204 DISEASES OF UNKNOWN ETIOLOGY 



case is probably infectious for three weeks after onset, so 

 that disinfecting measures should be continued for that 

 period. There is reason to believe that cases are infectious 

 before the disease becomes recognizable, thus making an epi- 

 demic difficult to control. There is as yet no reliable specific 

 treatment. The only laboratory test consists in finding in the 

 cerebrospinal fluid an excess of a certain organic substance 

 called globulin and a very small increase of cells. 



Mumps. This is an acute inflammatory infectious disease 

 of the salivary glands, the cause of which is not known. It 

 is disseminated by direct contact, and the virus is in the 

 saliva. 



Other Diseases. Other diseases which human beings may 

 contract due to invisible viruses, are foot-and-mouth disease 

 of cattle, dengue, beriberi, and pellagra. Nearly all of these 

 viruses are small enough to go through a porcelain filter. It 

 may be said in general that to protect one's self from the 

 infection the local lesions and skin eruptions should be 

 disinfected. 



Acute Articular Rheumatism. The modern conception of 

 this disease is that it is an acute infection. Many bacteria 

 have been described as its cause, but their defenders have not 

 built up unanswerable arguments in their support. The 

 theory now holding the stage is that a streptococcus called 

 Streptococcus rheumaticus enters by the tonsils, penetrates to 

 the blood stream, and settles in the joints. Certain it is that 

 we frequently have streptococcus sore-throat associated with 

 acute rheumatism, and that the inflammations of the heart 

 lining after this disease are frequently streptococcal. 



Impetigo Contagiosa. This is an acute pustular eruption 

 of the skin, thought, but not proved, to be due to the pus 

 cocci. Some observers maintain that a protozoon is the cause. 

 At all events pus cocci, both streptococci and staphylococci, 

 are present. The lesions are at first pustules, but soon break 

 down to flat ulcers. They occur chiefly upon the face. The 

 disease is transmitted by direct intimate contact, such as 



