Evidence for Horizontal and Vertical Transmission in Campylobacter Passage from Hen to Her Progeny

Abstract

Campylobacter is an important human pathogen, and consumption of undercooked poultry has been linked to significant human illnesses. To reduce human illness, intervention strategies targeting Campylobacter reduction in poultry are in development. For more than a decade, there has been an ongoing national and international controversy about whether Campylobacter can pass from one generation of poultry to the next via the fertile egg. We recognize that there are numerous sources of Campylobacter entry into flocks of commercial poultry (including egg transmission), yet the environment is often cited as the only source. There has been an abundance of published research globally that refutes this contention, and this article lists and discusses many of them, along with other studies that support environment as the sole or primary source. One must remember that egg passage can mean more than vertical, transovarian transmission. Fecal bacteria, including Campylobacter, can contaminate the shell, shell membranes, and albumen of freshly laid fertile eggs. This contamination is drawn through the shell by temperature differential, aided by the presence of moisture (the "sweating" of the egg); then, when the chick emerges from the egg, it can ingest bacteria such as Campylobacter, become colonized, and spread this contamination to flock mates in the grow house. Improvements in cultural laboratory methods continue to advance our knowledge of the ecology of Campylobacter, and in the not-so-distant future, egg passage will not be a subject continuously debated but will be embraced, thus allowing the development and implementation of more effective intervention strategies.

A Systematic Review Characterizing On-Farm Sources of Campylobacter spp. for Broiler Chickens

“…Previous reviews that looked at vertical transmission concluded this was a low risk exposure route for Campylobacter in broilers [12], [13], however based on the evidence identified in this SR there is evidence that vertical transfer occurs and due to well documented isolation issues, we cannot conclude on the relative importance of this source compared to others. There have been many investigations into potential biological mechanisms related to the survival of Campylobacter from egg to post-hatch stages [18], but more research is required to investigate this potentially under-recognized transmission route. It appears that any of these sources could result in an infected broiler flock as only a few susceptible birds are sufficient to result in flock-level colonization by the end of grow out [21], [92].…”

“…There has been an increasing amount of research done on Campylobacter in broilers and much advancement in the microbiological and molecular methods for identification and quantification of Campylobacter in a variety of samples. Previously conducted reviews on Campylobacter sources for poultry identify and prioritize control options, inform Campylobacter performance objectives and summarize evidence for vertical and horizontal transfer of Campylobacter in the poultry industry [5], [12], [16]–[18]. Studies investigating on-farm sources and risk factors in Canadian broiler flocks are limited, thus this systematic review (SR) examines the global evidence for sources and risk factors of Campylobacter and antimicrobial resistant- Campylobacter in broilers at the farm-level (excluding processing) to determine prevalence estimates and characterise epidemiological linkages described in available primary research.…”

Microbial Infections Are Associated with Embryo Mortality in Arctic-Nesting Geese

“…Most studies of avian embryo mortality from microbial pathogens have focused on trans-shell infection as the primary route of transmission (4-7). However, some species of bacteria (e.g., Salmonella, Campylobacter, and Mycoplasma species) are known to infect embryos prior to laying via direct contamination with infected reproductive organs (15,16,53). We attempted to identify the possible source and route of transmission of the commonly isolated Neisseria sp.…”

A Review of the Effect of Management Practices on Campylobacter Prevalence in Poultry Farms

“…However, C. jejuni can penetrate egg shells, indicating that contact with fecal material could contaminate the shells (Allen and Griffiths, 2001). Research has shown that C. jejuni can colonize egg contents by both oviduct colonization and fecal contamination of egg shells (Cox et al, 2012). …”