DISEASES WHOSE CAUSES ARE UNKNOWN 447 



which is suffering from the disease. It is a disease of the nerv- 

 ous system and in many respects resembles tetanus or lock- 

 jaw. Although the cause of the disease is not known, Pasteur 

 was able to devise a very efficient treatment which is admin- 

 istered at the various Pasteur institutes to be found in many 

 of the large cities throughout the civilized world. There is 

 plenty of time for the administration of this treatment after 

 the person is bitten by a rabid dog, and no one should fail 

 to take this treatment when bitten, however slightly, by a dog 

 that is supposed to be mad. It has been found that a dog is 

 able to infect a person for a day or two before it shows any 

 signs of the disease. 



520. Whooping Cough. A bacterium resembling that which 

 causes influenza is thought by some bacteriologists to be the 

 cause of this disease but the fact may not yet be said to be 

 fully established. The disease is extremely contagious and 

 a patient is sometimes able to infect others for some time after 

 apparent recovery. The disease is too often regarded as a 

 simple disease and is not avoided as it should be. With very 

 young children or with delicate children, it is often fatal. In 

 1907, 4856 children died of this disease in the United States. 



521. Scarlet Fever and Scarlatina. It is important for 

 every one to know that these two diseases are one and the same. 

 The severest type of scarlet fever may be contracted from a 

 mild case which is sometimes called scarlatina. The disease 

 seems to vary much in its virulence at different times and in 

 the case of different people. 



522. Measles. We have almost no clue whatever as to the 

 organism that causes this disease. It is probably entirely too 

 small to be seen with the highest power of the microscope. 

 This disease like most of the others of this list is subject to seri- 

 ous complications with other troubles and, consequently, the 

 patient needs the very best of care to avoid, if possible, the 

 complications. No one should think of getting along without 

 calling a physician in case of an attack of any of these diseases. 



523. Mumps. There is strong evidence that a certain 



