Re-emergence of Salmonella pullorum in commercial layers from Cochabamba, Bolivia

In March 2021, a Salmonella outbreak was detected in the Quillacollo Province from the Cochabamba Department, Bolivia. It occurred in 5-day-old commercial layers from the H&N (Brown Nick) line. The Mortality climbed to 30 %, the rest of birds had dehydration signs, urate deposition in ureters, hepatomegaly, cloacal clothing, enlarged spleen, greenish vitelline sac, yellowish bile bladder content and gizzard erosions. At the laboratory only Salmonella spp. (non-movil) was detected from liver, heart, bone marrow (medium amount), higher concentrations were obtained from vitelline sac, while small amounts were detected from bile. The acriflavin test revealed the presence of a smooth Salmonella (pathogenic). In some cases, small amounts of Eschericha coli and Proteus spp. were concurrently detected. At the hatchery, the analysis of pipped and rotten eggs also yielded Salmonella spp. All the hatchery samples showed high levels of contamination with Proteus spp. y Pseudomonas spp. The breeders of the contaminated chicks were eliminated. While the bacteriological analysis from samples (liver, spleen, bone marrow, cecal tonsils, cloacal swabs) obtained from other breeder flocks in the same farm were negative to Salmonella spp. Nevertheless, positive results could be obtained from dead breeders' cloacal swabs regardless of the flock. Biochemistry tests (Glucose,Lysine descarboxilase, indol, Ornityn descarboxilase and Manitol) resulted positive with acid and gas production. DNA samples were analyzed from several positive samples using a multiplex PCR at the National Diagnostic Service Department (SENASAG) in Cochabamba, Bolivia, confirming the presence of Salmonella enterica biovar Pullorum.

Automated summary

In March 2021, a Salmonella outbreak was detected in commercial layers of Brown Nick chickens in Quillacollo Province, Bolivia. The outbreak caused a mortality rate of 30% and exhibited various pathological symptoms. Salmonella spp. was detected in the deceased birds, as well as in samples from the hatchery and other breeder flocks, along with other bacteria. Further DNA analysis confirmed the presence of Salmonella enterica biovar Pullorum in the infected birds.