ABSTRACT
This chapter describes the diverse diseases caused by chlamydiae in different animal species and illustrates pathogenetic events and lesion development following chlamydial infections. Avian chlamydial infections may lead to pneumonia and airsacculitis, pericarditis, conjunctivitis, encephalitis, as well as intestinal infections and diarrhea. Chlamydial infections often establish a balanced host-parasite relationship in most animals known as natural hosts. The bird species of the economically important poultry industries are also natural and highly susceptible hosts for chlamydial infections. Chlamydial infection of birds thus may lead to pneumonia, airsacculitis, tracheitis, hepatitis, myocarditis, splenitis, nephritis, orchitis, enteritis, and encephalitis. The intestinal chlamydial infection of mammals is comparable to the infection of acutely, as well as persistently, infected birds which are known to excrete chlamydiae in the feces or diarrhea fluid. The electron microscopic analysis of the genital infection of guinea pigs provides an example of the potential role of specific strains of Chlamydia psittaci as a cause of infertility in animals.
