VIRULENT BACTERIUM SHIGELLA

PRERNA FOR IAS

VIRULENT BACTERIUM SHIGELLA

1. What is Shigella?

Shigella is a Gram-negative, rod-shaped, highly contagious bacterium that causes shigellosis, an infectious disease affecting the intestines. It was first identified in 1897 by Japanese bacteriologist Kiyoshi Shiga, after whom it is named. The bacterium invades the lining of the large intestine, causing inflammation and severe diarrhoea. Only a very small number of bacteria are needed to cause infection, making it highly infectious. Shigella is a major public health concern in developing countries where sanitation is poor. Early diagnosis, proper hygiene, and timely treatment are essential to prevent outbreaks and reduce disease transmission.

2. Symptoms

The symptoms of shigellosis usually appear one to three days after infection. Common symptoms include fever, abdominal pain, stomach cramps, watery or bloody diarrhoea (dysentery), nausea, and vomiting. Frequent bowel movements may lead to dehydration, weakness, and fatigue. In severe cases, complications such as seizures, kidney damage, or bloodstream infections may occur, especially in children and elderly individuals. Some infected people may experience only mild symptoms, while others become seriously ill. If diarrhoea is persistent, bloody, or accompanied by high fever and dehydration, immediate medical attention is necessary to prevent life-threatening complications.

3. How Does It Spread?

Shigella spreads mainly through the faecal-oral route, where bacteria from infected stool enter another person's mouth. Infection commonly occurs by consuming contaminated food or water, touching contaminated surfaces, or through poor hand hygiene after using the toilet. Even 10–100 bacteria can cause infection, making transmission extremely easy. Flies may also spread the bacteria by contaminating food. Crowded living conditions, poor sanitation, unsafe drinking water, and improper food handling increase the risk of outbreaks. Washing hands with soap, drinking clean water, and maintaining proper sanitation are the most effective ways to prevent the spread of shigellosis.

4. Global Burden

Shigellosis is a major global health problem, particularly in low- and middle-income countries. It causes an estimated 80–165 million infections and around 600,000 deaths each year, mainly among children under five years of age. The disease is especially common in regions with poor sanitation, including South Asia and sub-Saharan Africa. Frequent outbreaks occur in schools, refugee camps, and densely populated communities where access to clean water is limited. The disease places a significant burden on healthcare systems and economies. Improving sanitation, safe water supply, vaccination research, and public health awareness can greatly reduce its impact.

5. Who is Most at Risk?