S. Gallinarum Biovar Gallinarum¶

At a Glance

Background Information¶

Salmonella enterica subsp. enterica serovar Gallinarum (antigenic formula 1,9,12:–:–) is a serovar of the O:9 (D₁) serogroup. This serovar has two biovars: Gallinarum, and Pullorum. Biovar Gallinarum has been found to show host specificity for aquatic birds, and poultry and can cause fowl typhoid (FT) in birds of any age, often spreading through adult flocks. FT can spread through ingestion, such as contaminated food, water, or cannibalism, as well as through the respiratory system. Live attenuated vaccines (SG9R) to prevent FT were first created in 1956 with the development of the Gallinarum rough strain. Since serovar Gallinarum relies solely on domestic and aquatic fowl as its reservoir, as a result, the test-and-slaughter approach implemented through surveillance programs successfully eradicated the serovar from commercial poultry flocks in the United States, England, and Wales by the 1970s.

Studies have found that isolates from biovar Gallinarum can be multidrug-resistant. More specifically, antibiogram analysis revealed that biovar Gallinarum in the U.S. exhibited high prevalence of resistance to cephradine, trimethoprim-sulfamethoxazole, amoxicillin, streptomycin, and ampicillin. Farahani et al. found that the antibiotic resistance rates among 60 biovar Gallinarum isolates in Iran were as follows: penicillin (100%), nitrofurantoin (80%), nalidixic acid (45%), cefoxitin (35%), neomycin sulfate (30%), chloramphenicol (20%), and ciprofloxacin (5%).

Chickens are the primary hosts for biovar Gallinarum, although other bird species can also be affected. Besides chickens, biovar Gallinarum has been reported in turkeys, quail, guinea fowl, pheasants, peafowl, grouse, parrots, sparrows, ostriches, and ring-necked doves.

Biovar Gallinarum has been reported worldwide.

Animal outbreaks: There have been multiple outbreaks in chickens associated with biovar Gallinarum. Examples are shown below:

Year	Location	Breed	Number of cases
2014	Brazil	Japanese Quail	222¹
1990	Zambia	Layer	2400²

¹ The flock size is 400, and 222 birds died.

²The flock size is 10,000, and 2,400 birds died.

There have been no recent border rejections linked to this biovar.

There have been no recent recalls linked to this biovar.