samples. Samples from the treated groups collected on days D1 (pre-treatment) all the groups, D7 (2 days after ending therapy) and D14 were analyzed. Luminex assay quantified the biomarkers HMGB1, FABP3, myoglobin, troponin I and NTproBNP. Immune mediators (CXCL8, CCL2, CXCL9, CXCL10, TNF, IFN-γ, IL-17A, IL-12p70, IL-10, IL-6, IL-4, IL-2, and IL-1β) were quantified using cytometric bead array.

Results

At pretreatment, the two treatment groups were comparable demographically. At pre-treatment (D1), injury biomarkers (HMGB1, TnI, myoglobin and FABP3) were distinctly elevated. At D7, HMGB1 was significantly higher in the MP group (p=0.0448) compared to the placebo group, while HMGB1 in the placebo group diminished significantly by D14 (p=0.0115). Compared to healthy control samples, several immune mediators (IL-17A, IL-6, IL-10, MIG, MCP-1, and IP-10) were considerably elevated at baseline (all p≤0.05). At D7, MIG and IP-10 of the MP-group were significantly lower than in the placebo-group (p=0.0431, p=0.0069, respectively). Longitudinally, IL-2 (MP-group) and IL-17A (placebo-group) had increased significantly by D14. In placebo group, IL-2 and IL-17A continuously increased, as IL-12p70, IL-10 and IP-10 steadily decreased during follow-up. The MP treated group had IL-2, IFN-γ, IL-17A and IL-12p70 progressively increase while IL-1β and IL-10 gradually decreased towards D14. Moderate to strong positive correlations between chemokines and cytokines were observed on D7 and D14.

Conclusion

These findings suggest MP treatment could ameliorate levels of myoglobin and FABP3, but appeared to have no impact on HMGB1, TnI and NTproBNP. In addition, methylprednisolone relieves the COVID-19 induced inflammatory response by diminishing MIG and IP-10 levels. Overall, corticosteroid (methylprednisolone) use in COVID-19 management influences the immunological molecule and injury biomarker profile in COVID-19 patients.

Are Changes in Dynamic Knee Movement Control Related to Changes in Pain or Function in People With Knee Disorders? A Systematic Review and Meta-analysis

OBJECTIVE: To study whether changes in dynamic knee valgus or varus were associated with changes in pain or function in people with knee disorders. DESIGN: Systematic review with meta-analysis. LITERATURE SEARCH: We searched the MEDLINE, Embase, CINAHL, SPORTDiscus, Cochrane Library, and Web of Science, from inception up to January 2023. STUDY SELECTION CRITERIA: We included randomized controlled trials investigating the effects of nonsurgical (including nonpharmacological) interventions for knee disorders on frontal and transverse plane knee and hip movements during functional tasks, which reported pain and/or function outcomes. DATA SYNTHESIS: The relationship between changes in kinematics and pain/function was analyzed using a 2-stage structural equation modeling approach. RESULTS: From 42 202 records, 48 trials met the eligibility criteria. For people with patellofemoral pain (25 trials, n = 894), there was moderate evidence that changes in the knee and hip movements were significantly correlated with changes in pain and function (r= -0.69 to 0.73), except for the knee transverse plane movements and for the relationship between hip transverse plane movement and function. For people with knee osteoarthritis (15 trials, n = 704) and anterior cruciate ligament injuries (8 trials, n = 198), the evidence was limited and uncertain. CONCLUSION: The relationship between changes in movement control and clinical outcomes was consistent in people with patellofemoral pain. For people with knee osteoarthritis or anterior cruciate ligament injuries, there was a paucity of evidence that precluded a proper evaluation of the relationship between dynamic knee movement control, and pain and function. J Orthop Sports Phys Ther 2023;53(7):1-14. Epub: 18 April 2023. doi:10.2519/jospt.2023.11628.

Antigen-Specific Antibody Signature Is Associated with COVID-19 Outcome

Numerous studies have focused on inflammation-related markers to understand COVID-19. In this study, we performed a comparative analysis of spike (S) and nucleocapsid (N) protein-specific IgA, total IgG and IgG subclass response in COVID-19 patients and compared this to their disease outcome. We observed that the SARS-CoV-2 infection elicits a robust IgA and IgG response against the N-terminal (N1) and C-terminal (N3) region of the N protein, whereas we failed to detect IgA antibodies and observed a weak IgG response against the disordered linker region (N2) in COVID-19 patients. N and S protein-specific IgG1, IgG2 and IgG3 response was significantly elevated in hospitalized patients with severe disease compared to outpatients with non-severe disease. IgA and total IgG antibody reactivity gradually increased after the first week of symptoms. Magnitude of RBD-ACE2 blocking antibodies identified in a competitive assay and neutralizing antibodies detected by PRNT assay correlated with disease severity. Generally, the IgA and total IgG response between the discharged and deceased COVID-19 patients was similar. However, significant differences in the ratio of IgG subclass antibodies were observed between discharged and deceased patients, especially towards the disordered linker region of the N protein. Overall, SARS-CoV-2 infection is linked to an elevated blood antibody response in severe patients compared to non-severe patients. Monitoring of antigen-specific serological response could be an important tool to accompany disease progression and improve outcomes.

Prediction of malaria using deep learning models: A case study on city clusters in the state of Amazonas, Brazil, from 2003 to 2018

Background:

Malaria is curable. Nonetheless, over 229 million cases of malaria were recorded in 2019, along with 409,000 deaths. Although over 42 million Brazilians are at risk of contracting malaria, 99% percent of all malaria cases in Brazil are located in or around the Amazon rainforest. Despite declining cases and deaths, malaria remains a major public health issue in Brazil. Accurate spatiotemporal prediction of malaria propagation may enable improved resource allocation to support efforts to eradicate the disease.

Methods:

In response to calls for novel research on malaria elimination strategies that suit local conditions, in this study, we propose machine learning (ML) and deep learning (DL) models to predict the probability of malaria cases in the state of Amazonas. Using a dataset of approximately 6 million records (January 2003 to December 2018), we applied k-means clustering to group cities based on their similarity of malaria incidence. We evaluated random forest, long-short term memory (LSTM) and dated recurrent unit (GRU) models and compared their performance.

Results:

The LSTM architecture achieved better performance in clusters with less variability in the number of cases, whereas the GRU presents better results in clusters with high variability. Although Diebold-Mariano testing suggested that both the LSTM and GRU performed comparably, GRU can be trained significantly faster, which could prove advantageous in practice.

Conclusions:

All models showed satisfactory accuracy and strong performance in predicting new cases of malaria, and each could serve as a supplemental tool to support regional policies and strategies.

Metabolomic Profiling of Plasma Reveals Differential Disease Severity Markers in COVID-19 Patients

The severity, disabilities, and lethality caused by the coronavirus 2019 (COVID-19) disease have dumbfounded the entire world on an unprecedented scale. The multifactorial aspect of the infection has generated interest in understanding the clinical history of COVID-19, particularly the classification of severity and early prediction on prognosis. Metabolomics is a powerful tool for identifying metabolite signatures when profiling parasitic, metabolic, and microbial diseases. This study undertook a metabolomic approach to identify potential metabolic signatures to discriminate severe COVID-19 from non-severe COVID-19. The secondary aim was to determine whether the clinical and laboratory data from the severe and non-severe COVID-19 patients were compatible with the metabolomic findings. Metabolomic analysis of samples revealed that 43 metabolites from 9 classes indicated COVID-19 severity: 29 metabolites for non-severe and 14 metabolites for severe disease. The metabolites from porphyrin and purine pathways were significantly elevated in the severe disease group, suggesting that they could be potential prognostic biomarkers. Elevated levels of the cholesteryl ester CE (18:3) in non-severe patients matched the significantly different blood cholesterol components (total cholesterol and HDL, both p < 0.001) that were detected. Pathway analysis identified 8 metabolomic pathways associated with the 43 discriminating metabolites. Metabolomic pathway analysis revealed that COVID-19 affected glycerophospholipid and porphyrin metabolism but significantly affected the glycerophospholipid and linoleic acid metabolism pathways (p = 0.025 and p = 0.035, respectively). Our results indicate that these metabolomics-based markers could have prognostic and diagnostic potential when managing and understanding the evolution of COVID-19.

Spread of Gamma (P.1) Sub-Lineages Carrying Spike Mutations Close to the Furin Cleavage Site and Deletions in the N-Terminal Domain Drives Ongoing Transmission of SARS-CoV-2 in Amazonas, Brazil

The Amazonas was one of the most heavily affected Brazilian states by the COVID-19 epidemic. Despite a large number of infected people, particularly during the second wave associated with the spread of the Variant of Concern (VOC) Gamma (lineage P.1), SARS-CoV-2 continues to circulate in the Amazonas. To understand how SARS-CoV-2 persisted in a human population with a high immunity barrier, we generated 1,188 SARS-CoV-2 whole-genome sequences from individuals diagnosed in the Amazonas state from 1st January to 6th July 2021, of which 38 were vaccine breakthrough infections. Our study reveals a sharp increase in the relative prevalence of Gamma plus (P.1+) variants, designated Pango Lineages P.1.3 to P.1.6, harboring two types of additional Spike changes: deletions in the N-terminal (NTD) domain (particularly Δ144 or Δ141-144) associated with resistance to anti-NTD neutralizing antibodies or mutations at the S1/S2 junction (N679K or P681H) that probably enhance the binding affinity to the furin cleavage site, as suggested by our molecular dynamics simulations. As lineages P.1.4 (S:N679K) and P.1.6 (S:P681H) expanded (Re > 1) from March to July 2021, the lineage P.1 declined (Re < 1) and the median Ct value of SARS-CoV-2 positive cases in Amazonas significantly decreases. Still, we did not find an increased incidence of P.1+ variants among breakthrough cases of fully vaccinated patients (71%) in comparison to unvaccinated individuals (93%). This evidence supports that the ongoing endemic transmission of SARS-CoV-2 in the Amazonas is driven by the spread of new local Gamma/P.1 sublineages that are more transmissible, although not more efficient to evade vaccine-elicited immunity than the parental VOC. Finally, as SARS-CoV-2 continues to spread in human populations with a declining density of susceptible hosts, the risk of selecting more infectious variants or antibody evasion mutations is expected to increase. IMPORTANCE The continuous evolution of SARS-CoV-2 is an expected phenomenon that will continue to happen due to the high number of cases worldwide. The present study analyzed how a Variant of Concern (VOC) could still circulate in a population hardly affected by two COVID-19 waves and with vaccination in progress. Our results showed that the answer behind that was a new generation of Gamma-like viruses, which emerged locally carrying mutations that made it more transmissible and more capable of spreading, partially evading prior immunity triggered by natural infections or vaccines. With thousands of new cases daily, the current pandemics scenario suggests that SARS-CoV-2 will continue to evolve and efforts to reduce the number of infected subjects, including global equitable access to COVID-19 vaccines, are mandatory. Thus, until the end of pandemics, the SARS-CoV-2 genomic surveillance will be an essential tool to better understand the drivers of the viral evolutionary process.

Molecular epidemiology of methicillin resistant Staphylococcus species in healthcare workers of a blood bank in the Brazilian Amazon

BACKGROUND

Healthcare workers are susceptible to colonization by multiresistant bacteria, which can increase the risk of outbreaks.

METHODS

Samples were collected from the nasopharynx, hands, and lab coats of healthcare workers. The phenotypic identification was carried out using a VITEK®2 rapid test system. PCR tests for the mecA gene and the sequencing of the amplicons were performed. Staphylococcus epidermidis and Staphylococcus aureus phylogenies were reconstructed using the Bayesian inference.

RESULTS

A total of 225 healthcare workers participated in this study. Of these, 21.3% were male and 78.7% female. S. epidermidis and S.aureus showed high levels of resistance to penicillin, ampicillin, erythromycin, tetracycline and cefoxitin. The prevalence of methicillin resistant S. aureus was 3.16% and methicillin resistant S. epidermidis was 100%. Multilocus sequence typing identified 23 new S. epidermidis sequence types, and one new allele and sequence type for S. aureus. The frequency of methicillin-resistant S. epidermidis in nursing and hemotherapy technicians as a percentage of the total number of healthcare workers was 5.8-3.1%, while the frequency of methicillin resistant S. aureus in hemotherapy technicians and biomedics, as a percentage of the total number of healthcare workers was 4.2-8.9%%.

CONCLUSIONS

The healthcare workers at the city's blood bank, even when taking the necessary care with their hands, body and clothes, harbour methicillin-resistant S. aureus and S. epidermidis sequence types, which, as a potential source of multidrug resistant bacteria, can contribute to nosocomial infections among hematological patients.

Hemorrhagic and thrombotic manifestations in the central nervous system in COVID-19: A large observational study in the Brazilian Amazon with a complete autopsy series

SARS-CoV-2 affects mainly the lungs, however, other manifestations, including neurological manifestations, have also been described during the disease. Some of the neurological findings have involved intracerebral or subarachnoid hemorrhage, strokes, and other thrombotic/hemorrhagic conditions. Nevertheless, the gross pathology of hemorrhagic lesions in the central nervous system has not been previously described in Brazilian autopsy cases. This study aimed to describe gross and microscopic central nervous system (CNS) pathology findings from the autopsies and correlate them with the clinical and laboratory characteristics of forty-five patients with COVID-19 from Manaus, Amazonas, Brazil. Forty-four patients were autopsied of which thirty-eight of these (86.36%) were positive by RT-PCR for COVID-19, and six (13.3%) were positive by the serological rapid test. Clinical and radiological findings were compatible with the infection. The patients were classified in two groups: presence (those who had hemorrhagic and/or thrombotic manifestations in the CNS) and absence (those who did not present hemorrhagic and/or thrombotic manifestations in the CNS). For risk assessment, relative risk and respective confidence intervals were estimated. Macroscopic or microscopic hemorrhages were found in twenty-three cases (52,27%). The postmortem gross examination of the brain revealed a broad spectrum of hemorrhages, from spots to large and confluent areas and, under microscopy, we observed mainly perivascular discharge. The association analyses showed that the use of corticosteroid, anticoagulant and antibiotic had no statistical significance with a risk of nervous system hemorrhagic manifestations. However, it is possible to infer a statistical tendency that indicates that individuals with diabetes had a higher risk for the same outcome (RR = 1.320, 95% CI = 0.7375 to 2.416, p = 0.3743), which was not observed in relation to other comorbidities. It is unknown whether the new variants of the virus can cause different clinical manifestations, such as those observed or indeed others. As a result, more studies are necessary to define clinical and radiologic monitoring protocols and strategic interventions for patients at risk of adverse and fatal events, such as the extensive hemorrhaging described here. It is imperative that clinicians must be aware of comorbidities and the drugs used to treat patients with COVID-19 to prevent CNS hemorrhagic and thrombotic events.

Acid pH Increases SARS-CoV-2 Infection and the Risk of Death by COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect a broad range of human tissues by using the host receptor angiotensin-converting enzyme 2 (ACE2). Individuals with comorbidities associated with severe COVID-19 display higher levels of ACE2 in the lungs compared to those without comorbidities, and conditions such as cell stress, elevated glucose levels and hypoxia may also increase the expression of ACE2. Here, we showed that patients with Barrett's esophagus (BE) have a higher expression of ACE2 in BE tissues compared to normal squamous esophagus, and that the lower pH associated with BE may drive this increase in expression. Human primary monocytes cultured in reduced pH displayed increased ACE2 expression and higher viral load upon SARS-CoV-2 infection. We also showed in two independent cohorts of 1,357 COVID-19 patients that previous use of proton pump inhibitors is associated with 2- to 3-fold higher risk of death compared to those not using the drugs. Our work suggests that pH has a great influence on SARS-CoV-2 Infection and COVID-19 severity.

Performance of a sensitive haemozoin-based malaria diagnostic test validated for vivax malaria diagnosis in Brazilian Amazon

Background

Vivax malaria diagnosis remains a challenge in malaria elimination, with current point of care rapid diagnostic tests (RDT) missing many clinically significant infections because of usually lower peripheral parasitaemia. Haemozoin-detecting assays have been suggested as an alternative to immunoassay platforms but to date have not reached successful field deployment. Haemozoin is a paramagnetic crystal by-product of haemoglobin digestion by malaria parasites and is present in the food vacuole of malaria parasite-infected erythrocytes. This study aimed to compare the diagnostic capability of a new haemozoin-detecting platform, the Gazelle™ device with optical microscopy, RDT and PCR in a vivax malaria-endemic region.

Methods

A comparative, double-blind study evaluating symptomatic malaria patients seeking medical care was conducted at an infectious diseases reference hospital in the western Brazilian Amazon. Optical microscopy, PCR, RDT, and Gazelle™ were used to analyse blood samples. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and Kappa values were calculated.

Results

Out of 300 patients, 24 test results were excluded from the final analysis due to protocol violation (6) and inconclusive and/or irretrievable results (18). Gazelle™ sensitivity was 96.1 % (91.3–98.3) and 72.1 % (65.0–78.3) when compared to optical microscopy and PCR, respectively whereas it was 83.9 % and 62.8 % for RDTs. The platform presented specificity of 100 % (97.4–100), and 99.0 % (94.8–99.9) when compared to optical microscopy, and PCR, respectively, which  was the same for RDTs. Its correct classification rate was 98.2 % when compared to optical microscopy and 82.3 % for PCR; the test’s accuracy when compared to optical microscopy was 98.1 % (96.4–99.7), when compared to RDT was 95.2 % (93.0–97.5), and when compared to PCR was 85.6 % (82.1–89.1). Kappa (95 % CI) values for Gazelle™ were 96.4 (93.2–99.5), 88.2 (82.6–93.8) and 65.3 (57.0–73.6) for optical microscopy, RDT and PCR, respectively.

Conclusions

The Gazelle™ device was shown to have faster, easier, good sensitivity, specificity, and accuracy when compared to microscopy and was superior to RDT, demonstrating to be an alternative for vivax malaria screening particularly in areas where malaria is concomitant with other febrile infections (including dengue fever, zika, chikungunya, Chagas, yellow fever, babesiosis).

Exploring the influence of deforestation on dengue fever incidence in the Brazilian Amazonas state

INTRODUCTION

Dengue fever is the most prevalent arboviral disease in the Brazilian Amazon and places a major health, social and economic burden on the region. Its association with deforestation is largely unknown, yet the clearing of tropical rainforests has been linked to the emergence of several infectious diseases, including yellow fever and malaria. This study aimed to explore potential drivers of dengue emergence in the Brazilian Amazon with a focus on deforestation.

METHODS

An ecological study design using municipality-level secondary data from the Amazonas state between 2007 and 2017 (reported rural dengue cases, incremental deforestation, socioeconomic characteristics, healthcare and climate factors) was employed. Data were transformed according to the year with the most considerable deforestation. Associations were explored using bivariate analysis and a multivariate generalised linear model.

RESULTS

During the study period 2007-2017, both dengue incidence and deforestation increased. Bivariate analysis revealed increased incidences for some years after deforestation (e.g. mean difference between dengue incidence before and three years after deforestation was 55.47 cases per 100,000, p = 0.002), however, there was no association between the extent of deforestation and dengue incidence. Using a negative binomial regression model adjusted for socioeconomic, climate and healthcare factors, deforestation was not found to be related to dengue incidence. Access to healthcare was found to be the only significant predictor of dengue incidence.

DISCUSSION

Previous research has shown that deforestation facilitates the emergence of vector-borne diseases. However, no significant dose-response relationships between dengue incidence and deforestation in the Brazilian Amazonas state were found in this study. The finding that access to healthcare was the only significant predictor of dengue incidence suggests that incidence may be more dependent on surveillance than transmission. Further research and public attention are needed to better understand environmental effects on human health and to preserve the world's largest rainforest.

Factors associated with malaria in indigenous populations: A retrospective study from 2007 to 2016

Background

In Brazil malaria is most frequent in the Amazon region, mainly in the Amazonas state, where it is found the most proportion of indigenous people of the whole country. It is remarkable publications about malaria in the Amazon, although information on malaria in indigenous populations is still poorly explored.

Objective

Identify factors associated with malaria in indigenous populations.

Methods

Cross-sectional study of positive cases of malaria in the state of Amazonas, Brazil, from 2007 to 2016. Secondary data were obtained from the Epidemiological Surveillance Information System for Malaria and from the Mortality Information System, both from Brazil. To tackle with race missing data, cases with no race fulfilled were classified according to the probable location where infection occurred. This way, was imputed indigenous race for those which the probable infection location was indigenous village (aldeia). Variables tested with race were: sex, age, schooling, microscope surveillance slide type, parasitic infection species, parasitemia level, and timeliness of treatment. Multivariate logistic regression was used.

Results

A total of 1,055,852 cases of malaria were notified in the state of Amazonas. Among the factors that associate malaria and indigenous peoples, the most significant were sex, children and high levels of parasitemia. The magnitude of Plasmodium vivax infection is higher than Plasmodium falciparum, although this parasite was more frequent in indigenous than other races. In regards to mortality, 109 deaths were registered, most of them related to P. vivax.

Conclusion

The findings underscore the importance of look at indigenous people differently of other races. The associated factors highlight a profile of cases severity, because of highest parasitemia, many cases of P. falciparum although high frequency of P. vivax, and children. Furthermore, the mortality in indigenous, specially in older people is worrying

#StayHome: Monitoring and benchmarking social isolation trends in Caruaru and the Região Metropolitana do Recife during the COVID-19 pandemic

This technical report presents information related to the Social Isolation Index (SII) of the city of Caruaru, Pernambuco, Brazil. The data was provided by In Loco, a technology startup that has collected the movement of around 60 million Brazilians through cell phone location.

Social, demographic, health care and co-morbidity predictors of tuberculosis mortality in Amazonas, Brazil: a multiple cause of death approach

OBJECTIVES

Estimate TB mortality rates, catalogue multiple causes on death certificates in which TB was reported and identify predictors of TB from reporting on death certificates in the State of Amazonas, Brazil, based on a multiple cause of death approach.

METHODS

The death records of residents in the Amazonas state between 2006-2014 were analyzed and separated into three categories: TB not reported on the death certificate (TBNoR), TB reported as the underlying cause of death (TBUC) and TB reported as an associated cause of death (TBAC). Age standardized annual mortality rates for TBUC, TBAC and with TB reported (TBUC plus TBAC) were estimated for the State of Amazonas using the direct standardization method and World Health Organization 2000-2025 standard population. Mortality odds ratios (OR) for reporting of TBUC and TBAC were estimated using multinomial logistic regression.

RESULTS

Age standardized annual TBUC and TBAC mortality rates ranged between 5.9-7.8/105 and 2.7-4.0/105, respectively. TBUC was associated with being a resident in the State capital (OR = 0.66), of female gender (OR = 0.87), having an education level of 8 to 11, or 12 or more school years (OR = 0.67 and 0.50 respectively), non-white race/skin color (OR = 1.38) and place of death reported as in the State capital (OR = 1.69). TBAC was related to the triennium in which death occurred (OR = 1.21 and 1.22 for the years 2009-2011 and 2012-2014 respectively), age (OR = 36.1 and 16.5 for ages 15-39 and 40-64 years respectively) and when death occurred in the State capital (OR = 5.8).

CONCLUSIONS

TBUC was predominantly associated with predictors of unfavorable socioeconomic conditions and health care access constraints, whereas TBAC was mainly related to ages which were typical of high HIV disease incidence.

Do climate changes alter the distribution and transmission of malaria? Evidence assessment and recommendations for future studies

Malaria, a mosquito-borne infectious disease, is considered a significant global health burden. Climate changes or different weather conditions may impact infectious diseases, specifically those transmitted by insect vectors and contaminated water. Based on the current predictions for climate change associated with the increase in carbon dioxide concentrations in the atmosphere and the increase in atmospheric temperature, the Intergovernmental Panel on Climate Change predicts that in 2050, malaria may threaten some previously unexposed areas worldwide and cause a 50% higher probability of malaria cases. Climate-based distribution models of malaria depict an increase in the geographic distribution of the disease as global environmental temperatures and conditions worsen. Researchers have studied the influence of changes in climate on the prevalence of malaria using different mathematical models that consider different variables and predict the conditions for malaria distribution. In this context, we conducted a mini-review to elucidate the important aspects described in the literature on the influence of climate change in the distribution and transmission of malaria. It is important to develop possible risk management strategies and enhance the surveillance system enhanced even in currently malaria-free areas predicted to experience malaria in the future.

Tuberculosis and malaria walk side by side in the Brazilian Amazon: an ecological approach

OBJECTIVE

To assess the spatial distribution of TB and malaria incidence, as well as their spatial association with each other, regardless of environmental and socio-economic factors commonly reported as determinants of both disease rates among the municipalities of Amazonas State, Brazil between 2012 and 2015.

METHODS

Through an ecological approach considering municipalities of Amazonas, Brazil, as unit of analysis, a negative binomial regression model was used to assess association between malaria and TB rates, in which the dependent variable was the average municipal tuberculosis incidence rate.

RESULTS

Positive associations of overall malaria (β = 0.100 [CI = 0.032, 0.168], P = 0.004), P. vivax malaria (β = 0.115 [CI = 0.036, 0.195], P = 0.005), and P. falciparum malaria (β = 0.389 [CI = -0.0124, 0.791], P = 0.057) with TB rates were found, regardless of the sociodemographic factors included in the study.

CONCLUSION

In the Brazilian Amazon, TB and malaria are spatially associated. Therefore, it is very likely that co-infections also occur in this region, regardless of the HIV status.

Current vector control challenges in the fight against malaria in Brazil

In Brazil, malaria is an important public health problem first reported in 1560. Historically, fluctuations in malaria cases in Brazil are attributed to waves of economic development; construction of railroads, highways, and hydroelectric dams; and population displacement and land occupation policies. Vector control measures have been widely used with an important role in reducing malaria cases. In this review article, we reviewed the vector control measures established in the Brazilian territory and aspects associated with such measures for malaria. Although some vector control measures are routinely used in Brazil, many entomological and effectiveness information still need better evidence in endemic areas where Plasmodium vivax predominates. Herein, we outlined some of the needs and priorities for future research: a) update of the cartography of malaria vectors in Brazil, adding molecular techniques for the correct identification of species and complexes of species; b) evaluation of vector competence of anophelines in Brazil; c) strengthening of local entomology teams to perform vector control measures and interpret results; d) evaluation of vector control measures, especially use of insecticide-treated nets and long-lasting insecticidal nets, estimating their effectiveness, cost-benefit, and population acceptance; e) establishment of colonies of malaria vectors in Brazil, i.e., Anopheles darlingi, to understand parasite-vector interactions better; f) study of new vector control strategies with impacts on non-endophilic vectors; g) estimation of the impact of insecticide resistance in different geographical areas; and h) identification of the relative contribution of natural and artificial breeding sites in different epidemiological contexts for transmission.

The role of deforestation on American cutaneous leishmaniasis incidence: spatial-temporal distribution, environmental and socioeconomic factors associated in the Brazilian Amazon

OBJECTIVE

To analyse the temporal and spatial distribution as well as the environmental and socioeconomic factors associated with cutaneous leishmaniasis incidence in the state of Amazonas, Brazil from 2007 to 2015.

METHODS

Spatial and temporal distribution was evaluated from sequential thematic maps of the mean incidence rates of the disease. A negative binomial regression analysis was performed to evaluate the association of the factors studied with the mean incidence rate of ACL.

RESULTS

The average proportion of deforestation was negatively associated with the average incidence rate of cutaneous leishmaniasis in municipalities (β = -2.178; P = 0.019; 95%CI -3.996, -0.361), and the health system performance index (effectiveness) (β = -0.852; P = 0.008; 95%CI -1.481, -0.225). Conversely, the municipal human development index (MHDI) was a factor positively related to the average incidence among the municipalities (β = 7.728; P = 0.003; 95%CI 2.716, 12.738).

CONCLUSION

Our study shows the important impact of socioeconomic and environmental factors on ACL incidence in the Amazonas State.

Overview of artemisinin effectiveness during outset years of its implementation in the western Brazilian Amazon

BACKGROUND

METHODS

FINDINGS

MAIN CONCLUSIONS

Stepping into a dangerous quagmire: Macroecological determinants of Bothrops envenomings, Brazilian Amazon

Despite significant and successful efforts in Brazil regarding snakebites in the areas of research, antivenom manufacture and quality control, training of health professionals in the diagnosis and clinical management of bites, little is known about determinants of snakebites incidence in order to further plan interventions to reduce the impact of this medical condition. Understanding the complexity of ecological interactions in a geographical region is important for prediction, prevention and control measures of snakebites. This investigation aims to describe spatial distribution and identify environmental determinants of human envenoming by lancehead pit vipers (Bothrops genus), in the Brazilian Amazon. Aggregated data by the municipality was used to analyze the spatial distribution of Bothrops bites cases and its relationship with geographic and environmental factors. Eight geo-environmental factors were included in the analysis as independent variables: (1) tree canopy loss increase; (2) area with vegetation cover; (3) area covered by water bodies; (4) altitude; (5) precipitation; (6) air relative humidity; (7) soil moisture; and (8) air temperature. Human envenoming by lancehead pit vipers (Bothrops genus) in the Amazon region is more incident in lowlands [Adjusted regression coefficient [ARC] -0.0007 (IC95%: -0.001; -0.0006), p<0.0001], with high preserved original vegetation cover [ARC 0.0065 (IC95%: 0.0071; 0.0060), p<0.0001], with heaviest rainfall [ARC 0.0001 (IC95%: 0.00009; 0.0001), p<0.0001] and higher air relative humidity [ARC 0.0082 (IC95%: 0.0108; 0.0056), p<0.0001]. This association is interpreted as the result of the higher prey availability and further abundance of pit vipers in such landscapes.

Composition of sand fly fauna (Diptera: Psychodidae) and detection of Leishmania DNA (Kinetoplastida: Trypanosomatidae) in different ecotopes from a rural settlement in the central Amazon, Brazil

Background

Phlebotomine sand flies (Diptera: Psychodidae) are vectors of Leishmania species, the etiological agents of leishmaniasis, which is one of the most important emerging infectious diseases in the Americas. In the state of Amazonas in Brazil, anthropogenic activities encourage the presence of these insects around rural homes. The present study aimed to describe the composition and distribution of sand fly species diversity among the ecotopes (intradomicile, peridomicile and forest) in an area of American cutaneous leishmaniasis transmission and detect natural infection with Leishmania DNA to evaluate which vectors are inside houses and whether the presence of possible vectors represents a hazard of transmission.

Results

Phlebotomine sand flies were collected using light traps. A total of 2469 specimens representing 54 species, predominantly females (71.2%), were collected from four sites. Polymerase chain reaction analysis was performed on 670 samples to detect Leishmania DNA. Most of the samples (79.5%) were collected in the forest, with areas closer to rural dwellings yielding a greater abundance of suspected or proven vectors and a larger number of species containing Leishmania DNA. Nyssomyia umbratilis and Bichromomyia flaviscutellata were found near rural homes, and Ny. umbratilis was also found inside homes. Leishmania DNA was detected in different species of sand flies in all ecotopes, including species with no previous record of natural infection.

Conclusions

There is no evidence that vectors of American cutaneous leishmaniasis are becoming established inside homes, but there are sand flies, including Ny. umbratilis and other possible vectors, in environments characterized by a human presence. These species continue to be predominant in the forest but are prevalent in areas closer to ecotopes with a greater human presence. The existence of proven or suspected vectors in this ecotope is due to the structural organization of rural settlements and may represent a hazard of transmission. Although the detection of Leishmania DNA in species that were not previously considered vectors does not mean that they are transmitting the parasite, it does show that the parasite is circulating in ecotopes where these species are found.

Factors associated with unspecified and ill-defined causes of death in the State of Amazonas, Brazil, from 2006 to 2012

This study aimed to investigate factors associated with unspecified and ill-defined causes of death in the State of Amazonas (AM), Brazil. This is a cross-sectional study on 90,439 non-fetal deaths of residents in AM from 2006 to 2012. The hierarchical multinomial logistic model estimated odds ratios of unspecified and ill-defined causes of death. Ill-defined and unspecified causes of death proportional mortality was, respectively, 16.6% and 9.1%. Ill-defined causes showed a decreasing trend over the years, while unspecified causes only decreased in the last two years. Unspecified causes of death were associated with residence and death outside the capital, public roads, female gender, age group 10-49 years, brown skin color and when certified by forensic doctors. Ill-defined causes of death were associated with residence and occurrence outside capital, at home, ages 40 years and older, non-whites, not being single, low schooling, under medical care and when examiner was unknown. Ill-defined and unspecified cause mortality in the State of Amazonas decreased between 2006 and 2012 in AM and was associated with space and time, demographic and socioeconomic factors and medical care at the moment of death.

Snakebites as cause of deaths in the Western Brazilian Amazon: Why and who dies? Deaths from snakebites in the Amazon

Snake envenoming represents a major burden for public health worldwide. In the Amazon, the official number of cases and deaths detected is probably underestimated because of the difficulty riverine and indigenous populations have reaching health centers in order to receive medical assistance. Thus, integrated analysis of health information systems must be used in order to improve adequate health policies. The aim of this work is to describe a series of deaths and identify risk factors for lethality from snakebites in the state of Amazonas, Brazil. All deaths from snakebites reported to the Brazilian Notifiable Diseases Surveillance System (SINAN) and to the Mortality Information System (SIM; ICD10-10th revision, X.29), from 2007 to 2015, were included. Variables were assessed by blocks with distal (ecological variables), intermediate (demographics) and proximal (clinical variables) components to identify predictors of case fatality. A total of 127 deaths from snakebites were recorded, with 58 pairs found through linkage of the SINAN and SIM databases (45.7%), 37 (29.1%) deaths found only in SINAN and 32 (25.2%) found only in the SIM. Deaths occurred mostly in males (95 cases; 74.8%) living in rural areas (78.6%). The most affected age group was the ≥61 years old (36 cases; 28.4%). Snakebites were presumably due to Bothrops snakes in 68.5% of the cases and Lachesis in 29.5% based on clinico-epidemiological diagnosis. A proportion of 26.2% of the cases received treatment over 24 h after the bite ocurred. On admission, cases were mostly classified as severe (65.6%). Overall, 28 patients (22.0%). Deceased without any medical assistance Antivenom was given to 53.5%. In the multivariate analysis, a distance from Manaus >300 km [OR = 3.40 (95%CI = 1.99-5.79); (p < 0.001)]; age ≥61 years [OR = 4.31 (95%CI = 1.22-15.21); (p = 0.023)] and Indigenous status [OR = 5.47 (95%CI = 2.37-12.66); (p < 0.001)] were independently associated with case fatality from snakebites. Severe snakebites [OR = 16.24 (95%CI = 4.37-60.39); (p < 0.001)] and a lack of antivenom administration [OR = 4.21 (95%CI = 1.30-13.19); (p = 0.014)] were also independently associated with case fatality. Respiratory failure/dyspnea, systemic bleeding, sepsis and shock were recorded only among fatal cases. In conclusion, i) death from snakebites was underreported in the mortality surveillance system; ii) older age groups living in remote municipalities and indigenous peoples were the population groups most prone to death; iii) lack or underdosage of antivenom resulted in higher case fatality and iv) systemic bleeding, circulatory shock, sepsis and acute respiratory failure were strongly associated to fatal outcome.

What does not kill it makes it weaker: effects of sub-lethal concentrations of ivermectin on the locomotor activity of Anopheles aquasalis

Background

Malaria remains a major public health concern. Vector control measures based solely on insecticide treated nets (ITNs) and indoor residual spraying (IRS) have demonstrated not to be feasible for malaria elimination. It has been shown that ivermectin affects several aspects of Anopheles species biology. Along the Latin American seacoast, Anopheles aquasalis Curry plays an important role in malaria transmission. The observation of mosquitoes locomotor activity under laboratory conditions can reveal details of their daily activity rhythms, which is controlled by an endogenous circadian clock that seems to be influenced by external signals, such as light and temperature. In this study, we assessed basal locomotor activity and the effects of ivermectin on locomotor activity of the American malaria vector, An. aquasalis.

Methods

Adult females of Anopheles aquasalis used in experiments were three to five days post-emergence. Blood from one single subject was used to provide mosquito meals by membrane feeding assays. Powdered ivermectin compound was used to achieve different concentrations of drug as previously described. Fully engorged mosquitoes were individually placed into glass tubes and provided with 10% sucrose. Each tube was placed into a Locomotor Activity Monitor (LAM). The LAMs were kept inside an incubator under a constant temperature and a 12:12 h light:dark cycle. The average locomotor activity was calculated as the mean number of movements performed per mosquito in the period considered. Intervals of time assessed were adapted from a previous study. One-way ANOVA tests were performed in order to compare means between groups. Additionally, Dunnett’s method was used for post-hoc pairwise means comparisons between each group and control. Stata software version 13 was used for the analysis.

Results

Anopheles aquasalis showed a nocturnal and bimodal pattern for mosquitoes fed both control blood meals and sub-lethal concentrations of ivermectin. In this species, activity peaks occurred at the beginning of the photophase and scotophase in the control group. The nocturnal activity is evident and higher just after the evening peak and maintains basal levels of locomotion throughout the scotophase. In the entire group analysis, locomotor activity means of experimental sets were significantly lower than control for each period of time evaluated. In the survival group, the locomotor activity means of all treatment sets were lower than control mosquitoes for all intervals of time when both the whole period and scotophase were assessed. When the middle of scotophase was evaluated, means were significantly lower for LC₁₅ and LC₂₅, but not LC₅. For the beginning of photophase period, significant differences were detected only between control and LC₅. When both the photophase and scotophase were assessed alone, no significant differences were found. Mean locomotor activity was significantly lower for dead group when compared to survival group for all experimental sets when whole period, photophase, and scotophase were assessed.

Conclusions

Ivermectin seems to decrease locomotor activity of An. aquasalis at sub-lethal concentrations. The effects on locomotor activity increase according at higher ivermectin concentrations and are most evident during the whole scotophase as well as in the beginning and in the end of this phase, and sub-lethal effects may still be observed in the photophase. Findings presented in this study demonstrate that sub-lethal ivermectin effects reduce mosquito locomotor activity, which could diminish vectorial capacity and therefore the malaria transmission.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2563-0) contains supplementary material, which is available to authorized users.

Transovarial transmission of DENV in Aedes aegypti in the Amazon basin: a local model of xenomonitoring

BACKGROUND

Transovarial transmission of dengue virus in Aedes spp. mosquitoes is considered an important mechanism for the maintenance of the virus in nature and may be implicated in the occurrence of outbreaks and epidemics of the disease. However, there are few studies involving transovarial transmission and viral vector monitoring as a surveillance tool and control strategy. The present study evaluated transovarial transmission of dengue virus in Aedes aegypti populations as a xenomonitoring strategy in municipalities of the Amazonas state.

RESULTS

Aedes sp. eggs (13.164) were collected, with 30% viability of third- and fourth-instar larvae. Transovarial transmission of DENV was detected in all municipalities. The transovarial infection rate (TOR) in the municipalities was 46% of the DENV positive samples. The minimum infection rate (MIR) was 17.7 in the state, varying from 11.4 to 24.1 per 1,000 larvae tested in the respective municipalities. Four DENV serotypes were identified, with DENV I and IV being present in all municipalities investigated. The number of reported dengue fever cases varied during this period.

CONCLUSIONS

Our results suggest that transovarial transmission may be an important mechanism for the maintenance and spreading of the disease in Amazonas municipalities. Using qRT-PCR, it was possible to identify the four DENV serotypes in larval samples. The methodology used in the present study proved suitable as a DENV xenomonitoring model in immature mosquitoes, contributing to the development of systems for early detection of viral circulation and predictive models for the occurrence of outbreaks and epidemics of this disease.

TRIAL REGISTRATION

CAAE34025414200005015 .

Plasmodium vivax Landscape in Brazil: Scenario and Challenges

Brazil is the largest country of Latin America, with a considerable portion of its territoritory within the malaria-endemic Amazon region in the North. Furthermore, a considerable portion of its territory is located within the Amazon region in the north. As a result, Brazil has reported half of the total malaria cases in the Americas in the last four decades. Recent progress in malaria control has been accompanied by an increasing proportion of Plasmodium vivax, underscoring a need for a better understanding of management and control of this species and associated challenges. Among these challenges, the contribution of vivax malaria relapses, earlier production of gametocytes (compared with Plasmodium falciparum), inexistent methods to diagnose hypnozoite carriers, and decreasing efficacy of available antimalarials need to be addressed. Innovative tools, strategies, and technologies are needed to achieve further progress toward sustainable malaria elimination. Further difficulties also arise from dealing with the inherent socioeconomic and environmental particularities of the Amazon region and its dynamic changes.

Mortality Predictors in Patients with Severe Dengue in the State of Amazonas, Brazil

Dengue is a major public health problem in tropical and subtropical areas worldwide. There is a lack of information on the risk factors for death due to severe dengue fever in developing countries, including Brazil where the state of Amazonas is located. This knowledge is important for decision making and the implementation of effective measures for patient care. This study aimed to identify factors associated with death among patients with severe dengue, in Amazonas from 2001 to 2013. We conducted a retrospective cohort study based on secondary data from the epidemiological surveillance of dengue provided by the Fundação de Vigilância em Saúde do Amazonas, FVS (Health Surveillance Foundation) of the Secretaria de Saúde do Amazonas, SUSAM (Health Secretariat of the State of Amazonas). Data on dengue cases were obtained from the SINAN (Notifiable Diseases Information System) and SIM (Mortality Information System) databases. We selected cases of severe dengue with laboratory confirmation, including dengue-related deaths of residents in the state of Amazonas from January 1, 2001, to December 31, 2013. The explanatory variables analyzed were sex, age, level of education, spontaneous hemorrhagic manifestations, plasma extravasation and platelet count. Patients who died due to severe dengue had more hematuria, gastrointestinal bleeding, and thrombocytopenia than the survivors. Considering the simultaneous effects of demographic and clinical characteristics with a multiple logistic regression model, it was observed that the factors associated with death were age >55 years (odds ratio [OR] 4.98), gastrointestinal bleeding (OR 10.26), hematuria (OR 5.07), and thrombocytopenia (OR 2.55). Gastrointestinal bleeding was the clinical sign most strongly associated with death, followed by hematuria and age >55 years. The study results showed that the best predictor of death from severe dengue is based on the characteristic of age >55 years, together with the clinical signs of gastrointestinal bleeding, hematuria, and low platelet count.

Declining malaria transmission in rural Amazon: changing epidemiology and challenges to achieve elimination

Background

In recent years, considerable success in reducing its incidence has been achieved in Brazil, leading to a relative increase in the proportion of cases caused by Plasmodium vivax, considered a harder-to-eliminate parasite. This study aim is to describe the transmission dynamics and associated risk factors in a rural settlement area in the Western Brazilian Amazon.

Methods

A prospective cohort was established in a rural settlement area for 3 years. Follow-up included continuous passive case detection and monthly active case detection for a period of 6 months. Demographic, clinical and transmission control practices data were collected. Malaria diagnosis was performed through thick blood smear. Univariable and multivariable analyses of factors associated with malaria incidence were performed using negative binomial regression models. Factors associated with recurrence of P. vivax and Plasmodium falciparum malaria within 90 days of a previous episode were analysed using univariable and multivariable Cox-Proportional Hazard models.

Results

Malaria prevalence decreased from 7 % at the study beginning to 0.6 % at month 24, with P. vivax predominating and P. falciparum disappearing after 1 year of follow-up. Malaria incidence was significantly higher in the dry season [IRR (95 % CI) 1.4 (1.1–1.6); p < 0.001)]. Use of ITN was associated to malaria protection in the localities [IRR (95 % CI) 0.7 (0.6–0.8); p = 0.001)]. A recurrent P. vivax episode within 90 days was observed in 29.4 % of individuals after an initial diagnosis. A previous P. vivax [IRR (95 % CI) 2.3 (1.3–4.0); p = 0.006)] or mixed P. vivax + P. falciparum [IRR (95 % CI) 2.9 (1.5–5.7); p = 0.002)] infections were significantly associated to a vivax malaria episode within 90 days of follow-up.

Conclusions

In an area of P. falciparum and P. vivax co-endemicity, a virtual disappearance of P. falciparum was observed with P. vivax increasing its relative contribution, with a large proportion of recurring episodes. This finding reinforces the perception of P. falciparum being more responsive to early diagnosis and treatment and ITN use and the contribution of relapsing P. vivax to maintain this species’ transmission. In areas of P. vivax endemicity, antihypnozoite treatment effectiveness assessment in different transmission intensity may be a fundamental activity for malaria control and elimination.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1326-2) contains supplementary material, which is available to authorized users.

Deforestation, drainage network, indigenous status, and geographical differences of malaria in the State of Amazonas

Background

Malaria is a major public health problem worldwide. In Brazil, an average of 420,000 cases of malaria have been reported annually in the last 12 years, of which 99.7 % occurred in the Amazon region. This study aimed to analyse the distribution of malaria in the State of Amazonas and the influence of indigenous malaria in this scenario, to evaluate the correlation between incidence rates and socio-economic and environmental factors, and to evaluate the performance of health surveillance services.

Methods

This ecological study used secondary data obtained from the SIVEP-MALARIA malaria surveillance programme. The relationship between demographic, socio-economic and environmental factors, the performance of health surveillance services and the incidence of malaria in Amazonas, a multiple linear regression model was used.

Results

The crude rate of malaria in Amazonas was 4142.72 cases per 100,000 inhabitants between 2003 and 2012. The incidence rates for the indigenous and non-indigenous populations were 12,976.02 and 3749.82, respectively, with an indigenous population attributable fraction of only 8 %. The results of the linear regression analysis indicated a negative correlation between the two socio-economic indicators (municipal human development index (MHDI) and poverty rate) and the incidence of malaria in the period. With regard to the environmental indicators (average annual deforestation rate and percentage of areas under the influence of watercourses), the correlation with the incidence rate was positive.

Conclusions

The findings underscore the importance of implementing economic and social development policies articulated with strategic actions of environmental protection and health care for the population.