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In 2015, a novel thermophilic Campylobacter was isolated from cases of spotty liver disease in laying hens in the UK. In 2016, it was isolated from laying hens in Australia where it was formally named Campylobacter hepaticus and confirmed as the cause of spotty liver disease. It has also been isolated from laying hens in America. It is fastidious, grows slowly on first isolation and does not grow on media used to routinely isolate Campylobacter. Spotty liver disease is an acute, randomly distributed, focal, necrotic hepatitis causing mortality in up to 10% of a flock and a 10%–15% fall in egg production. It occurs mainly in free‐range hens or hens reared on the ground at around the time of peak lay. The incidence of the disease has increased in countries where there is an increase in keeping free‐range laying hens. It is similar to the condition avian vibrionic hepatitis which was reported in America, Europe and Australasia in the 1950s to 1970s and the agent isolated from cases of avian vibrionic hepatitis and C. hepaticus appear to be very similar. It is not known if C. hepaticus is zoonotic but whole genome sequencing shows that it is most closely related to the known zoonotic campylobacters Campylobacter jejuni and Campylobacter coli. Human exposure to C. hepaticus is likely through similar exposure routes. Analysis of the whole genome showed a reduction in the genes for iron metabolism compared to C. jejuni. A requirement for iron was confirmed as it showed reduced growth in an iron depletion assay and this may explain its tissue tropism. With a move towards free‐range egg production in many countries, the incidence of C. hepaticus hepatitis is likely to increase, but the identification of the causal agent will provide opportunities for the development of control methods. [ABSTRACT FROM AUTHOR]

Spotty liver disease (SLD) is characterized by multifocal liver lesions, mortality, and drop in egg production. The disease is emerging in Europe and Australia, particularly in free-range and floor-raised layer flocks. Campylobacter hepaticus has been recently identified as the causative agent of SLD. We report the isolation and characterization of C. hepaticus from livers of laying hens affected with SLD in the United States. Two isolates were characterized and found to be highly similar to those described from SLD cases in the United Kingdom and Australia. Initial isolation of C. hepaticus from liver samples required microaerophilic and thermophilic conditions and incubation for a particularly long duration (approximately 7 days). Morphologic and phenotypic properties of the isolates were typical for Campylobacter spp. Phylogenetic analysis based on 16S ribosomal RNA gene sequences and detection of a glycerol kinase gene confirmed the identity of the isolates as C. hepaticus. To the authors' knowledge, this is the first report of C. hepaticus isolation from layer chickens with SLD in the United States. With the increasing changes in the egg industry from conventional cages to cage-free housing systems, the incidence and economic impact of SLD could become significant.