38 



Arachnida 'and Myriopoda 



feature by which it can be distinguished from the closely allied 

 species 0. savignyi, Audouin. The disease called African Eelapsing 

 Fever or Tick Fever, which occurs in East and Central Africa, the 

 Belgian Congo, Angola, and Madagascar, is conveyed by 0. moubata. 

 This fever is caused by a minute spiral protozoon, a Spirochaeta, 

 which makes its way into the blood of the person bitten. 



The spirochaetes are chiefly found in the gut of the tick, and it 

 is supposed by Leishman and also by Hindle that infection takes 

 place through contamination of the wound from the excreta 

 voided by the tick whilst biting. 



The principal symptoms of African Tick Fever are headache, 

 vomiting, pain in the abdomen and purging, high temperature, etc. 



The first attack lasts from 

 two to four days, then the 

 temperature of the patient 

 falls, but there are usually 

 four or five more attacks 

 of fever at short intervals 

 before the disease has run 

 its course, hence the name 

 relapsing fever. Death takes 

 place in about 6 per cent, of 

 those affected by the disease. 

 Very similar diseases are 

 found in Europe, North 

 Africa, Asia, and Central 

 America, but it is not known 

 with certainty how they are 

 spread ; possibly by lice, 

 however. 

 The bite, even of uninfected specimens of this tick, is very 

 painful, causing itching and raised wheals on the skin. Like other 

 members of the family, Omithodoros moubata is very tenacious of 

 life. A number of specimens received from Uganda were kept alive 

 in a glass jar at the Natural History Museum, South Kensington, 

 and although kept without nourishment or fluid of any kind, one 

 of the specimens was still alive and vigorous after fourteen months. 

 The larval stage is inert in this species, being poorly developed, 

 and it is as a nymph that the tick emerges from the egg-shell. 

 After getting rid of its larval skin, this nymph is ready to feed. It 

 casts its skin several times before becoming fully developed, a 

 moult taking place after each meal of blood. The female tick does 



Fig. 17. 



Omithodoros moubata, Murray. 

 (After Castellani and Chalmers.) 



