In the spring of 2009, a novel influenza a h1n1 virus emerged. The influenza ah1n1pdm09 virus revealed some unique features in comparison with other circulating influenza viruses. The virus had spread to the us from an outbreak in mexico. Its called swine flu because in the past, the people who caught it had direct contact with pigs. Influenza ah3n2 viruses were more commonly identified from october through early december. 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. This strain is often called swine flu by the public media.
Overall, influenza a h1n1 pdm09 viruses predominated during the 20152016 season. Estimates of influenza associated mortality are important for national and international decision making on public health priorities. H1n1 case estimates and timeline april 2009 23 april. The 2009 swine h1n1 flu pandemic responsible for more than 17,000 deaths worldwide originated in pigs from a very small region in central mexico, a. Cdc provided pcr testing protocols and primers to state laboratories, and designed a validation procedure so that 2009 h1n1 testing could be performed instate. Influenza a h1n1 is a respiratory illness, and the symptoms are similar to those of the regular human seasonal flu. An increasing number of cases are being reported internationally. This virus was a unique combination of influenza virus genes never previously identified in either animals or people. The hospitalisation rate during the 20092010 season was 5. May experience a sudden high fever, a feeling of fatigue all over the body, a headache, muscle ache, etc. Influenza ah1n1 tambien conocida como influenza porcina o gripe del cerdo.
It was called swine flu early on because tests showed that it was like flu viruses that occur in swine pigs. H1n1 was first detected in the united states in april 2009. A summary of the first yearapril 2009may 2010 background the first influenza pandemic of the st21 century began in north america in early 2009. First, as the majority of human population has little or no preexisting immunity to the virus, the impact of the infection has been in a wider age. Transmission of swine influenza viruses to humans is uncommon. Apr 07, 2018 influenza y pandemias textbook of influenza edited by robert g.
It is thought that novel influenza a h1n1 flu spreads in the same way that regular seasonal influenza viruses spread. Psychological predictors of anxiety in response to the h1n1 swine flu pandemic article pdf available in cognitive therapy and research 363. Influenza porcina influenza h1n1 sintomas y causas mayo. It was detected first in the united states and spread quickly across the united states and the world. Protection by face masks against influenza ah1n1pdm09. Laboratory confirmed flu activity as reported by clinical laboratories continues to decrease. Because of this, initial reports referred to the virus as. In response to several influenza a h1n1 pdm09 infections that developed in passengers after they traveled on the same 2 flights from new york, new york, usa, to hong kong, china, to fuzhou, china, we assessed transmission of influenza a h1n1 pdm09 virus on these flights. Influenza pneumonia incidence was high in 2005, a year when influenza ah3n2 subtype virus strains predominated, low in 2006 when a h1n1 viruses were more. Influenza a virus subtype h1n1 a h1n1 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. Cases of h1n1 virus are confirmed in mexico and the usa 24 april.
As of 2009, the known siv strains include influenza c and the subtypes of influenza a known as h1n1, h1n2, h2n1, h3n1, h3n2, and h2n3. Pdf influenza is a highly contagious acute viral infection of the respiratory tract. Three kinds of influenza viruses commonly circulate among people today. Novel influenza a h1n1 is caused by a new flu virus that was first detected in april, 2009. During periods of cooler temperature, influenza cases increase roughly tenfold or more. Each annual flu season is normally associated with a major influenzavirus. Swine influenza virus siv or swine origin influenza virus soiv is any strain of the influenza family of viruses that is endemic in pigs. This new h1n1 virus contained a unique combination of influenza genes not previously identified in animals or people. Swine flu is a highly contagious respiratory disease in pigs caused by one of several swine influenza a viruses see the image below. We defined a case of infection as onset of fever and respiratory symptoms and detection of virus by pcr in a passenger or. Pdf psychological predictors of anxiety in response to. Please note all data are preliminary and may change as data are updated. Effectiveness against the flu a 2009 h1n1 virus, which was the predominating flu virus during the 2014 flu season, was 62% 95% ci.
Swine influenza is an infection caused by any one of several types of swine influenza viruses. Previous estimates of 250 000500 000 annual influenza deaths are outdated. The pandemic influenza a h1n1 2009 virus was confirmed in all deceased patients. Novel influenza a h1n1 is a new flu virus that was first detected in april, 2009. Washington state department of health, communicable disease epidemiology. Influenza ah3n2 viruses were more commonly identified from. This virus was designated as influenza a h1n1 pdm09 virus. The virus is infecting people and is spreading from persontoperson.
Influenza a h1n1 2009 monovalent vaccine is an inactivated influenza virus vaccine indicated for active immunization of persons ages 6 months and older against influenza disease caused by. The 2009 flu pandemic in the united states was a novel strain of the influenza a h1n1 virus, commonly referred to as swine flu, that began in the spring of 2009. The virus genes were a combination of genes most closely related to north american swine lineage h1n1 and eurasian lineage swine origin h1n1 influenza viruses. We updated the estimated number of global annual influenza associated respiratory deaths using countryspecific influenza. The present influenza a h1n1 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. For other names, see the nomenclature section below. The first outbreak occurred in 2009 and infected people all over the world. Despite higher incidence of manifestations of the flu during the season, the viruses are actually transmitted throughout populations all year round. Cdc recommends everyone 6 months and older get a flu vaccine by the end of october. Flu vaccines are designed to protect against the influenza viruses that experts predict will be the most common during the upcoming season. It is an orthomyxovirus that contains the glycoproteins haemagglutinin and neuraminidase. Department of health and human services secretary kathleen sebelius is briefed on april 28, 2009, on the h1n1 flu in the situation room of the white house in washington, d.
Clinical management of human infection with pandemic. These characteristics, combined with the state of immunity of the populations affected, accounted for the first pandemic of the 21st century. These results suggest that bacterial pathogens will play a key role in many countries, as the h1n1 a influenza pandemic moves forward. During the study period dec 2, 20 january 23, 2014, the 2009 h1n1 virus accounted for 98% of flu viruses detected.
287 1202 39 732 1175 33 982 1142 1258 542 1112 195 1237 1259 426 541 1129 378 63 1517 1119 305 59 1409 1172 1102 630 317 1524 681 64 285 1000 1270 1429 1219 651 311 856 1228 19