The main purpose of this paper has been to discuss the effects of psychological stress and other environmental factors on incidence of diseases. We were specifically concerned with stress that increased susceptibility of uninfected hosts when exposed to infection. If such stresses also reduced resources, fecundity and/or survivorship, there was a reduction in the host carrying capacity. In addi...

background and aims: the objective of this study was to investigate the effects of newcastle disease and infectious bronchitis vaccination programs in chickens. materials and methods and results: in the present study, 225 day-old broiler chicks divided into 5 groups. the groups were submitted to vaccinations, except for the non-vaccinated control group. the chickens in the groups 1 were kept as...

since the mid-19 th century, human activities have increased greenhouse gases such as carbon dioxide, methane, and nitrous oxide in the earth's atmosphere that resulted in increased average temperature. the effects of rising temperature include soil degradation, loss of productivity of agricultural land, desertification, loss of biodiversity, degradation of ecosystems, reduced fresh-water resou...

The main purpose of this paper has been to discuss the effects of psychological stress and other environmental factors on incidence of diseases. We were specifically concerned with stress that increased susceptibility of uninfected hosts when exposed to infection. If such stresses also reduced resources, fecundity and/or survivorship, there was a reduction in the host carrying capacity. In addi...