What Is B Type Flu

Genome Structure And Genetics

The Influenza B virus genome is 14,548 nucleotides long and consists of eight segments of linear negative-sense, single-stranded RNA. The multipartite genome is encapsidated, each segment in a separate nucleocapsid, and the nucleocapsids are surrounded by one envelope.

The subtypes of influenza A virus are estimated to have diverged 2,000 years ago. Influenza viruses A and B are estimated to have diverged from a single ancestor around 4,000 years ago, while the ancestor of influenza viruses A and B and the ancestor of influenza virus C are estimated to have diverged from a common ancestor around 8,000 years ago. Metatranscriptomics studies have also identified closely related “Influenza B-like” viruses such as the Wuhan spiny eel influenza virus and also “Influenza-B like” viruses in a number of vertebrate species such as salamanders and fish.

How The Flu Spreads

The flu is passed from person to person through the air. When an infected person coughs or sneezes, airborne droplets of the influenza virus can enter the mouth, nose or lungs of people nearby. A person might also become infected by touching a surface that has the virus on it, such as a door knob, and then touching his mouth or nose.

According to the CDC, adults with the flu are contagious one day before showing symptoms and up to five to seven days after becoming sick. Children and people with weakened immune systems may be contagious for a longer time period.

Symptoms usually appear within one to four days of the virus entering the body. Some people may be infected with the flu virus but have no symptoms, yet they may still pass the virus to others.

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• The flu is passed from person to person through the air.
• When an infected person coughs or sneezes, airborne droplets of the influenza virus can enter the mouth, nose or lungs of people nearby.

How Influenza Affects Your Body

The flu affects your whole bodyincluding your nose, throat and lungsand can lead to serious complications in those with chronic illness.

Many people who become sick with the flu say it is like being hit by a truck. Flu symptoms, such as high fever, cough and muscle aches, usually come on suddenly and are more severe than colds. Not only does having the flu impact your daily activities, it also leads to missed days from work and school.

Complications can include pneumonia, ear or sinus infections, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma or diabetes.

The flu can be fatal in elderly people, people with chronic diseases and anyone with a weak immune system.

Learn more about the connection between the flu and pneumonia.

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The Different Types Of Flu

What is type A flu?

Type A is typically thought to be more serious than Type B and is known to cause serious outbreaks that can increase your risk of disease. It is characterized by subtypes and strains and they are always constantly changing from one season to the next. These types are naturally hosted by wild birds such as ducks, geese, shorebirds and some mammals and an example of this is swine flu.2

Type A flu viruses are divided into subtypes based on proteins of the surface of the virus. There are 18 hemagglutinin subtypes and 11 types of neuraminidase subtypes . When you see H and N referring to a flu virus this is what that means1.

What is type B flu?

Type B influenza is only found in humans and people tend to see it as less severe than type A. This has been challenged in recent years however, and The Centers for Disease Control and Prevention reported that this could be equally as dangerous.2

B type flu viruses are divided into two lineages B/Yamagata and B/Victoria1.

What is type C flu?

Type C is the mildest form of the flu. For most people, this usually only causes mild respiratory infections.2

How Effective Is The Flu Shot

The effectiveness of the flu shot is different each year. Between 2009 to 2020, the flu shot was, on average, around 40% effective in preventing the flu. The reason the flu shot does not have a high disease-prevention rate is because the influenza virus mutates, or changes over time. This is why people do not have lifelong immunity to the flu after getting sick with it. The bodys immune system may not be able to use antibodies made for a previous flu infection for a different flu virus strain.

Since the flu virus changes each year, so does the vaccine. This is why you need a flu shot each year. Sometimes, the flu virus strains that are chosen dont completely match the virus strains that end up causing most infections during the flu season. This is why the vaccine isnt 100% effective. Even if you get sick with the flu, the flu vaccine can reduce how sick you get. Regardless, it is important to get vaccinated against the flu, since any decreased chance of infection is worth keeping you healthy.

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Subtypes Of The Influenza A Virus

Influenza A is further divided into different subtypes. These subtypes are based off of the combination of two proteins on the viral surface: hemagglutinin and neuraminidase . There are 18 different H subtypes and 11 different N subtypes.

For example, the most common influenza A subtypes that go around seasonally in humans are H1N1 and H3N2. In 2017, H3N2 spread to dogs in Florida. In 2015, this same strain also infected dogs in an earlier outbreak in Chicago.

Influenza A viruses can be further broken down into strains.

Unlike influenza A, influenza B isnt further divided into subtypes. But it can be broken down further into specific viral lineages and strains.

The naming of influenza virus strains is complex. It includes information such as:

• influenza type
• species of origin
• geographical origin

approved by the U.S. Food and Drug Administration in late 2018.

The zanamivir, oseltamivir, and peramivir medications noted above work by reducing the ability of the virus to release itself from infected cells. The newer drug, baloxavir marboxil works by reducing the ability of the virus to replicate.

These antiviral medications are most effective when started within the first 48 hours of your illness. Theyre ineffective in treating illness caused by influenza C.

Over-the-counter medications can be taken to relieve nasal congestion, fever, and aches and pains.

Getting lots of rest, eating a healthy diet, and drinking plenty of fluids helps your body fight the virus as well.

What Are The Symptoms Of The Flu In A Child

The flu is a respiratory disease, but it can affect the whole body. A child can become suddenly ill with any or all of these symptoms:

• Fever, which may be as high as 103°F to 105°F

• Body aches, which may be severe

• Headache

A cold is usually mild and often goes away after a few days. The flu can cause severe symptoms and lead to problems such as pneumonia and even death. The symptoms of the flu can be like other health conditions. Make sure your child sees his or her healthcare provider for a diagnosis.

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What Are Influenza Type A Flu And Type B Flu

When it comes to the flu, not all types are created equal. Youâve probably heard that there are a few different types of the flu. According to the CDC, there are three types of influenza viruses: influenza A, influenza B and influenza C.

Influenza A and B are the two main types that routinely spread in humans and cause seasonal flu epidemics. Influenza C viruses cause only mild respiratory infections and are not thought to be responsible for epidemics. 14, 15

Influenza A vs B: Brief History & Transmission

Influenza A viruses are the most harmful, as they can cause severe disease. Wild aquatic birds are often the hosts for a large variety of influenza A viruses. Sometimes these viruses are transmitted from bird to human and can cause devastating outbreaks. Some of the subtypes of influenza A that have caused the largest number of known human deaths are:14, 15

• H1N1, which caused Spanish Flu in 1918 and Swine Flu in 200911
• H2N2, which caused Asian Flu in 195722
• H3N2, which caused Hong Kong Flu in 196833
• H5N1, which caused Bird Flu in 200444

Influenza B almost exclusively infects humans and is less common than influenza A. Flu type B also mutates about two to three times more slowly than influenza A. Because humans are the natural host of influenza B, pandemics generally do not occur with influenza B viruses.22

Signs of Influenza A or Influenza B Symptoms

Influenza A and Influenza B Treatment

Type A Influenza And Its Subtypes

Type A influenza viruses are divided into subtypes, based on the presence of two glycoproteins on the surface of the virus. These glycoproteins are called hemagglutinin and neuraminidase . About 18 hemagglutinins have been identified, although generally, only H1, H2, and H3 are found in human influenza viruses. There are more than 100 types of neuraminidase, but only N1 and N2 have been positively linked to influenza epidemics in humans.

The above image shows the features of an influenza virus, including the surface proteins hemagglutinin and neuraminidase . Following influenza infection or receipt of the influenza vaccine, the bodys immune system develops antibodies that recognize and bind to antigenic sites, which are regions found on an influenza viruss surface proteins. By binding to these antigenic sites, antibodies neutralize flu viruses and prevent them from causing further infection. Source: CDC.

Hemagglutinin and neuraminidase are also called antigens, substances that, when introduced into the body, stimulate the production of an antibody. Currently, there are two subtypes of influenza A viruses found circulating among human populations: influenza A and influenza A .

Wild Birds Provide the Usual Reservoirs

Zhejiang province, China . Shanghai, a city with a population of 24 million, is located on the northern tip of Zhejiang province. Source: Uwe Dedering, Wikipedia Commons.

Genetic Evolution of H7N9 Virus in China, 2013

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What Is Influenza B

More people are being infected with influenza B early in the flu season, said Aaron Milstone, a professor of pediatrics at Johns Hopkins University School of Medicine.

“Typically, you see influenza A as the early wave of the flu, and influenza B starts to show up at the end of the spring,” he told USA TODAY. “This year, it just flip-flopped.”

Known to infect only humans and seals, influenza B tends to pass from human to human. There was little influenza B activity last season, according to the University of Minnesota’s Center for Infectious Disease Research and Policy.

It’s unclear, Milstone said, if there is a biological explanation for why influenza B emerges toward the end of the flu season and why this year is an exception.

How Do I Best Protect Myself From The Flu

Its important for everyone to prevent getting sick from the flu. Young children, older adults, and those with certain medical conditions such as asthma and HIV are at high risk for flu complications, so its important to prevent the spread of the flu in the community. Here are some ways to prevent the flu:

• Avoid contact with people who are sick.

• Limit contact with others if you are sick.

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Continue Learning About Cold And Flu

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.

Prevalence And Incidence Of Blood

No recipient-specific data is available on the prevalence and incidence of influenza virus infections. However, it can be assumed that the prevalence of antibodies against influenza viruses in these collectives is equivalent to that of the general population. No information is available on influenza virus infections transmitted by blood or blood products.

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Characteristics Of Influenza Viruses

Influenza viruses are members of the family Orthomyxoviridae. This family represents enveloped viruses the genome of which consists of segmented negative-sense single-strand RNA segments. There are four genera of this family: types A, B, C and Thogotovirus, of which, however, only genera A and B are clinically relevant for humans. The eight genome segments of influenza A and B viruses are loosely encapsidated by the nucleoprotein. The polymerase complexes consisting of the three polymerase proteins PB1, PB2, and PA are located at the ends of the nucleocapsids. These helical capsids are encircled by the M1 matrix protein and by a host-derived lipid bilayer envelope in which the virus surface glycoproteins haemagglutinin and neuraminidase as well as the M2 matrix protein are embedded . The HA is synthesized as precursor protein and cleaved by cellular serine proteases into the functional proteins HA1 and HA2. The amino acid sequence at the cleavage site determines HA processing by cellular proteases and thus, also the organ tropism. Mutations at the cleavage site of avian influenza viruses may lead to an insertion of alkaline amino acids. Ubiquitous proteases such as furin can cleave such a mutated HA and, as a consequence, permit systemic spreading of the virus. This mechanism changes a lowly pathogenic into a highly pathogenic avian influenza virus and has been associated so far only with subtype H5 and H7 viruses.

What Are The Types Of Influenza A

As well as infecting people, the influenza A virus can infect animals, including birds and pigs . In some cases, these types of influenza can be passed on to humans.

Bird flu: Avian influenza also known as ‘bird flu’ is a subtype of influenza virus A that mainly affects birds. The virus has caused serious infections in humans and deaths but has not been found in Australia.

Swine flu: This is a type of influenza A virus found in pigs. In 2009, a strain of flu virus known as H1N1 caused the respiratory infection in humans that was commonly referred to as swine flu. It spread rapidly around the world and became a pandemic. The 1918 flu pandemic was also caused by an influenza A H1N1 virus.

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Definition Of Exclusion Criteria

For influenza virus infections, the general exclusion criteria for febrile infections apply pursuant to the haemotherapy guidelines .

Special Precautions to Be Observed during the Pandemic Period

A risk/benefit analysis could be considered between a breakdown of blood supply and an emergency relaxation of the following donor selection criteria, in close coordination with the competent authorities:

• reduce haemoglobin requirement of 13.5 to 13 g/l for men and from 12.5 to 12 g/l for women ,
• increase donation frequency for platelet apheresis,
• increase age limit for multiple donors to approximately 70 years ,
• acceptance of donors already 1 week after recovery from influenza if subjective physical well-being has been restored ,
• influenza prophylaxis using medicinal products is not an exclusion criterion, if no clinical symptoms have appeared.

Is The Flu Contagious

The flu is very contagious. People can spread it from a day before they feel sick until their symptoms are gone. This is about 1 week for adults, but it can be longer for young kids.

The flu usually happens in annual epidemics. An epidemic is when an illness spreads quickly and infects lots of people in an area at the same time. Some years the epidemic is more severe and widespread than others. An epidemic that spreads worldwide is called a pandemic. This is far less common. There were three influenza pandemics in the 20th century, and one so far in the 21st century, in 2009 with influenza A .

During the coronavirus pandemic, experts found that wearing masks can help protect the community from the spread of germs. They recommended that all children age 2 and up wear a mask when out in public or around people who don’t live with them. Wearing masks can also help stop the spread of flu.

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Donor Testing And Significance

Donor testing for virus genome of influenza virus is not necessary on the basis of the present data situation.

Special Situation during the Pandemic Period

Donor screening with nucleic acid amplification techniques for the detection of viraemia cannot be introduced immediately from a technical point of view. No validated test systems are available. Up to now, there is no evidence for influenza transmission by blood products. The risk of an infection by blood products compared with the likelihood of infection through social contacts is therefore in all probability negligible. Considering the collection staff shortages to be expected, the use of the additional workload imposed by rapid tests for antigen detection including advice in the event of a positive outcome is questionable compared with the benefit to be expected.

How Is Influenza A Treated

If you have influenza, you are likely to get better within a week or so by:

• resting in bed
• taking mild pain relief to reduce your pain
• drinking plenty of liquids
• eating light foods when you are hungry

In some people, the flu can be severe and lead to serious complications such as pneumonia. This is mostly likely to affect the very young, the elderly, pregnant women, Aboriginal and Torres Strait Islander people, and people with chronic health problems.

If this sounds like you, your doctor might give you antiviral treatment to reduce your symptoms and prevent complications. These treatments are most effective when started within 2 days of flu symptoms appearing, so its important to ask your doctor whether this type of treatment is right for you.

Antibiotics only work for bacterial infections, so they won’t work for the flu, which is caused by viruses.

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