LACK OF EVIDENCE OF VERTICAL TRANSMISSION OF CAMPYLOBACTER IN ICELAND/SWEDISH POULTRY OPERATIONS

Authors: Callicott, Kenneth; Stern, Norman; Hiett, Kelli; REIERSEN, JARLE - CHIEF VET OFFICER; BERNDTSON, EVA - SWE-CHICK; FRIDRICKSDOTTIR, VALA - INST FOR EXP PATH; GUNNARSSON, EGGERT - INST FOR EXP PATH; GEORGSSON, FRANKLIN - ENV & FOOD AGENCY; LOWMAN, RUFF - CANADIAN FOOD INSPECTION

Submitted to: American Society of Microbiologists Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/27/2004
Publication Date: 5/23/2004
Citation: Callicott, K., Stern, N.J., Hiett, K.L., Reiersen, J., Berndtson, E., Fridricksdottir, V., Gunnarsson, E., Georgsson, F., Lowman, R. 2004. Lack of evidence of vertical transmission of Campylobacter in Iceland/Swedish poultry operations [Abstract]. American Society of Microbiologists. Poster N-284, p. 448.

Interpretive Summary:

Technical Abstract: Background: Campylobacter jejuni is a major cause of bacterial food infection in the industrial world. There is some evidence that C. jejuni are present in eggs and hatchery fluff, leading to the possibility of vertical transmission from hens to their offspring. Poultry operations in Iceland provide an excellent opportunity to study this possibility, as flocks are established solely from eggs imported from parent flocks in Sweden. This leaves limited opportunity for parents and offspring to share isolates through horizontal transmission. Methods: The sequence of the flaA short variable region (SVR) was determined for 160 Campylobacter isolates collected from 2001 through 2003. Of these isolates, 43 were from fecal samples from 10 parent flocks in Sweden, and 117 were from fecal samples from 20 offspring flocks in Iceland. The sequences were aligned using Clustal W, and a neighbor joining tree of unique alleles was created with maximum likelihood distances using the program PAUP*. Gene flow was estimated using the program DnaSP 3.53. Results: Twenty alleles were observed among the 160 isolates studied. Nine alleles were found in only one of the flocks studied. Of the remaining 11 alleles, 2 were found in multiple flocks in Sweden, 5 were found in multiple flocks in Iceland, and 3 were found in both Sweden and Iceland. However, there were no instances where the same allele was found both in a particular parent flock and its offspring. The phylogentic tree shows little grouping of isolates into clades restricted to Iceland or Sweden, and an estimate of gene flow using the method of Hudson, Slatkin and Maddison (1992) indicates sufficient gene flow (Nm=5.42)to prevent the divergence of Campylobacter in the two countries. Conclusions: We have not observed any Campylobacter flaA SVR alleles shared between parent and offspring flocks, which would suggest that vertical transmission is not occurring. However, an indirect measure of gene flow indicates substancial genetic exchange between the two countries. This gene flow might be the result of horizontal transmission via long-range vectors, such as migratory birds or humans.