Influenza, one of humanity’s oldest and most formidable diseases, has shaped global health and science for centuries, marked by recurring epidemics, transformative pandemics, and significant breakthroughs. Among its many strains, H3N2 has emerged as a notable subtype causing seasonal flu with occasional rises in cases, such as in 2025. Its very name carries a fascinating story rooted in ancient beliefs about how diseases spread.
The Origin of the Word “Influenza” and the Influence Theory
The word influenza comes from the Italian word influenza, which itself derives from the Medieval Latin influentia, meaning “influence” or “to flow into.” In medieval Europe, before the discovery of microbes, diseases were commonly believed to be caused by invisible forces affecting humans. In particular, people thought that epidemics were influenced by the stars or celestial bodies — an idea encapsulated in the Italian phrase influenza di stelle (“influence of the stars”). This astrological belief suggested that intangible fluids or emanations from the heavens could affect human health, triggering epidemics.
This notion of “influence” was so strong that the name influenza became synonymous with epidemic diseases thought to be triggered by these cosmic conditions. The term entered the English language during an outbreak in 1743 that spread through Europe and was anglicized in pronunciation. Over time, influenza specifically came to mean the disease we now know as the flu, though the root meaning still reminds us of how humankind once tried to explain illness in terms of celestial influence.
Early Outbreaks and Historical Pandemics
Records of influenza-like illnesses can be traced as far back as 412 BC with Hippocrates, but historically documented epidemics began in the 16th century — notably the 1510 pandemic that spread from Asia to Europe. Subsequent pandemics in 1557, 1580, and the 1780s showed influenza’s ability to cause widespread illness across continents.
The 19th century “Russian influenza” pandemic of 1890 was notable for prompting modern scientific collaboration, killing nearly a million people in Europe and sparking systematic study and international exchange.
The Catastrophic 1918 Spanish Flu
The 20th century began with the devastating Spanish flu pandemic (1918–1920), caused by an H1N1 strain. It infected roughly one-third of the global population and caused millions of deaths, profoundly shaping public health systems worldwide.
Subsequent Pandemics and Continued Challenges
Later 20th-century pandemics included the Asian flu (1957) and Hong Kong flu (1968, H3N2), each causing significant illness and death globally. The virus continues to evolve, causing seasonal outbreaks and regional rises such as the current increase in H3N2 cases in 2025.
Present-Day Challenge: Rise of H3N2 Cases in 2025
In 2025, health authorities have observed a noticeable increase in H3N2 influenza cases across several regions, including Delhi-NCR in India. This rise is attributed to seasonal factors such as post-monsoon weather changes, temperature variations, and increased outdoor activities that favor viral circulation. While the increase has led to more reported cases than earlier in the year, it reflects the typical seasonal fluctuation of influenza rather than a severe outbreak. The H3N2 subtype is known for causing somewhat more severe symptoms than other flu strains in certain populations, but overall the situation remains consistent with expected seasonal influenza patterns.
This seasonal rise highlights the ongoing challenge influenza poses each year and underscores the importance of general preventive measures such as good hygiene and hand washing.
Summary Table of Key Milestones
| Period | Milestone | Significance |
|---|---|---|
| Ancient times–1510 | Early illness descriptions, first documented pandemics | Cultural understanding of epidemics begins |
| 15th century | Naming of influenza reflecting “influence of stars” | Origin of the disease’s name tied to astrology |
| 1890 | Russian influenza pandemic | Scientific awareness and international study |
| 1918–1920 | Spanish flu pandemic | Massive mortality, public health transformation |
| 1957, 1968 | Asian and Hong Kong flu pandemics | Significant global illness and death |
| Present (2025) | Rise in H3N2 cases | Ongoing challenge in influenza control |
Influenza has a long and fascinating history that reflects both ancient beliefs and modern scientific understanding. From its name rooted in the idea of celestial “influence” to the ongoing seasonal patterns seen today, influenza continues to be a notable part of human health and culture.