Holidaymakers in Croatia have been hit by a surge in a diarrhoea-causing parasitic infections.
Nearly two-dozen Germans who travelled to Croatia in 2023 were struck down with cryptosporidium.
German health chiefs were spooked by the unusually high rates of the illness.
Fewer than five infections are usually traced back to the popular Balkan destination every year.
Officials investigating the spate of cases, located within Istria, a region that sits on the Adriatic coast in the north of Croatia, believe they might have all caught it from swimming in contaminated pools.
Officials investigating the spate of cases, located within Istria, a region that sits on the Adriatic coast in the north of Croatia, believe they might have all caught it from swimming in contaminated pools
Cryptosporidium, which can cause vomiting, stomach pains and a fever, can survive in swimming pools for up to a week.
The chlorine-resistant parasite is spread by contaminated faecal matter entering the mouth, such as while swimming.
Traces of dried poo can wash off an infected person’s anus.
Infected people can shed up to 100million cryptosporidium germs in a single bowel movement, according to the US Centers for Disease Control and Prevention (CDC). Swallowing just ten is enough to get ill.
All 23 cases occurred between July 31 and October 1, according to an investigation by a team at the Heidelberg Institute of Global Health and Robert Koch Institute.
They all had ‘potential exposure’ in Croatia, but their exact cause cannot be proven.
But officials didn’t probe whether the increase was down to more tourists from Germany visiting Croatia than in previous years.
Additionally, better testing in the wake of the pandemic may have detected more cases.
Yet upticks from travellers getting sick from cryptosporidium in other popular holiday destinations, like France, Greece and Italy, were not as sharp.
Writing in the journal Eurosurveillance, researchers said: ‘The odds of exposure in southern Europe — France, Greece, Italy, Portugal and Spain — were also increased, but by a much lower magnitude, indicating an effect specific for exposure in Croatia rather than a general trend.’
Information on the locations of ‘potential exposure’ in the nation were available in 21 cases.
Holidaymakers had stayed at 10 different camping resorts, nine of which were in the Istrian peninsula.
A survey, handed out by health officials to help pin down the cause of the outbreak — which 15 of the 23 tourists responded to — found 14 had used pools at their camping resorts.
Only two cases reported that they also swam in other pools or freshwater during their stay.
‘The only case without exposure to a pool reported contact to a symptomatic person within 14 days before disease onset,’ health officials said.
While they acknowledged heavy rainfall in early August could have caused water contamination, more than a quarter of cases ‘had already experienced symptoms’ before the change in weather, they added.
Biweekly analyses and monitoring of the sea water quality on Croatian beaches also reported ‘excellent water quality’ in Istria throughout summer 2023.
Numbers of the diarrhoea-causing parasite also spiked ‘significantly’ in Germany, researchers noted, from between 600 to 750 cases in 2018 and 2019 to 1,001 in 2023.
In October UKHSA officials revealed 2,411 cases of the stomach bug have been spotted across the UK, with weekly notifications peaking at 450 towards the end of September – triple the level normally expected
For most people, cryptosporidiosis — the technical name for the infection — is mild.
It typically clears on its own without any treatment within a few days or weeks.
However, for vulnerable people, like those with weakened immune systems and the elderly or patients undergoing cancer treatment, it can be more serious.
Due to its highly infectious nature people with symptoms such as diarrhoea and vomiting are told to stay off work or school until they have been free from these symptoms for at least 48 hours.
Last year, a review of worldwide parasite outbreaks found in water revealed swimming pools were behind 92 per cent of studied waterborne cryptosporidiosis outbreaks.
In October, UK Health Security Agency officials also said Britain was being battered by an ‘unprecedented’ outbreak of the diarrhoea-causing parasite.
Officials investigating the unusual cluster of cryptosporidium cases believed it could be linked to holidays abroad, as dozens of affected Brits had travelled to Spain and other Mediterranean countries.
Between August 14 and October 1, 2,411 cases had been logged across the UK.
Weekly notifications peaked at 450 towards the end of September — triple the level normally expected.
