1352 TSUTSUGAMU$HI FEVER AND ALLIED FEVERS 



red or orange in colour, is so small that it is almost invisible to the 

 naked eye, is found in large numbers on the inner surfaces of the 

 ears of field-mice [Arvicola natanedzumi Sasaki) caught in July 

 and August in the infected regions. The akamushi of other regions 

 do not cause the disease, which, of course, is against the chemical 

 theory as to the aetiology. Miyajima claims to have infected 

 monkeys by inoculating blood derived from a person suffering 

 from the disease, and also by the bites of the mites. Mice and 

 guinea-pigs are said to be immune — a statement which, however, 

 is opposed by Ogata. The larva has been reared and adult mites 

 obtained by Nagayo, Miyagawa, Mitamuar, and Imamura, as well 

 as by Miyajima and Okumura. The last-named suggest that the 

 correct name for the mite is Leptus akamushi (Brumpt). 



Only poor people enter the infected lands during the months of 

 July to October, and as any person who does so is liable to infection, 

 the disease is mostly found among the poor. 



Pathology.— The post-mortem reveals a small ulcer, sometimes 

 still covered by an eschar at the site of the bite, and enlargement 

 of the proximal lymphatic glands. The spleen is enlarged and 

 softened, the lungs are oedematous and congested, and the bronchial 

 mucosa is often slightly swollen and reddened, and the kidneys are 

 inflamed. We are not acquainted with any description of the 

 histology of the organs. 



Symptomatology. — ^The incubation period varies from four to 

 ten days (4-7 Scheube), during which there may be a feeling of 

 prostration, giddiness, and general malaise, but definite prodromata 

 are wanting. 



The disease begins with a chill and rigors, accompanied by 

 severe pain in the forehead and temples, and a sensation of weak- 

 ness, while the temperature quickly rises to 101° to 103° F. The 

 patient usually complains of pain in certain enlarged lymphatic 

 glands, which, on inspection, are found to be tender, quite distinct 

 from one another, and freely movable under the skin. A search 

 in the region drained by these glands may reveal a circular vesicle 

 measuring 2 to 4 millimetres in diameter, but more usually one or 

 more black or brownish necrotic areas of skin, surrounded by a 

 dullish red areola, are found. These areas indicate the sites of the 

 bites of the mite. 



The temperature continues to rise during the next few days, 

 reaching a maximum in the second week, when it may be as high 

 at 105° F. During this time the eschar has been thrown off the 

 necrotic area, and reveals a circular punched-out ulcer, the peri- 

 phery of which is red and infiltrated, but not painful nor tender. 

 About the fifth to the seventh day an eruption appears on the 

 face in the form of large red papules, which may become confluent 

 on the cheeks, giving the face a swollen appearance. From this 

 situation the eruption spreads all over the body, but more in the 

 form of macules than papules. These maculae, which are 2 to 

 5 millimetres in diameter, fade on pressure, but quickly return 



