Since the syndrome of Bullis fever was originally described (1), there have been rather persistent informal opinions that this disease is essentially one of the known prevalent diseases. This was based on some similarity either in clinical manifestation or in etiological agent. Thus far, no relationship has been demonstrated between Bullis fever and the rickettsial diseases such as typhus, Q fever, and Rocky Mountain spotted fever (2, 3, 4) although they are all associated with arthropods and the Bullis fever agent has been described as rickettsia-like in morphology. No relationship has been demonstrated between Bullis fever and Colorado tick fever (5); although these two diseases are associated with ticks, fatalities are relatively rare, and both are characterized by the development of a marked leucopenia in the course of the disease.

The syndrome of Bullis fever exhibits a clinical similarity to dengue fever, only to the extent of manifesting a leucopenia in the course of the disease.