Shigella infection: Hidden danger in contaminated food and water

Shigellosis is highly contagious and is transmitted through direct contact with an infected person, the faecal-oral route, or through contaminated food, water or surfaces. [iStockphoto]

A three-day bout of stomach pain and diarrhoea is often dismissed as a simple stomach bug. However, if symptoms become severe and you notice blood in your stool, it's important to seek medical attention.

This could be a sign of shigella infection, also known as shigellosis, a bacterial disease that affects the gastrointestinal system and causes stomach pain, diarrhoea, vomiting and fever.

According to Dr Winnie Rotich, a general practitioner who works as an assistant chief pharmacist in Kericho County, shigellosis is highly contagious and is transmitted through direct contact with an infected person, the faecal-oral route, or through contaminated food, water or surfaces.

"There are four major species of Shigella bacteria: Shigella dysenteriae, Shigella boydii, Shigella flexneri, and Shigella sonnei. The first two species are the leading cause of severe diarrhoea and death, especially among children in developing countries," says Dr Rotich.

Shigella infection is more common in children aged 12-59 months. Globally, Shigella is estimated to cause 80 to 165 million cases of disease and 600,000 deaths annually, with most cases occurring in children. In East Africa, the prevalence of Shigella species is 6.2 per cent, with a 14.6 per cent prevalence in Kenya.

Foodborne transmission is a significant contributor to Shigella cases. "Outbreaks have been reported among travellers who ate contaminated foods in hotels, airplanes and cruise ships," explains Dr Rotich.

People can contract Shigella from surfaces contaminated with faecal matter, changing diapers of an infected child, consuming contaminated raw foods, fruits and vegetables or drinking contaminated water.

Symptoms typically appear 1-2 days after exposure and can include bloody or prolonged diarrhoea, fever, stomach pain, nausea, vomiting and tenesmus (constant feeling that you need to poop but can't). Some infected individuals may not show symptoms but can still spread the bacteria through their faeces.

"Most people with shigellosis recover without antibiotics in 5-7 days," says Dr Rotich. "However, it's important for the infected to drink plenty of fluids to prevent dehydration."

Dr Rotich advises against using anti-diarrheal medicines like loperamide or diphenoxylate with atropine for bloody diarrhoea, as they can worsen symptoms. She recommends antibiotics such as ciprofloxacin and azithromycin, which may shorten the duration of fever and diarrhoea by about two days.

To reduce the risk of contracting or spreading shigellosis, wash your hands with soap and clean water before and after eating, wash and cook food thoroughly, avoid swallowing water in pools, lakes or ponds, and properly dispose of soiled diapers in a lined garbage can with a lid. "Wait for your partner to recover before engaging in sexual activities and follow safe food and water practices when travelling," advises Dr Rotich.

In severe cases, Shigella can cause dehydration due to diarrhoea, which can be fatal for children and the elderly. Complications may include systemic infections, seizures, post-infection arthritis and haemolytic uremic syndrome.

"People with bloody or prolonged diarrhoea lasting more than the days, severe stomach cramps or tenderness, fever, or feeling very sick should seek medical attention at the nearest healthcare facility," Dr Rotich advises.