Contact with animals linked to major outbreak of Cryptosporidium

Researchers have provided details of one of the largest Cryptosporidium outbreaks in England in recent years.

The outbreak of Cryptosporidium parvum was associated with a multi-day lambing event in the South West of England in 2023. The primary hypothesis was that exposure to lambs in designated feeding pens was the source of Cryptosporidium.

A study published in the journal Epidemiology and infection detailed how an outbreak investigation identified 23 laboratory-confirmed primary Cryptosporidium parvum cases, while the cohort study identified 83 cases of cryptosporidiosis-like illness. Individuals who held or cuddled a lamb in a pen were more likely to develop a cryptosporidiosis-like illness.

More than 4,000 laboratory-confirmed infections of the parasite are recorded in England every year. An industry code of practice supports minimizing infection risks from contact with animals at visitor attractions.

In April 2023, routine surveillance by the UK Health Security Agency (UKHSA) identified significantly higher Cryptosporidium laboratory reports in the South West of England compared to seasonally expected levels. A review of surveillance questionnaires found that many cases visited a single location to pet lambs in the preceding Easter holidays.

Access to the site provided access to one of four lamb pens for petting and bottle feeding while adults watched from outside the pen. Although hand-washing facilities and signage were present, they were not located near areas where animals came into contact, potentially reducing their use and effectiveness, scientists said.

Because the event had ended at the time of the site assessment, no animal or environmental sampling was conducted given the likely low yield of testing and the absence of an ongoing public risk.

Several patients admitted to hospital

During the 16 days, 1,372 tickets were pre-ordered for the animal contact event.

Five of the 23 confirmed primary cases reported hospitalization, while two more people were assessed and discharged through the emergency department. The median age of the primary cases was 11 years, ranging from 2 to 49 years; 65 percent were women; and the median time from event attendance to symptom onset was seven days, ranging from 2 to 8 days.

For the cohort study, a survey was sent to 647 email addresses linked to ticket bookings. The analysis included 157 responses, 75 primary cases and eight secondary cases.

Among the primary cases, there were 40 children under the age of 18. Self-reported symptoms, including diarrhea, were consistent with Cryptosporidium infection. More than half of the cases had symptoms that lasted six days or more, and four reported hospitalization.

There is evidence that awareness of the potential for disease transmission on farms reduces a person’s risk of disease.

“There is likely a need for greater awareness among clinicians of the public health benefits of stool testing in patients experiencing diarrhea after contact with livestock, and primarily for better public understanding of both the risks of disease transmission during petting animals as the post-exposure symptoms,” researchers said.

Parasite in vegetables

Another study assessed the presence of Cryptosporidium in pre-washed ready-to-eat (RTE) vegetables from retailers in Great Britain. In May and July 2023, 36 samples were purchased from four supermarkets in Canterbury.

Findings published in the journal Parasitology Research showed that 14 samples were PCR positive. Four had significant similarities to Cryptosporidium parvum.

Scientists say that finding the point in the chain where contamination has occurred is made more difficult by multiple vegetable varieties in one package. Vegetables from individual supermarket chains are packaged in their central facilities and distributed nationally.

Dr. Anastasios Tsaousis, from the University of Kent, said consumers need to be more aware of storing vegetables and washing hands before eating.

“Although our 2023 study cannot distinguish between live and inert Cryptosporidium, it is important that the presence of Cryptosporidium in pre-washed vegetables could mean that the sanitation practices applied by suppliers in the production chain need to be revised, such as improved hygiene measures during harvest. , processing, packaging, transport and storage.”

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