Population Genetics and Molecular Epidemiology of Shigella species
Kaisar Ali Talukder and Ishrat Jahan Azmi
from: Foodborne and Waterborne Bacterial Pathogens: Epidemiology, Evolution and Molecular Biology (Edited by: Shah M. Faruque). Caister Academic Press, U.K. (2012)
Shigellosis, also known as acute bacillary dysentery, produces inflammatory reactions and ulceration on the intestinal epithelium followed by bloody or mucoid diarrhoea. Shigellosis is caused by any one of the four species or groups of Shigella, namely, S. dysenteriae, S. flexneri, S. boydii, and S. sonnei. At least 54 serotypes or subtypes of Shigella are currently recognized, of which S. dysenteriae has 16 serotypes, S. flexneri has 17 serotypes and subserotypes, S. boydii has 20 and S. sonnei has a single serotype. Shigellosis can occur in sporadic, epidemic and pandemic forms. To develop an effective vaccine it is important to monitor the prevalent serotypes and their changes around the world because immunity to Shigella is serotype specific. The genetic variability between serotypes and emergence of atypical strains accentuates the problems to the development of an effective vaccine. In view of the emergence of new strains with altered characteristics than the ones established globally for many years, there is also a need for revising the nomenclature for the three groups of Shigella: flexneri, boydii and dysenteriae. This chapter discusses the recent serotyping scheme of Shigella with special focus on the emergence of new variants and the necessity to make an updated scheme. Furthermore, the epidemiology, phenotypic and molecular characteristics, population genetics and clinical impact of these variants have been described read more ...