Abstract
The mode of vertical transmission was studied with local isolate of Salmonella pullorum in hens and cocks. Twenty (20) hens and five cocks were experimentally infected by the oral route with 2 × 107 (CFU) dose of S. pullorum organisms at 21 weeks of age in hens and 29 weeks in cocks and in control (20 hens and five cocks) no bacteria was given. The used methods were reisolation of S. pullorum from different organs, blood, eggs and newly hatched chicks, and detection of S. pullorum by PCR from testicular tissue at different time intervals of experimental period. Five birds (four hens and one cock) randomly selected and sacrificed on 6 h before inoculation (BI) and one, two, three and four weeks of post-infection (PI) from infected and control group. S. pullorum was reisolated from 50% eggs of experimentally infected hens. Twenty percent hatchability was lost due to experimental S. pullorum infection. Piped chicks were 20% and embryo mortality was 15%. S. pullorum was isolated from 66.66% chicks. Seventy five percent testes were positive for S. pullorum by culture and biochemical test. S. pullorum was detected by PCR at one to three weeks PI from testicular tissues. It was clear that after oral route of infection with infective dose of S. pullorum, the bacteria invaded digestive epithelia and ultimately entered into blood inducing bacteremia and ultimately infected different organs and produced pathological lesions. It was also confirmed that the bacteria invaded ovary and egg follicles, and this infection persisted in ovary and egg follicles and transmitted into laid eggs then to hatched chicks. Key words: Vertical transmission, Salmonella pullorum, chickens.
Highlights
IntroductionPullorum disease (PD) is an acute, infectious, and fatal disease of chicks causing mortality as well as results in persistent infection and vertical transmission in layer birds (Wray and Davies, 2001; Ramasamy et al, 2012)
Pullorum disease (PD) is an acute, infectious, and fatal disease of chicks causing mortality as well as results in persistent infection and vertical transmission in layer birds (Wray and Davies, 2001; Ramasamy et al, 2012).PD in growing and mature fowl is characterized by a sudden drop in feed consumption, with ruffled feathers, and pale and shrunk combs
S. pullorum showed red - pink - white opaque coloured colonies surrounded by brilliant red zones in BGA
Summary
Pullorum disease (PD) is an acute, infectious, and fatal disease of chicks causing mortality as well as results in persistent infection and vertical transmission in layer birds (Wray and Davies, 2001; Ramasamy et al, 2012). PD in growing and mature fowl is characterized by a sudden drop in feed consumption, with ruffled feathers, and pale and shrunk combs. Other signs in laying hens are characterized by a drop in egg production, decreased fertility, and diminished hatchability. The prominent signs of PD are anorexia, diarrhoea, depression, and dehydration (Chauhan and Roy, 1996; Haider et al., 2003; Hossain et al, 2006). Pullorum disease may be transmited horizontally and vertically. Vertical transmission may result from contamination of the ovum following ovulation, but localization of Salmonella pullorum in the ovules before ovulation
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