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Oropouche virus disease across Latin America during the 2023–2025 epidemic: a multi-country case series

Summary and Authors: Oropouche Virus Disease across Latin America (2023–2025)

1. Article Identification and Authors

  • Original Title: Oropouche virus disease across Latin America during the 2023-2025 epidemic: a multi-country case series
  • Journal: The Lancet Regional Health – Americas (Vol. 65, January 2027)
  • DOI: https://doi.org/10.1016/j.lana.2026.101678
  • Authors (on behalf of the OROV-OUT writing group):
    1. Andrea Alemany (shared first authorship and corresponding author)
    2. Fio Vialard (shared first authorship)
    3. Joabi Nascimento
    4. Cintia Lepaus Thomas
    5. Ana Maria Peixoto Cabral Maia
    6. Anailma Aparecida Barbosa Lima de Souza
    7. Eduardo Augusto Duque Bezerra
    8. Anielle Pina-Costa
    9. Xacdiel Rodriguez
    10. Marco Cordova
    11. João Paulo Cola
    12. Heloisa Ferreira
    13. Suwellen Sardinha Dias de Azevedo
    14. Eric Arrivabene Tavares
    15. Barbara Baro
    16. Wuelton Monteiro
    17. Eline Ferreira Mendonça
    18. Antonio Silva Lima Neto
    19. Marcus Lacerda
    20. Andre Siqueira
    21. Rodrigo Ribeiro-Rodrigues
    22. Stalin Vilcarromero
    23. Jean-Paul Carrera
    24. Bruno Issao Matos Ishigami
    25. Patricia Brasil
    26. José Barbosa de Carvalho Júnior
    27. Luciano Pamploma Góes Cavalcanti
    28. Ethel Leonor Maciel
    29. Otavio Ranzani (shared senior authorship)
    30. Quique Bassat (shared senior authorship)
    31. Maria Paula Mourão (shared senior authorship)

2. Executive Summary

This study represents the largest multi-country clinical case series characterizing Oropouche virus (OROV) disease during the 2023–2025 Latin American epidemic—a period marked by the spread of a novel reassortant viral lineage (OROV BR-2015-2024) beyond the endemic Amazon basin, resulting in more than 29,000 confirmed cases across 11 countries.

Researchers analyzed 2,716 confirmed or probable cases (pediatric and adult patients) diagnosed between January 31, 2024, and November 4, 2025, across 10 states or provinces in Brazil (94% of cases), Peru (4%), and Panama (2%). Within Brazil, cases were reported in Espírito Santo (48%), Ceará (18%), Paraíba (16%), Pernambuco (9%), Rio de Janeiro (2%), Amazonas (2%), and Minas Gerais and São Paulo (less than 1%).

Although the vast majority of infections were mild and self-limiting (94%), the study documented severe organ manifestations, prolonged viral RNA shedding, and clinically relevant adverse pregnancy outcomes, highlighting the need for strengthened clinical recognition and expanded diagnostic windows.

3. Key Findings

Clinical Presentation and Duration

  • Patient Profile: Median age was 38 years (interquartile range: 25–51 years); 50.8% (1,379/2,716) were female, including 108 pregnant women. Comorbidities were present in 11.2% of participants (most commonly hypertension and diabetes mellitus).
  • Predominant Symptoms: Fever (88.8%), headache (88.0%), myalgia (58.8%), retro-orbital pain (47.4%), nausea (32.7%), and back pain (32.0%).
  • Age-Related Differences: Adults aged 65 years and older had lower frequencies of fever and headache but higher frequencies of myalgia and arthralgia, whereas children more commonly presented with fever and skin rash.
  • Prolonged Symptoms: While the median duration of illness was 3 days, 23% of participants with follow-up data experienced symptoms lasting more than 7 days (up to 65 days), and symptom recurrence was also reported.

Severity and Risk Factors

  • Hospitalizations and Mortality: 99.1% of patients were managed in outpatient settings. Only 25 patients (0.9%) required hospitalization (including 2 admitted to the ICU), and 1 death (less than 0.1%) occurred.
  • Complications: Documented complications included suspected arthritis (4.3%), mild hemorrhagic manifestations (1.5%, such as petechiae, gingival bleeding, and vaginal bleeding), and 7 cases of severe disease (0.3%) temporally associated with OROV infection, involving respiratory, neurological (one case compatible with Guillain-Barré syndrome), cardiac, renal, and hepatic systems.
  • Predictors of Complications: Older age (65 years and older), pre-existing comorbidities, a higher concurrent symptom burden (6 or more symptoms), clinical warning signs (abdominal pain and vomiting), and laboratory abnormalities (elevated liver enzymes/ALT, lymphopenia, elevated creatinine, and thrombocytopenia).

Pregnancy and Neonatal Outcomes

  • Among 108 pregnant women with symptomatic OROV infection (59 with completed pregnancies at the time of analysis), 15 (13.9%) experienced adverse pregnancy outcomes:
    • 6 stillbirths (5.6%): Four occurred in the third trimester with virological confirmation of vertical transmission (high OROV RNA levels detected post-mortem in fetal tissues, placenta, and umbilical cord).
    • 3 spontaneous abortions (2.8%): All occurred in the first trimester, between 3 and 14 days after maternal symptom onset.
    • 3 preterm births (2.8%) and 1 threatened preterm labor (0.9%), concentrated in the third trimester.
    • 2 neonatal outcomes: One newborn developed fever on day 3 of life (testing positive for OROV IgM at day 40), and one infant with Down syndrome died 14 days after birth (case under investigation).
  • Congenital Malformations: No congenital malformations (such as microcephaly) were observed among newborns assessed during follow-up.

Virological and Diagnostic Features

  • Serum Detection: RT-PCR positivity in serum peaked early (median of 2 days after symptom onset), though viral RNA remained detectable beyond 7 days in 39 participants (up to 42 days).
  • Urine Detection: In urine samples, the median time to RT-PCR positivity was 14 days, with 74% of tested samples remaining positive beyond 7 days (up to 49 days), indicating that urine testing significantly extends the diagnostic window.

4. Public Health and Clinical Implications

  1. Include Oropouche virus disease in the differential diagnosis of acute and prolonged febrile illnesses, integrating OROV into multiplex diagnostic panels alongside dengue, Zika, and chikungunya.
  2. Monitor clinical warning signs (abdominal pain and vomiting) and high-risk groups—particularly older adults with comorbidities and pregnant women—using basic hematology and liver function tests to guide early risk stratification.
  3. Incorporate urine samples into RT-PCR testing algorithms to improve case detection beyond the first week of symptoms.

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