Amoebiasis

Page last reviewed: 13/07/2011

Dysentery is an infection of the intestines that causes diarrhoea containing blood or mucus

Diarrhoea is the passing of three or more watery stools a day. Other symptoms of dysentery include:

  • stomach cramps
  • nausea (feeling sick)
  • vomiting (being sick)

In Ireland, most people who get dysentery only experience mild symptoms, such as diarrhoea and nausea. 

Read more about the symptoms of dysentery

When to see your GP

It is not always necessary to see a GP because dysentery often clears up within a few days.

However, you should see your GP if you have diarrhoea that contains blood or mucus and tell them if you have recently been abroad, particularly if it was to a country with poor sanitation.

Treatment is not always needed, but it is important to drink plenty of fluids to replace those that have been lost through diarrhoea.

Types of dysentery

There are two main types of dysentery:

  • dysentery caused by shigella bacteria (bacillary dysentery or shigellosis): this is the most common type of dysentery in Ireland. This form of dysentery is a notifiable disease. This means that if a GP diagnoses the condition, they must inform the local authority.
  • dysentery caused by an amoeba (a single-celled parasite)called Entamoeba histolytica (amoebic dysentery or amoebiasis): Entamoeba histolytica is found mainly in tropical areas, so this type of dysentery is picked up abroad

Both types of dysentery are commonly passed on through poor hygiene and people often become infected by eating contaminated food. Read more about the causes of dysentery.

Preventing dysentery

To minimise the risk of catching the condition, you should:

  • wash your hands with soap and water after using the toilet,
  • wash your hands before handling, eating or cooking food
  • wash the laundry of an infected person on the hottest setting possible

If travelling to an area with poor sanitation:

  • drink bottled water (make sure the seal in intact)
  • do not have ice in your drinks 
  • do not eat fresh fruit or vegetables that cannot be peeled before eating
  • avoid eating food or drink bought from street vendors (except drinks from properly sealed cans or bottles)

How common is dysentery?

While outbreaks of bacillary dysentery are relatively common

Amoebic dysentery is rare in Ireland. People are most likely to become infected while travelling in parts of the world where the disease is common, such as parts of Africa, South America and India.

Outlook

Amoebic dysentery is more serious than bacillary dysentery, but both types can be fatal if left untreated. However, most fatalities occur in developing countries where sanitation is often poor and people do not have access to medical treatment.

 

Glossary

Diarrhoea

Diarrhoea is the passing of frequent watery stools.


Bacteria

Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and others are good for you.


Page last reviewed: 13/07/2011

In Ireland, most people who get dysentery only have mild symptoms which often clear up within a few days.

Bacillary dysentery

Dysentery that is caused by shigella bacteria (bacillary dysentery or shigellosis) is the most common type of dysentery in Ireland.

Symptoms of bacillary dysentery usually begin one to seven days after infection. Common symptoms are mild stomach pains and bloody diarrhoea. These symptoms last for three to seven days and many people do not need to visit their GP.

There is usually a lot of diarrhoea to begin with, followed by smaller amounts that are passed frequently and sometimes painfully.

In more severe cases, symptoms can include:

  • watery diarrhoea that contains blood or mucus
  • nausea (feeling sick)
  • vomiting (being sick)
  • severe abdominal pain
  • stomach cramps
  • a high temperature (fever) of 38C (100.4F) or over

Amoebic dysentery

Dysentery that is caused by an amoeba (a single-celled parasite) is called amoebic dysentery or amoebiasis. Amoebic dysentery mainly occurs in tropical areas.

In some cases, amoebic dysentery does not cause any symptoms. However, an infected person will pass cysts (amoebas that are surrounded by a protective wall) in their stools when they go to the toilet, and can infect their surroundings (see  for more information).

If you do experience symptoms, they may start up to 10 days after you originally became infected. Symptoms of amoebic dysentery include:

  • watery diarrhoea, which can contain blood,
  • mucus or pus
  • nausea
  • vomiting
  • abdominal pain
  • fever and chills
  • bleeding from your rectum (back passage)
  • loss of appetite and weight loss

If you have amoebic dysentery, it is likely that you will have blood in your diarrhoea. This is because the amoebas attack the walls of the large intestine, causing ulcers (sores) to develop that can bleed. The passing of stools may be painful. Occasionally, the parasite can enter the bloodstream and spread to other organs in the body, particularly the liver, leading to the formation of an abscess (liver abscess).

The symptoms of amoebic dysentery usually last a few days to several weeks. However, without treatment, even if the symptoms disappear, the amoebas can continue to live in the bowel for months or even years. This means that the infection can still be passed on to other people and that the diarrhoea can return.

Page last reviewed: 13/07/2011

Bacillary dysentery

Bacillary dysentery (shigellosis) is caused by shigella bacteria.

There are four types of shigella:

  • Shigella sonnei: this is the most common type in Ireland and produces the mildest symptoms
  • Shigella flexneri
  • Shigella boydii
  • Shigella dysenteriae: this produces the most severe symptoms

The shigella bacteria are found in faeces and are spread through poor hygiene; for example, by not washing your hands after having diarrhoea.

If you do not wash your hands, you can transfer the bacteria to other surfaces. The bacteria can then infect someone else if they touch the surface and transfer the bacteria to their mouth. The bacteria will travel from the mouth to the bowel, invading the cells that line the large bowel. The bacteria multiply, killing the cells and producing the symptoms of dysentery.

In Ireland, most cases of bacillary dysentery are spread within families and in places where people are in close contact with one another, such as in schools, nurseries, military bases and day centres. The condition can be spread for up to four weeks after a person has become infected.

Dysentery is also spread through food that has been contaminated with human faeces (stools), particularly cold, uncooked food, such as salad. This is more likely to happen in countries where:

  • there is poor sanitation
  • water supplies and sewage disposal are inadequate
  • human faeces are used as fertiliser

Severe dysentery is more common in developing countries.

The time between coming into contact with the bacteria and the symptoms starting (the incubation period) is usually one to seven days.

Amoebic dysentery

Amoebic dysentery (amoebiasis) is caused by an amoeba (a single-celled parasite) called Entamoeba histolytica. It is mainly found in tropical areas so it is usually picked up abroad.

When the amoebas inside the bowel of an infected person are ready to leave the body, they group together and form a shell that surrounds and protects them. This group of amoebas is known as a cyst.

The cyst passes out of the person's body in their faeces and is able to survive outside the body. If hygiene standards are poor; for example, if the person does not dispose of their faeces hygienically, it can contaminate the surroundings, such as nearby food and water.

If another person then eats or drinks food or water that has been contaminated with faeces containing the cyst, they will also become infected with the amoeba. Amoebic dysentery is particularly common in parts of the world where human faeces are used as fertiliser.

After entering the person's body through their mouth, the cyst will travel down into their stomach. The amoebas inside the cyst are protected from the stomach's digestive acid. From the stomach, the cyst will travel to the intestines where it will break open and release the amoebas, causing the infection. The amoebas are able to burrow into the walls of the intestines and cause small abscesses and ulcers to form. The cycle then begins again.

The amoebas that cause dysentery can also be sexually transmitted during mouth-to-anus contact.

 

Page last reviewed: 13/07/2011

You should visit your GP if you have diarrhoea that contains blood or mucus. Tell your GP if you have recently been abroad, particularly if it was to a tropical country with poor sanitation where amoebic dysentery is common, such as India or Africa.

Stool sample

Dysentery is diagnosed by testing a sample of your stools (faeces) to see whether it contains the bacteria or amoebas that cause dysentery.

Other investigations

Other investigations may be used if dysentery has caused further problems, such as a liver abscess . Further tests could include:

  • an ultrasound scan: where high frequency sound waves are used to create an image of part of the inside of your body, such as your liver
  • a blood test: a blood sample may be tested for infection-fighting proteins called antibodies that are likely to be present if you have amoebic dysentery
  • a colonoscopy (see below)

Colonoscopy

A colonoscopy is a type of endoscopy that is used to examine your bowels.

During a colonoscopy, an endoscope is passed through your anus (the opening where solid waste leaves the body) and into your bowels. An endoscope is a long, thin, flexible tube with a light source and a video camera at one end. Images of the inside of your body are relayed to an external television monitor so that the walls of your bowels can be seen more clearly.

Your bowel needs to be empty when a colonoscopy is performed, so you will be given a special diet to eat for a few days before the examination. You will also be given a laxative (medication to help empty your bowel) on the morning of the examination and a sedative to help you relax.

A colonoscopy usually takes around an hour to complete and most people are able to go home after they have recovered from the effects of the sedative. After the procedure, you will probably feel a bit drowsy for a while, so you should arrange for someone to take you home.

Read more about endoscopy.

Glossary

Ultrasound
Ultrasound scans produce pictures of inside the body using sound waves.
Diarrhoea
Diarrhoea is the passing of frequent watery stools.
Stool
Stool (also known as faeces) is the solid waste matter that is passed from the body as a bowel movement.

Notifiable disease

Dysentery that is caused by Shigellosis is a notifiable disease which means that your GP has to inform the local Director of Public Health that you have dysentery. Public Health doctors need to know about an outbreak of dysentery so that they can try to identify the cause and, if necessary, take measures to prevent the condition spreading to other people.

Page last reviewed: 13/07/2011

Dysentery usually clears up after a few days and no treatment is needed. However, it is important to replace any fluids that have been lost through diarrhoea. 

Treating diarrhoea

Diarrhoea can be treated by:

  • drinking plenty of fluids
  • taking oral rehydration solutions (ORS)
  • eating when you are able to

Drink fluids

If you have diarrhoea and vomiting, you should drink plenty of fluids to replace those that have been lost and to avoid dehydration. Take small, frequent sips of water.

It is very important that babies and small children do not become dehydrated. You should make sure that your child takes frequent sips of water even if they vomit. Taking a small amount of fluid is better than not taking any at all. Avoid giving your child fruit juice or fizzy drinks because these can make their diarrhoea worse.

In severe cases of diarrhoea, fluid may need to be given through a drip into the arm in hospital.

Oral rehydration solutions (ORS)

If you are particularly vulnerable to the effects of dehydration; for example, because you are 60 years of age or over, your GP or pharmacist may suggest using an ORS. An ORS may also be recommended for your child if they are dehydrated or at risk of dehydration. Read about the complications of dysentery for more information about dehydration.

ORS usually come in sachets that are available without a prescription from your local pharmacist. You dissolve them in water and they help to replace salt, glucose and other important minerals that your body loses through dehydration.

Rehydration drinks can't cure diarrhoea but they can help treat or prevent dehydration. Don't use homemade salt or sugar drinks.

Advice about eating

Expert opinion is divided over when and what you should eat if you have diarrhoea. However, most experts agree that you should eat solid food as soon as you feel able to. Eat small, light meals and avoid fatty, spicy or heavy foods.

If you feel that you're unable to eat, it should not do you any harm, but make sure that you continue to drink fluids and eat as soon as you can.

If your child is dehydrated, avoid giving them any solid food until they have drunk enough fluids. Once they have stopped showing signs of dehydration; for example, they have become less irritable and started passing urine more frequently, your child can start to eat their normal diet.

If your child is not dehydrated, you should offer them their normal diet. If they refuse to eat, continue to offer drinks and wait until their appetite returns.

Medication

As most cases of dysentery only last for a short period of time, antibiotics are only used if dysentery does not clear up on its own. Antibiotics can also be used to stop dysentery spreading to other people.

Over using antibiotics to treat minor ailments can make them less effective in treating more serious or life-threatening conditions. As a result of this, antibiotics are not prescribed for mild cases of dysentery.

Bacillary dysentery

If you have moderate to severe dysentery that is caused by the shigella bacteria (bacillary dysentery or shigellosis), antibiotics may be recommended to shorten the length of time that your symptoms last.

A number of different antibiotics can be used, including ciprofloxacin. However, the exact antibiotic that is recommended is likely to depend on the organism's pattern of resistance to some antibiotics. Antibiotic resistance is where the medicines are no longer able to kill the bacteria that they are meant to fight.

Amoebic dysentery

If you have amoebic dysentery (amoebiasis), your GP may prescribe an antibiotic called metronidazole. They will let you know how long you need to take it for, which will usually be around five days. Tinidazole is a possible alternative medicine.

After you have finished taking the antibiotics, you should be given a course of diloxanide (a medicine that kills the more resistant amoebic cysts forms). You will need to take diloxanide for 10 days.

Glossary

Diarrhoea
Diarrhoea is the passing of frequent watery stools.
Vomiting
Vomiting is when you bring up the contents of your stomach through your mouth.
Dehydration
Dehydration is an excessive loss of fluids and minerals from the body.
Antibiotics
Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi. Examples of antibiotics include amoxicillin, streptomycin and erythromycin.
Drip
A drip is used to pass fluid or blood into your bloodstream through a plastic tube and needle, which goes into one of your arteries or veins.

Page last reviewed: 13/07/2011

Babies and young children with dysentery can quickly become dehydrated. Therefore it's very important they drink plenty of fluids to replace those that have been lost, otherwise dysentery can be fatal.

Signs of dehydration

Your child may be at increased risk of dehydration if they:

  • are less than one year of age; babies less than six months are particularly at risk
  • are less than two years of age and they were born with a low birth weight
  • have passed more than five watery stools in the last 24 hours
  • have vomited more than twice in the last 24 hours
  • have not been able to hold down fluids
  • have suddenly stopped breastfeeding

Symptoms of dehydration

Symptoms of dehydration in children include:

  • appearing to get more unwell
  • being irritable or lethargic (tired or sluggish)
  • passing urine infrequently
  • pale or mottled skin
  • cold hands and feet

Symptoms of dehydration in adults include:

  • lacking energy or feeling tired
  • loss of appetite
  • nausea (feeling sick)
  • feeling light-headed
  • dizziness
  • dry tongue
  • sunken eyes 
  • muscle cramps
  • pinched face
  • rapid heartbeat

Liver abscess

In rare cases, amoebic dysentery (amoebiasis) can spread from the intestine through the bloodstream to other parts of the body and cause an abscess (a painful collection of pus). This occurs most commonly to the liver, resulting in a condition that is known as hepatic amoebiasis.

Symptoms of a liver abscess include:

  • a high temperature (fever) of 38C (100.4F) or above
  • weakness
  • abdominal swelling
  • pain in the upper-right abdomen
  • cough
  • nausea (feeling sick)
  • jaundice:- a yellow tinge to the skin and the whites of the eyes that is caused by a build-up of bilirubin (a waste product that the liver usually picks up) 
  • loss of appetite
  • weight loss

Glossary

Liver
The liver is the largest organ in the body. Its main jobs are to secrete bile (to help digestion), detoxify the blood and change food into energy.

Dehydration
Dehydration is an excessive loss of fluids and minerals from the body.

Page last reviewed: 13/07/2011

Dysentery is spread as a result of poor hygiene.

To minimise the risk of catching the condition, you should:

  • wash your hands with soap and water after using the toilet and regularly throughout the day, particularly after coming into contact with an infected person
  • wash your hands before handling, eating or cooking food
  • wash your hands before handling babies and feeding children or elderly people
  • keep contact with an infected person to a minimum
  • avoid sharing towels
  • wash the laundry of an infected person on the hottest setting possible

Travel advice

Good hygiene and proper sanitation are an enormous challenge for people living in poor conditions in developing countries where there is little or no access to fresh water and disinfectant.

If you're travelling to a country that has a high risk of contamination by the amoeba that causes dysentery, the advice below can help prevent infection.

  • Don't drink the local water unless you're sure that its sterile (clean). Safe alternatives are bottled water or fizzy drinks from sealed cans or bottles.
  • If the water is not sterile, boil it for several minutes or use chemical disinfectant or a reliable filter.
  • Don't drink from public water fountains or clean your teeth with tap water.
  • Don't have ice in your drinks because it may be made from the local water.
  • Don't eat fresh fruit or vegetables that can't be peeled before eating.
  • Don't eat or drink milk, cheese or dairy products that haven't been pasteurised (a process that involves heating to destroy unwanted micro-organisms).
  • Don't eat or drink anything sold by street vendors (except drinks from properly sealed cans or bottles).

How long should I stay at home?

If you or your child has dysentery, you or they should stay at home until at least 48 hours after having the last episode of diarrhoea.

If you have dysentery and you work in a food or healthcare environment, you must tell your employer about your condition. Your local environmental health officer may be in touch with you to find out how you became ill.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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