MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 859 



and severe pains in the muscles and joints. The fever during the attack 

 shows a characteristic curve. There is a sudden rise of and main- 

 tained temperature for several days. Then a remission and a second 

 rise of temperature which is less than the first. 



Our knowledge of the cause of this disease rests chiefly upon 

 researches of Ashburn and Craig.* These authors conclude that 

 dengue is not contagious in the ordinary sense but that it is transmitted 

 through the bite of the mosquito (Culex fatigans). No visible organ- 

 ism could be demonstrated in either fresh or stained specimens of 

 blood from patients affected with dengue although such blood was 

 capable of producing a typical attack of dengue when inoculated 

 intravenously into healthy men. The authors likewise show that 

 blood from a case of dengue retained its infectiveness after passage 

 through a filter made of diatomaceous earth. 



FOOT-AND-MOUTH DISEASE! 



Foot-and-mouth disease is primarily a disease of cattle, though 

 the other domestic animals and man may be attacked. The disease 

 is very contagious and is characterized by the eruption of vesicles in 

 the mouths, on the udders and on the skin surrounding the hoofs of 

 cattle. It is very prevalent in European countries. There have been 

 three outbreaks in the United States all of which were promptly eradi- 

 cated by vigorous repressive measures instituted by the Federal 

 authorities. 



The cause of this disease is an invisible microorganism which exists 

 in the lymph from the vesicles which form in the mouths and on the 

 feet of cattle. This virus has never been cultivated artificially. It 

 passes through the Berkefeld cylinder but not through the finer-pored 

 Kitasato filters; it is quickly destroyed by formaldehyde, carbolic acid 

 and similar disinfectants. 



The disease is readily transmitted from one animal to another by 

 contact and the contagion may persist for some time in the manure, or 

 straw from infected stables. The milk of infected cows has been said 

 to produce the disease in children. 



Animals which recover from an attack remain immune for a short 

 time only; it is therefore not surprising that no satisfactory means of 

 artificial immunization has been devised. 



* Ashburn, P. M. and Craig, C. P.: Jour. Inf. Dis., Vol, IV, p. 440, 1907. 

 t Prepared by M. Dorset. 



