200 AIDS TO BACTERIOLOGY 



contract the disease, and with birds, rats, and fowls, may 

 mechanically carry infection. 



^Canine Distemper. Bacillus bronchisepticus (M'Gowan) 

 is described as present in the respiratory tract in distemper. 

 In culture a powerful nerve toxin is produced, and the 

 disease simulates infantile paralysis of man. Some cases 

 of distemper, at any rate, appear to have a filterable virus. 



Dikkop (blue tongue or horse sickness) is prevalent up 

 the Blue Nile. The virus is ultra- visible, and appears to 

 be conveyed by mosquitoes (Balfour). 



Sheep-pox. Cockayne says the organism passes through 

 a Berkefeld, but never through the Chamberland F. 



Yellow Fever. Sanarelli's B. icteroides (p. 96), previ- 

 ously supposed to cause this disease, is now regarded as a 

 casual invader. The virus proves to be filterable, ultra - 

 microscopic, and probably a protozoon. A species of 

 mosquito Stegomyia fasciata (calopus) is the transmitting 

 agent, and cannot convey the infection until twelve days 

 after biting a fever patient. The organism must have a 

 life cycle in the mosquito as well as one in man. Research 

 is in progress upon the relationship of the so-called 

 ' Seideliii bodies ' to the virus. Prophylactic measures, 

 aiming at the destruction of the insects and larvae, have 

 proved successful in the highest degree. 



Dengue. Ash burn and Craig passed dengue blood 

 through a porcelain filter, and with the filtrate produced 

 the disease in healthy men after an incubation period of 

 three and a half days. The disease is conveyed by a 

 mosquito, Culex fatigens, Wiedemann, which, after biting 

 an infected person, is not capable of conveying the disease 

 until a week has elapsed. 



Phlebotomus (Sandfly) Fever. The virus passes Berke- 

 feld and Chamberland F. filters. It is conveyed by a 

 sandfly, Phlebotomus pappatasii, which is not infective 

 until a week after biting. 



Mumps. Cocci have been found in this disease by many 

 authors, but Gordon found that in a proportion of cases 

 a virus that passes through a Berkefeld filter occurs in the 

 saliva. 



Variola and Vaccinia (Smallpox and Cowpox). Opinions 

 as to the relationship of these diseases are controversial, 

 the tendency being to regard vaccinia as a modified 

 form of variola. No specific organism can be distinctly 



