Psittacosis is primarily a disease of so-called psittacine birds such as parrots and parrakeets. The disease is transmissible to man, however, and is characterized by high fever associated with symptoms of an atypical pneumonia. Occasionally the disease can be transmitted from man to man, but the most common source of human infection is from parrots and parrakeets which have been kept as household pets. No doubt many infected birds will be distributed as Christmas presents, and the hazard at this time demands a warning.
Meyer and his colleagues1 at the Hooper Foundation in San Francisco have been persistent in their research on this disease. Much information on the nature of the virus which causes psittacosis is now available. On the basis of ultrafiltration measurements verified by photomicrographic studies it has been determined that the infective particle of psittacosis has a minimum size of from 0.2 to 0.3 micron. Furthermore