Intermittent long-term shedding and induction of carrier birds after infection of chickens early posthatch with a low or high dose of Salmonella enteritidis

Abstract

Poultry are very likely to become infected with Salmonella in the early posthatch period, due to environmental contamination. The purpose of this study was to evaluate the effect of infection dose on the risk of persistent infection in laying hens. In this study, young layer chicks were orally infected with a low (10(2) at 1 d posthatch) or a high dose (10(9) cfu at 1 wk posthatch) of Salmonella Enteritidis. The pattern and duration of fecal shedding was studied for 18 wk. All chickens shed Salmonella early after infection and shed Salmonella intermittently during the whole study period. There were more positive birds in the high-dose group than in the low-dose group in the first weeks following Salmonella exposure. From 10 wk postinfection onwards, however, birds that were orally infected with the low dose of Salmonella Enteritidis shed more Salmonella than the birds that received the high dose. At 18 wk of age, there was no difference in cecal colonization between the treatment groups. It can be concluded that infection of newly hatched chicks with a low dose of Salmonella Enteritidis can lead to persistent infection until onset of lay, hereby excreting Salmonella bacteria intermittently.

Phenotypic and molecular detection of Salmonella sp. on growing, rearing and production phases in a commercial group of laying hens

“…Moreover, the absence of Salmonella Livingstone on the remaining samples of rearing and production phases was probably due to the development of the immune system and the establishment of the normal intestinal microflora, which promoted elimination or reduction of bacteria levels. This occurrence is supported by Van Immerseel et al (2004), who have reported that newly hatched chicks can be infected by Salmonella, because they have immature immune system and a higher level of excretion of bacteria during their first weeks of life.…”

“…was found in 3.6% and 7.1% of meconium samples from CB and qPCR, respectively. The low positivity rate in meconium can be justified by Van Immerseel et al (2004) who have associated the weakened vertical contamination of Salmonella sp. in poultry with continuous vaccination and hygiene measures, besides strict disinfection.…”

Dissemination of Salmonella enteritidis by experimentally-infected pigeons

“…However, the absence of mortality may be expected as literature often demonstrates that this serotype may infect the bird, but do not cause any visible clinical signs (Hogue et al, 1997). The infected birds may act as carriers of the disease, infecting other birds (Van Immerseel et al, 2004). Therefore, the age of the studied pigeons, which were six months or older, may be the most plausible explanation of the absence of mortality.…”

A colonisation-inhibition culture consisting of Salmonella Enteritidis and Typhimurium ΔhilAssrAfliG strains protects against infection by strains of both serotypes in broilers

“…Newly hatched chicks are highly susceptible to Salmonella infections during the first days of life and inoculation with very low doses can result in persistent infections [2,8,9]. This high susceptibility has been associated with the absence of normal gut microbiota [3,4] and the immature immune system of young chickens [5][6][7].…”

“…This is mainly due to the absence of normal gut microbiota in young chickens and the immaturity of their immune system [3][4][5][6][7]. Infection during this period, even with low numbers of Salmonella, can lead to persistent carriers [8,9]. These broilers are often still infected at slaughter age, which may result in introduction of Salmonella in the slaughter house and food chain [10].…”