Reemergence of Dengue Virus Serotype 3, Brazil, 2023.

We characterized 3 autochthonous dengue virus serotype 3 cases and 1 imported case from 2 states in the North and South Regions of Brazil, 15 years after Brazil's last outbreak involving this serotype. We also identified a new Asian lineage recently introduced into the Americas, raising concerns about future outbreaks.

Human outbreaks of a novel reassortant Oropouche virus in the Brazilian Amazon region.

The Brazilian western Amazon is experiencing its largest laboratory-confirmed Oropouche virus (OROV) outbreak, with more than 6,300 reported cases between 2022 and 2024. Here, we sequenced and analyzed 382 OROV genomes from human samples collected in Amazonas, Acre, Rondônia, and Roraima states, between August 2022 and February 2024, to uncover the origin and genetic evolution of OROV in the current outbreak. Genomic analyses revealed that the upsurge of OROV cases in the Brazilian Amazon coincides with spread of a novel reassortant lineage containing the M segment of viruses detected in the eastern Amazon region (2009-2018) and the L and S segments of viruses detected in Peru, Colombia, and Ecuador (2008-2021). The novel reassortant likely emerged in the Amazonas state between 2010 and 2014 and spread through long-range dispersion events during the second half of the 2010s. Phylodynamics reconstructions showed that the current OROV spread was mainly driven by short-range (< 2 km) movements consistent with the flight range of vectors. Nevertheless, a substantial proportion (22%) of long-range (> 10 km) OROV migrations were also detected, consistent with viral dispersion by humans. Our data provides a view of the unprecedented spread and evolution of OROV in Brazilian western Amazon region.

[Exanthematous diseases and the first epidemic of dengue to occur in Manaus, Amazonas State, Brazil, during 1998-1999]. / Doenças exantemáticas e primeira epidemia de dengue ocorrida em Manaus, Amazonas, no período de 1998-1999.

In 1998, the FMT/IMT-AM foundation implemented the surveillance system to diagnose acute undifferentiated febrile syndromes, with the objective of active and passive surveillance in Brazilian western Amazonian rainforest to identify and diagnose the etiologic agents of acute fever. The diagnoses were performed using serological tests to detect IgM antibodies by ELISA (Enzyme-linked-immunosorbent assay) CDC/OPAS or using commercial kits. A total of 8,557 serum samples obtained from patients with clinical suspicion of dengue virus were analyzed. ELISA positive reaction to dengue virus was presented by 40% of the serum samples and 26% of the serum samples had positive ELISA reactions to other exanthematous viral diseases, such as rubella, measles, parvovirus, Oropouche virus and Mayaro virus.