The covid-19 pandemic has proven to doctors, patients, and the world that one pathogen can cause one or more manifestations of disease, in the same person; and can cause different manifestations of disease in different patients. Sir William Osler described syphilis as “The Great Imitator”, because it mimics many diseases and syndromes, as it becomes chronic and causes different symptoms during different stages of the disease.

Chlamydia species can also cause different manifestations of disease in the same patient and in different patients, as the acute infection becomes a chronic infection, and a chronic infection becomes a chronic disease. The predilections of the pathogen; the patients’ susceptibility, weak links, duration of infection, co-infections, and overall infectious burden; and environmental factors and/or chance, can impact the evolution from acute infection to chronic disease.

Routine diagnosis of immortal pathogens and parasites could give insight into many chronic diseases and co-morbid conditions, which may be caused by the same pathogens and combinations of pathogens, in different patients.