Shigella (the bacteria that causes shigellosis), spreads mainly through the fecal-oral route, meaning tiny amounts of infected stool enter another person's mouth. It is a genus of bacteria that is Gram negative, facultatively anaerobic, non-spore-forming, nonmotile, rod shaped, and is genetically nested within Escherichia coli. The genus is named after Japanese physician Kiyoshi Shiga, who discovered it in 1897. It causes disease in primates, but not in other mammals; it is the causative agent of human shigellosis It is only naturally found in humans and gorillas. During infection, it typically causes dysentery. It is a leading cause of bacterial diarrhea worldwide, with 80–165 million annual cases (estimated) and 74,000 to 600,000 deaths. It is one of the top four pathogens that cause moderate-to-severe diarrhea in African and South Asian children.

Common ways Shigella spreads include:

• Person-to-person contact: Especially in households, childcare centers, and crowded settings when hands are not washed properly after using the toilet or changing diapers.
• Contaminated food: Food handled by someone infected who didn't wash their hands thoroughly.
• Contaminated water: Drinking or swimming in water contaminated with sewage.
• Sexual contact: Activities involving oral-anal contact can transmit the bacteria.

Symptoms

Symptoms usually begin 1-3 days after exposure and may include:

• Diarrhea (sometimes bloody)
• Fever
• Stomach cramps
• Nausea
• Urgent need to pass stool

Most people recover within 5-7 days, but severe cases—especially in young children, older adults, or people with weakened immune systems—may require medical treatment.

How to prevent Shigella infection

• Wash your hands thoroughly with soap and water after using the toilet, changing diapers, and before preparing or eating food.
• Drink safe, clean water.
• Wash fruits and vegetables before eating.
• Avoid preparing food for others if you have diarrhea until you've fully recovered.
• Avoid swallowing water from pools, lakes, or untreated water sources.

Discovery

The Shigella genus is named after Japanese physician Kiyoshi Shiga, who researched the cause of dysentery. Shiga entered the Tokyo Imperial University School of Medicine in 1892, during which he attended a lecture by Shibasaburo Kitasato. Shiga was impressed by Kitasato's intellect and confidence, so after graduating, he went to work for him as a research assistant at the Institute for Infectious Diseases. In 1897, Shiga focused his efforts on what the Japanese referred to as a sekiri (dysentery) outbreak. Such epidemics were detrimental to the Japanese people and occurred often in the late 19th century. The 1897 sekiri epidemic affected >91,000, with a mortality rate of >20%.Shiga studied 32 dysentery patients and used Koch's postulates to successfully isolate and identify the bacterium causing the disease. He continued to study and characterize the bacterium, identified its methods of (Shiga-) toxin production, and worked to create a vaccine for the disease

By Archa Raveendran