Shigellosis: An Old Disease in New Clothes?

A new study published in PLoS Medicine by von Seidlein and colleagues is a landmark in research on shigellosis [1]. von Seidlein and colleagues conducted a prospective, population-based, multi-centre study of Shigella diarrhoea in six Asian countries, producing data on disease burden, clinical manifestations, and microbiology. The study provides, at the scale of a continent, critical epidemiological information regarding prevention strategies against a largely neglected disease that threatens to re-emerge due to its highly infectious potential and its ability to develop resistance to multiple drugs [2]. There is no sign that the incidence of diarrhoeal diseases, which are diseases of the poorest, is currently decreasing. Morbidity remains high, particularly in children younger than the age of fi ve years (3.2 diarrhoea episodes per child per year), according to active surveillance studies carried out between 1992 and 2000 [3]. With 2.5 million annual deaths, diarrhoea remains a leading public health concern, even though the attributed mortality has steadily declined in endemic areas, from 13.6 children per 1,000 per year in the period 1954–1979 to 4.9 children per 1,000 per year in the period 1992–2000 [3]. In other words, mortality has roughly halved in the past 20 years. Better primary care, education of mothers, and widespread implementation of oral rehydration therapy are probably the factors that signifi cantly contributed to the decreasing trends in mortality. Evaluating the health impact of diarrhoea and implementing therapeutic and preventive measures is a headache for national and international health authorities. Unlike other infectious diseases, such as tuberculosis, HIV/AIDS, and malaria, which are all caused by a single etiological agent, diarrhoea is etiologically diverse. Setting priorities for tackling diarrhoeal disease is a complex endeavour, and this complexity largely accounts for its status as a neglected disease. Priorities nonetheless emerge, such as the need to tackle cholera and cholera-like infections caused by enterotoxigenic Escherichia coli , rotavirus infection, and shigellosis. Another priority is vaccine development. Rotavirus vaccines are currently appearing on the market, and promising vaccines against the other pathogens that cause diarrhoea are in the pipeline [4]. The time, therefore, has come to update epidemiological and disease burden data on diarrhoeal diseases, particularly for shigellosis. In a retrospective, literature-based study on shigellosis published in 1999 [5] that has become the " gold standard " , projections suggested a mean annual morbidity of 165 million cases and a mean annual mortality of 1.1 million cases, 69 percent occurring …