Influenza B

Virus, Enveloped

VirusInfluenza B
StructureEnveloped
GenomeSingle stranded RNA, negative sense
FamilyOrthomyxoviridae
Primary HostHumans
Disease(s) CausedInfluenza
SymptomsFever, runny nose, sore throat, muscle aches, lethargy
Potential ComplicationsPneumonia, worsened heart conditions
Transmission ModeDirect contact with infected mucus, inhalation of aerosols, contact with contaminated fomites
Sites of Community OutbreaksSchools, hospitals, workplaces

Importance of Influenza B Virus

The Influenza B virus is an enveloped member of the Orthomyxoviridae family. Influenza B, along with Influenza A, is responsible for the respiratory illness influenza (flu).

Influenza B differs from influenza A in that influenza B only infects humans and seals, while influenza A infects a wide range of animals, including birds and pigs. This increased host range allows influenza A to mutate about 2-3 times faster than influenza B. Influenza B is still able to mutate fast enough to prevent lasting immunity, making prevention and regular vaccination essential.

Symptoms of influenza B match those of influenza A but tend to be a little less severe. Most people recover within a few days to two weeks, but complications, such as pneumonia, can occur. Because there is no non-human reservoir for influenza B, pandemics are unlikely to arise.

Importance of Disinfection: Survival of Influenza B on Surfaces and Potential for Transmission via Fomites

Influenza B is transmitted primarily through large, airborne droplets. Indirect transmission through contaminated surfaces is also possible. Self-infection can potentially occur when someone touches a contaminated surface and then transfers the virus to a mucous membrane, such as the epidermal lining of the nose or mouth.

Influenza B is enveloped and is therefore sensitive to inactivation by environmental factors. It can remain infectious for 1-2 days on nonporous surfaces like stainless steel. Because of its enveloped structure, influenza B is highly susceptible to a range of chemical disinfectants. Disinfectants that are effective against other enveloped viruses, including influenza A, may be effective against influenza B.

An influenza B strain is included in the yearly flu vaccine, but the actual circulating strain can vary. This means that vaccinated individuals can still develop influenza if they are infected with a different strain.

References
  • Bean, B., et al. "Survival of influenza viruses on environmental surfaces."Journal of Infectious Diseases 146.1 (1982): 47-51.
  • Nobusawa, Eri, and Katsuhiko Sato. “Comparison of the Mutation Rates of Human Influenza A and B Viruses.” Journal of Virology 80.7 (2006): 3675–3678. PMC. Web. 20 Jan. 2016.
  • Zambon, Maria C. "Epidemiology and pathogenesis of influenza." Journal of Antimicrobial Chemotherapy 44.suppl 2 (1999): 3-9.