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Home / Equine Research Bank / Viruses / Silent Circulation of the Saint Louis Encephalitis Virus amo...
Viruses2019; 11(11); 1029; doi: 10.3390/v11111029

Silent Circulation of the Saint Louis Encephalitis Virus among Humans and Equids, Southeast Brazil.

Abstract: Saint Louis encephalitis virus (SLEV) is a mosquito-borne flavivirus that occurs throughout the Americas, and is considered a public health threat. In Brazil, SLEV has been detected from human cases associated with dengue-like disease, but no neurological symptoms were reported. Furthermore, the epidemiology of SLEV in human populations is still poorly explored in the country. We reported serological and molecular detection of SLEV in a healthy population of equids and humans from rural areas in Southeast Brazil. A plaque reduction neutralization test was applied, and neutralizing antibodies were detected in 11 individuals (4.6%) and 60 horses (21.5%). A qPCR targeting the 5'UTR region and reverse transcription-PCR (RT-PCR) targeting the non-structural protein (NS5) gene were performed and three individuals tested positive in both assays. Subsequent phylogenetic analysis confirmed SLEV circulation and its findings suggest the occurrence of an asymptomatic or subclinical presence in human and animal cases, correlating with the risks for outbreaks and consequently burden of SLEV infections to public health. Preventive strategies should include improved surveillance in regions with a high probability of SLEV occurrence, improvement in diagnostic methods, and evaluation of exposure/risk factors that can favor SLEV emergence.
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Publication Date: 2019-11-05 PubMed ID: 31694207PubMed Central: PMC6893452DOI: 10.3390/v11111029Google Scholar: Lookup
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  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research paper records the discovery of Saint Louis encephalitis virus (SLEV) in healthy humans and horses in rural southeast Brazil. Currently, SLEV remains a relatively understudied public health threat in Brazil.

Overview of the Research

  • This paper focuses on Saint Louis encephalitis virus, a mosquito-borne flavivirus that is present all over the Americas. The virus is considered a threat to public health due to its potential harm to human beings and animals alike.
  • This research was carried out in Brazil where previous cases of SLEV were detected among people with dengue-like symptoms. However, these patients did not show any neurological indicators commonly associated with SLEV.
  • As a result, the main aim of this study was to explore the prevalence of SLEV among people and equines (horses, in particular) in rural areas of Southeast Brazil, even in the absence of symptoms.

Methodology and Results

  • The research conducted included the execution of a plaque reduction neutralization test to discern the presence of neutralizing antibodies, indicative of an immune response to SLEV. The results presented that 11 individuals (4.6%) and 60 horses (21.5%) had the antibodies.
  • The researchers also performed a qPCR assay and a reverse transcription-PCR test, targeting specific areas of the SLEV genetic sequence to provide molecular evidence of the virus. From these tests, three individuals tested positive.
  • Phylogenetic analysis was additionally utilized to help confirm the circulation of SLEV in the population under study.

Interpretation and Recommendations

  • The results suggested that there was silent circulation of SLEV in both humans and horses. This means that the virus was present even when there were no visible symptoms, implying SLEV can exist subclinically or presenting asymptomatic cases.
  • This unnoticed presence in human and animal cases could increase the risk of outbreaks and add to the burden of SLEV infection on public health. As such, it is not just the symptomatic cases but also the asymptomatic ones that should be included in considering the impact of the virus on public health.
  • To mitigate this risk, the study recommends improved surveillance in regions likely to have SLEV, refining diagnostic methodologies, and evaluating risk factors that may aid in the emergence of SLEV.

Cite This Article

APA
Barbosa Costa G, Marinho PES, Vilela APP, Saraiva-Silva AT, Crispim APC, Borges IA, Dutra AGS, Lobato ZIP, Dos Reis JKP, de Oliveira DB, Drumond BP, Kroon EG, Trindade GS. (2019). Silent Circulation of the Saint Louis Encephalitis Virus among Humans and Equids, Southeast Brazil. Viruses, 11(11), 1029. https://doi.org/10.3390/v11111029

Publication

Viruses
ISSN: 1999-4915
NlmUniqueID: 101509722
Country: Switzerland
Language: English
Volume: 11
Issue: 11
PII: 1029

Researcher Affiliations

Barbosa Costa, Galileu
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Marinho, Paula Eillany Silva
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Vilela, Ana Paula Pessoa
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Saraiva-Silva, Ana Teresa
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Crispim, Ana Paula Correia
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Borges, Iara Apolinário
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Dutra, Ana Gabriella Stoffella
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Lobato, Zélia Inês Portela
  • Laboratório de Pesquisa em Virologia Animal, Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270901, Brazil.
Dos Reis, Jenner Karlison Pimenta
  • Laboratório de Retroviroses, Departamento de Medicina Veterinária Preventiva, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270901, Brazil.
de Oliveira, Danilo Bretas
  • Faculdade de Medicina, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina 39100000, Brazil.
Drumond, Betania Paiva
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Kroon, Erna Geessien
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.
Trindade, Giliane de Souza
  • Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais. Avenida Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270901, Brasil.

MeSH Terms

  • Animals
  • Antibodies, Neutralizing / blood
  • Antibodies, Viral / blood
  • Asymptomatic Infections
  • Brazil / epidemiology
  • Dengue / diagnosis
  • Diagnosis, Differential
  • Encephalitis Virus, St. Louis / genetics
  • Encephalitis Virus, St. Louis / immunology
  • Encephalitis Virus, St. Louis / isolation & purification
  • Encephalitis, St. Louis / diagnosis
  • Encephalitis, St. Louis / transmission
  • Encephalitis, St. Louis / veterinary
  • Encephalitis, St. Louis / virology
  • Flaviviridae / isolation & purification
  • Genes, Viral
  • Horse Diseases / diagnosis
  • Horse Diseases / virology
  • Horses
  • Humans
  • Neutralization Tests
  • Phylogeny
  • Seroepidemiologic Studies

Conflict of Interest Statement

The authors declare that there is no conflict of interest.

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Citations

This article has been cited 8 times.
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