May 15, 2024

expert reaction to Cryptosporidium infections in South Devon

Scientists react to Cryptosporidium cases reported in South Devon. 

Prof Paul Hunter, Professor in Medicine, University of East Anglia (UEA), said:

What is cryptosporidium?

“Cryptosporidium is a protozoan parasite that causes diarrhoea in humans. There are many different species but two are the main causes of disease in humans. C. parvum whose main host is cattle and C. hominis whose main host is humans.”

What are the symptoms in humans? Should we worried about this outbreak?

“The main symptom is diarrhoea which can be prolonged lasting up to two weeks or more. Most people recover but in people with severely weakened immune systems it can cause severe disease and can even be fatal.” 

How serious is the infection? And is infection worse in certain groups?

“Before effective antiretroviral treatments for HIV/AIDS cryptosporidium would often be fatal as recovery didn’t happen. With effective control of AIDS nowadays we see far less severe cryptosporidiosis. There is no effective drug treatment for cryptosporidiosis and all we can do is keep people comfortable and replace fluids until recovery happens.”

What is the cause/source of the current outbreak?

“I do not have any inside information into the current outbreak. But if what is being reported is correct, it seems to be the drinking water. With drinking water associated outbreaks you generally see cases primarily in an area that is supplied by a single water treatment plant or supply reservoir. If this is the case, then it would mean that the water supply had been contaminated. Usually, the source of contamination is either human sewage or cattle manure. Most of the outbreaks that I investigated before I became a professor were due to cattle. But we investigated one outbreak where the problem was that a rabbit got into a mixer tank in the treatment plant. We also see outbreaks associated with swimming pools, drinking unpasteurized milk and in nurseries from time to time. Cryptosporidium can also be spread by certain sexual practices.”

Are we likely to see further outbreaks?

“We see far fewer outbreaks now than we did in the 1990s when I was more involved. This was due to improvements in treatment plants. However, we still see occasional outbreaks more commonly with small drinking water supplies. It is difficult to know how many outbreaks have occurred as the UKHSA does not publish regular summaries of such outbreaks anymore.” 

What can be done to prevent further outbreaks?

“Basically it’s making sure that our drinking water treatment and distribution systems are maintained in good working order. Swimming pool outbreaks could mainly be prevented if people with diarrhea did not hide the fact and still go swimming.”

Declared interests

Prof Paul Hunter: I am a member of the World Health Organization guideline committee on Drinking Water Quality and have given many talks over the years on Cryptosporidium. I also help with and lecture at an annual PhD students’ workshop in France that is funded by Suez a French water utility and I receive a small stipend for being on their scientific advisory committee.