DENGUE OUTBREAK IN MATO GROSSO STATE, MIDWESTERN BRAZIL

O vírus da dengue (DENV) é o arbovirus mais frequente no mundo. Neste estudo, é relatada uma epidemia de grandes proporções no estado de Mato Grosso (MT). Amostras de soro de 604 pacientes com doença febril aguda a menos de 5 dias foram inoculadas em células C6/36 seguida de Imunofluorescência indireta para os sorotipos do DENV e vírus da febre amarela e submetidas a multiplex-semi-nested-RT-PCR para 11 flavivírus. O DENV-4 foi isolado em 150/604 (24,8%) e DENV-1 em 19/604 (3,1%) amostras. Por RT-PCR, 331 (54,8%) pacientes foram positivos para DENV; 321 com infecções únicas (DENV-4 n=305; DENV-1 n=15; DENV-3 n=1), nove co-infecções entre DENV-1/DENV-4 e uma com DENV-2/DENV-4. O DENV-4 foi detectado em 315/331 (95,2%) pacientes de 17 municípios e o DENV-1 em 24/331 (7,2%) pacientes de 5 cidades da região centro-norte de MT e em Cuiabá. A incidência de infecção foi maior em pacientes de 20-39 anos (142/331; 42,9%). As sequências de nucleotídeos de região do gene NS5 do DENV-1 apresentaram maior similaridade com o genótipo V, do DENV-2 com Sudeste Asiático/Americano, DENV-3 com genótipo III e DENV-4 com genótipo II, considerados os mais frequentes no Brasil. Esta epidemia coincidiu com a introdução do DENV-4 no estado. Cuiabá foi considerada hiperendêmica para os quatro sorotipos do DENV, ressaltando a necessidade de vigilância para arbovírus em MT.Dengue virus (DENV) is the most frequent arbovirus worldwide. In this study, we report a large outbreak in Mato Grosso State (MT). Serum samples from 604 patients with acute febrile illness for less than five days were inoculated in C6/36 cells, then infected cells were subjected to an indirect immunofluorescence test for DENV serotypes and yellow fever virus. Serum samples were submitted to a multiplex-semi-nested-RT-PCR for 11 flaviviruses. DENV-4 was isolated in 150/604 (24.8%) and DENV-1 in 19/604 (3.1%) specimens. By RT-PCR, 331 (54.8%) samples tested positive for DENV; 321 had single infections (DENV-4 n = 305; DENV-1 n = 15; DENV-3 n = 1), nine had co-infections of DENV-1/DENV-4, and one of DENV-2/DENV-4. DENV-4 was detected in 315/331 (95.2%) positive patients from 17 municipalities, and DENV-1 in 24/331 (7.2%) patients from five cities in north-central MT and the city of Cuiaba. The incidence of infection was higher in patients aged 20-39 (142/331; 42.9%). The NS5 partial nucleotide sequence of DENV-1 was most similar to that of genotype V, DENV-2 to Southeast Asian/American, DENV-3 to genotype III, and DENV-4 to genotype II strains, considered the most frequent strains in Brazil. This outbreak coincided with the introduction of DENV-4 in the state. Cuiaba was hyperendemic for the four DENV serotypes, highlighting the necessity for arbovirus surveillance in MT

Molecular detection of Mayaro virus during a dengue outbreak in the state of Mato Grosso, Central-West Brazil

Mayaro virus (MAYV) is frequently reported in Pan-Amazonia. The aim of this study was to investigate the circulation of alphaviruses during a dengue outbreak in the state of Mato Grosso, Brazil. Serum samples from dengue-suspected patients were subjected to multiplex semi-nested reverse transcriptase polymerase chain reaction for 11 flaviviruses and five alphaviruses, to nucleotide sequencing and to viral isolation. MAYV was detected in 15 (2.5%) of 604 patients. Twelve were co-infected with dengue virus 4, which was isolated from 10 patients. The molecular detection of MAYV in dengue-suspected patients suggests that other arboviruses may be silently circulating during dengue outbreaks in Brazil

DENGUE OUTBREAK IN MATO GROSSO STATE, MIDWESTERN BRAZIL

Dengue virus (DENV) is the most frequent arbovirus worldwide. In this study, we report a large outbreak in Mato Grosso State (MT). Serum samples from 604 patients with acute febrile illness for less than five days were inoculated in C6/36 cells, then infected cells were subjected to an indirect immunofluorescence test for DENV serotypes and yellow fever virus. Serum samples were submitted to a multiplex-semi-nested-RT-PCR for 11 flaviviruses. DENV-4 was isolated in 150/604 (24.8%) and DENV-1 in 19/604 (3.1%) specimens. By RT-PCR, 331 (54.8%) samples tested positive for DENV; 321 had single infections (DENV-4 n = 305; DENV-1 n = 15; DENV-3 n = 1), nine had co-infections of DENV-1/DENV-4, and one of DENV-2/DENV-4. DENV-4 was detected in 315/331 (95.2%) positive patients from 17 municipalities, and DENV-1 in 24/331 (7.2%) patients from five cities in north-central MT and the city of Cuiaba. The incidence of infection was higher in patients aged 20-39 (142/331; 42.9%). The NS5 partial nucleotide sequence of DENV-1 was most similar to that of genotype V, DENV-2 to Southeast Asian/American, DENV-3 to genotype III, and DENV-4 to genotype II strains, considered the most frequent strains in Brazil. This outbreak coincided with the introduction of DENV-4 in the state. Cuiaba was hyperendemic for the four DENV serotypes, highlighting the necessity for arbovirus surveillance in MT

Novel viruses in salivary glands of mosquitoes from sylvatic Cerrado, Midwestern Brazil.

Viruses may represent the most diverse microorganisms on Earth. Novel viruses and variants continue to emerge. Mosquitoes are the most dangerous animals to humankind. This study aimed at identifying viral RNA diversity in salivary glands of mosquitoes captured in a sylvatic area of Cerrado at the Chapada dos Guimarães National Park, Mato Grosso, Brazil. In total, 66 Culicinae mosquitoes belonging to 16 species comprised 9 pools, subjected to viral RNA extraction, double-strand cDNA synthesis, random amplification and high-throughput sequencing, revealing the presence of seven insect-specific viruses, six of which represent new species of Rhabdoviridae (Lobeira virus), Chuviridae (Cumbaru and Croada viruses), Totiviridae (Murici virus) and Partitiviridae (Araticum and Angico viruses). In addition, two mosquito pools presented Kaiowa virus sequences that had already been reported in South Pantanal, Brazil. These findings amplify the understanding of viral diversity in wild-type Culicinae. Insect-specific viruses may present a broader diversity than previously imagined and future studies may address their possible role in mosquito vector competence

Natural transovarial transmission of dengue virus 4 in Aedes aegypti from Cuiabá, State of Mato Grosso, Brazil

INTRODUCTION: Dengue is the most prevalent arboviral disease in tropical areas. In Mato Grosso, outbreaks are reported every year, but studies on dengue in this state are scarce. METHODS: Natural transovarial infection of Aedes aegypti by a flavivirus was investigated in the Jardim Industriário neighborhood of Cuiabá, Mato Grosso. Eggs were collected with ovitraps during the dry, intermediate, and rainy seasons of 2012. After the eggs hatched and the larvae developed to adulthood, mosquitoes (n = 758) were identified and allocated to pools of 1-10 specimens according to the collection location, sex, and climatic period. After RNA extraction, multiplex semi-nested RT-PCR was performed to detect the four dengue virus (DENV) serotypes, yellow fever virus, West Nile virus and Saint Louis encephalitis virus. RESULTS: DENV-4 was the only flavivirus detected, and it was found in 8/50 pools (16.0%). Three of the positive pools contained females, and five contained males. Their nucleotide sequences presented 96-100% similarity with DENV-4 genotype II strains from Manaus, Amazonas. The minimum infection rate was 10.5 per 1000 specimens, and the maximum likelihood estimator of the infection rate was 11.6 (95% confidence interval: 4.8; 23.3). CONCLUSIONS: This study provides the first evidence of natural transovarial infection by DENV-4 in Ae. Aegypti in Mato Grosso, suggesting that this type of infection might serve as a mechanism of virus maintenance during interepidemic periods in Cuiabá, a city where dengue epidemics are reported every year. These results emphasize the need for efficient vector population control measures to prevent arbovirus outbreaks in the state

Detection of Oropouche virus segment S in patients and inCulex quinquefasciatus in the state of Mato Grosso, Brazil

This study aimed to investigate the circulation of Orthobunyavirus species in the state of Mato Grosso (MT) Brazil. During a dengue outbreak in 2011/2012, 529 serum samples were collected from patients with acute febrile illness with symptoms for up to five days and 387 pools of female Culex quinquefasciatuscaptured in 2013 were subjected to nested-reverse transcription-polymerase chain reaction for segment S of the Simbu serogroup followed by nucleotide sequencing and virus isolation in Vero cells. Patients (5/529; 0.9%) from Cuiabá (n = 3), Várzea Grande (n = 1) and Nova Mutum (n = 1) municipalities were positive for the S segment of Oropouche virus (OROV). Additionally, eight/387 Cx. quinquefasciatuspools were positive for the segment, with a minimum infection rate of 2.3. Phylogenetic analysis indicated that all the samples belong to the subgenotype Ia, presenting high homology with OROV strains obtained from humans and animals in the Brazilian Amazon. The present paper reports the first detection of an Orthobunyavirus, possibly OROV, in patients and in Cx. quinquefasciatus mosquitoes in MT. This finding reinforces the notion that arboviruses frequently reported in the Amazon Region circulate sporadically in MT during dengue outbreaks

Viola phlebovirus is a novel Phlebotomus fever serogroup member identified in Lutzomyia (Lutzomyia) longipalpis from Brazilian Pantanal

Abstract Background High throughput sequencing (HTS) boosted the discovery of novel viruses and new variants of known viruses. Here we investigated the presence of viruses in 12 pools of sand flies captured in three climatic periods in RAPELD grids at Rio Claro, Chapada dos Guimarães and at Pirizal, North Pantanal, Mato Grosso State, Midwestern Brazil by HTS, viral isolation of a putative Phlebovirus positive pool in Vero cells, RT-PCR and transmission electron microscopy (TEM). Results One pool containing three Lutzomyia (Lutzomyia) longipalpis sand flies captured in the transitional climatic period in North Pantanal showed a tripartite genomic sequence of a putative novel Phlebovirus belonging to the phlebotomus fever serogroup. Phylogenetic analysis revealed this virus is closely related and share a common ancestor with phleboviruses included in the same clade: Chagres, Urucuri and Uriurana virus. RNA-dependent RNA polymerase (RdRP) presented 60%, 59% and 58% of amino-acid (aa) similarity with these phleboviruses, respectively. Similarity of Nucleoprotein and NSs protein codified by ambissense strategy of segment S was of 49% and 37%, respectively, with the proteins of the closest phlebovirus, Uriurana virus. Glycoproteins (G1, G2) and NSm protein presented 49% and 48% aa similarity with Chagres and Uriurana virus, respectively. Uriurana virus was isolated from sand flies in Brazilian Amazon and Urucuri from rodents in Utinga forest, Pará State. Chagres virus is an arbovirus responsible for outbreaks of febrile illness in Panama. This phlebovirus was isolated in Vero cells, confirmed by TEM and RT-PCR for the L segment of the virus, and named Viola phlebovirus. Conclusions HTS, viral isolation, RT-PCR and TEM showed the presence of one virus in sand flies from North Pantanal with identity to a putative novel Phlebovirus from phlebotomus fever serogroup, named Viola phlebovirus