Influenza H1N1

Type: Viral

Geography: Worldwide

Cases Per Year: 700 million to 1.4 billion cases during the 2009 pandemic (April 2009 to April 2010), seasonal circulation since 2010

Fatality Rate: 0.1%

First Discovered: 1918 during the Spanish flu in Kansas by Dr. Loring Miner

H1N1 has multiple strains, with the most notable ones causing the 1918-1919 Spanish flu and the 2009-2010 swine flu pandemic. H1N1 is often called “swine flu” because its genetic makeup is similar to influenza viruses that were identified in pigs.

While the virus is more severe than the seasonal flu, the symptoms themselves are very similar to those of other influenzas, including fever, dry cough, headache, muscle or joint pain, sore throat, chills, fatigue, and runny nose. Diarrhea, vomiting, and neurological problems have also been reported in some cases. People at higher risk of complications include people over age 65, children younger than 5, children with neurodevelopmental conditions, pregnant women in the third trimester, and people with underlying medical conditions. The virus is spread mainly by person to person contact, through air droplets when an infected coughs or sneezes, or through touching an infected surface and hen touching one’s face.

During the pandemic, the virus existed on all continents.

Photo: Influenza H1N1 – Electron micrograph.