Shigellosis: report of a workshop.

INTRODUCTIONShigellosis continues to be a major public-health problem and remains endemic in many developing countries. Among Shigella species, Shigella dysenteriae type 1 poses a particular threat because of the severity of disease and its epidemic potential. Epidemics due to S. dysenteriae type 1 tend to occur at intervals of about a decade, and although few outbreaks have been reported over recent years, the problem should not be considered to be solved. There is no reason to believe that new outbreaks will not occur in the future because the same conditions that prevailed during outbreaks in the past are still present and include over-crowding, poor sanitation, sub-standard hygiene, and unsafe water supplies, while no other prevention measures have been developed in the interim.Efforts to control shigellosis should include measures targeting behaviour, personal hygiene, sanitation, and water supply, in addition to proper case management of patients. Until now, fluoroquinolones, such as ciprofloxacin and norfloxacin, have been active against Shigella, but outbreaks due to S. dysenteriae type 1 strains, resistant to these antibiotics, have been documented recently. If past patterns hold true, new epidemics of shigellosis due to fluoroquinolone-resistant S. dysenteriae type 1 may be expected during the coming years, particularly in South Asia. Detection of past epidemics has often been delayed, and the antibiotic sensitivity profile of the strains was often either ignored or not appreciated. Improved epidemiological surveillance systems are needed to detect these outbreaks, determine the antibiotic sensitivity patterns, and prepare for interventions.In this context, a workshop on shigellosis was jointly organized by the World Health Organization (WHO), ICDDR,B: Centre for Health and Population Research, the International Vaccine Institute (IVI), and United States Agency for International Development. Representatives from research laboratories and public-health professionals from both developing and industrialized countries were present. The purpose of the workshop was to:a. review the burden of dysentery from different regions of the world;b. review surveillance techniques for shigellosis;c. prepare recommendations for controlling endemic and epidemic shigellosis (WHO guidelines); andd. define research priorities which will lead to improved methods for controlling shigellosisThe workshop emphasized improved surveillance and practical interventions for control.BURDEN OF DISEASEThe burden of disease in Asia was estimated by reviewing studies initiated in Asian countries after 1990, and of which the results were published. Total morbidity and mortality attributable to Shigella were estimated through extrapolation. Overall, shigellosis remains a common disease in the continent. The annual numbers of episodes and deaths due to Shigella in Asia were estimated to be 91 million and 414,000 respectively. S. flexneri is the commonest serotype, followed by S. sonnei. Resistance to common antibiotics is frequent and is alarming in the case of S. dysenteriae type 1.The Diseases of the Most Impoverished (DOMI) Programme of IVI is currently conducting shigellosis disease-burden studies in Bangladesh, China, India, Indonesia, Pakistan, Thailand, and Viet Nam. Methods include retrospective collection of existing data, prospective surveillance, and behavioural and economic studies. Overall, a population of 568,000 has been placed under surveillance for two years. Data have been collected so far from four sites. Morbidity due to shigellosis was higher than expected: 64,755 episodes of diarrhoea have so far been detected, including 3,304 episodes of shigellosis. The overall crude incidence rates of shigellosis ranged from 1 to 12/1,000 per year, and the case-fatality rate was as low as 1.5 per 1,000 Shigella-associated episodes. However, these figures were corrected to take into account the lack of sensitivity of the culture techniques and patients escaping the passive surveillance network. …