How Did Cryptosporidium Find its Way into the Lancashire Water Supply?

Around 300,000 Lancashire homes were put on alert last week when the parasite cryptosporidium was found to be present in a wastewater treatment plant in Preston. As a precaution, the water body United Utilities advised residents to boil all water used for drinking, brushing teeth or preparing food prior to using it.

But with so many precautions in place to purify our drinking water, how did this parasite find its way into the supply?

Animal Waste to Blame

Although the Drinking Water Inspectorate (the governing body responsible for investigating the outbreak) has refused to comment on the source of the parasite while its investigation is ongoing, United Utilities themselves have confirmed that animal faeces or an animal carcass were the most probable causes.

This hypothesis was lent weight by the testimony of Dr Derek Gatherer, who is an expert of viruses and disease at Lancaster University. “Human strains are often spread from person to person, but in cases of water contamination it tends to be animal faeces or a carcass that gets into the supply,” explained Dr Gatherer. “How likely a sheep or cow would get stuck in the water system I don’t know, but they will be able to confirm the source once they get results back.”

Despite stringent measures to purify drinking water, the parasite was found during routine testing at the Franklaw wastewater treatment plant in Preston. The site is checked every two days for signs of cryptosporidium (among other contaminants) and although uncommon, it’s highly resistant nature to chlorine must have allowed it to bypass traditional methods of water disinfection.  

A Rare Occurrence

Such a water contamination scare is rare but not unheard of. Back in 2005, D?r Cymru Welsh Water was fined £60,000 and had to shell out a further £70,000 in costs for allowing an outbreak of cryptosporidium in North Wales, which affected 231 people.

In 2008, 22 people fell prey to another outbreak of the parasitic bug in Northamptonshire. Anglian Water, the supplier, came under heavy criticism for allowing a rabbit to enter the water tank and contaminate the supplies with cryptosporidium.

However, these two cases are the only example of outbreaks in the UK since 2000, with this most recent Lancashire scare being the third. As yet, no confirmed cases of sickness due to ingestion of the water have been reported, and due to the amount of time that has elapsed, it looks like United Utilities might have acted quick enough to avoid an outbreak.

All three of the recent cases have been minor and have not led to any prolonged illnesses or deaths. In certain circumstances, however, the bacteria can have widespread implications. In 1993, cryptosporidium infiltrated a single water plant and affected as many as 400,000 residents. It remains the largest waterborne outbreak in US history. Luckily, it seems the Lancashire case will not nearly be quite so serious.