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. In this study, 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).

Mayaro virus detection in the western region of Pará state, Brazil.

Introduction: Mayaro virus (MAYV) was found in Pará state, Brazil, in 1955. Since then, sporadic outbreaks have occurred in different regions of the country.

Methods: Serum sample were collected from 49 individuals in 2016 and were initially tested for dengue virus (DENV) by real-time (RT) polymerase chain reaction (PCR).

Human parvovirus B19 genotype 1 in suspected dengue patients of Tefé, Amazonas State, Brazil.

Introduction: Human parvovirus B19 (B19V) is a common pathogen, which on infection causes variety of clinical conditions from benign self-limiting exanthematous disease and other similar pathologies to fetal death.

Methods: We collected 341 serum samples between the first and fourth day after the onset of symptoms from all patients suspected of dengue fever who were attended at Regional Hospital of Tefé. Initially, patients were screened for malaria by blood smear test and negative samples were sent to Fundação de Medicina Tropical Doutor Heitor Vieira Dourado (FMT-HVD) situated in Manaus (AM) for dengue testing using semi-nested multiplex PCR.

Human Orthobunyavirus Infections, Tefé, Amazonas, Brazil.

Introduction: Several orthobunyaviruses are important arthropod-borne pathogens, responsible for a variety of diseases in humans, from acute febrile illness to encephalitis.

Methods: We collected serum samples from a series of dengue suspected cases in Tefé, a mid-size city located in the interior of the Amazonas state, Brazil. Viral RNA extraction was performed, and specimens were tested for dengue virus using RT-PCR.

Arboviral diseases in the Western Brazilian Amazon: a perspective and analysis from a tertiary health & research center in Manaus, State of Amazonas.

The Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), located in Manaus, the capital of the State of Amazonas (Western Brazilian Amazon), is a pioneering institution in this region regarding the syndromic surveillance of acute febrile illness, including arboviral infections. Based on the data from patients at the FMT-HVD, we have detected recurrent outbreaks in Manaus by the four dengue serotypes in the past 15 years, with increasing severity of the disease.

P. vivax malaria and dengue fever co-infection: a cross-sectional study in the Brazilian Amazon.

Background: Malaria and dengue are the most prevalent vector-borne diseases worldwide and represent major public health problems. Both are endemic in tropical regions, propitiating co-infection. Only few co-infection cases have been reported around the world, with insufficient data so far to enhance the understanding of the effects of co-infection in the clinical presentation and severity.

Identification of dengue viruses in naturally infected Aedes aegypti females captured with BioGents (BG)-Sentinel traps in Manaus, Amazonas, Brazil.

Introduction: In Manaus, the first autochthonous cases of dengue fever were registered in 1998. Since then, dengue cases were diagnosed by the isolation of viruses 1, 2, 3, and 4.

Methods: One hundred eighty-seven mosquitoes were collected with BioGents (BG)-Sentinel traps in 15 urban residential areas in the Northern Zone of Manaus and processed by molecular tests.

Clinical profile of concurrent dengue fever and Plasmodium vivax malaria in the Brazilian Amazon: case series of 11 hospitalized patients.

Malaria and dengue fever are the most prevalent vector-borne diseases worldwide. This study aims to describe the clinical profile of patients with molecular diagnosis of concurrent malaria and dengue fever in a tropical-endemic area. Eleven patients with concurrent dengue virus (DENV) and Plasmodium vivax infection are reported.

Simultaneous circulation of all four dengue serotypes in Manaus, State of Amazonas, Brazil in 2011.

Introduction: Manaus, the capital city of the state of Amazon with nearly 2 million inhabitants, is located in the middle of the Amazon rain forest and has suffered dengue outbreaks since 1998.

Methods: In this study, blood samples were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), aimed at identifying dengue virus serotypes.

Results: Acute phase sera from 432 patients were tested for the presence of dengue virus.

Serological evidence of hantavirus infection in rural and urban regions in the state of Amazonas, Brazil.

Hantavirus disease is caused by the hantavirus, which is an RNA virus belonging to the family Bunyaviridae. Hantavirus disease is an anthropozoonotic infection transmitted through the inhalation of aerosols from the excreta of hantavirus-infected rodents. In the county of Itacoatiara in the state of Amazonas (AM), Brazil, the first human cases of hantavirus pulmonary and cardiovascular syndrome were described in July 2004.

Co-infection of Dengue virus by serotypes 3 and 4 in patients from Amazonas, Brazil.

The natural co-infection with dengue virus can occur in highly endemic areas where different serotypes have been observed for many years. We report here four cases of DENV-3/DENV-4 co-infection detected by serological and molecular tests among 674 patients with acute undifferentiated fever from the tropical medicine reference center of Manaus City, Brazil, between 2005 and 2010. Analysis of the sequences obtained indicated the presence of genotype 3 and 1 for DENV-3 and DENV-4 respectively.

Dengue virus type 4, Manaus, Brazil.

We report dengue virus type 4 (DENV-4) in Amazonas, Brazil. This virus was isolated from serum samples of 3 patients treated at a tropical medicine reference center in Manaus. All 3 cases were confirmed by serologic and molecular tests; 1 patient was co-infected with DENV-3 and DENV-4.

[Occurrence of parvovirus B19 in Manaus, AM].

Investigation of 1,107 cases of exanthematous diseases in Manaus allowed the identification of the first 47 cases of human parvovirus B19 in the city. Parvovirus B19 was characterized by a combination of signs and symptoms such as fever, chronic headache, arthralgia, myalgia and exanthema. The frequency of exanthema was higher in individuals less than fifteen years old.

[Exanthematous diseases and the first epidemic of dengue to occur in Manaus, Amazonas State, Brazil, during 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.