Influenza is a contagious respiratory illness caused by influenza viruses, affecting the nose, throat, and sometimes the lungs. Symptoms range from mild to severe. Types A and B are the primary causes of seasonal epidemics.
Influenza B in Adults
Adults can contract influenza B, a type of influenza virus that primarily circulates among humans. Unlike influenza A, which can infect both humans and animals and cause pandemics, influenza B viruses are typically found only in people. While influenza A is generally more common, influenza B can still cause widespread illness and account for a significant portion of global flu cases, sometimes around 23%.
Influenza B is highly contagious, spreading through respiratory droplets released when an infected person coughs, sneezes, or talks. These droplets can infect others directly or indirectly via contaminated surfaces. Symptoms in adults are similar to influenza A, appearing suddenly and including fever, chills, cough, sore throat, and a runny or stuffy nose. Individuals may also experience muscle aches, headaches, and fatigue. Vomiting or diarrhea can occur, though these are more common in children.
Diagnosis and Treatment Approaches
Diagnosing influenza B in adults involves laboratory tests to identify the virus. Molecular tests, such as RT-PCR, are highly accurate, detecting viral RNA in respiratory specimens with results available within 24 hours. Rapid influenza diagnostic tests (RIDTs) provide quicker results, within 10 to 15 minutes, but have lower sensitivity than RT-PCR. A negative RIDT result may require confirmation, especially during high flu activity.
Treatment for influenza B in adults includes supportive care to alleviate symptoms. This involves getting rest, staying hydrated, and using over-the-counter medications like acetaminophen or ibuprofen for fever and body aches. For individuals at higher risk of complications or with severe illness, antiviral medications may be prescribed. These drugs, such as oseltamivir, zanamivir, peramivir, and baloxavir, inhibit viral replication and can reduce illness severity and duration, particularly when started within 48 hours of symptom onset.
Preventing Influenza B Infection
The most effective way for adults to prevent influenza B infection is annual vaccination. Seasonal flu vaccines are formulated each year to protect against prevalent influenza B strains. An annual flu shot helps the body develop protective antibodies, reducing infection risk and lessening illness severity if infection occurs.
In addition to vaccination, general preventive measures limit influenza B spread. Practicing good hand hygiene, such as frequent washing with soap and water or using an alcohol-based hand sanitizer, helps remove virus particles. Avoiding close contact with sick individuals, covering coughs and sneezes, and refraining from touching the eyes, nose, and mouth also reduce infection chances. These actions contribute to preventing influenza virus transmission.