Britain is being battered by an 'unprecedented' outbreak of a diarrhoea-causing parasite.
Cases of cryptosporidium — which tin past successful swimming pools for up to a week — are 3 times higher than normal.
Health chiefs are baffled arsenic to nan root of nan outbreak, which has dispersed to each area of nan nation.
But early investigations suggest nan spike is linked to swimming, including successful pools.
Officials investigating nan different cluster of cryptosporidium cases judge it could beryllium linked to holidays abroad, arsenic dozens of affected Brits had travelled to Spain and different Mediterranean countries.
2,411 cases of nan tummy bug person been spotted crossed nan UK, pinch play notifications peaking astatine 450 towards nan extremity of September - triple nan level usually expected
As good arsenic diarrhoea, cryptosporidium tin origin vomiting, tummy pains and fever.
The chlorine-resistant parasite is dispersed by contaminated faecal matter entering nan mouth, specified arsenic while swimming.
Traces of dried poo tin lavation disconnected an infected swimmer's anus.
Infected group tin shed up to 100million cryptosporidium germs successful a azygous bowel movement, according to nan US Centers for Disease Control and Prevention (CDC).
Swallowing conscionable 10 is capable to get ill.
A UK Health Security Agency (UKHSA) investigation into nan outbreak said nan summation was observed successful August, erstwhile location was a emergence successful routine stool samples analysing cryptosporidium infections.
Since then, 2,411 cases person been discovered crossed nan UK.
Weekly notifications peaked astatine 450 towards nan extremity of September — triple nan level usually expected.
Officials fishy moreover these numbers are an underestimation of nan existent numbers of Brits infected, pinch galore suffering symptoms without seeking treatment.
Reporting nan outbreak successful nan diary Eurosurveillance, UKHSA experts wrote: 'Given nan standard and geographical dispersed of nan exceedance crossed regions and nations of nan UK, a azygous section vulnerability is an improbable cause.'
A study of almost 500 patients, handed retired by wellness officials to thief pin down nan origin of nan outbreak, showed 54 per cent of those infected had been overseas 14 days earlier suffering their first symptoms.
Of nan 215 cases for which much elaborate recreation accusation was available, astir half reported travelling to either Spain's mainland aliases islands specified arsenic Majorca and Ibiza.
Two-thirds had gone swimming earlier being plagued by symptoms.
'Our first findings would propose swimming (either successful nan UK aliases abroad), including nan usage of pools, and overseas recreation to a assortment of destinations whitethorn underlie nan existent increase,' they wrote.
But different imaginable sources of nan 'unprecedented and ongoing nationwide summation successful cases' couldn't beryllium ruled out, nan squad said.
'At this stage, different sources, for illustration contaminated food, cannot beryllium excluded arsenic contributing to nan exceedance,' they wrote.
The experts added that they were moving connected a nationalist wellness accusation run urging nan nationalist to not usage swimming pools while suffering cryptosporidium symptoms because for 14 days aft signs of unwellness person cleared arsenic they tin still infect others.
They besides added they are moving pinch their EU equivalents, the European Centre for Disease Prevention and Control, to thief them pinch further investigations into sources of nan outbreak.
For astir people, cryptosporidiosis — nan method sanction for nan infection — is mild.
It typically clears connected its ain without immoderate curen wrong a fewer days aliases weeks.
However, for susceptible people, for illustration those pinch weakened immune systems and nan aged aliases patients undergoing cancer treatment, it tin beryllium much serious.
Due to its highly infectious quality group pinch symptoms specified arsenic diarrhoea and vomiting are told to enactment disconnected activity aliases schoolhouse until they person been free from these symptoms for astatine slightest 48 hours.