FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Mem Inst Oswaldo Cruz / Orthoflavivirus nilense surveillance in the State of Piauí,...
Memorias do Instituto Oswaldo Cruz2025; 120; e240218; doi: 10.1590/0074-027602402180

Orthoflavivirus nilense surveillance in the State of Piauí, northeastern Brazil.

Abstract: The cycle of the Orthoflavivirus nilense (West Nile virus - WNV) involves birds and mosquitoes, while humans and equids serve as terminal hosts. In 2014, the first human case in Brazil was confirmed in Piauí State. Objective: To investigate the presence of WNV in birds, mosquitoes, and equids in municipalities of Piauí. Methods: Collections were carried out following recommendations from the Ministry of Health of Brazil, in 11 municipalities (all with human cases or bird mortality), where biological samples were collected from birds, mosquitoes, and equids. The Viral RNA extraction was performed using a commercial kit, following the manufacturers' recommendations; samples were subjected to reverse transcription and polymerase chain reaction, with specific primers for WNV. Results: 2,706 samples were collected (636 birds, belonging to 99 species; 420 equids, and 1,650 mosquitoes, grouped into 346 pools, totaling 18 species. No collected sample yielded a positive result, corroborating with other studies showing the difficulty of molecular detection of WNV in healthy animals, which may explain the non-detection, in addition to the delayed diagnosis in humans. Conclusions: A local investigation involving suspected cases is still recommended in animals; however, in locations with late diagnosis in humans we suggest a serological survey of asymptomatic birds and equids.
Get Full Text
Publication Date: 2025-07-07 PubMed ID: 40638500PubMed Central: PMC12237142DOI: 10.1590/0074-027602402180Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

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.

Overview

  • This study aimed to detect the presence of West Nile virus (WNV), known as Orthoflavivirus nilense, in birds, mosquitoes, and equids in the northeastern Brazilian state of Piauí, an area with previously reported human cases.
  • The researchers collected biological samples from multiple species and tested them for WNV but found no positive cases, highlighting challenges in molecular detection and suggesting alternative surveillance approaches.

Research Context and Objective

  • WNV is a virus transmitted primarily between birds and mosquitoes, with humans and equids (horses and related species) serving as incidental or terminal hosts.
  • In 2014, Piauí State confirmed the first human case of WNV infection in Brazil, increasing the need for surveillance in the region to understand viral circulation.
  • The main objective was to investigate whether WNV is present in vectors (mosquitoes) and hosts (birds and equids) in specific municipalities of Piauí where human cases or bird deaths have been reported.

Methods

  • Sampling was conducted in 11 municipalities selected due to WNV-related factors (presence of human cases or bird mortality).
  • Birds, mosquitoes, and equids were systematically sampled according to guidelines recommended by Brazil’s Ministry of Health.
  • Biological samples included:
    • 636 birds from 99 species.
    • 420 equids.
    • 1,650 mosquitoes pooled into 346 groups, representing 18 species.
  • Laboratory testing involved:
    • Extraction of viral RNA using commercial kits per manufacturer instructions.
    • Reverse transcription to convert RNA into complementary DNA.
    • Polymerase chain reaction (PCR) with WNV-specific primers to amplify viral genetic material for detection.

Results

  • No samples from birds, mosquitoes, or equids tested positive for WNV RNA.
  • The absence of molecular detection aligns with previous studies suggesting:
    • WNV is difficult to detect molecularly in apparently healthy animals, as viral RNA may be present only transiently or at low levels.
    • Delays between animal infection and sample collection reduce chances of positive viral RNA detection.
    • Late diagnoses in human cases further complicate linking animal infections to human outbreaks.

Conclusions and Recommendations

  • While no WNV RNA was found, the study recommends continuing local investigations when suspected cases appear in animals to monitor viral activity.
  • In locations where human diagnosis is often delayed, molecular testing may not be effective due to timing issues.
  • Instead, the authors propose serological surveys that detect antibodies against WNV in asymptomatic birds and equids, which can reveal past exposure rather than active infection.
  • This approach could provide valuable epidemiological information to understand WNV circulation patterns and help prevent outbreaks.

Cite This Article

APA
Lobato OL, Nogueira TDS, Lima TET, Andrade FJDC, de Macedo MGG, Pereira RS, Xavier J, Amorim MR, Barbosa PP, da Rocha AS, Silva SDC, Alcantara LCJ, de Souza WM, Proenca-Modena JL, Costa ÉA, Lima Neto AS, Feitosa LCS, Pires E Cruz MDS, Silva SMMS, Baêta SAF, Vieira MADCES, Deem SL, Catenacci LS. (2025). Orthoflavivirus nilense surveillance in the State of Piauí, northeastern Brazil. Mem Inst Oswaldo Cruz, 120, e240218. https://doi.org/10.1590/0074-027602402180

Publication

Memorias do Instituto Oswaldo Cruz
ISSN: 1678-8060
NlmUniqueID: 7502619
Country: Brazil
Language: English
Volume: 120
Pages: e240218
PII: e240218

Researcher Affiliations

Lobato, Osmaikon Lisboa
  • Universidade Federal do Piauí, Centro de Ciências Agrárias, Teresina, PI, Brasil.
  • Universidade Federal do Piauí, Programa de Pós-Graduação em Tecnologias Aplicadas a Animais de Interesse Regional, Teresina, PI, Brasil.
Nogueira, Tayná da Silva
  • Universidade Federal do Piauí, Bom Jesus, PI, Brasil.
Lima, Tobias Emílio Tavares
  • Universidade Federal do Piauí, Bom Jesus, PI, Brasil.
Andrade, Felipe José da Costa
  • Universidade Federal do Piauí, Bom Jesus, PI, Brasil.
de Macedo, Marília Gabryelle Guimarães
  • Universidade Federal do Piauí, Bom Jesus, PI, Brasil.
Pereira, Rayane de Souza
  • Universidade Federal do Oeste da Bahia, Programa de Pós-Graduação em Ciências Ambientais, Barreiras, BA, Brasil.
Xavier, Joilson
  • Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
Amorim, Mariene Ribeiro
  • Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Genética, Evolução, Microbiologia e Imunologia, Campinas, SP, Brasil.
Barbosa, Priscilla Paschoal
  • Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Genética, Evolução, Microbiologia e Imunologia, Campinas, SP, Brasil.
da Rocha, Alex Sobrinho
  • Universidade Federal do Piauí, Bom Jesus, PI, Brasil.
Silva, Silvokleio da Costa
  • Universidade Federal do Piauí, Bom Jesus, PI, Brasil.
Alcantara, Luiz Carlos Junior
  • Fundação Oswaldo Cruz-Fiocruz, Instituto René Rachou, Belo Horizonte, MG, Brasil.
de Souza, William M
  • University of Texas Medical Branch, Department of Microbiology and Immunology, Galveston, TX, USA.
  • University of Texas Medical Branch, World Reference Center for Emerging Viruses and Arboviruses, Galveston, TX, USA.
Proenca-Modena, José Luiz
  • Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Genética, Evolução, Microbiologia e Imunologia, Campinas, SP, Brasil.
Costa, Érica Azevedo
  • Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
Lima Neto, Adelino Soares
  • Laboratório Central de Saúde Pública do Piauí, Teresina, PI, Brasil.
Feitosa, Lauro César Soares
  • Universidade Federal do Piauí, Centro de Ciências Agrárias, Teresina, PI, Brasil.
Pires E Cruz, Maria do Socorro
  • Universidade Federal do Piauí, Centro de Ciências Agrárias, Teresina, PI, Brasil.
Silva, Silvana Maria Medeiros de Sousa
  • Universidade Federal do Piauí, Centro de Ciências Agrárias, Teresina, PI, Brasil.
Baêta, Silvia de Araújo França
  • Universidade Federal do Piauí, Centro de Ciências Agrárias, Teresina, PI, Brasil.
Vieira, Marcelo Adriano da Cunha E Silva
  • Instituto de Doenças Tropicais Natan Portella, Teresina, PI, Brasil.
Deem, Sharon L
  • Institute for Conservation Medicine, Saint Louis Zoo, St Louis, Missouri, USA.
Catenacci, Lilian Silva
  • Universidade Federal do Piauí, Centro de Ciências Agrárias, Teresina, PI, Brasil.
  • Universidade Federal do Piauí, Programa de Pós-Graduação em Tecnologias Aplicadas a Animais de Interesse Regional, Teresina, PI, Brasil.
  • Institute for Conservation Medicine, Saint Louis Zoo, St Louis, Missouri, USA.
  • Centro de Inteligência em Agravos Tropicais Emergentes e Negligenciados, Teresina, PI, Brasil.
  • Universidade Federal do Pará, Programa de Pós-Graduação em Saúde Animal na Amazônia, Castanhal, PA, Brasil.

MeSH Terms

  • Animals
  • Brazil / epidemiology
  • West Nile virus / isolation & purification
  • West Nile virus / genetics
  • Culicidae / virology
  • Equidae / virology
  • Birds / virology
  • RNA, Viral / analysis
  • Reverse Transcriptase Polymerase Chain Reaction
  • Humans
  • West Nile Fever / epidemiology
  • West Nile Fever / veterinary
  • Horses

Conflict of Interest Statement

The authors declare no conflict of interest

References

This article includes 56 references
  1. de Castro-Jorge LA, Siconelli MJL, Ribeiro BDS, de Moraes FM, de Moraes JB, Agostinho MR. West Nile virus infections are here Are we prepared to face another flavivirus epidemic?. Rev Soc Bras Med Trop 2019;52:e20190089.
    pubmed: 30942263
  2. Figueiredo LTM. West Nile virus infection in Brazil. Rev Soc Bras Med Trop 2019;52:e20190226.
    pubmed: 31166492
  3. Lorenz C, de Azevedo TS, Chiaravalloti-Neto F. Impact of climate change on West Nile virus distribution in South America. Trans R Soc Trop Med Hyg 2022;116(11):1043–1053.
    pubmed: 35640005
  4. Vieira MACS, Romano APM, Borba AS, Silva EVP, Chiang JO, Eulálio KD. Case report West Nile virus encephalitis: the first human case recorded in Brazil. Am J Trop Med Hyg 2015;93(2):377–379.
    pmc: PMC4530764pubmed: 26055749
  5. Costa ÉA, Giovanetti M, Catenacci LS, Fonseca V, Aburjaile FF, Chalhoub FLL. West Nile virus in Brazil. Pathogens 2021;10(7):896–896.
    pmc: PMC8308589pubmed: 34358046
  6. De Siqueira RF, Hansen VS, Martins MFM, Leal MLR, Bondan EF. Infecção pelo vírus da febre do Nilo Ocidental em equinos no Estado de São Paulo. Acta Sci Vet 2022;50:737–737.
  7. Martins LC, da Silva EVP, Casseb LMN, da Silva SP, Cruz ACR, Pantoja JAS. First isolation of West Nile virus in Brazil. Mem Inst Oswaldo Cruz 2019;114(1):e180332.
    pmc: PMC6343470pubmed: 30672980
  8. Siconelli MJL, Jorge DMM, de Castro-Jorge LA, Fonseca-Júnior AA, Nascimento ML, Floriano VG. Evidence for current circulation of an ancient West Nile virus strain (NY99) in Brazil. Rev Soc Bras Med Trop 2021;54:e0687–e2020.
    pmc: PMC8008906pubmed: 33681933
  9. Silva ASG, Matos ACD, da Cunha MACR, Rehfeld IS, Galinari GCF, Marcelino SAC. West Nile virus associated with equid encephalitis in Brazil, 2018. Transbound Emerg Dis 2019;66(1):445–453.
    pubmed: 30318735
  10. MS - Ministério da Saúde. Guia de vigilância de epizootias em primatas não humanos e entomologia aplicada à vigilância da febre amarela. Brasília: Ministério da Saúde; 2014.
  11. Tolsá MJ, García-Peña GE, Rico-Chávez O, Roche B, Suzán G. Macroecology of birds potentially susceptible to West Nile virus. Proc Biol Sci 2018;285(1893):20182178–20182178.
    pmc: PMC6304048pubmed: 30963915
  12. Ross AL, von Matter S, Straube F, Accordi I, Cândido JF, Júnior. Ornitologia e conservação: ciência aplicada, técnicas de pesquisa e levantamento. Rio de Janeiro: Technical Books; 2010. Capturando aves; pp. 77–104.
  13. Silva M, Auricchio P. Aves de Teresina. Arujá: Terra Brasilis Didáticos Editora; 2019.
  14. Sigrist T. Guia de campo Avis Brasilis. Avis Brasilis 2009.
  15. Nicola PA, Kaminski N, La Torre GMD, Barcik JJ, Santos EKMR. Guia de aves do Campus de Ciências Agrárias da UNIVASF. Petrolina: Franciscana; 2012.
  16. Sudia W, Chamberlain R. Battry-operated light trap, an improved model. Mosq News. 1962;22:126–129.
    pubmed: 3066845
  17. Consoli RAGB, Lourenço-de-Oliveira R. Principais mosquitos de importância sanitária no Brasil. Rio de Janeiro: Fundação Oswaldo Cruz; 1994.
  18. Forattini OP. Culicidologia médica. São Paulo: Edusp; 2002.
  19. Kuno G. Universal diagnostic RT-PCR protocol for arboviruses. J Virol Methods. 1998;72(1):27–41.
    pubmed: 9672130
  20. Catenacci LS, Ferreira M, Martins LC, De Vleeschouwer KM, Cassano CR, Oliveira LC. Surveillance of arboviruses in primates and sloths in the Atlantic Forest, Bahia, Brazil. Ecohealth. 2018;15(4):777–791.
    pubmed: 30117001
  21. Lanciotti RS, Kerst AJ, Nasci RS, Godsey MS, Mitchell CJ, Savage HM. Rapid detection of West Nile virus from human clinical specimens, field-collected mosquitoes, and avian samples by a TaqMan reverse transcriptase-PCR assay. J Clin Microbiol. 2000;38(11):4066–4071.
    pmc: PMC87542pubmed: 11060069
  22. MS - Ministério da Saúde . Guia de vigilância em saúde. 5. Brasília: Ministério da Saúde; 2022.
  23. Penazziová K, Korytár L, Pastorek P, Pistl J, Rusnáková D, Szemes T. Genetic characterization of a neurovirulent West Nile virus variant associated with a fatal great grey owl infection. Viruses. 2021;13(4):699–699.
    pmc: PMC8073349pubmed: 33920598
  24. Pérez-Ramírez E, Llorente F, Jiménez-Clavero MA. Experimental infections of wild birds with West Nile virus. Viruses. 2014;6(2):752–781.
    pmc: PMC3939481pubmed: 24531334
  25. CDC West Nile and dead birds. Centers for Disease Control and Prevention. 2025 https://www.cdc.gov/west-nile-virus/media/files/Bird_species_West_Nile_virus_U.S..pdf
  26. Chalhoub FLL, de EM, Queiroz-Júnior, Duarte BH, de Sá MEP, Lima PC, de Oliveira AC. West Nile virus in the State of Ceará, northeast Brazil. Microorganisms. 2021;9(8):1699–1699.
    pmc: PMC8401605pubmed: 34442778
  27. Melandri V, Guimarães AE, Komar N, Nogueira ML, Mondini A, Fernandez-Sesma A. Serological detection of West Nile virus in horses and chicken from Pantanal, Brazil. Mem Inst Oswaldo Cruz. 2012;107(8):1073–1075.
    pmc: PMC4782916pubmed: 23295763
  28. Morel AP, Webster A, Zitelli LC, Umeno K, Souza UA, Prusch F. Serosurvey of West Nile virus (WNV) in free-ranging raptors from Brazil. Braz J Microbiol. 2021;52(1):411–418.
    pmc: PMC7966667pubmed: 33108590
  29. Ometto T, Durigon EL, de Araujo J, Aprelon R, de Aguiar DM, Cavalcante GT. West Nile virus surveillance, Brazil, 2008-2010. Trans R Soc Trop Med Hyg. 2013;107(11):723–730.
    pubmed: 24008895
  30. Vicente MO, França FGR, Araujo HF. Abundance, temporal variation, and microhabitat use of the house sparrow, Passer domesticus (Passeriformes Passeridae), in urban and anthropogenic environments in northeastern Brazil. Zoologia. 2024;41:e23081
  31. Ferreira MC. Geographic distribution in Brazil and reproductive parameters of native and introduced sparrows (Passer domesticus) Brasília: Universidade de Brasília; 2017.
  32. Santos MP, Santos MD. Bird communities in two vegetation physiognomies of the Caatinga in the State of Piauí, Brazil. Ararajuba. 2004;12(2):113–123.
  33. Caten HT, de Oliveira JP, Pascotto MC. Anais do VIII Congresso Brasileiro de Ecologia. Caxambu: Sociedade Brasileira de Ecologia; 2007. Alimentação de Cyanocorax cyanopogon (Corvidae, Passeriformes, Aves) em uma área de Cerrado na região leste de Mato Grosso; pp. 1–1.
  34. Hufnagel L, dos Santos NB, Regolin AL. Curso de Campo da UFMG; 2015; Belo Horizonte, Brasil. Belo Horizonte: Universidade Federal de Minas Gerais; 2016. Ambiente e paisagem influenciam o comportamento de presas do caburé; pp. 83–83.
  35. da Cunha FCR, de Vasconcelos MF. Birds attracted by the vocalization of the Ferruginous Pygmy-owl Glaucidium brasilianum (Aves Strigidae) Rev Bras Ornitol. 2009;17(2):144–149.
  36. de Barros FM. Área de vida, uso e seleção de habitat pela corujinha-do-mato Megascops choliba (Strigiformes: Strigidae) em uma área de cerrado na região central do Estado de São Paulo. São Paulo: Universidade de São Paulo; 2011.
  37. Roda SA, Pereira GA. Distribuição recente e conservação das aves de rapina florestais do Centro Pernambuco. Rev Bras Ornitol. 2006;14(4):331–344.
  38. Santos WM, Rosado FR. Dados preliminares da biologia do gavião-carijó (Rupornis magnirostris, Gmelin, 1788) na região noroeste do Paraná. Rev Agronegócio Meio Amb. 2009;2(3):421–430.
  39. Lignon JS. de Souza Júnior P.Souza EC.Monteiro SG.Pinto DM Achados parasitológicos em gavião-carijó (Rupornis magnirostris) (Accipitriformes Accipitridae) no Pampa Gaúcho-Uruguaiana, RS, Brasil. Sci Anim Health. 2021;9(1):44–53.
  40. Valim MP, Serra-Freire RT, Fonseca MA, Serra-Freire NM. Níveis de enzootia por ectoparasitos em amostras de rolinha [Columbina talpacoti (Temminck, 1810)] no Rio de Janeiro, Brasil. Entomol Vect. 2004;11:589–598.
  41. De Souza VB, Amâncio S, Melo C. Anais do VIII Congresso de Ecologia do Brasil. Caxambu: Sociedade de Ecologia do Brasil; 2007. Columbina talpacoti como bioindicadora de qualidade ambiental em área urbana; pp. 1–1.
  42. Azevedo RA. A avifauna da lagoa do horto florestal, região Amazônica, Zé Doca, Maranhão, Brasil. Zé Doca: Universidade Estadual do Maranhão; 2024.
  43. Cestari C, Pacheco JF. Aves Emberizidae Coryphospingus pileatus (Wied 1821) a new gathered bird species to São Paulo State and evidences of southern geographic expansion in Brazil. Check List. 2010;6:501–502.
  44. ICMBio Arenaria interpres. SALVE. 2025 https://salve.icmbio.gov.br
  45. Petry R, Peter ÂS, Guadagnin DL. Avifauna do Rio Grande do Sul e doenças emergentes conhecimento atual e recomendações para a vigilância ornitológica da Influenza Aviária e da Febre do Nilo Ocidental. Rev Bras Ornitol. 2006;14(3):269–277.
  46. Catenacci LS, Silva MC, Tajra FS, Barbosa MEC, Nogueira TS, Lima TET, et al. Bases conceituais históricas e registro epidemiológico da Febre do Nilo Ocidental no Piauí. Bol Observ Epidemiol. 2022
  47. Angenvoort J, Brault AC, Bowen RA, Groschup MH. West Nile viral infection of equids. Vet Microbiol. 2013;167(1-2):168–180.
    pmc: PMC4581842pubmed: 24035480
  48. Paré J, Moore A. West Nile virus in horses - what do you need to know to diagnose the disease. Can Vet J. 2018;59(10):1119–1119.
    pmc: PMC6135266pubmed: 30510321
  49. Pauvolid-Corrêa A, Morales MA, Levis S, Figueiredo LTM, Couto-Lima D, Campos Z. Neutralising antibodies for West Nile virus in horses from Brazilian Pantanal. Mem Inst Oswaldo Cruz. 2011;106(4):467–474.
    pubmed: 21739036
  50. Pauvolid-Corrêa A, Campos Z, Juliano R, Velez J, Nogueira RMR, Komar N. Serological evidence of widespread circulation of West Nile virus and other flaviviruses in equines of the Pantanal Brazil. PLoS Negl Trop Dis. 2014;8(2):e2706.
    pmc: PMC3923745pubmed: 24551266
  51. Silva JR, de Medeiros LC, dos Reis VP, Chávez JH, Munhoz TD, Borges GP. Serologic survey of West Nile virus in horses from Central-West, Northeast and Southeast Brazil. Mem Inst Oswaldo Cruz. 2013;108(7):921–923.
    pmc: PMC3970643pubmed: 24037110
  52. Weber MN, Mosena ACS, Baumbach LF, da Silva MS, Canova R, dos Santos DRL. Serologic evidence of West Nile virus and Saint Louis encephalitis virus in horses from Southern Brazil. Braz J Microbiol. 2021;52(2):1021–1027.
    pmc: PMC8105465pubmed: 33797731
  53. Nunes JPN, Neto, Reis LAM, Freitas MNO, do Nascimento BLS, das Chagas LL, da Costa HHM. First isolation and genome sequence analysis of West Nile virus in mosquitoes in Brazil. Trop Med Infect Dis. 2023;8(4):237–237.
    pmc: PMC10143329pubmed: 37104362
  54. Moura S, Pessoa F, Oliveira F, Lustosa AH, Soares C. Animais silvestres recebidos pelo Centro de Triagem do IBAMA no Piauí no ano de 2011. Enciclopédia Biosfera. 2012;8:1–15.
  55. Vidaña B, Busquets N, Napp S, Pérez-Ramírez E, Jiménez-Clavero MÁ, Johnson N. The role of birds of prey in West Nile virus epidemiology. Vaccines. 2020;8(3):550–550.
    pmc: PMC7564710pubmed: 32967268
  56. Bayeux JJM, Silva ASG, de Queiroz GA, Santos BSAS, Rocha MN, Rehfeld IS. Epidemiological surveillance of West Nile virus in the world and Brazil. Braz J Vet Res Anim Sci. 2019;56(4):e164335

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 99,030 horse owners like you who receive our email updates on horse health and nutrition.