11 Deadly Diseases That Traveled Between Animals to Humans, And Vice Versa

Influenza pandemics.

The 20th century was marked as one of the most severe pandemics of all time. The virus spread across the world between 1918 and 1919, and even though there’s no universal consensus regarding where the virus is originated, it took the lives of more than 50 million people in a relatively short period of time.

At that time, one-third of the world’s population has become infected with the virus, somewhere around 500 million people, while 50 million lost their lives, as previously mentioned. It was first identified in the United States by military personnel in 1918, leading to 675,000 deaths in the country caused by the H1N1 virus with avian origins, as data from the Centers for Disease Control and Prevention (CDC), has shown.

Unlike the novel coronavirus or other viruses that are deadly to older individuals, people with pre-existing health conditions, or others with a weakened immune system, the 1918 strain was very dangerous for young adults. In fact, the elderly seemed to have immunity built up from other H1N1 pandemics, which made most of them survive the infection.

That year, as o consequence of the pandemic, the average life expectancy dropped by 12 years in the United States. In 2009, another H1N1 virus also known as (H1N1)pdm09 hit the world again, resulting in more than 60.8 million cases in the United States, and 12,469, according to the Centers for Disease Control and Prevention (CDC).

Additionally, (H1N1)pdm09 is believed to have killed about 575,400 individuals across the globe in a one-year period, as the CDC estimates. This time, the H1N1 strain originated in pig herds, in certain areas in North America and Eurasia.