A project led by the National Food Institute, Technical University of Denmark, has developed a test method to improve the likelihood of identifying Campylobacter-positive chicken flocks.

Being able to identify Campylobacter-positive flocks before they arrive at the slaughterhouse allows them to be slaughtered after the negative flocks to avoid cross-contamination along the production line.

The method was worked on in the EU project, AIR-SAMPLE, which began in January 2018 and runs until June 2020. Other partners are the Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise “Giuseppe Caporale” in Italy, Veterinary Research Institute in the Czech Republic, National Veterinary Research Institute in Poland and Norwegian Veterinary Institute.

The aim was to develop and validate air sampling as a low-cost and multi-purpose alternative to fecal droppings or boot swabs for surveillance, monitoring and eradication of Campylobacter in confined and biosecured broiler production operations.

Denmark recorded its highest number of Campylobacter infections ever in 2019, according to the Statens Serum Institut. An SSI report shows the number of patients was 5,389 this past year compared to 2018 when 4,547 cases were recorded.

New method versus current standard
Many chicken producers in the EU use the sock method to test whether the bacterium is present.

The person in charge of testing puts gauze around their footwear and walks through the chicken house. The gauze is placed in a growth medium for 48 hours during which time any bacteria that were trapped in the gauze can multiply.

The liquid is then put onto agar plates, which are left for another 48 hours to allow the bacteria to grow and make it possible to determine if the flock is infected with Campylobacter. In total, it takes more than four days before the producers know whether their flocks are positive when using this method.

The new test method yields test results in two hours. It uses a type of mini-vacuum cleaner and is fitted with a special filter, which collects bacteria in the chicken house. The filter is analyzed with a PCR-test, which isolates DNA and determines whether Campylobacter bacteria are present in the sample and in what quantities.

Researchers did field testing in four EU countries in Northern, Southern, Central and Western Europe. They used Norwegian chicken flocks as negative control, as chicken feces from these flocks are normally Campylobacter-negative.

Tests found no infections in Norway. Results also show up to four times more chicken flocks show signs of Campylobacter being present with the new method compared to sock samples.

A previous project from 2010 to 2015, called CamCon, found the air sampling approach was sensitive, cost-effective and user friendly under various poultry farming conditions.

AIR-SAMPLE is one project in the One Health European Joint Programme that ends in December 2022. It involves more than 40 partners including the German Federal Institute for Risk Assessment (BfR), French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Public Health England, Norwegian Institute of Public Health, Public Health Agency of Sweden and Dutch National Institute for Public Health and the Environment.