H1N1

H1N1

Influenza A(H1 N1)is the subtype of influenza A virus that was the most common cause of human influenza(flu) in 2009.
Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a small fraction of all seasonal influenza.H1N1 strains caused a small percentage of all human flu infections in 2004-2005.
In June 2009,WHO declared the new strains of swine-origin H1N1 as a pandemic,moving the alert level to phase6.This novel virus spread worldwide and had caused about 17,000 deaths by the start of 2010.
***On August 10,2010,WHO declared the H1N1 influenza pandemic over,saying worldwide flu activity had returned to typical seasonal patterns.

Notable incidents:
(1)Spanish flu(1918 flu pandemic)
(2)In 1976,a novel swine influenza A(H1N1)caused severe respiratory illness in 13 soldiers with 1 death at Fort Dix,New Jersey.
(3)The 1977-78 Russian flu epidemic was caused by strain Influenza A/USSR/90/77(H1N1).It infected mostly children and young adults under 23 because a similar strain was prevalent in 1947-57,causing most adults to have substantial immunity.
(4)In the 2009 flu pandemic,the virus isolated from patients in the United States was found to be made up of genetic elements from 4 different influenza viruses;North American swine flu,North American avian flu,human influenza,and swine influenza virus typically found in Asia and Europe-"an unusually mongrelised mix of genetic sequences."This new strain appears to be the result of reassortment of human influenza and swine influenza viruses,in all 4 different strains of subtype H1N1.
(5)2015 India outbreak
Swine flu was reported in India in early 2015.The disease affected more than 31,000 people.
(6)2017 Maldives outbreak
Maldives reported swine flu in early 2017.501 people were tested for the disease;185(37%)of those tested were positive for the disease.4 people from these 185 died due to this disease.
Infants,frail older people,those with underlying chest pathology and pregnant women are at risk.Pregnant women who contract the H1N1 infection are at a greater risk of developing complications because of hormonal changes,physical changes and changes to their immune system to accommodate the growing fetus.