ASTROVIRIDAE FAMILY

Astroviridae family contains only two genera of viruses; and these include Mamastrovirus (which contain the human Astroviruses and animal Astroviruses) and Avastrovirus (which contain viruses that infect birds such as ducks and turkeys). The human Astroviruses cause infection in humans while the animal Astroviruses infect other mammals including pigs, cattle, sheep and cats. Astroviruses are non-enveloped viruses that posses a ss(+)RNA genome. They have an icosahedral nucleocapsid and viruses in this family measure between 28-30 nm in diameter. Astroviruses are resistant to ether, chloroform and lipid solvents. Just like the Picornaviruses, Astroviruses are also amongst the smallest known viruses owing to the size of the virion. Astroviruses replicate in the cytoplasm and they are released from their host cell via cell lysis.

The Astroviruses cause disease in both humans and animals. Astroviruses cause an acute gastrointestinal disease or diarrhea in humans; and this intestinal viral infection is usually self-limiting in nature. They cause gastrointestinal infections in people of all age groups but infections with Astroviruses are most common in immunocompromised people, young children and older people. Astroviruses like the sapoviruses, Picornaviruses, reoviruses, caliciviruses and adenoviruses can be generally referred to as enteric viruses because they cause mild diarrhea and other forms of enteritis in their human host. They have a worldwide distribution. Astroviruses are transmitted in human populations through the feacal-oral route. And the consumption of food or water contaminated with the virus is a usual means of transmission of the pathogen.

Astroviruses are significant food borne pathogens, and they are responsible for a number of foodborne illnesses across the globe. Person-to-person transmission of Astroviruses via direct body contact and transmission through fomites or contaminated surfaces is also possible. Astroviruses are shed in large amounts in the feaces of infected people; and thus such persons could serve as active means of transmitting the disease agent in defined human population. Frequent and proper hand washing, proper sewage disposal, and good environmental sanitation or decontamination is vital to the effective control and prevention of Astrovirus infection inclusive of other gastroenteritis caused by other enteric viruses as aforementioned.

SELECTED REFERENCES

Acheson N.H (2011). Fundamentals of Molecular Virology. Second edition. John Wiley and Sons Limited, West Sussex, United Kingdom.

Ahmad K (2002). Norwalk-like virus attacks troops in Afghanistan. Lancet Infect Dis, 2:391.

Alan J. Cann (2005). Principles of Molecular Virology. 4th edition. Elsevier Academic Press,   Burlington, MA, USA.

Alba R, Bosch A and Chillon M (2005). Gutless adenovirus: last-generation adenovirus for gene therapy. Gene Ther, Suppl 12:S18-S27.

Alberts B, Bray D, Johnson A, Lewis J, Raff M, Roberts K and Walter P (1998). Essential Cell Biology: An Introduction to the Molecular Biology of the Cell. Third edition. Garland Publishing Inc., New York.

Balows A, Hausler W, Herrmann K.L, Isenberg H.D and Shadomy H.J (1991). Manual of clinical microbiology. 5th ed. American Society of Microbiology Press, USA.

Barrett   J.T (1998).  Microbiology and Immunology Concepts.  Philadelphia,   PA: Lippincott-Raven Publishers. USA.

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