Shigellosis - Signs and Symptoms


Shigellosis is an infection of the large intestine caused by a type of bacteria known as Shigella. Globally an estimated 140 million people develop shigellosis each year and about 600,000 die. Most of these deaths occur in developing countries among children under the age of five. In the United States, only 20,000 cases are reported each year but the actual number of infections is likely more than 200,000 annually.

Also known as bacteria dysentery, Shigellosis is primarily associated with diarrhea but its severity can range from only mild to very severe. Also while most infected people usually present some symptoms, at times an individual may contain the Shigella bacteria in his body without displaying any symptoms at all.  Although these people develop no evident signs after they've been infected with shigella, their feces are still contagious. Among the signs which are most commonly associated with this disease in adults are:

  1. A brief fever
  2. Fever with mild diarrhea which may go away on its own
  3. high fever, abdominal cramping and severe diarrhea that can contain blood, mucus and pus. This happens because the Shigella bacteria produce toxins that attack the lining of the large intestine, causing swelling and ulcers on the intestinal wall which lead to bleeding and eventually the appearance of blood in stool. This is usually seen in around a quarter of patients infected with Shigella bacteria; these people can have ten to thirty bowel movements each day, along with a persistent urge to have a bowel movement that can even lead to rectal prolapse which is an abnormal protrusion of the rectum.  At times if the diarrhea does not stop and there is threat of dehydration, hospitalization may be required.
  4. In rare cases, Shigella bacteria can affect parts of the body other than the digestive tract. When this happens, there can be seizures, confusion or coma, kidney failure and rashes. According to the Centers for Disease Control and Prevention of the US government, about 2% of persons who are infected with one type of Shigellas, the Shigella flexneri, later develop pains in their joints, irritation of the eyes, and painful urination. This is called post-infectious arthritis. It can last for months or years, and can lead to chronic arthritis. This condition is caused by a reaction to Shigella infection that happens only in people who are genetically predisposed to it.

Shigellosis is quite common in children between the ages of one to four. Kids of this age group are especially at risk because they are starting to use the toilet and often forget to wash their hands. However infants below six months rarely contract shigellosis though when they do, they are at the highest risk of becoming seriously ill.

  1. In kids with shigellosis, the first bowel movement is often large and watery. Later bowel movements may be smaller, but the diarrhea may have blood and mucus in it.
  2. Bowel movements may also be painful; the anus may become sore and tender due to repeated bowel movements.
  3. Along with diarrhea, Children are more likely to come down with high fever due to a shigella infection.
  4. Other symptoms associated with an upset digestive tract will be present like vomiting, nausea and loss of appetite. Reluctance to eat anything accompanied with diarrhea and vomiting may result in marked weight loss in kids infected with shigellosis.
  5. Very rarely, kids can be infected with extremely virulent strains of shigella in which case they may develop signs like convulsions or seizures, a stiff neck, a headache, extreme tiredness, and confusion. All these symptoms required urgent medical attention and most likely hospitalization too.
  6. The most common complication associated with shigellosis in kids is dehydration. This happens when the level of water in the body sinks to very low levels due to repeated vomiting and diarrhea. this is dangerous because body fluids contain certain salts and compounds which are critical to the healthy functioning of the body. symptoms of dehydration, which can include:
  • dry or sticky mouth
  • few or no tears when crying
  • eyes that look sunken into the head
  • in a baby, the fontanelle, or soft spot on top of head looks sunken
  • lack of urine or wet diapers for 6 to 8 hours in an infant or only a very small amount of dark yellow urine
  • lack of urine for 12 hours in an older child or only a very small amount of dark yellow urine
  • dry, cool skin
  • lethargy or irritability
  • fatigue or dizziness in an older child
  1. other complications associated with shigellosis are arthritis, skin rashes, and kidney failure but these happen only in very rare conditions.

Most of the usual symptoms of Shigellosis are quite common for other infections of the digestive tract. For instance diarrhea and abdominal cramps can be caused by a wide variety of other bacteria or viruses which cause stomach flu. This is why the symptoms of shigellosis need to be confirmed with accurate diagnosis by a health practitioner for effective treatment. Thus a doctor will ask the patient about their symptoms and about the appearance of their bowel movements. The doctor will also want to know if the person has recently travelled to developing countries, been in contact with people who have severe diarrhoea or might have been exposed to contaminated pools, lakes or food. Final diagnoses of shigellosis will be based on a physical examination and the results of laboratory tests. These tests include taking a swab of the patient’s rectum or a sample of his stool since the shigella bacteria is found in the feces of infected persons. If the patient has signs of dehydration or significant blood loss, additional blood tests may be necessary.

In people with a healthy immune system, Shigellosis is usually self-limiting. If these people suffer only from symptoms like a brief fever and mild diarrhea, they can be expected to feel better after a few days, with adequate rest, hydration and simple foods. The symptoms of mild shigellosis usually continue from five to seven days. However in children, the elderly or those with weak immunity, the symptoms of shigellosis can lead to complications like severe dehydration and if not treated promptly, even death.