Argentina is currently experiencing an uptick in respiratory virus activity, primarily driven by the influenza A(H3N2) virus, according to the latest Boletín Epidemiológico Nacional (BEN). While this seasonal increase aligns with historical trends for this time of year, public health officials confirm that the circulation of influenza A has accelerated the start of the respiratory season. Genomic surveillance by the ANLIS Malbrán identifies the J.2.4.1 (K) subclade as the dominant strain circulating across the country.
Why is influenza A(H3N2) the primary driver?
The influenza A(H3N2) virus accounts for 98% of all reported influenza cases in Argentina, according to the Ministry of Health. Data from the most recent epidemiological week shows a 45.6% positivity rate among outpatient visits, indicating widespread transmission. The ANLIS Malbrán genomic sequencing reports that 86% of the 297 samples analyzed between 2025 and 2026 belong to the J.2.4.1 (K) subclade. The NOA (Northwest) and Centro regions remain the most affected, reporting 90 and 80 cases respectively for the 2026 season to date.
What is the status of the chikungunya outbreak?
The chikungunya outbreak in Argentina is currently in a phase of decline following a peak in epidemiological week 16. The Ministry of Health reports a total of 2,694 confirmed and probable cases for the season. Salta remains the province with the highest burden, accounting for 1,446 of those cases. While the national trend is downward, health authorities emphasize that transmission persists in provinces such as Catamarca, Santiago del Estero, and Buenos Aires, requiring continued local vigilance.
How does the current dengue situation compare to previous reports?
Unlike the surge in respiratory viruses, dengue activity in Argentina remains low, with only 65 confirmed cases reported for the current season. According to the National Epidemiological Bulletin, 57% of these cases are autochthonous, meaning they were contracted domestically without travel history. The remaining 43% are linked to travel in endemic countries, including Brazil, Paraguay, and Colombia. Although national numbers are low, health officials are monitoring an increase in “probable” case notifications in Buenos Aires, Córdoba, Tucumán, and Santa Fe. The Ministry of Health urges clinicians to prioritize diagnostic confirmation for all suspected cases to maintain accurate surveillance.
Key Takeaways for Public Health
- Respiratory Viruses: Influenza A(H3N2) is the dominant pathogen, with the J.2.4.1 (K) subclade identified as the primary variant.
- Chikungunya: The outbreak is retreating, but active monitoring is still necessary in the NOA region and specific provinces like Buenos Aires.
- Dengue: Current case counts are low, but authorities are increasing diagnostic efforts for probable cases to prevent undetected community spread.
- Clinical Guidance: Healthcare providers are encouraged to improve the quality of epidemiological surveillance by completing diagnostic studies for all probable viral cases.
The Ministry of Health continues to track these trends through the Boletín Epidemiológico Nacional, which provides weekly updates on the shifting landscape of infectious diseases across the country.