ABSTRACT This study aimed at determining the clinical and pathological effects of the coinfection of young SPF chickens with chicken anemia virus (CAV) and Mycoplasma gallisepticum (MG) vaccine strains. The clinical signs, gross and microscopic lesions were determined after the experimental coinfection broilers with a CAV genotype 1 vaccine strain given intraperitoneally on the first day of age and a MG F-strain vaccine given intranasally on the 8th day of age. The experimental groups included the negative control (group 1), a group infected with the MG F-strain vaccine (group 2), and a group coinfected with CAV and MG vaccines (group 3). Chicks were examined clinically and post mortem at 23 days of age, and gross and microscopic lesions of the trachea, thymus, and air sacs were compared among treatments (Kruskal-Wallis test). Infections were confirmed by PCR for specific genetic fragments of each agent in the target tissues. Mortality was only observed in chicks on group 3, with two deaths and more severe lesions in the trachea, thymus and air sacs compared with groups 1 and 2 (p< 0.01). Dead chicks presented reduced thymus and spleen size, hemorrhagic trachea with catarrhal exudate and partial obstruction, pericarditis, catarrhal airsacculitis, lungs with liquid and ascites. The surviving chicks in group 3 showed more severe respiratory changes than those in group 2, in addition to thymus and spleen size reduction. Results indicate the adverse effects of the coinfection of young chickens with MG F-strain and CAV genotype 1 vaccines.

The mortality of passerines native of Southern Minas Gerais, Brazil, in August 2006 and the examination of sentinel free-range chicken eggs in August 2007 in an area surrounding a car battery lead smelter plant is described. The high levels of lead, as detected in the passerines (4.80-12.74 mg/kg) at the onset of mortality and at the follow-up sampling of the free-range chicken eggs (25.02-35.21 mg/kg in shells, 0.41-1.36 mg/kg in yolks and 0.40-0.75 mg/kg in the albumins), used as environmental sentinels, indicated the continuing lead pollution.

The occurrence of CAV in backyard chickens in the metropolitan area of Belo Horizonte, Brazil, was evaluated. The spleen and thymus of chickens from different origins were collected for DNA extraction and nested-PCR. CAV genome was detected in 30% of the flocks (n=20) examined. CAV origin for backyard chickens is speculated, taking into consideration its widespread incidence in the chicken industry, the contamination of live vaccines with CAV prior to its eradication from SPF flocks, and the use of attenuated CAV vaccines.