Mystery salmonella outbreak alert as 50 sickened, 10 hospitalised with poisoning – extraordinarily uncommon pressure of ‘unknown supply’

Health chiefs have launched an urgent national investigation into a mystery salmonella poising outbreak that has affected more than 50 and hospitalised ten. 

Genetic testing has revealed in all cases the infection were caused by the rare Salmonella Blockley strain, also referred to as S. Blockley, which the UK Health Security Agency (UKHSA) warned is particularly severe. 

In meeting notes from September 2024, which are only now being reported, the watchdog admitted ‘the source of the outbreak is currently unknown’.

Cases of S. Blockley are more often seen in east Asia and the US, and have only been recorded in a European countries a handful of times. 

As of September 2024, when the urgent meeting was held, 54 cases had been confirmed by local testing labs, and some were resistant to standard antibiotics.

There had been 36 cases in England, seven in Wales and 11 in Scotland, with sample dates ranging between July 27 and Aug 24, 2024.

The ages of patients ranged from two to 85 however the most affected group, with 13 cases, was those in the 50 to 59 bracket. 

Ten of 21 people with information available were hospitalised, and ‘there are early indications of greater than expected clinical severity of infection’, the meeting notes added. 

Health chiefs have launched an urgent national investigation into a mystery salmonella poising outbreak that has affected 54 people and hospitalised ten 

S. Blockley, like all salmonella, causes salmonellosis, and leads to symptoms such as diarrheoa, fever, abdominal cramps, and vomiting.

However studies suggest some patients may continue to experience symptoms for up to ten years after infection. 

A previous case report, published in a medical journal in 2006, suggest S. Blockley triggered arthritis in an previously healthy young man which persisted for a decade.  

The bacteria have been found in chickens although in previously identified cases in Germany, the cause was thought to be smoked eel.

Other outbreaks have been linked to unpasturised egg in ice cream.

UKHSA said a national level investigation had been opened due to the number of cases, and indicated healthcare professionals needed to be alert.

According to UKHSA, there was no indication that those who fell ill travelled before becoming infected. 

The watchdog said it suspected ‘involvement of an international supply chain’. 

S. Blockley, like all salmonella, causes salmonellosis, and leads to symptoms such as diarrheoa, fever, abdominal cramps, and vomiting 

A UKHSA spokesperson confirmed their investigation was ongoing, and the course remained unconfirmed, however it believed there have been no further cases of S. Blockley.

They added: ‘Gastrointestinal bacteria, such as Salmonella, can be spread from person to person as well as from food. 

‘Anyone with diarrhoea or vomiting should wash their hands thoroughly after using the bathroom and avoid handling food or preparing food for others where possible. 

‘Please avoid returning to work or sending unwell children to school or nursery until at least 48 hours after symptoms have cleared.’