Frequency of pleural effusion in dengue patients by severity, age and imaging modality: a systematic review and meta-analysis.

BACKGROUND: Identification of pleural effusion (PE) in dengue infection is an objective measure of plasma leakage and may predict disease progression. However, no studies have systematically assessed the frequency of PE in patients with dengue, and whether this differs across age and imaging modality. METHODS: We searched Pubmed, Embase Web of Science and Lilacs (period 1900-2021) for studies reporting on PE in dengue patients (hospitalized and outpatient). We defined PE as fluid in the thoracic cavity detected by any imaging test. The study was registered in PROSPERO (CRD42021228862). Complicated dengue was defined as hemorrhagic fever, dengue shock syndrome or severe dengue. RESULTS: The search identified 2,157 studies of which 85 studies were eligible for inclusion. The studies (n = 31 children, n = 10 adults, n = 44 mixed age) involved 12,800 patients (30% complicated dengue). The overall frequency of PE was 33% [95%CI: 29 to 37%] and the rate of PE increased significantly with disease severity (P = 0.001) such that in complicated vs. uncomplicated dengue the frequencies were 48% and 17% (P < 0.001). When assessing all studies, PE occurred significantly more often in children compared to adults (43% vs. 13%, P = 0.002) and lung ultrasound more frequently detected PE than conventional chest X-ray (P = 0.023). CONCLUSIONS: We found that 1/3 of dengue patients presented with PE and the frequency increased with severity and younger age. Importantly, lung ultrasound demonstrated the highest rate of detection. Our findings suggest that PE is a relatively common finding in dengue and that bedside imaging tools, such as lung ultrasound, potentially may enhance detection.

Left ventricular function by strain in uncomplicated malaria: a prospective study from the Brazilian Amazon.

We hypothesized that adults with uncomplicated malaria have lower left ventricular contractile function compared to the general population and that this improves after antimalarial treatment. We examined uncomplicated malaria and the general population from the Western part of the Brazilian Amazon Basin. All persons underwent an echocardiographic examination and peripheral blood smears. Left ventricular function was assessed by speckle tracking analysis of global longitudinal strain (GLS). Logistic regression models were used to assess the association between malaria status (yes/no) and GLS and improvement in GLS by follow-up was assessed using a paired T-test. We enrolled 99 adults with uncomplicated malaria (mean age 40 years, 46% female) of whom 75 had Plasmodium vivax, 22 Plasmodium falciparum and two had both species [median 1595 (528 to 6585) parasites/mm3]. Seventy adults completed a follow-up examination after standard malaria treatment (median 31 days). We examined 486 from the general population (mean age 41 years, 63% female). In persons with malaria at baseline, GLS was lower compared to the general population (18.7% vs. 19.4%, P = 0.002) and GLS improved at follow-up (19.2%, P = 0.032). In multivariable models adjusted for clinical, socioeconomic and echocardiographic confounders, baseline GLS remained significantly associated with malaria status [odds ratio 2.45 (95%CI 1.00 to 7.25), P = 0.023 per 1% increase]. Parasite density was associated with worsening in GLS [+ 16% (+ 0% to + 34%), P = 0.047 per 1 unit increase in GLS]. Adults with uncomplicated malaria had lower GLS compared to the general population and this improved after completed antimalarial treatment. Our results suggest that malaria infection may affect left ventricular contractile function, however, further studies are needed to fully elucidate such a relationship.

Potential role of transthoracic echocardiography for screening LV systolic dysfunction in patients with a history of dengue infection. A cross-sectional and cohort study and review of the literature.

BACKGROUND: Dengue virus can affect the cardiovascular system and men may be at higher risk of severe complications than women. We hypothesized that clinical dengue virus (DENV) infection could induce myocardial alterations of the left ventricle (LV) and that these changes could be detected by transthoracic echocardiography. METHODOLOGY/PRINCIPAL FINDINGS: We examined individuals from Acre in the Amazon Basin of Brazil in 2020 as part of the Malaria Heart Study. By questionnaires we collected information on self-reported prior dengue infection. All individuals underwent transthoracic echocardiography, analysis of left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS). We included 521 persons (mean age 40±15 years, 39% men, 50% urban areas) of which 253 (49%) had a history of dengue infection. In multivariable models adjusted for clinical and sociodemographic data, a history of self-reported dengue was significantly associated with lower LVEF (ß = -2.37, P < 0.01) and lower GLS (ß = 1.08, P < 0.01) in men, whereas no significant associations were found in women (P > 0.05). In line with these findings, men with a history of dengue had higher rates of LV systolic dysfunction (LVEF < 50% = 20%; GLS < 16% = 17%) than those without a history of dengue (LVEF < 50% = 7%; GLS < 16% = 8%; P < 0.01 and 0.06, respectively). CONCLUSIONS/SIGNIFICANCE: The findings of this study suggest that a clinical infection by dengue virus could induce myocardial alterations, mainly in men and in the LV, which could be detected by conventional transthoracic echocardiography. Hence, these results highlight a potential role of echocardiography for screening LV dysfunction in participants with a history of dengue infection. Further larger studies are warranted to validate the findings of this study.

Is self-rated health associated with cardiovascular risk factors and disease in a low-income setting? A cross-sectional study from the Amazon Basin of Brazil.

OBJECTIVE: Prior studies have suggested that self-rated health may be a useful indicator of cardiovascular disease. Consequently, we aimed to assess the relationship between self-rated health, cardiovascular risk factors and subclinical cardiac disease in the Amazon Basin. DESIGN: Cross-sectional study. SETTING, PARTICIPANTS AND INTERVENTIONS: In participants from the Amazon Basin of Brazil we obtained self-rated health according to a Visual Analogue Scale, ranging from 0 (poor) to 100 (excellent). We performed questionnaires, physical examination and echocardiography. Logistic and linear regression models were applied to assess self-rated health, cardiac risk factors and cardiac disease by echocardiography. Multivariable models were mutually adjusted for other cardiovascular risk factors, clinical and socioeconomic data, and known cardiac disease. OUTCOME MEASURES: Cardiovascular risk factors and subclincial cardiac disease by echocardiography. RESULTS: A total of 574 participants (mean age 41 years, 61% female) provided information on self-rated health (mean 75±21 (IQR 60-90) points). Self-rated health (per 10-point increase) was negatively associated with hypertension (OR 0.87 (95% CI 0.78 to 0.97), p=0.01), hypercholesterolaemia (OR 0.89 (95%CI 0.80 to 0.99), p=0.04) and positively with healthy diet (OR 1.13 (95%CI 1.04 to 1.24), p=0.004). Sex modified these associations (p-interaction <0.05) such that higher self-rated health was associated with healthy diet and physical activity in men, and lower odds of hypertension and hypercholesterolaemia in women. No relationship was found with left ventricular ejection fraction <45% (OR 0.97 (95% CI 0.77 to 1.23), p=0.8), left ventricular hypertrophy (OR 0.97 (95% CI 0.76 to 1.24), p=0.81) or diastolic dysfunction (OR 1.09 (95% CI 0.85 to 1.40), p=0.51). CONCLUSION: Self-rated health was positively associated with health parameters in the Amazon Basin, but not with subclinical cardiac disease by echocardiography. Our findings are of hypothesis generating nature and future studies should aim to determine whether assessment of self-rated health may be useful for screening related to policy-making or lifestyle interventions. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov: NCT04445103; Post-results.

Prevalence and Dynamic Changes in Lung Ultrasound Findings among Adults with Uncomplicated Malaria and Controls in the Amazon Basin, Brazil.

Malaria patients are at risk of cardiopulmonary complications but diagnosis and management can be difficult in resource-limited settings. B-lines on lung ultrasound (LUS) mark changes in lung density; however, little is known about their role in malaria. We aimed to examine the prevalence of B-lines in adults with malaria at baseline and follow-up compared with controls in the Amazon Basin. We also examined the relationship between B-lines and left ventricular ejection fraction. We performed eight-zone LUS, echocardiography, and blood smears in 94 adults (mean age 40 years, 54% men) with uncomplicated malaria and 449 controls without heart failure, renal insufficiency or lung disease (mean age 41 years, 38% men). Examinations of adults with malaria were repeated after antimalarial treatment, corresponding to a median of 30 days (interquartile range [IQR] 27-39). Adults with malaria suffered from Plasmodium vivax (N = 70, median 2,823 [IQR 598-7,698] parasites/µL) or P. falciparum (N = 24, median 1,148 [IQR 480-3,128] parasites/µL). At baseline, adults with malaria more frequently had ≥ 3 B-lines (summed across eight zones) compared with controls (30% versus 2%, P value < 0.001), indicating higher lung density. When examinations were repeated, only 6% of adults with malaria had ≥ 3 B-lines at follow-up, which was significant lower compared with baseline (median reduction 3 B-line; P value < 0.001). B-lines were not significantly associated with left ventricular ejection fraction in adults with malaria. In conclusion, B-lines detected by LUS were more frequent in adults with uncomplicated malaria compared with controls and decreased after completed antimalarial treatment.

Prevalence of rheumatic heart disease in adults from the Brazilian Amazon Basin.

BACKGROUND: Rheumatic heart disease (RHD) continues to be a burden in low- and middle-income countries and prevalence estimates are lacking from South America. We aimed to determine the prevalence of RHD in the Brazilian Amazon Basin. METHODS: We examined a random sample of adults (≥18 years) from the general population, who underwent echocardiographic image acquisition by a medical doctor. All images were analyzed according to (i) the 2012 World Heart Federation criteria and (ii) a simplified algorithm for RHD from a previously validated risk score (categories: low-, medium-, high-risk) which involved assessment of the mitral valve (leaflet thickening and excessive motion, regurgitation jet length) and aortic valve (thickening and any regurgitation). RESULTS: A total of 488 adults were screened (mean age 40 ± 15 years, 38% men). The prevalence of RHD was 39/1000 adults (n = 17 definite and n = 2 borderline). Fourteen (74%) had pathological mitral regurgitation, four (21%) mitral stenosis, 0 (0%) pathological aortic regurgitation and six (32%) both mitral and aortic valve disease. None had a prior diagnosis of RHD, 10 (53%) had positive cardiac auscultation and two (11%) reported a history of rheumatic fever. The simplified algorithm identified four (21%) adults as low-risk, six (32%) as intermediate, and nine (47%) as high-risk. CONCLUSIONS: The prevalence of RHD was 39/1000 in adults from the Brazilian Amazon Basin, indicating the need for screening programs in remote areas. A simplified model was only able to categorize every second case of RHD as high-risk. External validation of simplified screening models to increase feasibility in clinical practice are encouraged.

Tropical diseases and risk of hypertension in the Amazon Basin: a cross-sectional study.

Although infectious diseases have been associated with cardiovascular conditions, little is known about tropical disease burden and hypertension. We hypothesized that a history of tropical infections was associated with hypertension. We examined participants from outpatient clinics in the Amazon Basin who were interviewed about prior exposure to tropical diseases, including dengue, malaria hospitalization, and leishmaniasis. Hypertension was defined as a prior physician diagnosis of hypertension, treatment with anti-hypertensive medication, or a systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥90 mmHg. We used logistic regression models to examine the relationship between tropical infectious disease and hypertension. We included 556 participants (mean age 41 ± 15 years, 61% women) of whom 214 (38%) had hypertension and 354 (64%) had a history of tropical infectious disease. The distribution of tropical diseases was: dengue 270 (76%), malaria hospitalization 104 (29%) and leishmaniasis 48 (14%). Any prior tropical infection was significantly associated with prevalent hypertension (odds ratio 1.76 [95% CI 1.22-2.54], P = 0.003) and the association remained significant after adjusting for age, sex, body mass index, diabetes, hypercholesterolemia, socioeconomic status, smoking, vegetable intake and serum creatinine. Persons with a history of ≥2 tropical infections (n = 64) had the greatest risk of hypertension (odds ratio 2.04 [95% CI 1.15-3.63], P = 0.015). In adjusted models, prior infection with dengue was associated with hypertension (P = 0.006), but no associations were found with malaria hospitalization (P = 0.39) or leishmaniasis (P = 0.98). In conclusion, a history of tropical infectious disease was associated with hypertension. This finding supports the idea that pathogen burden may be related to cardiovascular conditions.

Frequency of Electrocardiographic Alterations and Pericardial Effusion in Patients With Uncomplicated Malaria.

Studies have proposed that malaria may lead to electrocardiographic (ECG) changes and pericardial inflammation. We aimed to investigate the frequency of ECG alterations, determined by ECG and Holter monitoring, and pericardial effusion in patients with malaria infection. We performed a prospective observational study of adult patients with uncomplicated malaria in Amazonas, Brazil. Peripheral blood smears, ECG, and bedside echocardiography were conducted before antimalarial treatment and repeated at follow-up after completed treatment. We evaluated the diagnostic value of PR-segment depression, PR-segment elevation, and Spodick's sign for detecting pericardial effusion. A subset of patients underwent Holter monitoring at baseline. Among 98 cases of uncomplicated malaria (55% men; mean age 40 years; median parasite density 1,774/µl), 75 had Plasmodium vivax, 22 Plasmodium falciparum, and 1 had mixed infection. At baseline, 17% (n = 17) had PR-segment depression, 12% (n = 12) PR-segment elevation, 3% (n = 2) Spodick's sign, and the prevalence of pericardial effusion was 9% (n = 9). ECG alterations had sensitivities of 22% to 89% and specificities of 88% to 100% for detecting pericardial effusion at baseline. PR-segment depression had the best accuracy (sensitivity 89%, specificity 90%). Of the 25 patients, 4 patients who did not have pericardial effusion, displayed nonsustained ventricular tachycardia, determined by Holter monitoring (median duration 43 hours). Follow-up examination data were obtained for 71 patients (median 31 days), for whom PR-segment depression, elevation, and pericardial effusion had reduced significantly (p <0.05). In conclusion, our findings suggest that ECG alterations may be useful to detect pericardial effusion in malaria and that these findings decrease after completed antimalarial treatment.

Reference values for left ventricular dimensions, systolic and diastolic function: a study from the Amazon Basin of Brazil.

Country- and ethnicity-specific reference values for echocardiographic parameters are necessary for decision making. No prior studies have examined reference values in adults from the Amazon Basin of Brazil. We performed echocardiographic examinations in 290 healthy adults (mean age 37 ± 14 years, 40% male) from the Brazilian Amazon. Left ventricular (LV) dimensions and volumes were obtained and indexed to body surface area. We also assessed systolic (LV ejection fraction [LVEF] and global longitudinal strain [GLS]) and diastolic function. LV dimensions and volumes were larger in males compared to females, but after indexation only volumes remained larger (P < 0.001 for all). Parameters of systolic function, were significantly greater in females (LVEF 50 to 68%, GLS - 17 to - 24%) than in males (LVEF 50 to 67%, GLS - 15 to - 23%, P < 0.05). Upper limits of normality for cardiac dimensions (indexed and non-indexed) were markedly higher compared to contemporary guidelines (American Society of Echocardiography) and the Brazilian subgroup in the World Alliance Society of Echocardiography (WASE). Lower limit of normality for LVEF (both sex 50%) and upper limit of normality for the left atrial volume index (LAVI) (male: 31 mL/m2, female: 25 mL/m2) were within normal range but slightly lower compared to guidelines and the WASE study. Other diastolic parameters, including E/A-ratio, E/e' ratio and peak tricuspid regurgitation velocity were compatible with present recommendations. Normal reference ranges of echocardiographic parameters in healthy adults from the Brazilian Amazon Basin may be different compared to international guidelines and data from other regions of Brazil. This applies specifically for LVEF and LAVI.

Levels of hepatitis B antibody titers are affected by age and doses gap time in children from a high endemic area of the western Amazon.

BACKGROUND: Despite completion of the vaccine schedule for hepatitis B virus (HBV), children may display levels of HBV surface antibodies (anti-HBs) that are considered inadequate for sufficient protection (<10 IU/L). AIMS: Our aim was to investigate if age and gap time between HBV vaccine doses may negatively affect the levels of anti-HBs in children, and if these relationships are modified by sex. METHODS: In a high-endemic HBV region of the western Brazilian Amazon we enrolled children who had completed the HBV vaccine schedule. All children underwent analysis of anti-HBs and a clinical examination. RESULTS: We included 522 children (mean age 4.3 ± 0.8 years; 50% male). Median anti-HBs was 28.4 [interquartile range (IQR) 5.4 to 128.6] IU/L and 32% had anti-HBs <10 IU/L. The median gap time from last to preceding dose was 2.4 [IQR 2.1 to 3.3] months. Levels of anti-HBs decreased with higher age (-42% per year increase [95%CI -56% to -24%], p<0.001), but not with longer gap time (+23% per month increase [95%CI -16% to +62%], p = 0.249). After adjusting for relevant confounders, gap time became significant (p = 0.032) and age remained a significant predictor of anti-HBs (p<0.001). CONCLUSION: One third of assessed children displayed anti-HBs <10 IU/L. Levels of anti-HBs decreased with higher age and increased with longer gap time between the last two doses.

Plasmodium vivax metacaspase 1 (PvMCA1) catalytic domain is conserved in field isolates from Brazilian Amazon.

In the present study, we investigated the genetic diversity of Plasmodium vivax metacaspase 1 (PvMCA1) catalytic domain in two municipalities of the main malaria hotspot in Brazil, i.e., the Juruá Valley, and observed complete sequence identity among all P. vivax field isolates and the Sal-1 reference strain. Analysis of PvMCA1 catalytic domain in different P. vivax genomic sequences publicly available also revealed a high degree of conservation worldwide, with very few amino acid substitutions that were not related to putative histidine and cysteine catalytic residues, whose involvement with the active site of protease was herein predicted by molecular modeling. The genetic conservation presented by PvMCA1 may contribute to its eligibility as a druggable target candidate in vivax malaria.

Recombinant Plasmodium vivax circumsporozoite surface protein allelic variants: antibody recognition by individuals from three communities in the Brazilian Amazon.

Circumsporozoite protein (CSP) variants of P. vivax, besides having variations in the protein repetitive portion, can differ from each other in aspects such as geographical distribution, intensity of transmission, vectorial competence and immune response. Such aspects must be considered to P. vivax vaccine development. Therefore, we evaluated the immunogenicity of novel recombinant proteins corresponding to each of the three P. vivax allelic variants (VK210, VK247 and P. vivax-like) and of the C-terminal region (shared by all PvCSP variants) in naturally malaria-exposed populations of Brazilian Amazon. Our results demonstrated that PvCSP-VK210 was the major target of humoral immune response in studied population, presenting higher frequency and magnitude of IgG response. The IgG subclass profile showed a prevalence of cytophilic antibodies (IgG1 and IgG3), that seem to have an essential role in protective immune response. Differently of PvCSP allelic variants, antibodies elicited against C-terminal region of protein did not correlate with epidemiological parameters, bringing additional evidence that humoral response against this protein region is not essential to protective immunity. Taken together, these findings increase the knowledge on serological response to distinct PvCSP allelic variants and may contribute to the development of a global and effective P. vivax vaccine.

Plasmodium falciparum infection dysregulates placental autophagy.

Plasmodium (P.) falciparum malaria during pregnancy has been frequently associated with severe consequences such as maternal anemia, abortion, premature birth, and reduced birth weight. Placental damage promotes disruption of the local homeostasis; though, the mechanisms underlying these events are still to be elucidated. Autophagy is a fundamental homeostatic mechanism in the natural course of pregnancy by which cells self-recycle in order to survive in stressful environments. Placentas from non-infected and P. falciparum-infected women during pregnancy were selected from a previous prospective cohort study conducted in the Brazilian Amazon (Acre, Brazil). Newborns from infected women experienced reduced birth weight (P = 0.0098) and placental immunopathology markers such as monocyte infiltrate (P < 0.0001) and IL-10 production (P = 0.0122). The placentas were evaluated for autophagy-related molecules. As a result, we observed reduced mRNA levels of ULK1 (P = 0.0255), BECN1 (P = 0.0019), and MAP1LC3B (P = 0.0086) genes in placentas from P. falciparum-infected, which was more striking in those diagnosed with placental malaria. Despite the protein levels of these genes followed the same pattern, the observed reduction was not statistically significant in placentas from P. falciparum-infected women. Nevertheless, our data suggest that chronic placental immunopathology due to P. falciparum infection leads to autophagy dysregulation, which might impair local homeostasis during malaria in pregnancy that may result in poor pregnancy outcomes.

Antibody Responses Against Plasmodium vivax TRAP Recombinant and Synthetic Antigens in Naturally Exposed Individuals From the Brazilian Amazon.

Thrombospondin-related adhesive protein (TRAP) is essential for sporozoite motility and the invasion of mosquitoes' salivary gland and vertebrate's hepatocyte and is, thus, considered a promising pre-erythrocytic vaccine candidate. Despite the existence of a few reports on naturally acquired immune response against Plasmodium vivax TRAP (PvTRAP), it has never been explored so far in the Amazon region, so results are conflicting. Here, we characterized the (IgG and IgG subclass) antibody reactivity against recombinant PvTRAP in a cross-sectional study of 299 individuals exposed to malaria infection in three municipalities (Cruzeiro do Sul, Mâncio Lima and Guajará) from the Acre state of the Brazilian Amazon. In addition, the full PvTRAP sequence was screened for B-cell epitopes using in silico and in vitro approaches. Firstly, we confirmed that PvTRAP is naturally immunogenic in the cohort population since 49% of the individuals were IgG-responders to it. The observed immune responses were mainly driven by cytophilic IgG1 over all other sublcasses and the IgG levels that was corelated with age and time of residence in the studied area (p < 0.05). Interestingly, only the levels of specific anti-TRAP IgG3 seemed to be associated with protection, as IgG3 responders presented a significantly higher time elapse since the last malaria episode than those recorded for IgG3 non-responders. Regarding the B-cell epitope mapping, among the 148 responders to PvTRAP, four predicted epitopes were confirmed by recognition of antibodies (PvTRAPR197-H227; PvTRAPE237-T258; PvTRAPP344-G374; and PvTRAPE439-K454). Nevertheless, the frequency of responders against these peptides were low and did not show a clear correlation with the antibody response against the corresponding antigen. Moreover, none of the linear confirmed epitopes were located in the binding regions of PvTRAP in respect to the host cell ligand. Collectively, our data confirm the PvTRAP immunogenicity among Amazon inhabitants, while suggesting that the main important B-cell epitopes are not linear.

Ethno-knowledge and attitudes regarding snakebites in the Alto Juruá region, Western Brazilian Amazonia.

BACKGROUND: The Alto Juruá region, located in the extreme western part of the Brazilian Amazonia, possesses an indigenous and riverine population which is involved in agricultural and forest extraction activities, and is a region that stands out for its high incidence of snakebites. OBJECTIVES: To assess the attitudes of the victims, the characteristics of the snakes and the circumstances of the snakebites which occurred in a region where human populations are highly exposed to snakes. METHODS: The study was conducted at the Regional Hospital of Juruá in the Municipality of Cruzeiro do Sul (Acre), which regularly attends victims of snakebites in the Alto Juruá region. The snakes that caused the envenomations were identified from clinical and epidemiological diagnosis of the symptoms and signs that patients presented during hospital, and by enzyme immunoassay for venom detection using serum samples of the patients, or by identification of the snake responsible for the envenomation when it was taken to the hospital or photographed. People who suffered or witnessed the snakebite were interviewed to assess the circumstances of the bite, the attitude adopted after the accident and whether they recognized the species of snake that caused the envenomation. RESULTS: There were 133 cases of snakebite (76.24/100.000 inhabitants), mainly involving male individuals living in the rural area and who had a low level of education. The most affected groups were farmers (48%) and children and teenagers (39%). It was observed that 8.3% of them presented a history of recurrence for bites. The lower limbs were the most affected anatomical region (84%). The Bothrops atrox snake, mainly small specimens (mostly juveniles), was the main species involved in the envenomations (83.4%). Snakebites occurred mainly in forest areas, backyards of houses in rural areas and near to aquatic environments, during activities (walking, farming, extractivism, hunting). Most of the time, the snake was on the ground and the bite occurred because of the approximation of the individual, either by trampling or by approximation of a hand. Half of the victims performed some kind of inadequate first aid (not drinking water, use of tourniquet, incision at the site of the bite, use of black stone, drinking a compound "Específico Pessoa"). CONCLUSIONS: Snakebite is an important cause of morbidity in the Alto Juruá region. Bothrops bites are mostly caused by small-sized specimens, probably due to the greater abundance of B. atrox juveniles, and also because small snakes are more difficult for people to see. People are more often bitten on the lower limbs probably due to the size of B. atrox (small and medium) and because the snakes are usually on the ground in most situations. Many victims resort to ineffective actions that can cause complications and also delay serotherapy. A low level of education is a factor that may contribute to worse outcomes in snakebites since it is associated with a lack of knowledge of preventive and first aid measures.

Plasmodium vivax ookinete surface protein (Pvs25) is highly conserved among field isolates from five different regions of the Brazilian Amazon.

The Plasmodium vivax Ookinete Surface Protein (Pvs25) is one of the leading malaria Transmission-Blocking Vaccine candidates based on its high immunogenicity in animal models, transmission-blocking activity of antibodies elicited in clinical trials and high conservation among P. vivax isolates from endemic areas. However, the polymorphism in gene encoding Pvs25 in endemic areas from South America has been poorly studied so far. Here, we investigated the genetic polymorphism of pvs25 in P. vivax isolates from five different regions of the Brazilian Amazon (Cruzeiro do Sul, Mâncio Lima, Guajará, Manaus and Oiapoque) and its impact on antigenicity of predicted B-cell epitopes using gene sequencing and epitope prediction tools. Firstly, only a non-synonymous substitution was found in the 657 bp amplified fragment in all sequenced samples, which represented an exchange of Gln by Lys at position 87 (Q87K) of protein amino acid sequence (domain II EGF-like). Q87K substitution was also present in all studied sites with a total frequency of 37.8%. Cruzeiro do Sul presented Q87K substitution in almost half of the isolates (48.4%), and an expressive frequency (40.5%) was also found in Manaus, while in Mâncio Lima, Guajará and Oiapoque, the frequencies were low (23.5%, 25% and 22.2% respectively). We also observed the Q87K mutation in a predicted B-cell epitope of pvs25, with no significant changes on its putative antigenicity. Our data suggest that the pvs25 gene is conserved among isolates from different Brazilian Amazon geographic regions, an important observation considering the antigen potentiality as a vaccine candidate to cover distinct P. vivax endemic areas worldwide.

Analysis of the lymphocyte cell population during malaria caused by Plasmodium vivax and its correlation with parasitaemia and thrombocytopaenia.

BACKGROUND: The mechanisms of activation and regulation of T lymphocytes and their cytokines in malaria caused by Plasmodium vivax are complex and poorly understood. Previous data suggest that T cells balance protective immune responses with immune mediated pathology in malaria. This study investigates the lymphocytic profile of patients infected with P. vivax by identifying and quantifying the specific sub-populations of Th1, Th2, Th17 and Treg cells and observing the correlation between parasitaemia and the number of platelets. METHODS: A cross-sectional study was carried out in an endemic area of the state of Acre, Brazil. In order to obtain identification and quantification of lymphocyte sub-populations through flow cytometry, blood samples were collected from 50 individuals infected with P. vivax and 20 non-infected controls. To differentiate Th1 from Th2, the presence of cytokines IL-4 and TNF was examined by enzyme-linked immunosorbent assay. Utilizing the Mann-Whitney and Spearman coefficient tests, comparison and correlation analysis were rendered to test the parasitaemia and the number of platelets relationship. RESULTS: The data indicate that individuals infected with P. vivax present a significant reduction in Th1, Th2 and Th17 cell sub-populations when compared to the non-infected control group. A negative correlation exists between parasitaemia and platelet counts in individuals infected with P. vivax. There is no correlation of parasitaemia or thrombocytopaenia with any sub-population of T lymphocytes analysed. Interestingly, patients with serum Th1 cytokine profile present inversely proportional parasitaemia to the increase in the number of Th1, Th2, Th17 and Treg cells while patients with serum Th2 cytokine profile present directly proportional parasitaemia to the increase in number of Th1 and Th2 cells. Regarding the number of platelets, patients with serum Th1 cytokine profile show a correlation directly proportional to the Th17 sub-population. In contrast, platelet counts are directly proportional only to Treg and activated Treg cells in patients with serum Th2 cytokine profile. CONCLUSIONS: During the P. vivax infection patients with serum Th1 versus Th2 cytokine profile present different biological mechanisms for activating the immune system against parasite load.

Malaria during pregnancy and newborn outcome in an unstable transmission area in Brazil: A population-based record linkage study.

BACKGROUND: Malaria in pregnancy (MiP) is one of the major causes of mortality and morbidity in tropical regions, causing maternal anemia, intrauterine growth retardation, preterm birth, and low birth weight (LBW). The integration of the information systems on pregnancy and malaria could prove to be a useful method of improved decision making for better maternal-child health. METHODS: A population-based observational study acquired information retrospectively from all live births that occurred between 2006 and 2014 in Cruzeiro do Sul (Acre, Brazil). Social and clinical data of the mother and newborn was extracted from the Information System of Live Births. Malaria episodes information was obtained from the Brazilian Epidemiological Surveillance Information System Malaria. A deterministic record linkage was performed to assess malaria impact on pregnancy. RESULTS: The studied population presented a malaria incidence of 8.9% (1283 pregnant women infected), of which 63.9% infected by Plasmodium (P.) vivax. Reduction of newborn birth weight at term (small for gestational age (SGA) and LBW) has been found associated with P. vivax infection during pregnancy (SGA-OR 1.24, 95% CI 1.02-1.52, p = 0.035; term LBW-OR 1.39, 95% CI 1.03-1.88, p = 0.033). Additionally, P. falciparum infection during pregnancy has been found to be associated with preterm births (OR 1.54, 95% CI 1.09-2.18, p = 0.016), which is related with late preterm births (OR 1.59, 95% CI 1.11-2.27, p = 0.011). CONCLUSIONS: Despite the decrease of malaria cases during the evaluation period and regardless of Plasmodium species, we present evidence of the deleterious effects of MiP in a low transmission area in the Amazonian region.

Polymorphisms in Plasmodium vivax Circumsporozoite Protein (CSP) Influence Parasite Burden and Cytokine Balance in a Pre-Amazon Endemic Area from Brazil.

Mechanisms involved in severe P. vivax malaria remain unclear. Parasite polymorphisms, parasite load and host cytokine profile may influence the course of infection. In this study, we investigated the influence of circumsporozoite protein (CSP) polymorphisms on parasite load and cytokine profile in patients with vivax malaria. A cross-sectional study was carried out in three cities: São Luís, Cedral and Buriticupu, Maranhão state, Brazil, areas of high prevalence of P. vivax. Interleukin (IL)-2, IL-4, IL-10, IL-6, IL-17, tumor necrosis factor alpha (TNF-α, interferon gamma (IFN-γ and transforming growth factor beta (TGF-ß were quantified in blood plasma of patients and in supernatants from peripheral blood mononuclear cell (PBMC) cultures. Furthermore, the levels of cytokines and parasite load were correlated with VK210, VK247 and P. vivax-like CSP variants. Patients infected with P. vivax showed increased IL-10 and IL-6 levels, which correlated with the parasite load, however, in multiple comparisons, only IL-10 kept this association. A regulatory cytokine profile prevailed in plasma, while an inflammatory profile prevailed in PBMC culture supernatants and these patterns were related to CSP polymorphisms. VK247 infected patients showed higher parasitaemia and IL-6 concentrations, which were not associated to IL-10 anti-inflammatory effect. By contrast, in VK210 patients, these two cytokines showed a strong positive correlation and the parasite load was lower. Patients with the VK210 variant showed a regulatory cytokine profile in plasma, while those infected with the VK247 variant have a predominantly inflammatory cytokine profile and higher parasite loads, which altogether may result in more complications in infection. In conclusion, we propose that CSP polymorphisms is associated to the increase of non-regulated inflammatory immune responses, which in turn may be associated with the outcome of infection.

Effectiveness of the Live Births Information System in the Far-Western Brazilian Amazon.

The Live Birth Information System (SINASC) was implemented in 1990 for the purpose of providing information about the live-birth characteristics for the establishment of specific health indicators. This work evaluates the information quality of SINASC in relation to its data completeness and coverage for five municipalities from the State of Acre from 2005 to 2010. Lack of information (not filled out or stated as "unknown") was estimated for each variable. Coverage was estimated comparing the Civil Register office statistics in accordance with the mother's municipality of residence. An increase in incompleteness of the majority of variables was observed, and also a decrease in coverage between 2005 and 2010 in these municipalities. These findings do not tally with results from the majority of studies that use SINASC as a data source. The results of this work highlight the relevance of continuous capacity building and the incentive for accurate and complete data inclusion, as well as awareness of the importance of SINASC for public health policies.