When diarrhoea from Shigella could prove fatal

Diarrhoea with bloody stools and fever, abdominal cramp and straining, can claim children’s lives if coupled with altered mental status or seizure.

Shigellosis often affects the brain and cause Shigella encephalopathy. Photo: Shehzad Noorani / icddr,b

The pathogen Shigella causes diarrhoea known as Shigellosis. It often leads to that condition when a patient’s brain is affected, showing symptoms of seizures, altered consciousness or even developing coma.

An icddr,b study has recently shown that children younger than five years of age who develop this condition, known as Shigella encephalopathy, are more at risk of death than children who suffer from a Shigella infection without encephalopathy.

Deaths caused by Shigella encephalopathy are often associated with excess accumulation of water within the brain or brain haemorrhage although more research is needed to understand why these deaths occur.

Shigellosis is common in Bangladesh and other Asian countries in the developing world where it is a major cause of death from diarrhoea in children under five. According to WHO estimates, 80 million cases of bloody diarrhoea from Shigellosis cause 700,000 deaths a year.

“Some children develop seizures during diarrhoea and show abnormal mental state which is an early indication of probable Shigella encephalopathy,” says Dr Farzana Afroze, assistant scientist and senior medical officer at icddr,b hospitals and principal author of the study published in PLOS NTDs.

Among the findings of the study conducted among cases from icddr,b hospitals, Shigella encephalopathy was found independently associated with hyponatremia – low sodium levels in blood.

Timely diagnosis of Shigella encephalopathy can help save more lives. Photo: Shehzad Noorani / icddr,b

Diagnosing fatal Shigellosis from clinical symptoms is not plain and simple. “Patients often lose little fluid during diarrhoea apparently but do not realise that sodium levels might have gone lower due to Shigella infection,” explains Dr Md. Jobayer Chisti, senior scientist at icddr,b hospitals and senior author of the study.

“Shigella continues to be a public health threat although prevalence of fatal cases and death rates have become lower,” he adds.

Shigella pathogens transmit primarily via fecal matter from infected persons and further through contaminated food and water and through flies.

“Hand washing with soap, improved sanitation and drinking water are the first line of defence,” adds Dr Chisti who is also head of clinical research at icddr,b hospitals, clinical lead, ICU and consultant physician of respiratory ward at icddr,b’s Dhaka hospital.

The study also found that children who developed Shigella encephalopathy were more likely to have sepsis and/or dehydrating diarrhea having shorter duration prior hospital admission.

“These findings can help doctors diagnose fatal cases quickly and prompt for appropriate interventions to save lives,” says Dr Afroze.