Shigella Bacteria Outbreak in Kerala

Context

An outbreak of shigella bacteria is believed to be the reason behind the recent incident of suspected food poisoning in Kasaragod district, Kerala.

About Shigella

• Shigella is a bacterium that belongs to the enterobacter family — a group of bacteria that reside in the intestine, not all of which cause disease in humans. 
• It mainly affects the intestine and results in diarrhoea, sometimes bloody, stomach pain, and fever.
• The infection spreads easily as it takes only “a small number of bacteria to make someone ill”.
• It is a food- and water-borne infection, and can happen when someone consumes contaminated food — like in the case from Kerala — unwashed fruit or vegetables.
• The disease is easily spread by direct or indirect contact with the excrement of the patient. 
• You can get the infection if you swim or take a bath in contaminated water.
• The annual number of shigellosis episodes throughout the world is estimated to be 164.7 million.
• Currently, there are no vaccines available for shigellosis.

How widespread is Shigella infection?

• Shigellosis happens, but it is not a very common infection. We usually see infections like typhoid and cholera because of contaminated foods. Perhaps one in 100 cases of diarrhoea in our hospital would be shigellosis.
• Shigella outbreaks appear to be exacerbated during pregnancy and in children under five years of age, and in those with weakened immune systems.
• There are four types of Shigella bacteria that affect humans-
• Shigella sonnei
• Shigella flexneri
• Shigella boydii
• Shigella dysenteriae
• The fourth type causes the most severe disease because of the toxin it produces.

Precautions

• Hydration: The cornerstone of shigella treatment is the maintenance of hydration and electrolyte balance.
• In young children, oral rehydration with a reduced osmolarity solution is indicated to treat the WHO-defined category of some dehydration and is preferable to intravenous fluids unless severe dehydration is present.
• Use of Antibiotics: Although shigellosis is primarily self-limiting, antibiotics are recommended for reducing illness duration and for preventing transmission.
• The current drugs of choice are third-generation cephalosporins (ceftriaxone or cefixime) and macrolides (azithromycin).
• Public Hygiene: Handwashing is said to reduce shigella transmission by 70%. Recommended public health control measures are exclusion of ill people with shigellosis from work, food preparation, and childcare.