CAUSING ACUTE INFECTIONS. 81 



way of the respiratory tract, and the symptoms of the 

 disease manifest themselves after an incubation period 

 of three to seven days. The symptoms following in- 

 fection through the skin are characterized by headache, 

 high fever, stiffness in the limbs, restlessness, and 

 anxiety. Collapse frequently follows. The lymphatic 

 glands are enlarged, particularly those in the inguinal 

 region, which are called buboes. Infection by way of 

 the respiratory tract begins abruptly with pneumonia. 

 The mortality rate for this disease is very high, 80 

 to 90 per cent. 



The bacilli of the plague are present in the swollen the disease 



is spread 



lymphatic glands, the sputum, urine, and intestinal 

 discharges, and the infection may be spread directly 

 from these sources. The chief way, however, in which 

 the infection is spread is from the bites of the rat-flea, 

 which transmits the disease from rat to rat and from 

 rat to man. Unsanitary conditions have little to do 

 with the occurrence of the plague, except that they 

 favor infestation with rats. To> prevent the disease 

 from spreading, all patients must be quarantined, all 

 discharges destroyed, and all articles that have come 

 in contact with the patient disinfected. To prevent ways of 

 rats from, breeding, all stables and outhouses should be 

 cleaned up, and all possible sources of food-supply cut 

 off. Dwelling-houses should be made rat-proof as far 

 as possible. The importation of the disease into ports 

 not infected should be guarded against by fumigating 

 ships from infected countries and the isolation of sus- 

 pected cases during the period of incubation. 



