After considering all the evidence, the the Health Protection Agency (HPA) on Friday concluded that "consumption of products made by Cadbury Schweppes was the most credible explanation for the outbreak of S. Montevideo".
Cadbury did not respond in time for publication of this story to a request for an interview from FoodProductionDaily.com.
The scandal has already cost the company millions of euros to make the recall and damaged public trust in its products.
Cadbury's failure to follow new EU-wide hygiene rules, known as Hazard Analysis and Critical Control Point (HACCP) analysis, also serves as a warning to other processors who may also have been tardy in making sure the system is in place at all their plants.
The company now faces possible regulatory action and consumer suits over its failure to report to food regulators that its private testing in January had found the rare Salmonella strain in its products. After the Food Standards Agency made the news public in June, Cadbury withdrew seven of its products, amounting to one million chocolate bars, from the UK market.
The HPA said interviews with 15 of the 37 people affected by an outbreak of Salmonella montevideo earlier this year indicated that 13 of them reported eating products made by Cadbury.
The HPA said its the analysis allowed the exclusion of a particular retailer, eating out or eating take-away food, as the source of the outbreak.
"No food products or brands were identified as being common among cases with the exception of confectionery products which were reported by 14 cases," the HPA stated. "Thirteen (87 per cent) of the cases interviewed reported eating products from Cadbury Schweppes plc. One of the two remaining cases reported consumption of confectionery products."
The HPA also confirmed that samples taken from Cadbury's factories showed the same Salmonella montevideo was present in January and February. The dates of the outbreak in the population was from February to June.
The HPA also noted the decrease in the frequency of cases of Salmonella montevideo following the company's recall of a number of its chocolate products.
In January this year, the company discovered that waste water from a plant in Herefordshire had dripped down into the milk chocolate crumb, a mix that is blended with other ingredients to make some of the company's chocolate bars. The pipe was fixed but despite finding the Salmonella pathogen in some of its products, the company failed to make a recall at the time.
Cadbury claims in a press release it did not disclose to officials that its products could be contaminated with the Salmonella montevideo strain as only 'minute' traces of the bacteria were found and the company deemed the risk too low.
The Advisory Committee on the Microbiological Safety of Food (ACMSF) released a damning report in July in which it stated that: "The presence of salmonella in ready-to-eat foods such as chocolate is unacceptable at any level."
The ACMSF also said that the company failed to correctly implement EU-wide guidelines laid down by international food safety codes, known as Hazard Analysis and Critical Control Point (HACCP) analysis. New EU hygiene directives came into force at the start of this year, embodying HACCP principles in the bloc's law.
"Cadbury's risk assessment does not address the risk of Salmonella in chocolate in a way which the ACMSF would regard as a modern approach to risk assessment," the ACMSF stated.
The findings of the report, published by the UK's Food Standards Agency (FSA), concluded that Cadbury had used methods of product testing that were likely to underestimate the presence of the bacteria. A negative result from the tests would not necessarily mean that the product was uncontaminated.
"Based on the information provided, Cadbury appears to have used methods for product testing which the committee considered would underestimate the level and likelihood of salmonella contamination," the advisory committee stated in its report. "Sample heterogeneity including clumping of bacteria will influence the MPN (most probable number) estimate and therefore the approach cannot be relied upon in foods such as chocolate."
HACCP is a science based and systematic method of identifying specific hazards and measures for their control to ensure the safety of food. HACCP is a tool to assess hazards and establish control systems that focus on prevention rather than relying mainly on end-product testing.
Cadbury has since said it would improve cleaning processes at its Herefordshire factory. Following a meeting with the FSA in July, Cadbury agreed to undertake 'remedial action', which would involve changing cleaning regimes in the plant and stepping up testing for a wider range of products.
In a statement, Cadbury Schweppes said it was "moving to a protocol in which any product evidencing contamination is destroyed."
According to the FSA, Cadbury has pledged to carry out a positive release system whereby products will only be released for consumption if they test negative for the salmonella bacteria.
The full financial impact of the incident will not be known until Cadbury Schweppes releases their annual results on August 2.
JP Morgan Cazenove, the investment broker for Cadbury, estimates the cost of the product withdrawals at £5m and another £20m (€29m) in sales due to lack of consumer confidence in the brand. The company also faces possible regulatory action for allegedly not disclosing the information.