PREVENTIVE MEDICINE 261 



eased to healthy horses is no doubt largely brought about by the in- 

 discriminate use of grooming tools and harness, the organism being 

 abundantly present in the pus from the lesions. Many observers 

 regard flies as being important agents in the spread of the disease. 

 The existence of the cryptococcus is largely maintained by the 

 insidious nature of the malady. The period of incubation is as a 

 rule very prolonged, e.g., Perrin* noted that in 5 cases the average 

 period was 118 days, and Drouin believes that it is never less than 

 three months. It is thus easily understood how new centres are 

 established by the sale of apparently healthy but in reality infected 

 animals. The disease is not as a rule fatal, though the duration in 

 untreated animals is very long. Cases are generally slowly pro- 

 gressive, and tend to recur after apparent recovery. The crypto- 

 coccus is very resistant to destructive agencies, and especially to 

 chemical disinfectants. There is reason to believe that discharges 

 in a stable may maintain their virulence for at least a month, f 



PREVENTIVE MEASURES. Any cases of the disease occurring 

 in Great Britain have by law to be destroyed. Prevention of this 

 disease calls for a vigorous attitude on the part of the hygienist 

 due to the prolonged incubation period, the resistance of the 

 organism to ordinary antiseptics and to the tendency of the disease 

 to recur. After the destruction of cases diagnosed a very close 

 watch upon contacts is necessary. The stud cannot be declared 

 free until six months after the infected animals have been destroyed. 

 Greatest care must be exercised in disinfecting grooming tools, 

 clothing, &c., as pointed out by Olver. $ Heat should be the disin- 

 fecting agent used, as the organism is so resistant to disinfectants 

 of a chemical nature. Sponges must not be used, and in hospitals 

 it is important to forbid the indiscriminate use of swabs and anti- 

 septic fluids ; all such should be discarded after first use. To pre- 

 vent introduction from countries in which the disease occurs animals 

 should be carefully examined at the port of entry. 



The two following diseases bear in some degree a resemblance 

 to epizootic lymphangitis and to farcy in their clinical characters, 

 though not as a rule so severe and in no case so serious from the 

 point of view of the hygienist. 



1. ULCERATIVE LYMPHANGITIS OR ULCERATIVE CELLULITIS. 



Due to the bacillus of Preisz-Nocard, which chiefly affects equines 



but is also met with in various lesions in other animals, e.g., caseous 



pneumonia of sheep. It is also encountered at times in other skin 



* Trap. Vet. Bull., 1917, Vol. V., p. 183. 



t Report, C.V.O., Bd. of Agric., 1905. 



t Wallis-Hoare, Syst. Vet. Med., 1913, Vol. I., p. 1300. 



