The UK is currently dealing with an alarming rise of crypto—the diarrhea-causing intestinal parasite, not the baffling currency. In a report this month, health officials documented a much higher number of cases than expected so far in 2023. It’s not clear yet why crypto is surging in the country, though the increase may be tied to international travel.
In medicine and biology, “crypto” has long been the shorthand for Cryptosporidium, a genus of microscopic protozoa that usually infect the gut and cause gastrointestinal illness in humans and other animals (both the parasites and disease they cause are commonly called crypto). The infection can easily spread through direct contact with an infected person’s poop, but crypto parasites are also hardy enough to survive for months in soil and water.
The most common symptom of crypto is watery diarrhea, followed by cramps, dehydration and low grade fever. Typically, people are sick with crypto for about one to two weeks, though sometimes symptoms can wax and wane for up to a month. And in people with weakened immune systems, the infection can become chronic or life-threatening. The parasite can rarely reach the respiratory tract, causing other problems.
Crypto is a persistent public health problem around the globe and is a leading cause of waterborne disease in the U.S. and other countries. But UK health officials have noticed a nationwide increase in cases this year. Their findings are detailed in a paper published last week in the journal Eurosurveillance.
The jump in crypto cases seems to have begun in August, based on lab testing results (in the UK and the U.S., every documented case of crypto has to be reported to the government). Between mid-August to late September, there were over 2,400 cases of lab-confirmed crypto in the UK. Summer is supposed to be the peak season for crypto, but the surge is far above even this expected increase. Cases have started to slow down as of late October but remain much higher than normal.
So far, at least, there doesn’t seem to be an easy explanation behind the crypto surge. Officials haven’t identified any specific sources of exposure or settings that might give rise to a large outbreak, such as recreational pools or drinking water supplies. But surveys of infected people have yielded some potential clues. Compared to last year, the percentage of people reporting recent travel to other countries hasn’t changed, but it’s possible that the surge could be tied to people visiting specific regions or to swimming more frequently this summer.
“Our initial findings would suggest that swimming (either in the UK or abroad), including the use of pools, and foreign travel to a variety of destinations may underlie the current increase,” the report authors wrote.
The team says they’re working with travel-related public health agencies in the UK to ensure that travelers are informed about crypto, and they are corresponding with other health authorities in Europe to further investigate the surge.
As for the average person worried about catching crypto, some practical steps to take include: not swallowing swimming water (especially if it hasn’t been treated), making sure your at-home meals are well-cooked, and avoiding unpasteurized milk and other food products. In general, people who have recently experienced diarrhea should also wait at least two weeks before getting into a shared body of water.