Emergence of a novel swineorigin influenza a h1n1 virus in humans external icon. Influenza diagnosis clinical and epidemiological characteristics increase of febrile respiratory illness lab isolation of influenza virus from clinical specimen e. Initially, the unit functioned with a who consultant and a national counterpart, who, after further training in epidemiology, was appointed in 1961, as the epidemiologist of the department of health services. These characteristics, combined with the state of immunity of the populations affected, accounted for the first pandemic of the 21st century. Looking at the domestic and international cases to date 22 may, 2009, although special attention should be paid for highrisk group, such as those with underlying medical conditions e. May experience a sudden high fever, a feeling of fatigue all over the body, a headache, muscle ache, etc. The new swine flu virus is actually a genetic mixture of two strains, both found in swine, of unknown origin. The hospitalisation rate during the 20092010 season was 5. Novel swine influenza virus subtype h3n1, united states. For this reason, they are described as h1n1, h1n2 etc. Jan 22, 2016 the influenza ah1n1pdm09 virus revealed some unique features in comparison with other circulating influenza viruses. Avian influenza a viruses are designated as highly pathogenic avian influenza hpai or low pathogenicity avian influenza lpai based on molecular characteristics of the virus and the ability of the virus to cause disease and mortality in chickens in a laboratory setting. Reassortment of strains of influenza a h1n1 of avian, porcine and human origin. The pandemic influenza ah1n1 2009 virus was confirmed in all deceased patients.
The advice was based on available information about the new influenza a h1n1 virus as well as data on the natural history, pathogenesis and clinical characteristics of human infections caused by seasonal and avian influenza viruses. We conducted a retrospective cohort study of all patients admitted to the university hospital heidelberg, germany, with laboratoryconfirmed influenza a h1n1 pdm09 infection from may 2009 through april 2011. Europe has now entered a new interpandemic phase of seasonal influenza. Influenza, often called the flu, is an infection of the upper airway the nose and throat, caused by an influenza virus. Field and epidemiologic investigations external icon. Influenza a virus infects various animal species and transmits among different hosts, especially between humans and swine. Influenza viruses are known for their ability to change their antigenic structure and create new viral strains, possibly changing biological characteristics such virulence, infectivity or host range. A person with influenza is at risk of other infections, including viral or bacterial pneumonia which is an infection of the lungs.
The number of confirmed cases of influenza a h1n1 infection is increasing in japan, and it is thought to spread further. Infection occurs at all ages, but during epidemics the morbidity is. Emergence of a novel swineorigin influenza a h1n1 virus in humans laboratory supplemental pdf icon 4. Swine may serve as a mixing vessel to create new reassortants that could infect humans. Influenza a h1n1pdm09 virus ph1n1 was the causal factor of the recent flu pandemic, which claimed several hundred lives. Pdf 2009 influenza ah1n1 monovalent vaccines for children. Pdf influenza is a highly contagious acute viral infection of the respiratory tract. The proportion of severely diseased patients dramatically increased from 14% in 200910 to 46% in 201011. Highly pathogenic and low pathogenic avian influenza a viruses. Creative commons attributionnoncommercialsharealike license. It is an orthomyxovirus that contains the glycoproteins haemagglutinin and neuraminidase. Since influenza a h1n1 could possibly cause a change in the symptoms of influenza, there is a possibility that the symptoms will change with new cases. Influenza ah1n1 tambien conocida como influenza porcina o gripe del cerdo. Influenza viruses are known for their ability to change their antigenic structure and create new viral strains, possibly changing biological characteristics such virulence, infectivity or.
The influenza ah1n1pdm09 virus revealed some unique features in comparison with other circulating influenza viruses. We studied risk factors for a severe clinical outcome in hospitalized patients with laboratoryconfirmed influenza ah1n1pdm09 infection at the university hospital heidelberg in the pandemic and first postpandemic seasons. Influenza pandemics may occur when an influenza virus acquires an ha protein through reassortment, which is then efficiently transmitted from human to human and emerges in the human population with little or no existing immunity. The mortality rate is low in pigs and recovery usually occurs within 710 days. Influenzavirus a subtipo h1n1 wikipedia, a enciclopedia livre. We identified 102 patients in 200910 and 76 in 201011. The 2009 flu outbreak in humans, known as swine influenza or h1n1 influenza a, refers to influenza a due to a new h1n1 strain called swineorigin influenza virus a soiv. The typical swine influenza swine flu is an acute viral infection of the respiratory tract in pigs, caused by type a influenza virus.
As of 11 am edt april 25, 2009, 8 laboratory confirmed cases of swine influenza infection have been confirmed in the united states. The epidemiology unit was established in 1959 with assistance from world health organization who to strengthen surveillance of communicable diseases. The influenza virus leads to respiratory disease that results in a. The present influenza ah1n1 virus is a new virus subtype of influenza affecting humans, which contains segments of genes from pig, bird and human influenza viruses in a combination that has never been observed before anywhere in the world. Thus, monitoring and characterizing influenza viruses in swine are important in preventing interspecies transmission. Swine influenza h1n1 cdc, in collaboration with public health officials in california and texas, is investigating cases of febrile respiratory illness caused by swine influenza h1n1 viruses. Influenza viruses are cultured in chick embryo and cell culture mdck. We report the emergence and characterization of a novel h3n1. Changes in severity of influenza ah1n1pdm09 infection.
Influenza virus h1 n1 is the subtype of influenza a virus that was the most common cause of human influenza flu in 2009, and is associated with the 1918 outbreak known as the spanish flu. Influenza a virus is a highly mutable virus with frequent antigenic drift and occasional antigenic shift. Pandemic h1n1 was first observed in the year 1918 in spain, where it caused millions of deaths. What is the difference between the new influenza ah1n1 and swine influenza. The known subtypes of influenza a virus that create influenza in pigs and are endemic in pigs are h1n1, h1n2, h3n1 and h3n2. Later, several outbreaks of influenza virus were reported in 1968, 1998, 2009. Europe has now entered a new interpandemic phase of seasonal. A letra h referese a proteina hemaglutinina e a letra n a proteina neuraminidase. This work is licensed under a creative commons attribution. The 2009 influenza ah1n1 pandemic was declared over in august 2010 by the world health organization.