- Change Language
- Home
- Overview
- Subscribers
- Locations
- Newsroom
Updated: September 2025
Mpox was first detected in 2003 during an outbreak linked to prairie dogs that had been housed near imported animals from Ghana, prior to being sold as pets. This was the first instance of human mpox infections reported outside of Africa. The virus wasn't detected again in the US until 2021 when two travelers with a travel history to Nigeria tested positive.
During the global outbreak of mpox clade II in 2022, infections were first reported in May and eventually led to community transmission.
Clade I mpox was first detected in November 2024 in California in an individual who had recently travelled to an African country experiencing an ongoing outbreak. Since then, additional imported infections have been detected.
Testing is available through public and private healthcare providers.
Vaccination is available for people with certain risk factors.
More information is available on the U.S. Centers for Disease Control and Prevention (CDC) mpox website.
H5N1 was first reported in January 2015 in a wild bird in Washington. It was detected again in January 2022 and has since caused outbreaks in wild and commercial birds across multiple states. H5N1 has also been detected in mammals, with outbreaks in livestock first reported in March 2024.
H5N2 was first detected in 1983 in poultry in Pennsylvania and Virginia. It was detected again in 2004 on a single poultry farm in Texas and in December 2014 in wild birds, subsequently causing outbreaks in domestic poultry in several states in 2015.
H5N8 was first detected in December 2014 in a wild bird in Washington. Outbreaks were subsequently detected in poultry in several states in 2015.
H5N9 was first confirmed in January 2025 in a poultry farm located in California.
H7N3 was detected in March 2020 in poultry farms in North Carolina and South Carolina.
H7N8 was detected in January 2016 in Indiana in poultry.
H7N9 was first detected in March 2017 in Tennessee in poultry. It was detected again in March 2025 in poultry in Mississippi.
H5N1, a highly pathogenic avian influenza (HPAI), was first detected in a Colorado poultry farm worker in April 2022. Human infections have been detected since 2024 due to an ongoing multistate H5N1 outbreak in dairy cows, poultry and wild birds. Most of these infections have been mild; however, several have required hospitalisation, and there has been one death. While most infections were in individuals exposed to infected animals, one in Missouri and two in California had no known exposures. There has been no evidence of sustained human-to-human transmission of H5N1 in the country.
H7N2, a low pathogenic avian influenza (LPAI), was first detected in 2002 in a Virginia poultry farm worker who developed mild symptoms. Since then, three additional infections have been reported, one in 2003 in New York without a known exposure and two in 2016 in individuals exposed to infected cats during an H7N2 outbreak in a New York City animal shelter.
Influenza A(H3N2)v regularly circulates in pigs in the US and was first detected in humans in 2011. In 2012, over 300 human infections were reported, including one fatality. Since then, sporadic cases have occurred, primarily linked to individuals visiting fairs where swine are present. In August 2018, there was a likely instance of human-to-human transmission but no sustained transmission.
Between 2022 and 2024, several infections have been reported, with variants A(H3N2)v and A(H1N2)v identified. During this period, there was no human-to-human transmission detected.
The CDC notes that while variant swine flu has occasionally spread between people, the majority of cases do not result in person-to-person transmission.
The first confirmed COVID-19 cases were reported in January 2020.
For more information, see the CDC COVID-19 dashboard and website.
Two imported cases of MERS-CoV occurred in 2014. One was in Florida and the other in Indiana, they were unrelated to each other. Both patients worked in healthcare facilities in Saudi Arabia. No further transmission occurred within the United States.
The national pandemic preparedness plan is available on the CDC website.
HMPV facts and FAQs, and other respiratory illnesses.
International SOS Podcast on "HMPV in China"
Additional data provided by
English
Japanese
