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Cryptosporidiosis is the disease causedCryptosporidium parasites in the gut by infection with protozoan parasites called Cryptosporidium. The disease causes production losses in livestock farming and is also a significant cause of disease and morbidity in humans. This group of parasites can infect a wide range of animal species including cattle, sheep, goats, pigs, horses, deer and camelids, through the faecal oral route. Infections tend to be more severe in neonatal animals and infections in adult animals tend to be subclinical. Clinical signs occur 3-7 days after infection and include profuse watery diarrhoea, inappetance, gastrointestinal discomfort, abdominal tension, nausea and a mild fever.

Infected neonatal animals will shed as many as 10 million oocysts per gram of faeces and oocyst excretion may occur for over 10 days. The oocysts are fully developed and infectious when shed allowing rapid dissemination of infection throughout the herd and into the environment. Cryptosporidium is recognised as a major contaminant of drinking and recreational waters and is very difficult to control due to its resistance to standard water disinfection processes. The most common species detected in human outbreaks in the UK are Cryptosporidium parvum (a zoonotic pathogen) and Cryptosporidium hominis, which appears to infect only humans with no animal reservoir having been identified.

Diagnosis of infection is usually by microscopic examination of stained faecal smears to look for the presence of Cryptosporidium oocysts. This may be followed up by molecular typing tools to identify species, sub species and strains.

Humans are very susceptible to infection by Cryptosporidium and as few as 5 oocysts may cause clinical infection. Clinical symptoms include profuse watery diarrhea, inappetance, abdominal discomfort and dehydration. In addition, nausea, vomiting and a mild febrile response may be experienced. Vulnerable groups include the very young, the elderly and those that are immuno-compromised. There is no effective chemotherapy available that will target intracellular stages of the parasite.

To become infected with Cryptosporidium, one has to ingest oocysts and transmission risk is mostly attributed to drinking contaminated water, either “drinking water” or “recreational water” (swimming pools or rivers) or eating contaminated food. A further source of infection is due to a break down of personal hygiene when having contact with infected animals, particularly young animals, on farms or petting zoos but potentially also pets.

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Printed from on 16/08/17 02:06:23 PM

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