After the Zika virus (ZIKV) epidemic in the Americas in 2016, both Zika and dengue incidence declined to record lows in many countries in 2017–2018, but in 2019 dengue resurged in Brazil, causing ~2.1 million cases. In this study we use epidemiological, climatological and genomic data to investigate dengue dynamics in recent years in Brazil. First, we estimate dengue virus force of infection (FOI) and model mosquito-borne transmission suitability since the early 2000s. Our estimates reveal that DENV transmission was low in 2017–2018, despite conditions being suitable for viral spread. Our study also shows a marked decline in dengue susceptibility between 2002 and 2019, which could explain the synchronous decline of dengue in the country, partially as a result of protective immunity from prior ZIKV and/or DENV infections. Furthermore, we performed phylogeographic analyses using 69 newly sequenced genomes of dengue virus serotype 1 and 2 from Brazil, and found that the outbreaks in 2018–2019 were caused by local DENV lineages that persisted for 5–10 years, circulating cryptically before and after the Zika epidemic. We hypothesize that DENV lineages may circulate at low transmission levels for many years, until local conditions are suitable for higher transmission, when they cause major outbreaks.

Emerging arthropod-borne viruses (arboviruses), such as chikungunya and Zika viruses, are a major threat to public health in countries like Brazil where biodiversity is high and medical care is sometimes precarious. West Nile fever is a disease caused by the West Nile Virus (WNV), an RNA virus belonging to the Flaviviridae family. It is transmitted by infected mosquitoes to numerous animals like birds, reptiles and mammals, including human and non-human primates. In the last decade, the number of reported cases of WNV infection in humans and animals has increased in the Americas. Circulation of WNV in forests and rural areas in Brazil has been detected based on serological surveys and, in 2014, the first case of West Nile fever was confirmed in a patient from Piauí State. In 2018, the virus was isolated for the first time from a horse from a rural area in the state of Espírito Santo presenting with a neurological disorder; this raises the possibility that other cases of WNV encephalitis may have occurred without clinical recognition and without laboratory diagnosis by specific assays. The imminent WNV outbreak poses a challenge for Brazilian clinicians and researchers. In this review, we summarize the basic biological and ecological characteristics of this virus and the clinical presentation and treatment of febrile illnesses caused by WNV. We also discuss the epidemiological aspects, prophylaxis of WNV infections, and monitoring strategies that could be applied in the possibility of a WNV outbreak in Brazil.

After Zika virus (ZIKV) emerged and caused an epidemic in the Americas in 2016, both Zika and dengue incidence declined in the following years (2017-2018) to a record low in many countries. Following this period of low incidence, dengue resurged in 2019 in Brazil, causing ~2.1 million cases. The reasons for the recent fluctuations in dengue incidence and the maintenance of dengue virus (DENV) through periods of low transmission are unknown. To investigate this, we used a combination of epidemiological and climatological data to estimate dengue force of infection (FOI) and model mosquito-borne transmission suitability since the early 2000s in Brazil. Our estimates of FOI revealed that the rate of DENV transmission in 2018-2019 was exceptionally low, due to a low proportion of susceptible population rather than changes to ecological conditions. This supports the hypothesis that the synchronous decline of dengue in Brazil may be explained by protective immunity from pre-exposure to ZIKV and/or DENV in prior years. Furthermore, we sequenced 69 genomes of dengue virus serotype 1 (DENV-1) and DENV-2 circulating in Northeast and Southeast Brazil, and performed phylogeographic analyses to uncover patterns of viral spread. We found that the outbreaks in Brazil in 2019 were caused by DENV lineages that were circulating locally prior to the Zika epidemic and spread cryptically during the period of low transmission. Despite the period of low transmission, endemic DENV lineages persisted for 5-10 years in Brazil before causing major outbreaks. Our study challenges the paradigm that dengue outbreaks are caused by recently introduced new lineages, but rather they may be driven by established lineages circulating at low levels until the conditions are conducive for outbreaks.

RESUMO:O objetivo deste estudo foi a comparação entre diferentes testes de diagnóstico para tuberculose bovina. Foram realizados o isolamento bacteriano, a caracterização histopatológica, a identificação de bacilos álcool-ácido resistentes e a detecção do DNA de M. bovis pela reação em cadeia da polimerase, em bovinos adultos abatidos em matadouros frigoríficos sob o Serviço de Inspeção Federal, valendo-se de amostras de linfonodos com lesões macroscópicas sugestivas de tuberculose, identificadas e coletadas durante o abate. O isolamento bacteriano foi realizado pelo cultivo em meios de cultura sólidos; a caracterização histopatológica, pela coloração com hematoxilina-eosina; e a identificação de bacilos álcool-ácido resistentes foi feita pela coloração de Ziehl-Neelsen. A detecção de DNA foi realizada em amostra extraída das lesões sugestivas de tuberculose pela reação em cadeia da polimerase, seguida da nested reação em cadeia da polimerase e por meio das colônias isoladas para identificação do M. bovis, utilizando-se também da reação em cadeia da polimerase . Os resultados obtidos permitiram concluir que os testes histopatológicos, o isolamento bacteriano e a identificação de bacilos álcool-ácido resistentes são aconselháveis para o diagnóstico da tuberculose bovina. Além disso, ensaios de reação em cadeia da polimerase utilizando amostras de lesões sugestivas de tuberculose são um modo mais rápido e promissor para diagnosticar a enfermidade, no entanto não deve ser utilizado sozinho, em virtude da baixa sensibilidade apresentada neste estudo. PALAVRAS-CHAVE: doenças infecciosas; Mycobacterium bovis;tuberculose; zoonose. ABSTRACT:Our goal for this article is to compare several different diagnosis tests for bovine tuberculosis identification. We have performed bacterial isolation, histopathological characterization, acid-fast bacilli (AFB) identification and M. bovis DNA detection. Lesions suggestive of Tuberculosis were sampled from bovine lymph nodes during slaughtering of bovines at an abattoir that operates under federal inspection. The bacterial isolation was performed in solid culture mediums, the histopathological characterization was made by Hematoxylin-eosinstaining, and AFB identification by Ziehl-Neelsen staining. Bacterial DNA detection was performed by Polymerase Chain Reaction (PCR) using DNA from two different sources, directly collected from the tuberculosis-like lesions (PCR followed by nested PCR) and from isolated bacteria. We have concluded that the multi-step approach, including histopathological characterization, bacterial isolation and AFB identification, is strongly recommended to diagnose tuberculosis in bovines. Furthermore, PCR assays using specimens of lesions suggestive of tuberculosis are a faster and more promising way to diagnose the disease. However, it should not be used alone due to the low sensitivity shown in this study.

Introduction: In Brazil, West Nile virus (WNV) was first detected, in 2018, in horses with neurological disease. Aim: We report the first case of WNV infection in a horse from Ceará state and the complete genome sequence of an isolate from Espírito Santo state. Both infections occurred in 2019. Methods: WNV was isolated from the tissues of a horse with neurological signs in Espírito Santo and sequenced by MiSeq. Results: Phylogenetic analysis revealed that the isolate belongs to lineage 1a, clustering with the NY99 strain, a strain that has not circulated in the USA since 2005. Conclusions: Our findings reinforce the hypothesis that WNV has been silently circulating in Brazil for many years.