INSECTS AND HUMAN DISEASE 141 



TICKS AND HUMAN DISEASE 



That ticks, by their bites, could cause disease in human 

 beings has been known for more than two hundred years. 

 Drury, in an account of a visit to Madagascar, 1702-1720, 

 said that very few people would enter the dwellings of the 

 Vazimbas because of an insect called "Poroponjy" by the 

 natives. This insect, which resembles a cattle tick, was 

 only found among the Vazimbas, who held it in some 

 esteejn, because the fear of it prevented a neighbouring 

 tribe, the Sakalaves, from entering their dwellings. A 

 bite from this tick entailed an illness of six weeks to 

 two months' duration. Livingstone first described "human 

 tick disease " in Portuguese East Africa, and at the present 

 day tick fever, clinically identical with relapsing fever, 

 occurs in the Oriental province of Congo Free State, and 

 is well known and feared by the natives. 



The actual cause of the disease is a spirochaete, that is 

 to say, an exceedingly minute, spiral, thread-like organism. 

 When spirochaetes are numerous, they can easily be seen 

 in rapid motion in a blood preparation from an infected 

 patient. These blood parasites are transmitted by a tick 

 known as Ornithodorus moubata (fig. 40), which the natives 

 call " Kimputu." Concerning them, Livingstone says : "Be- 

 fore the Arabs came bugs were unknown. . . . One may 

 know where these people have been by the absence or pres- 

 ence of these nasty vermin." The explanation is probably 

 that the natives live in mere temporary abodes, and for 

 varied, and often trivial reasons, they will strike camp and 

 found a village elsewhere, whilst the Arabs, on the other 

 hand, construct more substantial dwellings and live in per- 

 manent villages. In these houses the ticks are to be found 

 in the cracks of mud floors, in odd corners where dust has 

 collected, in thatched roofs, near the hearth, and especially 

 just inside the doors where the natives are in the habit of 

 sitting. The ticks have entered the Oriental province with 



