_Symptoms._—These differ a little in different parts of the world. The incubation period is usually from five to ten days. The onset is remarkably sudden. The patient has a chill or shivering fit, becomes giddy, develops a bad frontal headache, feels as if he had been beaten all over, and frequently vomits. He has often a difficulty in walking, and soon becomes seriously ill. Delirium is not infrequent. The tongue, unlike that in typhus fever, remains moist throughout the illness. Thirst, restlessness, and vomiting are very characteristic of the condition, and the urine is scanty. As a general rule recovery takes place, but sometimes the patient grows gradually worse and dies. As a rule, however, the temperature falls very suddenly, and the patient is better. After a week or so a relapse occurs. The temperature again shoots up, and remains up for several days. Then there is a second crisis, another relapse, and so on for perhaps three or four times. Most cases recover, and once convalescence is established the patient soon gets well. _Prophylaxis._—The disease being lice-borne, it is necessary to take all steps to prevent contact with these insects (see _Lice_, p. 196). The organism has been shown to be capable of passing through intact mucous membranes and unbroken skin. Hence it is advisable to be careful when attending a case, for the organism has been found in sweat and tears, while the patient’s blood is, of course, infectious. _Treatment._—Careful nursing and a light diet. Attend to the state of the mouth and of the bowels. The arsenic preparation, known as salvarsan (kharsivan), is a specific remedy, and can cut the disease short; but it can be administered only by a medical man. Otherwise there is no treatment save the symptomatic. _Rheumatism._ This is a disease which frequently follows exposure to damp and cold, and is on that account not uncommon in the tropics. It is often hereditary. After one attack, rheumatism is always liable to recur in the same individual, and on this account it is necessary that persons liable to the disease should use special precautions. _Acute rheumatism or Rheumatic Fever._—This is really an infectious disease due to a specific organism, and is quite different from the ordinary rheumatism of everyday life. _Symptoms._—It begins by a shivering fit, with rise of temperature and general sickness, and the joints, usually wrists, ankles, or knees, become painful, tender, and afterwards swollen. It resembles other feverish conditions in the rapid pulse and breathing, the constipation, scanty and high-coloured urine, etc., but it differs from most of them in the presence of a profuse and sour-smelling perspiration, resembling the odour of butter-milk.