The value of the examination of sputum for tubercle bacilli depends almost solely on their presence, and it is generally recognized that repeated failure to find them does not exclude the existence of tuberculosis in the lungs.
This fact is intimately connected in its relation to differential diagnosis, with the characteristics of the sputum in parasitic hemoptysis, for in this disease some of the general symptoms of tuberculosis, such as emaciation, general weakness and anemia, are usually associated with the continued expectoration of bloodstained, mucopurulent material. There are obvious reasons, especially applicable to certain parts of the United States, why parasitic hemoptysis should be excluded in cases suspected of being tuberculous, and in which the sputum is free from tubercle bacilli, although it continuously possesses various admixtures with blood.
This is illustrated by the following account of a case admitted to my service in the St. Vincent's
MACKENZIE AD. A CASE OF PARASITIC HEMOPTYSIS OR INFECTION WITH THE DISTOMA WESTERMANII.. JAMA. 1904;XLII(18):1133-1135. doi:10.1001/jama.1904.92490630019001f