The Centers for Disease Control and Prevention reported 13 cases of psittacosis among poultry plant workers at two processing plants in Virginia and Georgia that are owned by the same company. Laboratory tests confirmed the presence of Chlamydia psittaci, the type of bacteria that causes psittacosis, which causes mild illness in people. Common symptoms include fever and chills, headache, muscle aches and a dry cough. The most common vector of infection is by breathing in dust containing dried secretions from infected birds. The bacteria are not spread by preparing or eating chicken, the agency noted.