Cryptosporidium outbreak in Sweden
The Swedish Public Health Agency reports investigating an outbreak of the parasitic disease cryptosporidiosis.
Since 15 December 2023, 68 people from 14 regions have been reported infected with Cryptosporidium in Sweden. Most of the disease cases are from Halland and Jönköping.
Typing of a selection of samples shows that 13 out of 18 belong to the same type of Cryptosporidium, which indicates that the disease cases have a common source of infection.
The Swedish Food Agency and the Public Health Agency are investigating the outbreak to identify the source of infection, which is suspected to be fresh food.
Cryptosporidium is a protozoan parasite. Several different species of Cryptosporidium have been described, mainly two of which, Cryptosporidium hominis and Cryptosporidium parvum, are associated with infection in humans. Cryptosporidium hominis has almost exclusively been found in humans, while infection with C. parvum is a zoonosis. It is above all young animals, such as calves and lambs, that are affected by disease.
Cryptosporidium must have a host (human or other animal) to reproduce in. No reproduction occurs freely in the environment. Humans, cattle (especially calves), lambs and other animals can be reservoirs. The infectious agent is excreted in the oocyst form with the feces, and infection occurs mainly via fecal-contaminated water or via foodstuffs. Transmission between people can also occur.
The infectious dose, i.e. the smallest amount of the infectious agent needed to get the infection, is small.
The incubation period is approximately seven days (two to twelve days is the range).
The disease is characterized by watery diarrhea, abdominal pain, nausea, headache and fever. Vomiting is less common, especially in adults. Some infected people get no symptoms at all. Complications are rare, but if the patient has reduced immunity (as in AIDS), the diarrhea can be life-threatening.
Good hand, water and food hygiene prevents infection. Cryptosporidium, like several other protozoa, is highly resistant to chlorination. There is no vaccine.