Is influenza the same as the flu?
Influenza is commonly called the flu, but it's not the same as stomach "flu" viruses that cause diarrhea and vomiting. For most people, the flu resolves on its own.
What is the flu and why is it so dangerous?
The influenza A and B viruses that routinely spread in people (human influenza viruses) are responsible for seasonal flu epidemics each year. The best way to reduce the risk of flu and its potentially serious complications is by getting vaccinated each year.
How does influenza change its genome?
Influenza viruses undergo constant genetic change, which has substantial impact on induced immunity and considerations for vaccine composition. Two main types of changes are recognized. Point mutations and recombination events occur in the viral genome, resulting in constant emergence of new virus variants.
What is genetic characterization of the flu?
This process of comparing genetic sequences is called genetic characterization. CDC uses genetic characterization for the following reasons: To determine how closely “related” or similar flu viruses are to one another genetically. To identify genetic changes that affect the virus’ properties.
Is influenza genetic or environmental?
Genetics. Several epidemiological and experimental studies suggest that influenza-induced disease has a significant genetic component.
Are there many genetic forms of influenza?
Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 through H18 and N1 through N11, respectively).
Does influenza change your DNA?
Overall, this study provides evidence that infection with influenza viruses can cause epigenetic changes like DNA methylation. This mechanism is being used to regulate the expression of host inflammatory genes and thus can play an important role in regulating host immune responses against influenza viruses.
What type of disease is the influenza?
Influenza (flu) is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. Some people, such as older people, young children, and people with certain health conditions, are at higher risk of serious flu complications.
Which is worse influenza A or B?
In the past, it was thought that infection with influenza A was more severe than infection with influenza B. However, a 2015 study in adults with influenza A and influenza B found they both resulted in similar rates of illness and death.
What causes influenza?
The flu is caused by an influenza virus. Most people get the flu when they breathe in tiny airborne droplets from the coughs or sneezes of someone who has the flu. You can also catch the flu if you touch something with the virus on it, and then touch your mouth, nose, or eyes.
Is the flu virus RNA or DNA?
-stranded RNAAll influenza viruses consist of single-stranded RNA as opposed to dual-stranded DNA. The RNA genes of influenza viruses are made up of chains of nucleotides that are bonded together and coded by the letters A, C, G and U, which stand for adenine, cytosine, guanine, and uracil, respectively.
What diseases can change your DNA?
The study from the laboratory of Peter Scacheri, associate professor of genetics and genome sciences, shows that multiple DNA changes, or variants, work in concert to affect genes, leading to autoimmune diseases including rheumatoid arthritis, Crohn's disease, celiac disease, multiple sclerosis, lupus and colitis.
What causes flu virus to mutate?
Antigenic Shift Because influenza virus genomes are formed by 8 separate pieces of RNA (called “genome segments”), sometimes these viruses can “mate,” in a process called, “reassortment.” During reassortment, two influenza viruses' genome segments can combine to make a new strain of influenza virus.
Is influenza A serious illness?
If you're young and healthy, the flu usually isn't serious. Although you may feel miserable while you have it, the flu usually goes away in a week or two with no lasting effects. But children and adults at high risk may develop complications that may include: Pneumonia.
Is flu and influenza the same?
The flu, also called influenza, is a respiratory infection caused by viruses. Each year, millions of Americans get sick with the flu. Sometimes it causes mild illness. But it can also be serious or even deadly, especially for people over 65, newborn babies, and people with certain chronic illnesses.
Where did the influenza originate?
The history of influenza begins with Hippocrates (5th century BC) who first reported that an influenza-like illness spread from Northern Greece to the islands south and elsewhere.
How many variants of the common cold are there?
More than 200 different viruses are known to cause the symptoms of the common cold. An estimated 30-35% of all adult colds are caused by rhinoviruses.
How often does influenza mutate?
Previously, Parvin et al. reported a mutation rate for the NS gene of influenza A virus A/WSN/33(H1N1) (WSN) of 1.5 × 10−5 mutations per nucleotide per infectious cycle during the growth of a single plaque in MDCK cells (23).
What's the difference between A and B flu?
Strains of influenza B are exclusively contracted by humans, while A can be carried (and spread) by animals, however, both strains are transmitted mainly by respiratory droplets from coughing and contact with an infected person.
What is the difference between influenza A and influenza B?
Influenza A is usually the more common form of the virus and tends to circulate early in the season, while influenza B is normally less common and shows up late in the season. This season, influenza B has been more common and is circulating earlier than in previous seasons.
What are the subtypes of influenza A?
Current subtypes of influenza A viruses that routinely circulate in people include: A (H1N1) and A (H3N2). Influenza A subtypes can be further broken down into different genetic “clades” and “sub-clades.”. See the “Influenza Viruses” graphic below for a visual depiction of these classifications. This graphic shows the two types ...
How many different subtypes of influenza are there?
Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 through H18 and N1 through N11, respectively).
What type of virus is not known to cause illness?
Influenza type C infections generally cause mild illness and are not thought to cause human flu epidemics. Influenza D viruses primarily affect cattle and are not known to infect or cause illness in people. Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N).
What are the two lines of influenza B?
Influenza B viruses are not divided into subtypes, but instead are further classified into two lineages: B/Yamagata and B/Victoria. Similar to influenza A viruses, influenza B viruses can then be further classified into specific clades and sub-clades. Influenza B viruses generally change more slowly in terms of their genetic and antigenic properties than influenza A viruses, especially influenza A (H3N2) viruses. Influenza surveillance data from recent years shows co-circulation of influenza B viruses from both lineages in the United States and around the world. However, the proportion of influenza B viruses from each lineage that circulate can vary by geographic location.
Which virus is more genetically and antigenically different from the other viruses?
Of all the influenza viruses that routinely circulate and cause illness in people, influenza A (H3N2) viruses tend to change more rapidly, both genetically and antigenically. Influenza A (H3N2) viruses have formed many separate, genetically different clades in recent years that continue to co-circulate.
Is there a co-circulation of influenza B?
Influenza surveillance data from recent years shows co-circulation of influenza B viruses from both lineages in the United States and around the world. However, the proportion of influenza B viruses from each lineage that circulate can vary by geographic location.
Is hemagglutinin parentheses?
For influenza A viruses, the hemagglutinin and neuraminidase antigen description are provided in parentheses (e.g., influenza A (H1N1) virus, influenza A (H5N1) virus)
What is the flu?
Influenza (flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness. Serious outcomes of flu infection can result in hospitalization or death. Some people, such as older people, young children, and people with certain health conditions, are at high risk of serious flu complications. There are two main types of influenza (flu) virus: Types A and B. The influenza A and B viruses that routinely spread in people (human influenza viruses) are responsible for seasonal flu epidemics each year.
How to reduce the risk of the flu?
The best way to reduce the risk of flu and its potentially serious complications is by getting vaccinated each year.
How many subtypes of influenza A are there?
. There are 18 known HA subtypes and 11 known NA sub types. Many different combinations of HA and NA proteins are possible.
What is the most common H7 virus?
The most frequently identified H7 viruses associated with human infection are Asian lineage avian influenza A (H7N9) viruses, which were first detected in China in 2013. While human infections are rare, these have commonly resulted in severe respiratory illness and death.
What is the difference between H5N1 and H7N2?
For example, an “H7N2 virus” designates an influenza A virus subtype that has an HA 7 protein and an NA 2 protein. Similarly, an “H5N1” virus has an HA 5 protein and an NA 1 protein. All known subtypes of influenza A viruses can infect birds, except subtypes H17N10 and H18N11, which have only been found in bats.
How many H5 viruses are there?
There are nine known subtypes of H5 viruses#N#external icon#N#( H5N1, H5N2, H5N3, H5N4, H5N5, H5N6, H5N7, H5N8, and H5N9). Most H5 viruses identified worldwide in wild birds and poultry are LPAI, but occasionally HPAI viruses have been detected. Sporadic H5 virus infection of humans has occurred, such as with Asian lineage HPAI H5N1 viruses currently circulating among poultry in Asia and the Middle East. Human infection of H5N1 virus infections have been reported in 16 countries, often resulting in severe pneumonia and greater than 50% mortality.
Is avian influenza a low pathogenic virus?
Highly Pathogenic and Low Pathogenic Avian Influenza A Viruses. Avian influenza A viruses are designated as highly pathogenic avian influenza (HPAI) or low patho genicity 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.
Can H3N8 cause illness in dogs?
Some subtypes are found in other infected animal species. For example, H7N7 and H3N8 virus infections can cause illness in horses, and H3N8 virus infection cause illness in horses and dogs.
What is the only species of influenza A?
Species: Influenza A virus. Subtypes. See text. Influenza A virus causes influenza in birds and some mammals, and is the only species of the genus Alphainfluenzavirus of the virus family Orthomyxoviridae. Strains of all subtypes of influenza A virus have been isolated from wild birds, although disease is uncommon.
What is influenza type A?
Influenza type A viruses are RNA viruses categorized into subtypes based on the type of two proteins on the surface of the viral envelope:
What was the H3N2 virus?
A severe form of the H3N2 virus killed several children in the United States in late 2003. The dominant strain of annual flu in January 2006 was H3N2. Measured resistance to the standard antiviral drugs amantadine and rimantadine in H3N2 increased from 1% in 1994 to 12% in 2003 to 91% in 2005.
Where is H3N2 endemic?
"Contemporary human H3N2 influenza viruses are now endemic in pigs in southern China and can reassort with avian H5N1 viruses in this intermediate host.".
What is the avian flu?
Avian influenza is sometimes called avian flu, and colloquially, bird flu. In 2011, researchers reported the discovery of an antibody effective against all types of the influenza A virus.
What is the only species of Alphainfluenzavirus?
Influenza A virus. Influenza A virus causes influenza in birds and some mammals, and is the only species of the genus Alphainfluenzavirus of the virus family Orthomyxoviridae. Strains of all subtypes of influenza A virus have been isolated from wild birds, although disease is uncommon.
How does the Influenza virus reactivate?
Influenza virus is able to undergo multiplicity reactivation after inactivation by UV radiation, or by ionizing radiation. If any of the eight RNA strands that make up the genome contains damage that prevents replication or expression of an essential gene, the virus is not viable when it alone infects a cell (a single infection). However, when two or more damaged viruses infect the same cell (multiple infection), viable progeny viruses can be produced provided each of the eight genomic segments is present in at least one undamaged copy. That is, multiplicity reactivation can occur.
How long does it take for the flu to go away?
If you're young and healthy, the flu usually isn't serious. Although you may feel miserable while you have it, the flu usually goes away in a week or two with no lasting effects. But children and adults at high risk may develop complications that may include:
What is the name of the virus that attacks the respiratory system?
Influenza is a viral infection that attacks your respiratory system — your nose, throat and lungs. Influenza is commonly called the flu, but it's not the same as stomach "flu" viruses that cause diarrhea and vomiting.
What are the effects of cancer on the immune system?
Weakened immune system. Cancer treatments, anti-rejection drugs, long-term use of steroids, organ transplant, blood cancer or HIV / AIDS can weaken the immune system. This can make it easier to catch the flu and may also increase the risk of developing complications.
What to do if you have the flu?
If you have flu symptoms and are at risk of complications, see your doctor right away. Taking antiviral drugs may reduce the length of your illness and help prevent more-serious problems. If you have emergency signs and symptoms of the flu, get medical care right away.
How do viruses travel through the air?
Influenza viruses travel through the air in droplets when someone with the infection coughs, sneezes or talks. You can inhale the droplets directly, or you can pick up the germs from an object — such as a telephone or computer keyboard — and then transfer them to your eyes, nose or mouth.
How long is a person contagious after a virus?
People with the virus are likely contagious from about a day before symptoms appear until about five days after they start. Children and people with weakened immune systems may be contagious for a slightly longer time.
What are the chronic illnesses?
People who have chronic illnesses, such as asthma, heart disease, kidney disease, liver disease and diabetes
What is the term for the genetic change of influenza A?
In addition to antigenic drift, larger genetic change events, termed “antigenic shift”, can occur among influenza A viruses. Antigenic shift occurs less frequently than antigenic drift, and generally arises though genetic reassortment among different viruses. These events can lead to new or substantially different influenza A viruses, for which there is little pre-existing immunity in the population. Such viruses can be associated with widespread pandemic influenza illness, if they exhibit efficient and sustained transmission among humans ( 1 ). In April 2009, a novel influenza A (H1N1) virus caused the most recent worldwide pandemic. This virus was antigenically distinct from human influenza A (H1N1) viruses in circulation from 1977 through spring 2009 ( 6, 7 ).
When does influenza occur?
In general, however, annual epidemics of influenza typically occur in the United States during the fall and winter.
Is obesity a risk factor for severe illness?
Prior to the 2009 pandemic , obesity had not been recognized as a risk factor for severe influenza illness. However, several studies during the 2009 pandemic noted a high prevalence of obesity among persons with severe illness attributable to A (H1N1)pdm09 ( 89-91 ). In a case-cohort study, among persons aged ≥20 years, hospitalization with illness attributable to laboratory-confirmed influenza A (H1N1)pdm09 was associated with extreme obesity (body mass index [BMI] ≥40) even in the absence of other risk factors for severe illness (odds ratio [OR]=4.7; 95%CI 1.3–17.2) ( 92 ). Death was associated with both obesity, defined as BMI ≥30 (OR=3.1; 95%CI 1.5–6.6) and extreme obesity (OR=7.6; 95%CI 2.1–27.9). A Canadian cohort study covering 12 seasons (1996–97 through 2007–08) found that persons with a BMI of 30.0–34.9 and those with a BMI ≥35 were more likely than normal-weight persons to have a respiratory hospitalization during influenza seasons (OR=1.45; 95%CI 1.03–2.05 for BMI 30–34.9 and OR=2.12; 95%CI 1.45– 3.10 for BMI ≥35) ( 93 ). A retrospective cohort study of Australian national health insurance data between 2006 and 2015 found that compared to adults with a healthy BMI, those with a BMI of 30 to <40 had a higher risk of influenza-associated hospital admission (aHR=1.57, 95%CI 1.22–2.01); those with a BMI of ≥40 had an even higher risk (aHR=4.81, 95%CI 3.23—7.17) (94). Conversely, a two-season prospective cohort study (2007–09) in the United States found no association between obesity and medically attended LCI, including both seasonal and pandemic virus circulation ( 95 ). In a four-season (2010-11 through 2013-14) cohort study conducted in Mexico of children and adults with viral ILI, influenza infection was significantly associated with increased risk of hospitalization among adults who were either underweight or morbidly obese. Among children in this study, influenza was not analyzed separately; obesity was associated with increased risk for hospitalization for ILI due to any viral pathogen ( 96 ).
When did the B virus co-circulate?
Influenza B viruses from both lineages have co-circulated during most influenza seasons since the 1980s ( 3, 4 ). Influenza viruses undergo constant genetic change, which has substantial impact on induced immunity and considerations for vaccine composition. Two main types of changes are recognized.
Is obesity a risk factor for influenza?
Prior to the 2009 pandemic , obesity had not been recognized as a risk factor for severe influenza illness. However, several studies during the 2009 pandemic noted a high prevalence of obesity among persons with severe illness attributable to A (H1N1)pdm09 ( 89-91 ).
Can a fever be a congenital anomaly?
A meta-analysis of 22 observational studies of congenital anomalies following influenza exposure during the first trimester of pregnancy noted associations with several types of congenital anomalies, including neural tube defects, hydrocephaly, heart and aortic valve defects, digestive system defects, cleft lip, and limb reduction defects ( 70 ). However, many of the included studies were conducted during the 1950s through 1970s, and a nonspecific definition of influenza was used (any reported influenza, ILI, or fever with influenza, with or without serological or clinical confirmation). A 2005 meta-analysis of fifteen observational studies noted an association between maternal fever and neural tube defects ( 71 ). Associations between maternal fever and congenital heart defects ( 72) and orofacial cleft ( 73) have been reported in some studies; in one study of congenital anomalies such as orofacial clefts, congenital heart defects, and omphalocele, the association with maternal fever was ameliorated among those mothers who had taken multivitamins ( 74 ).
Is influenza a pregnancy risk?
Some studies of pregnancy outcomes have suggested increased risk for pregnancy complications attributable to maternal influenza illness; others have not. A review of data from the National Inpatient Sample (a publicly available hospital discharge database; www.hcup external icon – us.ahrq.gov/nisoverview.jsp external icon) external icon covering the 1998–99 through the 2001–02 seasons and including over 6.2 million hospitalizations of pregnant women, reported increased risk for fetal distress, preterm labor, and cesarean delivery among those women with respiratory illness during influenza seasons, compared with women without respiratory illness ( 62 ). A study of 117,347 pregnancies in Norway during the 2009–10 pandemic noted an increased risk for fetal death among pregnant women with a clinical diagnosis of influenza (adjusted hazard ratio [aHR]=1.91; 95%CI 1.07–3.41) ( 63 ). A cohort study conducted among 221 hospitals in the United Kingdom observed an increased risk for perinatal death, stillbirth, and preterm birth among women admitted with confirmed 2009 (H1N1) infection ( 64 ). In a retrospective cohort study of 86,779 pregnancies in which 192 cases of LCI were identified during the 2012-14 and 2013-14 seasons, women infected during the first trimester had a significantly lower mean length of gestation than uninfected women (38 vs. 39 weeks). The infants of those infected with influenza B had a 4% lower mean percent of optimal weight ( 65 ). However, other studies of infants born to women with LCI during pregnancy have not shown higher rates of prematurity, preterm labor, low birth weight, or lower Apgar scores compared with infants born to uninfected women ( 66-68 ).
What is the name of the drug that stops the virus from replicating?
A new medication called baloxavir marboxil ( Xofluza ), created by a Japanese pharmaceutical company, was approved in October 2018 by the U.S. Food and Drug Administration (FDA) Trusted Source. . This antiviral drug helps stop the influenza virus from replicating.
What is the type of influenza?
What is type A influenza? Influenza — also known as the flu — is a contagious viral infection that attacks your respiratory system. Influenza viruses that infect humans can be classified into three main groups: A, B, and C. Type A influenza infection can be serious and cause widespread outbreaks and disease. Common symptoms of type A infection can ...
What are the symptoms of the flu?
Common signs of an influenza infection include: coughing. runny or stuffy nose. sneezing. sore throat. fever. headache.
How does influenza A clear?
In some cases, influenza A symptoms can clear on their own with ample rest and fluid intake. In other cases, your doctor may prescribe antiviral medication to fight the infection.
How long does it take for flu symptoms to go away?
chills. body aches. Sometimes, influenza A symptoms may resolve on their own. However, if symptoms persist for more than a week without improvement, schedule a visit with your doctor.
What are the side effects of oseltamivir?
Though effective, these medications can cause side effects such as nausea and vomiting.
How long does it take for a doctor to test for influenza?
In this procedure, your doctor swabs your nose or throat. The test will detect influenza viral RNA within 30 minutes or less.