High seroprevalence of antibodies against arboviruses in postpartum women in Salvador, Brazil.

Objectives: Arboviruses represent a major challenge to public health in Brazil. Dengue (DENV) virus has been endemic for decades, and the introduction of Zika (2015) and Chikungunya (2014) viruses (CHIKV) has imposed a significant burden on the country. The present study aimed to investigate the seroprevalence of Zika virus (ZIKV), DENV and CHIKV in women in Salvador, Bahia-Brazil. Methods: Cross-sectional study involving postpartum women admitted to a maternity hospital in Salvador, Brazil. Anti-ZIKV, anti-DENV and anti-CHIKV immunoglobulin G was measured by enzyme-linked immunosorbent assay. Results: A total of 302 women were enrolled with a median age: 26 years, interquartile range (21-33). Most self-declared as mixed-race or black skin color (92.4%). The seroprevalence was 57% for ZIKV); 91.4% for DENV, and 7.6% for CHIKV. Most participants denied awareness of previous arboviral infection, although 67 (22.3%) reported a previous history of ZIKV infection, 34 (11.1%) DENV infection and 9 (3%) CHIKV infection. Conclusion: Our data indicate a high prevalence of past ZIKV and DENV infections in the population studied. Most of the participants remain susceptible to future CHIKV infection, highlighting the need for preventive and educational interventions. Our results suggest the need for continuous epidemiological surveillance of arboviral diseases, particularly among women residing in at-risk regions.

Phylogenetic Reconstructions Reveal the Circulation of a Novel Dengue Virus-1V Clade and the Persistence of a Dengue Virus-2 III Genotype in Northeast Brazil.

Dengue fever is among the most significant public health concerns in Brazil. To date, the highest number of Dengue notifications in the Americas has been reported in Brazil, with cases accounting for a total number of 3,418,796 reported cases as of mid-December 2022. Furthermore, the northeastern region of Brazil registered the second-highest incidence of Dengue fever in 2022. Due to the alarming epidemiological scenario, in this study, we used a combination of portable whole-genome sequencing, phylodynamic, and epidemiological analyses to reveal a novel DENV-1 genotype V clade and the persistence of DENV-2 genotype III in the region. We further report the presence of non-synonymous mutations associated with non-structural domains, especially the NS2A (non-structural protein 2A), as well as describe synonymous mutations in envelope and membrane proteins, distributed differently between clades. However, the absence of clinical data at the time of collection and notification, as well as the impossibility of monitoring patients in order to observe worsening or death, restricts our possibility of correlating mutational findings with possible clinical prognoses. Together, these results reinforce the crucial role of genomic surveillance to follow the evolution of circulating DENV strains and understand their spread across the region through inter-regional importation events, likely mediated by human mobility, and also the possible impacts on public health and outbreak management.

Guillain-Barré Syndrome and Miller Fisher Syndrome in Association With an Arboviral Outbreak: A Brazilian Case Series.

Introduction: Guillain-Barré syndrome (GBS) in association with arboviruses, such as Zika, chikungunya, and dengue, has been previously documented; however, Miller-Fisher Syndrome (MFS) and other GBS subtypes are rarely reported. Methods: We identified a series of GBS and MFS cases that were followed during the Zika virus outbreak in Salvador, Brazil (2015-2016). Blood and CSF samples were collected for virus diagnosis. In addition, serological studies to verify previous arboviral infection and electromyography (EMG) were performed. Results: Of the 14 patients enrolled, 10 were diagnosed with GBS, including three GBS subtypes (two cases of bifacial weakness with paresthesia and one case of paraparetic GBS), and four as MFS. IgM antibodies against one or more of three arboviruses were present in 11 (78.6%) patients: anti-zika IgM positivity in eight (57%), anti-Chikungunya IgM in three (21%), and anti-Dengue in one (7%) individual. A single case was positive for both anti-Dengue IgM and anti-Chikungunya IgM, suggesting co-infection. EMG revealed an AIDP pattern in all nine patients analyzed. Conclusion: The current case series contributes to our knowledge on the clinical presentation of arbovirus-associated GBS and its subtypes, including MFS, and serves as an alert to clinicians and other healthcare professionals in regions affected by arbovirus outbreaks. We highlight the importance of recognizing arboviruses in diagnosing GBS and its subtypes.

Maternal and congenital infections arising from Zika, dengue and Chikungunya arboviruses in Salvador, Brazil.

BACKGROUND: Salvador was one of the Brazilian cities most affected during the 2015 Zika virus (ZIKV) outbreak. METHODS: A cross-sectional study was performed with enrolment of parturients and their newborns. RESULTS: Positive IgM antibodies for ZIKV, dengue (DENV) and Chikungunya (CHIKV) were present in 6.9, 11.9 and 22.8% of the parturients, and IgG antibodies were detected in 72.3, 92.3 and 38.6%, respectively. No cases of DENV congenital infection were identified. ZIKV and CHIKV congenital infections were observed in 16.5 and 13% of newborns, respectively. CONCLUSIONS: High exposure rates to the three arboviruses and the identification of newborns with ZIKV and CHIKV congenital infections reinforces the necessity of ZIKV and CHIKV prenatal and neonatal screening in endemic regions.

Immunomodulatory treatment with thalidomide in experimental leptospirosis in Golden Syrian hamsters (Mesocricetus auratus).

BACKGROUND: The benefit of antibiotics in leptospirosis is limited when treatment is started four days after symptoms appear, and new adjuvant therapeutic options are urgently needed. METHODS: Hamsters (Mesocricetus auratus) were infected by Leptospira interrogans strain L1-130, and groups were assigned based on no treatment (NONE), thalidomide only (TAL), ampicillin only (AMP) or both (AMP-TAL). Treatment was started two days after the onset of symptoms (experiment 1) and immediately after detection of the first death (experiment 2). RESULTS: Experiment 1: all hamsters from the groups AMP and AMP-TAL survived (n=8), while all hamsters from groups NONE (n=6) and TAL (n=8) died. The AMP and the AMP-TAL groups showed no renal or liver pathology and absent or very low leptospiral burden in target organs. Experiment 2: lethal outcome was observed in 6/6 hamsters in the NONE group, 8/8 in the TAL group, and 6/8 in both the AMP and AMP-TAL groups. Thalidomide showed no survival benefit when compared to hamsters treated with ampicillin alone. The TAL, AMP and AMP-TAL groups had very low tissue leptospiral counts. CONCLUSION: Thalidomide had minimal impact on survival in the late treatment of leptospirosis hamster model.

O Papel do óxido nítrico na patogênese da leptospirose experimental em hamsters e camundongos / The role of nitric oxide in the pathogenesis of experimental leptospirosis in hamsters and mice

A patogênese da leptospirose é pouco compreendida e os estudos com. enfoque na resposta inflamatória sistêmica ou local são escassos, em especial no que se refere ao papel do óxido nítrico (NO) e da enzima óxido nítrico sintase induzível (iNOS). Dados de ensaios em culturas de células renais sugerem um papel importante da liberação de mediadores inflamatórios, tais como NO, na resposta às leptospiras e consequente nefrite intersticial. A transposição destes achados para o modelo in vivo foi pouco explorada. Por outro lado, estudos em humanos sugerem que a liberação sistêmica de NO correlaciona-se com a gravidade da doença renal e, portanto, pode ser um potencial alvo para terapia adjuvante à antibioticoterapia. O presente trabalho estudou a correlação da iNOS com distúrbios hidroeletrolíticos na patogênese da leptospirose. No modelo experimental de hamsters, avaliamos a associação da inibição dos efeitos do NO, através da terapia combinada de antibioticoterapia padrão e azul de metileno, com distúrbios eletrolíticos, alterações histopatológicas em hamsters e sobrevida. Nenhum benefício da terapia adjuvante com azul de metileno foi demonstrado. No modelo de camundongos transgênicos, investigamos o efeito da ausência do gene da iNOS na nefrite intersticial e na quantidade de bactérias observadas nos tecidos. A ausência do gene iNOS esteve associado a menor frequência de nefrite intersticial grave. Maiores estudos são necessários para investigar a função da inibição da produção de NO na patogenia da doença e da nefrite associada a leptospirose.

The pathogenesis of leptospirosis is poorly understood, and there are few studies fusing on the systemic or local inflammatory responses, especially referring to the role of nitric oxide (NO) and the enzyme inducible nitric oxide synthase (iNOS). Data from in vitro studies suggest an important role of inflammatory mediators, such as NO, in the response to leptospires in the development of interstitial nephritis. The transposition of these findings to an in vivo model was little explored. However, studies in humans suggest that systemic liberation of NO is correlated with severity of renal disease and therefore can be potential target to adjuvant therapy along with antibiotic therapy. The present work evaluated the correlation of iNOS with the pathogenesis of leptospirosis. In the experimental hamster model, we evaluated the effect of inhibiting downstream effects of NO on electrolytic disorders, histopathological changes and survival. No benefit of methylene blue treatment could be observed when compared to antibiotic (ampicillin) therapy only. In the mouse transgenic model, we investigated the effect of the absence of the Inos gene in interstitial nephritis and in the bacterial burden in target tissues. The absence of a functional iNOS gene was associated with lower frequency of severe interstitial nephritis.

Ionic imbalance and lack of effect of adjuvant treatment with methylene blue in the hamster model of leptospirosis.

Leptospirosis in humans usually involves hypokalaemia and hypomagnesaemia and the putative mechanism underlying such ionic imbalances may be related to nitric oxide (NO) production. We previously demonstrated the correlation between serum levels of NO and the severity of renal disease in patients with severe leptospirosis. Methylene blue inhibits soluble guanylyl cyclase (downstream of the action of any NO synthase isoforms) and was recently reported to have beneficial effects on clinical and experimental sepsis. We investigated the occurrence of serum ionic changes in experimental leptospirosis at various time points (4, 8, 16 and 28 days) in a hamster model. We also determined the effect of methylene blue treatment when administered as an adjuvant therapy, combined with late initiation of standard antibiotic (ampicillin) treatment. Hypokalaemia was not reproduced in this model: all of the groups developed increased levels of serum potassium (K). Furthermore, hypermagnesaemia, rather than magnesium (Mg) depletion, was observed in this hamster model of acute infection. These findings may be associated with an accelerated progression to acute renal failure. Adjuvant treatment with methylene blue had no effect on survival or serum Mg and K levels during acute-phase leptospirosis in hamsters.

Ionic imbalance and lack of effect of adjuvant treatment with methylene blue in the hamster model of leptospirosis

Leptospirosis in humans usually involves hypokalaemia and hypomagnesaemia and the putative mechanism underlying such ionic imbalances may be related to nitric oxide (NO) production. We previously demonstrated the correlation between serum levels of NO and the severity of renal disease in patients with severe leptospirosis. Methylene blue inhibits soluble guanylyl cyclase (downstream of the action of any NO synthase isoforms) and was recently reported to have beneficial effects on clinical and experimental sepsis. We investigated the occurrence of serum ionic changes in experimental leptospirosis at various time points (4, 8, 16 and 28 days) in a hamster model. We also determined the effect of methylene blue treatment when administered as an adjuvant therapy, combined with late initiation of standard antibiotic (ampicillin) treatment. Hypokalaemia was not reproduced in this model: all of the groups developed increased levels of serum potassium (K). Furthermore, hypermagnesaemia, rather than magnesium (Mg) depletion, was observed in this hamster model of acute infection. These findings may be associated with an accelerated progression to acute renal failure. Adjuvant treatment with methylene blue had no effect on survival or serum Mg and K levels during acute-phase leptospirosis in hamsters. .