Cryptosporidium

This parasite is responsible for a type of food poisoning which usually occurs after consuming contaminated food or water. It also occurs following contact with an infected object or touching a surface which has been in contact with infected faeces.

The official term for this illness is ‘cryptosporidiosis’.

This infection can occur in any part of the world and is considered to be one of the most common waterborne infections. However, it is more prevalent in developing countries.

This illness is very similar to giardiasis.

Most cases clear up without the need for treatment but this illness can cause complications for people with a compromised immune system, for example HIV positive or full blown AIDS.

The cryptosporidium parasite

This single cell parasite is found within the intestines of both humans and animals and causes an acute but short term illness. Each cryptosporidium undergoes a life cycle (series of developmental changes) within its human or animal ‘host’ which includes the ability to infect the soft tissues within the intestines, causing cryptosporidiosis.

This illness causes these parasites to be excreted out of the body as a result of the frequent bouts of watery diarrhoea. This increases the risk of this infection spreading to other people.

How does this life cycle work?

Part of this life cycle includes a dormant stage in which this parasite changes into cysts known as ‘oocysts’. These cysts are able to survive outside their natural environment irrespective of the conditions.

But once they encounter a favourable environment such as the inside of the intestines they break open and release smaller parasites which then invade the lining of the intestines.

This results in inflammation and an infection.

Causes of cryptosporidiosis

These include:

• Contact with infected food, water or soil which has been contaminated with this parasite. This occurs through faecal matter.
• Eating food which has been handled by someone who is already infected, for example meat.
• Swimming in untreated water
• Eating fruit, vegetables or salads which have been washed in contaminated water.
• Touching a surface which has already been contaminated
• Eating raw food which has been infected
• Contact with an infected animal, e.g. on a farm
• Caring for someone who is already infected

If you have been in contact with animal or human faeces which have been infected with the cryptosporidium parasite then you are at a high risk of contracting this illness. This often occurs as a result of touching near or inside the mouth after exposure to the parasite.

A good example of this is failure to wash the hands after contact with infected water or faeces. It is easy to forget to do this or to only give your hands a quick rinse but this does not prevent the infection from taking a hold within you.

A popular form of transmission is that of drinking untreated water whilst hiking or camping. Plus another risk is swimming in untreated lakes or rivers which have been contaminated with this parasite.

Transmission of the cryptosporidium parasite

The parasitical oocysts enter the body as a result of drinking infected water or eating food, for example a salad which has been washed in contaminated water.

These oocysts attach themselves to the walls of the small intestine. Once they have done so they then multiply and trigger an infection. This infection is cryptosporidiosis.

Once they have undergone their life cycles these oocysts are usually excreted from the body where they have the potential to cause further infection.

Symptoms of cryptosporidiosis

This illness starts once the parasite has been ingested. The incubation period is around 7 days following the initial contact (or ingestion) and causes the following symptoms:

• Watery diarrhoea
• Fever
• Nausea
• Vomiting
• Stomach cramps
• Weight loss
• Tiredness
• General feeling of being unwell
• Dehydration (usually as a result of the diarrhoea)

The diarrhoea is the main symptom and can persist for several weeks. This takes the form of frequent bouts which along with these other symptoms, can reappear at a later date.

This illness usually occurs within the small intestine but there is a possibility that the other parts of the digestive system may be affected. There is also a chance it could affect the respiratory tract.

Some people find that they develop these symptoms again after a short recovery period.

But this illness usually lasts for only 1 to 2 weeks in people who are normally healthy and with fully functioning immune systems.

However, people with weakened immune systems can develop serious even fatal forms of this illness.

Risks for people with weakened immune systems

Anyone who has HIV, AIDS or has undergone cancer treatment such as chemotherapy is at risk of developing a serious form of this illness.

This is due to the fact that their immune systems is less effective at fighting this infection which results in a serious form of illness compared to others.

People with a healthy immune system tend to experience only a mild form of this illness but those people with poorly functioning immune system are likely to develop a serious or chronic form of this illness.

In some cases this may even be fatal.

The extent of the illness will largely depend upon the extent of the damage to the immune system. In other words, the greater the extent of the immunosuppression the greater the severity of the illness.

Complications include:

• Biliary cirrhosis (damaged bile ducts within the liver)
• Pancreatitis (inflammation of the pancreas)
• Cholecystitis (inflammation of the gallbladder)
• Lactose intolerance (intolerance to milk)

This illness can spread to include the pancreas and gallbladder in people with a weakened immune system. They will also find that develop chronic diarrhoea which is very similar to cholera and are, subsequently, at greater risk of dehydration.

Severe cases will require hospital treatment.

Other people at a similar risk include babies, young children and pregnant women. Babies are especially vulnerable to dehydration.

Diagnosing cryptosporidiosis

This illness is diagnosed via a stool sample.

A stool sample is medical jargon for a commonly performed test in which a small sample of your faeces is obtained and sent to a laboratory for further analysis.

The laboratory will examine this sample under a microscope which will enable them to check for the presence of this parasite.

This is a difficult illness to diagnose so you will be asked to collect several samples over a period of a few days.

If a diagnosis of cryptosporidiosis is confirmed then a treatment plan will be developed. However, this is more complex in people with weak immune systems.

Treatment for cryptosporidiosis

If you contract a mild form of this illness then drink plenty of fluids, e.g. water and consider taking an oral re-hydration powder.

These oral re-hydration powders can be purchased at any pharmacy and are easy to use. They are available as sachets which are dissolved in water. Each sachet contains salts, glucose and other essential minerals.

Babies and young children may require their fluids via an intravenous drip which has to be done at a hospital. Any loss of fluid is risky but excessive loss is particularly dangerous for babies and infants due to their smaller body weight.

If you are the parent of a bay or infant who has developed this illness then ask your GP for advice. Your GP may recommend hospital treatment in this situation.

Is there any medication for cryptosporidiosis?

There are several types of medicine available although they appear to have limited success. These include paromomycin and azithromycin.

More evidence is needed especially as their effects are unproven in cases of people with weakened immune systems.

There is one medication in particular called nitazoxanide which can reduce the duration of the symptoms but it is currently unlicensed in the UK.

Preventing cryptosporidiosis

Adopting a few good hygiene measures will prevent the risk of you developing cryptosporidiosis. These include:

• Washing your hands each time you handle food, visit the bathroom or are caring for child with diarrhoea.
• Always wash your hands after touching an animal or contact with animal faeces.
• Keep an infected child away from school or nursery until their symptoms have cleared.
• Ensure that your child washes his/her hands every time they visit the bathroom.
• Avoid swimming until the illness has cleared.
• Wear gloves when gardening especially if you are handling soil

If your immune system is weak due to conditions such as HIV or AIDS; or you have undergone cancer treatment such as chemotherapy; or you have recently had a transplant and are taking immunosuppressant drugs then avoid contact with anyone who has cryptosporidiosis.