THE LATENCY OF AFRICAN COAST FEVER. 



By E. M. Jarvis, F.R.CA^S. 



African coast fever was imported into South Africa by way 

 of the sea and railway into Southern Rhodesia from German 

 East Africa in the year 1901. 



Certain dealers purchased cattle in the German hinterland, 

 and brought them down to the coastal portions. They had not 

 been there very long before a heavy mortality ensued, when 

 the owners thought it time to realise, so they commenced to 

 ship the animals down the East Coast of Africa, discharging 

 some at Beira. Eighty-two head were sent by train to Southern 

 Rhodesia, of which number half were off-loaded at Umtali, and 

 the other half were sent to Salisbury. 



From these two centres the disease was carried by ox trans- 

 port — (a) to Melsetter, Inyanga, and thence to Rusapi, ( //) to 

 Mazoe, Alarendellas, Charter, Gwelo ; from thence in two direc- 

 tions, ( I ) to Selukwe and Victoria, ( 2 ) to Bulawayo, Mzingwani 

 and Gwanda. In fact, the white settled portions were mainly 

 affected, and were more or less devastated of their cattle by the 

 disease in 1901, 1902, and 1903. 



An interval of desultory outbreaks followed, and then the 

 disease almost disappeared until four years ago, when apparently 

 unaccountable recrudescences took place. 



The writer has noticed that these reappearances have the 

 following characteristics : — 



( I ) They re-occur over the line of the original invasion. 



(2) That remnants of herds from former outbreaks were 

 invariablv amongst the cattle in which the disease recrudesced. 



(3) Tliat the disease was usually first detected in the 

 calves. 



(4) That in nearly every instance the outbreak was pre- 

 ceded bv two or three cases of indefinable fever, blood smears 

 from v/hich proved to be without visible evidence of, or to 

 contain a few, protozoal bodies found in the lymphocytes, but 

 without recognizable characters. 



(5) That eventually, usually upon the fourth case, which 

 occurred some weeks later, positive microscopical evidence of the 

 parva with intense invasion of the erythrocytes was forth- 

 coming. 



( 6 ) That the year was divided by periods of — ■ 



(a) Prevalence. 



(b) Quiescence. 



(7) That the appearances and disappearances of the Koch's 

 bodies were likewise periodical. 



(8) That the Koch's bodies were present in greater or lesser 

 numbers, de]:)ending on the time of year. 



(9) That the examination of the gland-puncture smears 

 would first be positive, later negative, showing tliat the Koch's 

 bodies tended to disappear in the same animal. 



