37 



in type and in course, and recovery is usually rapid and complete, 

 .more so than in the case of either affection separately, 



Hatori (J.)- On the Endemic Tsutsugamushi Disease of Formosa. — • 



Ami. Trop. Med. ParasU., Liverpool, xiii, no. 3, 10th December 

 1919, pp. 233-258, 2 plates. 



The endemic exanthematous fever in the Karenko District of 

 Eastern Formosa has been proved to be related to the tsutsugamushi 

 'or kedani disease of Northern Japan. yf 



The transmitter of the virus is a mite, apparently identical Avith ' ^ 

 the Japanese species, Trombidium {Tromhicula) akamushi, Brumpt. 

 The natural hosts of this parasite include Mils rattus rufcscens (common 

 liouse rat of the island), M. decamanus, M. musculns, M. agmrius, 

 etc., and such insectivores as Grocidura miisehata. Pheasants, 

 chickens and even dogs and cats may be infested by the mite. Human 

 beings are attacked when passing through infested fields or forests. 

 The mite-infested localities are limited to the valleys, uncultivated 

 land covered with tall grass and flat or sloping ground covered with 

 thick forest. Mites from the ear of an infested rat were noticed 

 to leave the host when fully fed and enter the soil, where they moult 

 and transform to nymphs. An attempt to develop these nymphs 

 on vegetable matter was unsuccessful. The mites probably acquire 

 the virus in the adult stage and transfer it to their offspring. The 

 spread of the mites is chiefly due to tlie migration of their hosts, 

 such as rodents, etc. 



Larvae of another species were found in certain fields living freely 

 on grasses. This species has been provisionally named Tromhicula 

 pseudoakamuslii (non Tanaka) by the author, as he considers it a 

 new species, although Prof. Miyajima believes the larva to be identical 

 with the European Leptiis aninmnalis and the adult with Tromhicula 

 mediocris, Berl., of Java. It apparently does not infest man. 



The causative virus of the disease is probably of ultra-microscopic 

 nature, as no organism has been isolated. The fever usually appears 

 in April and persists till July, after which it declines, rising again in 

 October and subsiding in November. Immigrants are apparently 

 more susceptible to the virus than the natives. Experiments with 

 animals show that some species of indigenous monkeys are definitely 

 susceptible to the virus either tlirough inoculation of a patient's 

 blood or through bites of the mites in an infected field, whereas others 

 seem resistant ; this is probably due to an immunity arising from 

 attack in their previous habitat. 



Comparisons are made between the Japanese and Formosan 

 tsutsugamushi disease and allied endemic glandular fevers; The 

 clinical aspect and treatment of the disease is discussed. Preventive 

 measures include complete protection of the body when traversing 

 mite-infested areas and thorough disinfection of all clothes prior 

 to entering dwelhng houses. Cleanliness is essential, and the body 

 should be well examined after field work for red spots, wliich must 

 either be excised or the mite removed from the centre with a needle. 



The infested areas should be cleared by burning, and brought under 

 cultivation. All inhabitants of infested territory should be educated 

 as to the nature of the disease and its transmitter. 



