Influenza type B is one of three types of flu virus, the other two being type A and type C. Of the three, types A and B cause seasonal flu and can lead to epidemics. Between November and April, the time period known as flu season, is when most flu epidemics occur, according to Nemours Foundation.
The symptoms of type B flu tend to be milder than those of type A, but are similar in nature. When someone contracts type B flu, symptoms such as headache, fever and fatigue typically come on rapidly. A runny nose, congestion, sore throat, muscle aches and nonproductive cough may also develop in someone with influenza type B. Children may also exhibit stomach symptoms, such as nausea and vomiting, when infected with type B flu.
Unlike type A flu, which has three major viral strains and many subtypes that are constantly changing, type B only has one major strain and changes fairly slowly. The process used by type B influenza to change itself is called antigenic drift. According to Medline Plus, antigenic drift occurs when the virus slowly mutates over time, and these new mutations spread across the globe as people become immune to older subtypes.
Some people are more at risk of catching type B influenza than others. Children and people over age 50 may be more likely to become infected with all varieties of the flu, and may also be more prone to developing complications, although complications from type B flu are rare. Pregnant women, people with asthma, health care personnel, people who work in long-term care facilities, and parents or caregivers of young babies under six months of age may also consider taking precautionary measures against type B flu, such as receiving an annual flu shot.
The seasonal flu vaccine given yearly includes protection against that year's most common strains of both type A and type B flu. Preventive measures that individuals can take at home include frequent hand washing, staying away from anyone infected with the flu and maintaining a healthy immune system.
Treatment for type B influenza can help alleviate symptoms ,but cannot cure the virus. However, individuals infected with type B flu can expect to feel relief in about one to two weeks as the body clears the virus itself. Over-the-counter decongestants and pain relief medicine can be used to help the affected person feel better in the meantime. Some people also use nasal saline sprays or a neti pot to help clear congestion caused by the flu.