Oropouche Virus Spreads to Cuba via Brazilian Lineage

The Oropouche virus (OROV) has established local transmission in Cuba, marking a significant expansion of the virus beyond its traditional Amazonian endemic zones. According to a study published in Nature, the outbreak resulted from a single introduction event from the Brazilian state of Acre in early February 2024, subsequently spreading across 99 Cuban municipalities.

How Oropouche Virus Entered Cuba

Genomic sequencing of human serum samples confirms that the Cuban outbreak is linked to the OROVBR-2015–2025 clade, a reassortant lineage currently circulating in Brazil. Researchers used maximum likelihood phylogenetic analysis to determine that the Cuban sequences form a monophyletic cluster (OROV-CU) nested within the Brazilian AMACROII subclade.

The study identifies the Brazilian state of Acre as the most probable origin point. This conclusion is supported by a Bayes factor test showing significant support for a transmission rate between Acre and Cuba, while other Brazilian regions showed no such link. Data from the Cuban International Health Control Program notes that Acre serves as a major departure hub for flights to Cuba, providing a plausible transport route for the virus.

Timeline of the Cuban Outbreak

The virus likely entered Cuba around February 10, 2024. However, it remained undetected for approximately three months. The Cuban Ministry of Public Health did not confirm local transmission until May 27, 2024, after surveillance for acute febrile illness in Santiago de Cuba identified a surge of cases that tested negative for dengue.

By August 28, 2024, health authorities reported 506 confirmed cases. The virus’s movement followed a specific geographical pattern:

• Initial Epicenter: Central provinces including Ciego de Ávila, Sancti Spíritus, and Camagüey served as the entry point from March to July.
• Westward Spread: The virus moved through Mayabeque and Artemisa, reaching Pinar del Río and Matanzas in mid-May and Havana in late June.
• Eastward Spread: Transmission expanded through Holguín, reaching Santiago de Cuba and Guantánamo in early May.

Transmission Drivers and Vector Risks

OROV is primarily transmitted to humans through the bite of Culicoides paraensis midges. While the virus is typically associated with the Amazon, its presence in Cuba suggests it can adapt to new environments. Researchers detected the virus in pools of Culex quinquefasciatus mosquitoes and Ceratopogonidae midges, though the exact role of each species in the Cuban outbreak remains under investigation.

The speed of the spread in Cuba was notably higher than in the Brazilian Amazon. The median dispersion velocity in Cuba was 1.90 km per day. More importantly, 70% of viral movements in Cuba exceeded 10 km, compared to only 30% in the Brazilian Amazon. This indicates that the movement of infected people, rather than the limited flight range of midges, drove the interprovincial spread across the island.

Clinical Manifestations and Global Health Impact

The Pan American Health Organization (PAHO) issued an alert regarding OROV circulation in the Americas after the virus spread beyond the Amazon region in 2024. While OROV generally causes a mild illness, medical literature reports more severe complications, including:

• Meningitis and encephalitis
• Guillain–Barré syndrome
• Vertical transmission (mother-to-fetus)

The emergence of the virus in Cuba demonstrates its capacity to move beyond traditionally endemic areas. Health officials emphasize that shifting climatic and demographic patterns may facilitate further spread across the Americas, necessitating strengthened global surveillance and improved vector control.

Oropouche Virus Quick Facts