Shigellosis : challenges & management issues

Infectious diseases kill about 11 million children each year while acute diarrhoeal diseases account for 3.1 million deaths in children under 5 yr of age, of which 6,00,000 deaths annually are contributed by shigellosis alone. Shigellosis, also known as acute bacillary dysentery, is characterized by the passage of loose stools mixed with blood and mucus and accompanied by fever, abdominal cramps and tenesmus. It may be associated with a number of complications of which haemolytic uraemic syndrome is the most serious. Shigellosis is caused by Shigella spp. which can be subdivided into four serogroups namely S.sonnei, S.boydii, S.flexneri and S.dysenteriae. Organisms as low as 10-100 in number can cause the disease. Shigellosis can occur in sporadic, epidemic and pandemic forms. Epidemics have been reported from Central American countries, Bangladesh, Sri Lanka, Maldives, Nepal, Bhutan, Myanmar and from the Indian subcontinent, Vellore, eastern India and Andaman and Nicobar islands. Plasmid profile of shigellae in Kolkata has shown a correlation between presence of smaller plasmids and shigellae serotypes- indicating epidemiological changes of the species. Diagnosis of shigellosis is essentially clinical. Laboratory diagnosis includes stool culture and polymerase chain reaction (PCR). Treatment includes use of an effective antibiotic, rehydration therapy (if there is dehydration) and appropriate feeding during and after an episode of shigellosis. Hand-washing is the single most important strategy for prevention of transmission of shigellosis from person to person. A safe and effective vaccine should be developed against the more important circulating strains i.e., S. dysenteriae type 1 and S. flexneri 2a.