The influenza virus nicknamed "swine flu," which led to the deaths of an estimated 10,000 people in the US back in 2009, is on the rise again this flu season. And this time, the H1N1 virus looks to be having a more severe impact on young people, as The Washington Post reports. Since late last year in California alone, 243 people under the age of 65 have died from the disease. Nationwide, there are no accurate counts on overall influenza-related deaths for adults, but over 22,000 samples have tested positive for H1N1 in this flu season, according to statistics maintained by the Centers for Disease Control and Prevention (CDC). And the number of people with H1N1 infections is almost certainly much higher, as CDC spokesperson Jason McDonald told The Verge. "These samples only represent a fraction of the infected population," McDonald said.

California has been among the hardest hit by the recent outbreak, with some hospitals in the San Francisco Bay Area setting up tents on their lawns due to the deluge of patients with flu-like symptoms. North Carolina, too, is on track to set a grim new all-time record for number of flu-related deaths, with 64 reported as of this week. The virus originally took on the nickname "swine flu" at the beginning of the 2009 outbreak because it was thought to be similar to one found in pigs, but it cannot be passed to humans by pigs, nor by eating pork products. Unfortunately for those looking to self-diagnose, the symptoms of H1N1 are the same as other, less deadly types of influenza viruses. The best defense against H1N1 is a flu vaccine.