A European audit of measures to control Salmonella in Poland has found instances where detection of the pathogen was 100 times lower in testing by food businesses versus official tests.
Compared with government sampling results, the level of companies’ Salmonella detection in turkey fatteners and broilers was 100 times lower in 2016. For the first quarter of 2017, for breeding chickens, there were 10 positive flocks with nine detected only by government testing, which was much less frequent than food business operator (FBO) testing.
“The much lower rate of detection of food business operator sampling renders this element practically ineffective to detect Salmonella, which may be a reason that outbreaks still occur even when all other Salmonella National Control Programme measures are correctly in place,” according to a report on the audit.
The audit team said authorities have been aware of the difference in detection rates for several years, but could not identify a motive. Training on own check sampling is mostly annually. They also said that because the sampling protocol is identical in FBO and official sampling, and because regular training is provided, there shouldn’t be such an extreme difference in detection rates.
Food business and official test results
The audit, from Feb. 6 to 15 this year, was part of the Directorate-General for Health and Food Safety (DG SANTE) schedule. The objective was to evaluate the Salmonella National Control Programmes (SNCPs) in different poultry populations.
The team visited an official laboratory, broiler and turkey fattener holdings, two egg packing centers, two breeding holdings – one for hens and one for turkeys – and two laying hen holdings with adult and rearing flocks.
“Test results data provided by the competent authority for 2016, show that positive flocks detected by FBO sampling and official sampling indicate a detection rate approximately 100 times higher from official samples of 4.3 percent (36 of 829 tests) versus 0.04 percent (17 of 39,577 tests) from FBO samples,” according to the section of the report on broilers.
“Test results data … show that positive turkey fattener flocks detected by FBO sampling and official sampling indicate a detection rate approximately 100 times higher from official samples of 3.2 percent (six of 187 tests) versus 0.03 percent (two of 6,686 tests) from FBO samples,” according to the section on turkeys.
Following the audit in 2015 and the Salmonella outbreak of 2016, Polish authorities have changed the SNCPs, relevant national legal rules, and instructions and official checks related to the control programs.
The SNCPs were generally in line with EU requirements and correct restrictive measures were imposed and/or taken by farmers when needed and were well documented. Their implementation has achieved low Salmonella prevalence, in compliance with European Union targets, for broilers and for breeding and fattening turkeys.
However, for laying hens in particular, epidemiological investigations have frequently not identified the source of infection. The competent authority has taken steps to address this and established dedicated epidemiological teams in 2018.
Multi-country Salmonella outbreak
At the time of the audit, Polish authorities had not identified the source of a 2016 multi-country Salmonella outbreak ultimately linked to eggs. An EFSA and ECDC assessment in late 2017 found additional cases caused by Salmonella Enteritidis, belonging to the same clusters as in 2016, had been reported by member states.
From February to November 2017, eight EU countries reported 196 confirmed and 72 probable cases of Salmonella enteritidis. A total of 340 historical confirmed cases and 374 historical probable infections were recorded before February 2017 by 16 countries.
From January 2015 to December 2017 in the Rapid Alert System for Food and Feed (RASFF) portal, there were 12 notifications linked to Salmonella in table eggs and egg products of Polish origin, of which 84 percent were due to Salmonella enteritidis. During that same timeframe, 60 percent of 122 alerts linked to Salmonella in poultry meat products were due to Salmonella enteritidis.
The most common cause of Salmonella infection in 2016 in Poland was from Salmonella enteritidis which caused 7,543 cases – an increase of 13.8 percent compared to 2015. Desserts, including cakes with cream and ice cream, was the most frequently identified source of infection in outbreaks followed by eggs.
During the 2016 outbreak, the official lab visited by auditors needed up to three weeks from detection of Salmonella to provide results on serotyping. That was due to factors including the high number of additional samples to be serotyped during the crisis period and the exhaustion of the stock of reagents.
In both of the laying hen holdings visited affected by the outbreak, measures restricting marketing of eggs from them as class A eggs for direct human consumption was implemented after Salmonella detection, without waiting for serotyping, to prevent additional risk for consumers, according to authorities.
The audit team said the delays indicated the system did not satisfactorily deal with high demand on its capacities in crisis times, in particular to assure timely testing.
“The measures implemented still prevented additional risk to consumers, nevertheless, without the serotyping result, the competent authorities could have faced legal difficulties in imposing the necessary marketing restrictions,” the auditors wrote.
Because of this outbreak, additional official sample testing covering all holdings supplying packing centers identified as the possible source of infected eggs was carried out. This resulted in detection of infection in holdings/flocks that had until then only had Salmonella negative results.
Vaccination of poultry flocks against Salmonella is voluntary and food businesses do it at their own expense. Laying hen flocks are reported as positive even when relevant Salmonella serotypes are only detected in dust samples.
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