Investigation of Spotty Liver Disease and Campylobacter hepaticus in Layer Flocks—A Field Study

Abstract

Campylobacter hepaticus (C. hepaticus) was recently discovered as the causative agent of Spotty Liver Disease (SLD). SLD affects laying hens and causes significant economic losses in egg production in several countries throughout the world. Field observations reveal that cases of SLD appear with a high risk of reoccurrence, specifically in free-range and organic brown-feathered layer lines. Possible factors contributing to the development of SLD still have to be elucidated. In this field study, one free range (Flock 1) and one organic flock (Flock 2) of brown laying hens kept on farms with a history of clinical SLD were monitored for C. hepaticus colonization, clinical signs, and egg production from 16 to 79 wk of age on the first farm and from 17 to 83 wk of age on the other. The flocks showed a significant drop in egg production at 32 to 39 or 56 wk of age, respectively, which was associated with macroscopically visible liver lesions typical for SLD. Interestingly, in both cases observed clinical disease was linked to a stressful event: heat stress for Flock 1 and respiratory symptoms for Flock 2. C. hepaticus was detected by PCR during the acute phase of the disease in Flock 1. At 50 wk after the initial clinical outbreak had waned, C. hepaticus was still able to be isolated by culture in this flock. This clearly demonstrates that C. hepaticus persists either in the birds or their environment. We speculate that this long persistence may favor chronic SLD in affected flocks and the reoccurrence of SLD in subsequent flocks. Clinically less severe SLD outbreaks may be observed after re-exposure of clinically recovered flocks.RESUMEN. Investigación sobre la necrosis hepa ´tica focal y Campylobacter hepaticus en parvadas de ponedoras: Un estudio de campo.Campylobacter hepaticus (C. hepaticus) se descubrió recientemente como el agente causante de la necrosis hepa ´tica focal (SLD por sus siglas en inglés). La necrosis hepa ´tica focal afecta a las gallinas de postura y provoca importantes pérdidas económicas en la producción de huevo en varios países del mundo. Las observaciones de campo revelan que los casos de necrosis hepa ´tica focal aparecen con un alto riesgo de recurrencia, específicamente en las líneas de ponedoras de plumaje marrón bajo condiciones de pastoreo y de producción orga ´nica. Aún deben dilucidarse los posibles factores que contribuyen al desarrollo de la necrosis hepa ´tica focal. En este estudio de campo, en una parvada mantenida en pastoreo (parvada 1) y en una parvada bajo producción orga ´nica (parvada 2) de gallinas de postura de color marrón criadas en granjas con antecedentes de necrosis hepa ´tica focal se monitorearon la colonización por C. hepaticus, los signos clínicos y la producción de huevos desde las 16 a las 79 semanas de edad en la primera granja y de las 17 a las 83 semanas de edad en la segunda granja. Las parvadas mostraron una caída significativa en la producción de huevo entre las 32 a 39 semanas, o a las 56 semanas de edad, respectivamente, que se asociaron con lesiones he...