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Gallibacterium anatis
 Gallibacterium anatis'' is a Gram-negative, non-motile, encapsulated, beta-hemolytic coccobacillus of the Pasteurellaceae family that forms grayish, round, semi-transparent colonies, 0.5-1 mm in diameter. It is a species known for its virulent effect on chickens and has been a subject of interest over the past decade to combat the economic losses in the egg industry. Gallibacterium was recently established as a new genus within the family Pasteurellaceae. Bacteria belonging to this genus have previously been reported as Pasteurella anatis, avian Pasteurella haemolytica-like organisms or Actinobacillus salpingitidis.''



Background Information
About 10 years ago, a sudden drop in egg production was observed in poultry zones with dense egg-laying hen populations. No known disease could account for the decrease. Pasteurella hemolytica-like bacteria were isolated from sick birds. Since this strain was an opportunistic pathogen, it was given no attention. However, further study by Dr. Fernando Galindo allowed identification of these organisms as what is today called Gallibacterium anatis biovar haemolytica. This bacterium is widely known for its effect on economic losses in the egg industry.

Pathology
A study from the Journal of Clinical Microbiology recognizes the importance of this bacterium in chicken diseases. According to the study, Gallibacterium was found to be prevalent in the upper respiratory tracts and the lower genital tracts of healthy chickens. However, Gallibacterium isolates were also recovered in pure culture from a range of pathological lesions in chickens, including lesions from chickens with septicemia, oophoritis, follicle degeneration, salpingitis with or without peritonitis, peritonitis, enteritis, and diseases of the respiratory tract. Also, previous attempts to assess the pathogenic potential of Gallibacterium have indicated that different strains have highly different levels of virulence. Therefore, different strains of Gallibacterium anatis could be more harmful than others.

Other studies done in peacocks suggest the lesion induced by Gallibacterium antis to be non pathognomic. Similar to most of the genus Pasteurellacae, Gallibacterium anatis is a phenotypically heterogeneous group of bacteria which makes their identification difficult. Therefore, genotypic diagnostic techniques may be more suitable for future understanding of pathogenesis and epidemiology.

Specific affect on chickens
Gallibacterium anatis bacteria are responsible for decreased egg production. Therefore, their attack on the reproductive system of chickens is the primary point of interest. G. anatis affects particularly the reproductive tract in both commercial layers and breeders, resulting in important lesions such as ovarian atrophy, hemorrhages and regression, with ruptured, misshapen follicles, non-functional oviduct with hemorrhages and internal laying, in addition to lesions in other body parts like peritonitis and enlarged kidneys.

Specifically, the lighter birds are most susceptible between 22 and 34 weeks of age. This disease is more frequent in broiler breeders at approximately 40 weeks of age. Infection results in important economic losses, since during the sub-clinical stage birds are apparently healthy at the time egg production drop or delayed laying peak occur. During the clinical stage, egg drop is accompanied by nasal discharge, fever, depression, dropping, cyanotic combs, anorexia, dehydration, greenish diarrhea, prostration, and variable mortality rates.



One important point to note is that the lesion/egg drop severity varies depending on these different bacterial biogroups involved. Egg production can decrease from 85 to 18 percent.