What is amoebic dysentery?
These species are able to burrow through the intestinal wall and spread through the bloodstream to infect other organs, such as the liver, lungs and brain.
Amoebic dysentery (amoebiasis) is an infection of the intestine (gut) caused by an amoeba called Entamoeba histolytica that, among other things, can cause severe diarrhoea with blood.
But it may cause milder chronic symptoms of:
- frequent loose stools
- abdominal pain
- cramps
- fatigue
- intermittent consitipation.
- diarrhoea with abdominal swelling
- flatulence.
The amoebae are then able to move through the digestive system and take up residence in the intestine and cause an infection.
How do you get amoebic dysentery?
Entamoeba histolytica can exist in two forms in contaminated food and drink:- as free amoebae (known as 'trophozoites')
- as infective cysts, which are a group of amoebae surrounded by a protective wall, that have been passed (excreted) in the carrier's faeces (human or animal).
On the other hand, cysts are particularly resistant to the acidic contents of the stomach, and food contaminated with cysts represents a genuine risk of infection.
When the cysts reach the intestine of another person, the individual amoebae are released from the cysts and are able to cause infection.
Amoebic dysentery is passed on by careless or negligent hygiene, where contaminated food and drink is consumed without adequate heat treatment.
Salads washed with contaminated water are a common method of spread.
What does amoebic dysentery feel like?
Amoebic dysentery may not demonstrate any symptoms for long periods of time (months, even years). But infected individuals still excrete cysts and, consequently, infect their surroundings.When the amoebae attack, they damage the walls of the large intestine – causing ulceration and subsequent bleeding.
The milder symptoms of this are:
- stomach cramps (colic)
- painful passage of stools (tenesmus)
- bloody, slimy diarrhoea that's often foul smelling.
The amoebae may be transported via the blood to the liver and other organs and usually do NOT give rise to a high temperature (this can be useful ie bloody diarrhoea with a fever suggests a bacterial infection) and a seriously debilitated condition.
In the long term, the amoebae can, among other things, form enormous cysts in the liver and other organs, which sometimes may only be discovered on investigation by a doctor for other conditions, such as unexplained weight loss or illness.
What can you do to help yourself?
In practice, the only way to avoid infection with amoebic cysts is to ensure that everything you eat or drink has been washed or sterilised properly and cooked thoroughly.Drinking water can be made safe in two ways:
- by boiling it for 10 to 15 minutes (a little longer at high altitudes), and then cooling it rapidly and keeping it covered
- by adding water-purifying tablets and then leaving the mixture to stand for at least 15 minutes before use
- by using a filtration device such as Aquapure Traveller (combined ceramic and chemical filters) or Lifesaver system.
Foods to avoid include salads, unpeeled fruit and ice cream.
Ice cubes may also have been made with contaminated water. So, avoid having drinks that contain ice cubes, unless you're certain that the water used to make them has been sterilised.
Diagnosis
Anyone who develops bloody diarrhoea should see a doctor as soon as possible and ensure that they tell the doctor they have been travelling in the tropics, as amoebic dysentery doesn't normally occur in the UK.In the presence of the classic symptoms of amoebic dysentery, the diagnosis can often be made by means of a stool analysis.
Bloody diarrhoea is seen in many other illnesses, but in tropical areas the diagnosis will typically be either amoebic dysentery or shigellosis (bacillary dysentery which is caused by bacteria and more likely associated with a fever).
Treatment
Amoebic dysentery is treated with metronidazole or tinadazole.A problem arises in that some of the parasites will not respond to treatment and the medicines required to totally get rid of the disease after the above treatment are not readily available (ie Paromomycin o diloxanide furoater).
Complications, such as perforation of the intestinal wall or the presence of abscesses within the body's organs, require specialist hospital treatment.
In an emergency for instance, if you have bloody diarrhoea and are on holiday in the tropics and cannot get medical help: you can treat yourself with metronidazole, eg two 400mg tablets, three times a day for five days. This is the dose for adults who are neither pregnant nor breastfeeding.
It's important to avoid drinking alcohol during treatment. Even if you have to treat yourself, it's important to see a doctor to ensure that the treatment has been truly effective.
UK General Practitioners are not supposed to provide NHS prescriptions for travellers away for longer than three months.
As metronidazole requires a prescription, you could ask your own doctor or travel clinic to write a private prescription in advance if you know that you will be travelling to remote tropical areas where access to a doctor or hospital may be difficult.
Such prescriptions need to be issued privately, ie the cost of the drug has to be paid in full to the pharmacist.
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