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.

In silico serotyping tools used by NCBI PD cannot differentiate between Gallinarum and Enteritidis, nor can they distinguish at the biovar level. Additional genetic features need to be incorporated for accurate serotyping. NCBI PD link for serovar Gallinarum or Enteritidis: https://www.ncbi.nlm.nih.gov/pathogens/isolates/#(taxgroup_name:%22Salmonella%20enterica%22)%20AND%20computed_types:(%22serotype=Gallinarum%20or%20Enteritidis%22) 

Genetic characteristics:  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%). 

Animal reservoir: 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.

Geographical distribution: Biovar Gallinarum has been reported worldwide.

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

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

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

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

Recalls: There have been no recent recalls linked to this biovar.

Relevant links: 

1. https://pmc.ncbi.nlm.nih.gov/articles/PMC10812584/#:~:text=Salmonella%20enterica%20subsp.,disease%20(PD)%2C%20respectively
2. https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.001653?crawler=true#:~:text=Both%20biovars%20cause%20invasive%20and,often%20progresses%20through%20mature%20flocks.
3. https://www.cfsph.iastate.edu/Factsheets/pdfs/fowl_typhoid.pdf
4. https://www.sciencedirect.com/science/article/pii/S1056617119304234#:~:text=Live%20attenuated%20vaccines%20were%20first,except%20for%20the%20SG9R%20strain.
5. https://www.jstor.org/stable/1589326?origin=crossref
6. https://www.cabidigitallibrary.org/doi/pdf/10.5555/20063033929
7. https://www.microbiologyresearch.org/content/journal/acmi/10.1099/acmi.0.000775.v6
8. https://pmc.ncbi.nlm.nih.gov/articles/PMC10628085/#:~:text=This%20study%20showed%20a%20positive,gallinarum%20biovars%20are%20multidrug%2Dresistant.
9. https://www.uvm.edu/sites/default/files/media/fowl_typhoid.pdf
10. https://www.sciencedirect.com/science/article/pii/B9780444525123001832
11. https://www.nature.com/articles/s41597-022-01605-x
12. https://www.jstor.org/stable/1592212?seq=3
13. https://bioone.org/journals/avian-diseases/volume-58/issue-3/10796-021114-Case.1/Fowl-Typhoid-Salmonella-Gallinarum-Outbreak-in-Japanese-Quail-Coturnix-coturnix/10.1637/10796-021114-Case.1.full