CHAPTER XXXVII

TSUTSUGAMUSHI

DEFINITION AND SYNONYMS

=Definition.=—This is an acute febrile disease caused by the bite of the larval Kedani mite of the region where the infection prevails. The onset is characterized by headache and giddiness, a rather rapidly rising temperature and swelling of the lymphatic glands draining the region in which is situated a small necrotic ulcer marking the site of the bite. With injected conjunctivae, continuous fever and hyperaesthesia, the disease goes on for about a week when a macular eruption appears about face, then chest, extremities and trunk. About ten days after the appearance of the eruption there is a fall of fever by lysis.

[Illustration: FIG. 139.—The Kedani mite. _Trombidium akamushi._ (From Ruge and zur Verth.)]

=Synonyms.=—Flood fever, Japanese River fever, Kedani mite disease. Shimamushi.

HISTORY AND GEOGRAPHICAL DISTRIBUTION

=History.=—There are records which would indicate that the disease has been known for more than 1000 years.

=Geographical Distribution.=—It is only in the western part of the island of Nippon, when the banks of the Shinanogawa are inundated each spring, that we find the disease. The disease is supposed to be confined to Japan although Ashburn and Craig have thought a disease observed by them in the Philippines as possibly identical.

ETIOLOGY AND EPIDEMIOLOGY

The cause is unknown, but has been attributed by some to various bacteria and by others to a protozoon.

Nagayo attaches importance to piroplasm-like forms found in the spleen and lymphatic glands.

Kawamuro and his colleagues could not demonstrate any organism by any method of examination. The virus is in the blood and even as small an amount as 0.001 cc. may infect a monkey although 0.1 cc. is usually required. The virus is present also in the enlarged lymph glands. Heating the blood at 50°C. for 10 minutes destroys the virus. Recently Hayashi has reported as cause minute rod, ring-shaped or spheroid bodies which when stained with Giemsa’s stain are brought out in the lymphocytes and endothelial phagocytes of lymph nodes and spleen. They also occur in the blood plasma and in severe cases in red blood cells. He has transmitted the disease to monkeys, guinea pigs and rabbits. These bodies resemble bacteria, in this respect resembling the organisms of typhus and spotted fever of the Rocky Mountains. Hayashi regards the organism as resembling _Theileria parva_ and _Bartonella bacilliformis_, and believes he has shown the field mouse to be a reservoir of the virus.

The disease is not communicable from person to person and only follows the bite of a larval mite, _Trombidium akamushi (Leptotrombidium akamushi)_. This is a minute orange-red arachnoid which can scarcely be seen with the naked eye. This mite is only a source of danger in the region of the inundated river banks, its bite not producing the disease elsewhere.

Persons harvesting hemp during August are liable to contract the disease if bitten by the larval mite.

The mite is found in large numbers on the ears of field mice, these hosts, however, not appearing to be suffering from any particular disease.

PATHOLOGY

Other than the local ulcer and the swollen regional glands, there is little that is definite. The spleen shows enlargement and there is also swelling of the mesenteric glands. The lower part of the ileum may show injection.

SYMPTOMATOLOGY

=A Typical Case.=—About one week after receiving the bite of the larval mite, which may not have been noticed by the patient, there develop chilliness, giddiness and headache, with a rising temperature. In two or three days from the onset, painful glands are noticed in certain regions as of groin, axilla or neck. From these glands we can often by following inflamed lymphatics find the small necrotic ulcer which is often located in the armpit or in the region of the genitals. There is a dark red areola about the ulcer which is only slightly tender. The glands are not very much enlarged and are not excessively tender. There may be general glandular enlargement following that of the primary swellings. The pulse rate is only from 80-100, notwithstanding the rise of the fever to 104°F. or even 105°F.

The body is decidedly hyperaesthetic and the conjunctivae are injected. There is frequently deafness. About the seventh day a macular eruption appears first on the face and then spreads to chest, extremities and trunk. The eruption never becomes petechial. The tongue becomes dry and cracked. There is often a cough. The blood shows a leucopenia. The eruption disappears in from seven to ten days and the fever becomes remittent or intermittent and, after a few days, reaches normal. Parotitis may occur as a complication.

Schüffner has described a similar disease from Sumatra. The mortality is, however, only 3% as against the 30% in Japan. He thinks it is transmitted by a tick. In his cases the necrotic ulcer and glandular enlargements were followed by a roseola which reached its maximum on the eighth to tenth day and was most marked on the trunk and flanks. The nervous symptoms resembled typhoid fever and there was a lymphocytosis.

Symptoms in Detail

_The Nervous System._—There is marked giddiness and headache at the onset. Hyperaesthesia of the body is quite characteristic. There is often delirium at night. Deafness is frequently noted.

_The Cutaneous System._—A small necrotic ulcer about ⅙ inch in diameter, with a dusky red areola, is noted at the site of the bite of the larval mite. The healing of the ulcer is delayed well on into convalescence.

About one week after the onset a dusky macular eruption appears first on the face (cheeks), then going to the chest, legs, forearms and trunk. It is not marked on neck, arms or thighs. It never becomes petechial.

_Fever Course._—The temperature, which on the first day or two reaches only 101° to 103°F., becomes later on higher and continuous. About the tenth day from the appearance of the eruption it begins to fall, becoming remittent and then intermittent.

_The Lymphatic System._—Very characteristic is the swelling of the glands proximal to the initial ulcer. The connecting lymphatics may be inflamed. Later on other glands may show slight swelling and tenderness.

The spleen is usually enlarged.

_The Blood._—There is no change in the red cells but there is a leucopenia.

DIAGNOSIS

In the differential diagnosis the limited geographical distribution should prevent error and, in particular, where one has the initial necrotic ulcer, with enlargement of the glands draining the region in which it is located, there should be little confusion. Of course plague may have a primary vesicle or ulcer with enlargement of neighboring glands; these glands however are matted together and are exquisitely tender.

Then too the eruption of tsutsugamushi and the early and more stuporous state of plague should differentiate, even without the aid of the laboratory.

It is usual to consider tsutsugamushi, typhus fever and spotted fever of the Rocky Mountains as having many characteristics in common. These diseases may best be differentiated by the fever course and eruption as shown in the following table:

------------------+-------------------------+--------------------------- | Fever course | Eruption ------------------+-------------------------+--------------------------- _Tsutsugamushi_ |Fever increases each day |Begins on face, then chest, | until reaching maximum | legs, forearms and trunk. | about 4th or 5th day. | Does not become petechial. | Fall by lysis after | First appears about 7th | fading of eruption. | day. ------------------+-------------------------+--------------------------- _Tabardillo._ |Onset and termination |Begins on abdomen, sides of _Typhus fever._ | of fever characterized | chest, thence going to _Brill’s | by considerable | extremities. Petechial disease._ | abruptness. | tendency. First appears | | about 5th day. ------------------+-------------------------+--------------------------- _Spotted fever |Gradual rise during a |Begins on forearms and leg. of the Rocky | week with lysis. | Petechial tendency. May Mountains._ | | have gangrene of prepuce | | and scrotum. First appears | | on 2d to 5th day. ------------------+-------------------------+---------------------------

TREATMENT

There is no specific treatment. It may be necessary to use drugs to combat the insomnia.

The serum of monkeys which have recovered from the disease seems to have some value.

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