Shigella is a gram negative bacterium that is responsible for causing infection and inflammation in large intestine. In medical parlance the infection is also called shigellosis or bacillary dysentery. The prominent symptoms of shigella infection are diarrhea with blood and mucus in stool.
The bacterium is named after Kiyoshi Shiga, who in 1897 was the first person to recognize an association of certain form of bacteria and epidemic dysentery. There are many species belonging to shigella family, but the most virulent among them is shigella dysenteriae.
The infection is spread through direct contact with stool or through eating and drinking contaminated food and water.
Causes And Epidemiology Of Shigella Infection
Shigella infection occurs when the bacteria is swallowed accidentally. Infection is common around the world. Adults as well as children both are affected. Shigella infection can occur in epidemics or it can occur in few isolated cases. Epidemics occur in overcrowded places having poor sanitation facilities, particularly when there is no proper sewage disposable system available.
The most common route of transmission is from person to person by feco-oral contamination. The principle route of infection is when a patient does not wash his hands properly after defecation and handles food and water. Drinking such contaminated food and water can spread the infection from one person to another.
Shigella infection can also be picked up if a person touches contaminated lavatory seats, flushing handles, taps and doorknobs. The bacteria has ability to survive on finger and objects for few hours. Contaminated finger can easily spread the bacteria in food and water. Even flies can transmit infection from the exposed feces. The infection is also common in a gay male who is sexually active. Infection spreads in them due to oral-anal contact.
Signs And Symptoms Of Shigellosis
The incubation period is short, it means the symptoms start to manifest within 2 to 3 days after the entry of germs into the gut. Often the symptoms are so mild and they escape detection. The person is ambulant with few loose stools, mild cramps and fever. However, some species of shigella such as S. flexneri and S. dysenteriae produce more severe symptoms.
In such cases patient may suffer from frequent episodes of diarrhea throughout the day with fever. There may be passage of blood stained mucus in the stool (red currant jelly like stool) and pus with colicky pain and tensemus (rectal spasm).
The patient appears toxic and restless, dehydrated with rapid and feeble pulse. Children with severe form of shigellosis may have associate febrile seizures. They often have accompanying symptoms such as loss of appetite, recurrent infections after an attack of shigelosis.
Treatment For Shigella Infection
The infection caused by shigella bacteria can mild or severe and its impact may vary from one person to another. The infection is self limited and resolves in 6 to 7 days. For a mild form of disease patient may only require replenishing the lost fluid and salt, specifically if the patient is having good general health.
However, the disease can often have serious impact of children, elderly and people with immunocompromised state. Besides intravenous fluids in severe cases antibiotics are valuable as they shorten the course of illness and sometime even prove life saving. Mild cases may only need oral fluid and low roughage diet.