filter which will retain ordinary bacteria. However, this experimental influenza was not as severe as the natural disease. Later, Shope showed that in the natural disease a strain of the Pfeiffer bacillus, called Hemofihilus influenza suis, plays a cooperative role. MAX A. LAUFFER When hogs were infected with both the virus and the University of Pittsburgh, bacillus, typical influenza resulted. In other words Pittsburgh, Pennsylvania swine influenza is the result of the simultaneous infection with influenza virus and influenza bacillus. CCORDING to textbooks onmedicine, the disease, All this was known in 1931, but the cause of human tnfluenza, has been recognized for many centuries. influenza was still unknown. Indeed, i t could only be Medical historians refer to epidemics during the Mid- surmised that the swine disease really was related to dle Ages. The f i s t epidemic recorded in America is the human disease. However, in 1933, Smith, Ansaid to have been in 1647. Sporadic outbreaks are drewes, and Laidlaw in England showed that a disease fairly common, minor epidemics occur very frequently, could be transferred to the ferret from humau patients and serious pandemics seem to occur about three or four suffering with influenza (2). It was next shown that times in a century. The disease is usually mild, but this ferret disease could be transmitted from one experioccasionally extremely severe forms of it are experi- mental animal to another by means of a bacteria-free enced. During the pandemic of 191&19, i t is estimated filtrate. Therefore, the causative agent can be prethat from 6 to 15 million people died as a result of in- sumed to be a virus. Next, i t was learned that ferrets fluenza. Some authorities place the death figure in the developed an immunity and that the serum from an imUnited States alone a t about half a million. Even mune ferret could neutralize the virus. Also, i t was total war practiced on a global scale has difficulty com- shown that the serum from man recovered from inpeting with that record. fluenza would neutralize this ferret virus. Thus, the The cause of influenza has only recently been deter- presumed relationship between the ferret virus disease mined with reasonable assurance. It is generally be- and humau influenza was strengthened. lieved that the ancients attributed the disease to the It remained only to prove beyond doubt that the influence of the constellations. In fact, etymologists causative agent of this experimental disease is also the tell us that the word, "influenza," owes its origin to causative agent of human influenza. This was done by this belief. During the pandemic of 1892 Pfeiffer iso- producing experimental human influenza with it, first lated a bacterium from patients suffering with the in Russia by SmorodintseE and associates (3), later in disease and regarded this organism as the causative Australia by Bnmet and Foley (41, and finally by Henle, or etiologic agent. This bacterium, whose generic name Henle, and Stokes of Philadelphia (5). It was not found is Hemo#hdus influenzae, is familiarly known as the necessary to introduce the Pfeiffer bacillus simultanePfeiffer bacillus. Even though difficulty was experi- ously in order to produce human influenza. Because of enced from the iirst in producing experimental influ- the thrice demon
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17 OdO\ ,A" .*,. (13) FRANCIS,T., JR.,AND J. E. SALK, .%ience, 96,499 (1942). (14) STANLEY, W. M., 1.ExPtl. Med., 81, W 3 (1945). (15) LAuaaEn. M. A.. AND W. M. STANLEY. ibid...80.531 - ~~, (1944). ~-~ --, ii6j LAWPEER: M. A,: AND G. L. MILLER,ibid.. 80.521 (1944).
.- .- ., - -,- - - ,- - - .,. (18) STANLEY, W. M:, jbid., 79.255 (1944); ibid., 79,267 (1944). C. A,, ~ b d83.11 . (1946). (19) KNIGHT, R.C., AND R . W. G. WYCKOBB, PIOC. SOC.E ~ p t l . (20) WILLIAMS, Biol. Med., 58, 265 (1945). D. G., A. R. TAYLOR, I. W. MCLEAN, D. BEARD, (21) SHARP, AND I. W. BEARD. Science.. 100. 151 (1944): .. 1. B i d . chem:. 159,29 (1945). M. A., 1.A m . Chem. Soc., 66; 1195 (1944). (22) LAWFFER, (23) KNIGHT,C. A., I . EZpt1. Med..BO, 83 (1944). (24) LAuaaEn, M. A., AND H. L. CARNELLY, Arch. Biochem., 8,
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(25) LAUWER, M. A., AND E.M. SCOTT, aid., 9,75 (1946). SOC.Exptl. (26) FRIEDEWALD, W. F., AND E. G. PICKELS, PIOC. B i d . Med., 52,261 (1943); 1.Exptl. Ned., 79,301 (1944). (27) SHARP, D. G., A. R. TAYLOR, I. W. MCLEAN, D. BEARD, AND J. W. BEARD, J. Biol. Chem., 156, 585 (1944). W. M., Chen. Eng. News, 24,755 (1946). (28) STANLEY, (29) Army Influenza Commission, I.Am. Med. Assoc., 124, 982 (1944); Am. I . Hyg.,4Z, 1,12,21,28,45,57,94 (1945). AND W. F. FRIEDEWALD, (30) HIRST. G. K., E. R. RICKARD, J . Exptl. Med., 80,265 (1944).
