Flu (Influenza)

Timeline of Human Flu Pandemics*

Including human cases of avian and swine influenza viruses.

 Major pandemic
 The appearance of a new influenza strain in the human population

1918

 Pandemic
“Spanish flu” H1N1
The most devastating flu pandemic in recent history, killing more than 500,000 people in the United States, and 20 million to 50 million people worldwide.

1957-58

 Pandemic
"Asian flu" H2N2
First identified in China, this virus caused roughly 70,000 deaths in the United States during the 1957-58 season. Because this strain has not circulated in humans since 1968, no one under 30 years old has immunity to this strain.

1968-69

 Pandemic
"Hong Kong flu" H3N2
First detected in Hong Kong, this virus caused roughly 34,000 deaths in the United States during the 1968-69 season. H3N2 viruses still circulate today.

1976

Four soldiers in a US army base in New Jersey are infected with swine influenza, resulting in one death.

1977

 Appearance of a new influenza strain in humans
“Russian flu” H1N1
Isolated in northern China, this virus was similar to the virus that spread before 1957. For this reason, individuals born before 1957 were generally protected; however children and young adults born after that year were not because they had no prior immunity.

1997

 Appearance of a new influenza strain in humans
H5N1
The first time an influenza virus was found to be transmitted directly from birds to people, with infections linked to exposure to poultry markets. Eighteen people in Hong Kong were hospitalized, six of whom died.

1999

 Appearance of a new influenza strain in humans
H9N2
Appeared for the first time in humans. It caused illness in two children in Hong Kong, with poultry being the probable source.

2002

 Appearance of a new influenza strain in humans
H7N2
Evidence of infection is found in one person in Virginia following a poultry outbreak.

2003

 Appearance of a new influenza strain in humans
H5N1
Caused two Hong Kong family members to be hospitalized after a visit to China, killing one of them, a 33-year-old man. (A third family member died while in China of an undiagnosed respiratory illness.)

H7N7
In the first reported cases of this strain in humans, 89 people in the Netherlands, most of whom were poultry workers, became ill with eye infections or flu-like symptoms. A veterinarian who visited one of the affected poultry farms died.

H7N2
Caused a person to be hospitalized in New York.

H9N2
Caused illness in one child in Hong Kong.

2004

 Appearance of a new influenza strain in humans
H5N1
Caused illness in 47 people in Thailand and Vietnam, 34 of whom died. Researchers are especially concerned because this flu strain, which is quite deadly, is becoming endemic in Asia.

H7N3
Is reported for the first time in humans. The strain caused illness in two poultry workers in Canada.

H10N7
Is reported for the first time in humans. It caused illness in two infants in Egypt. One child’s father is a poultry merchant.

2005

H5N1
The first case of human infection with H5N1 arises in Cambodia in February. By May, WHO reports 4 Cambodian cases, all fatal. Indonesia reports its first case, which is fatal, in July. Over the next three months, 7 cases of laboratory-confirmed H5N1 infection in Indonesia, and 4 deaths, occur.

On December 30, WHO reports a cumulative total of 142 laboratory-confirmed cases of H5N1 infection worldwide, all in Asia, with 74 deaths. Asian countries in which human infection with H5N1 has been detected: Thailand, Vietnam, Cambodia, Indonesia and China.

2006

H5N1
In early January, two human cases of H5N1 infection, both fatal, are reported in rural areas of Eastern Turkey, while cases in China continues to spread. As of January 25, China reports a total of 10 cases, with 7 deaths. On January 30, Iraq reports its first case of human H5N1 infection, which was fatal, to the WHO.

In March, the WHO confirmed seven cases of human H5N1 infection, and five deaths, in Azerbaijan. In April, WHO confirmed four cases of human H5N1 infection, and two fatalities, in Egypt.

In May, the WHO confirmed a case of human H5N1 infection in the African nation of Djibouti. This was the first confirmed case in sub-Saharan Africa. Throughout 2006, 115 human cases of H5N1 infection occur, with 79 deaths.

2007

H7N7
In May, four cases of H7N7 avian influenza were confirmed in the United Kingdom among individuals exposed to infected poultry.

2008

H5N1
On May 28, Bangladesh reports its first case of human H5N1 infection to the WHO. By the end of the year, 40 cases are confirmed in Bangladesh, Cambodia, China, Egypt, Indonesia and Vietnam.

2009

H5N1
On January 7, Indonesia confirmed a new case of human infection with H5N1 influenza. Since that time, new cases have been identified in Egypt, China, Indonesia and Vietnam.

Appearance of a new influenza strain in humans

H1N1
In April, human infection with a new strain of H1N1 influenza is confirmed in Mexico. Within weeks, human infections spread to the United States and cases begin occurring in other regions around the world.

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