KA-2024-BHM-000008 - [2025] EWHC 2093 (KB)

The judge’s review of the expert evidence on causation

As regards causation, Dr Bowling, the Appellant’s gastroenterologist, who had previously concluded that the enteritis was caused by cyclospora, said:

“Infection is transmitted through consumption of food or water and is contaminated by cyclospora. Food often implicated in outbreaks include soft fruit like raspberries and salad products. The incubation period is 2 to 14 days. Given that the claimant consumed no food in Mexico other than the hotel and she will not have acquired this infection in the UK or on the flight, it is reasonable to conclude on the balance of probabilities the infection was acquired at the hotel. There has been comment on poor food hygiene. Clearly, this is a subjective opinion that cannot be verified, but may be of relevance.”

However, in answer to Part 35 questions about causation, Dr Bowling deferred to the microbiologists. He readily accepted in evidence that that the question of causation rested with the microbiologists, as did the question of whether there would be an outbreak of gastroenteritis amongst more guests if a closed system broke down.

The Respondent’s gastroenterologist, Professor Bjarnason, proceeded on the basis, contrary to what was found by the judge, that there was evidence that the Appellant had been unwell before she left for Mexico. He said:

“The presence of cyclospora in the stool is accepted but if she was symptomatic before travelling it is difficult to establish the time of acquisition of cyclospora infection in Mexico, it is entirely possible, if not probable, that she acquired it under these circumstances during her numerous excursions rather than at the all-inclusive resort.”

“On the other hand, if the court concludes that she did not have gastroenteritis and accepts her account of events, the possibility that cyclospora caused the symptoms on her third full day of holiday, this would not be impossible from consideration of incubation times, the range being two to 14 days, but unlikely from considering of the median incubation time, seven days. It seems there is less than a five per cent chance of cyclospora causing symptoms two to three days from exposure.”

Professor Bjarnason was sceptical that, even if the cyclospora was acquired in Mexico, it was acquired in the hotel. He said:

“Deciding the most likely mode of acquisition is shrouded with problems …. The preferential mode of acquisition in rural Mexico mostly involves and association with contamination water, but this may not apply to all-inclusive resorts….Collectively this would make it difficult to conclude the hotel served its citizens food contaminated by cyclospora. There are numerous other modes of acquisition.”

Professor Bjarnason accepted that the Appellant had developed gastroenteritis in Mexico and probably from within the premises. He said that it could be from food, water, touch, aerosols, or any one of the 30 pathogens that he said are touched upon in its report.

The Appellant’s microbiology expert, Professor Threlfall, said that isolation or identification of a pathogenic organism in suspect foods at the time of the individual’s illness is essential for definitive confirmation of the source and vehicle of infection. In other words, you can only be sure of the cause of pathogenic infection if you can isolate the food or drink etc which was the vector for the infection. That was not possible in the Appellant’s case. Professor Threlfall went on to say:

“Without this information, diagnosis of the putative vehicle of the infection has to be based on a probability assessment, based on the person’s history of consumption of foods and beverages before becoming unwell, together with their activity history and scrutiny of relevant hotel records, assuming these are made available, supplemented by knowledge of pathogenic microorganisms in the immediate vicinity.”

Professor Threlfall said that, on the balance of probabilities he considered it extremely likely that an item of food or beverage provided by and consumed in the hotel which was contaminated with cyclospora was responsible for the Appellant’s illness. Professor Threlfall did not consider it likely that the Appellant would have become infected with cyclospora during an excursion. He said:

“Although she did attend four excursions after this time, she was unwell, throughout and could not enjoy these events. Although there is a possibility she contracted her infection during these excursions and not as a result of food prior to these events, on the balance of probabilities I consider this to be extremely unlikely.”

Professor Threlfall said that this was because the Appellant was already unwell before she embarked upon the excursions.

Professor Threlfall accepted in cross-examination that the fact that the hotel records did not show any other entries of illness in July 2016 was not consistent with breach of a closed system, when considered against 37 such entries in a four-month period. Professor Threlfall said that food and drink is not the only cause of gastric illness, but it is the usual cause. He accepted that there can be other causes, and it was hard to say what caused an individual contamination, as opposed to a widespread contamination, without details of the pathogen. He accepted that, for example, pathogens can be ingested from swimming pool water, and such pathogens can be chlorine-resistant.

As for Dr Gant, the judge reminded himself that Dr Gant took the view that the national reference laboratory’s test of the Appellant’s stool sample, which did not show cyclospora oocytes, was the more reliable. He said that the cause of the Appellant’s illness was unlikely to be a general problem with the food in the absence of a more general outbreak amongst guests. Dr Gant said that all that was needed for a person to suffer gastric illness was the ingestion of a pathogen, and this could happen in various ways. For example, if a person’s hand came into contact with a pathogen and the person’s hand then touched their mouth, they could ingest the pathogen in that manner.