The fevers in this group are characterized by definite peculiarities by which they may be classified under one clinical head.
These fevers are relatively less frequent to tropical and subtropical regions than to temperate climes, where they usually occur alone. In tropical and subtropical countries they appear in their pure form only in the cooler half of the year, especially at the beginning of spring; while in the temperate climates they occur as primary infections even in summer and autumn.
They are characterized clinically by paroxysms, which adhere to a pretty definite type: in other words, they belong among the typical intermittent fevers. At the beginning of the disease a remittent or continued fever may occur, from which the typical paroxysms eventually develop, though this is only exceptional. The paroxysms are usually well developed and show three stages that are readily differentiated. These fevers extremely rarely manifest a pernicious character, and are almost never fatal unless as a result of complications.* At the acme of the paroxysm, suggestions of serious symptoms may arise, but they quickly disappear.
The treatment of these fevers is very satisfactory. Quinin acts promptly, as a rule, in twenty four to forty eight hours. Relapses occur, but are much less frequent than in fevers of the second group, and usually appear to be due to insufficient therapy or new infection. As a result of the characteristic symptoms of this infection the clinical picture presented by it is quite monotonous. The different organs participate in a regularly mild way and no local phenomena are to be anticipated. Moreover, the diagnosis is usually very easy, and is, as a rule, recognized by the patient or his friends.
* Although Torti, in his communication to Mercatus (loc. cit., Lib. ii, Cap. II, Scholium 1), affirms that not only the tertian, but even the quartan, may become pernicious, this is only an apparent contradiction of the standpoint which we have taken. When Torti spoke of the quartan becoming pernicious, he meant that it might become so after being transformed into a continued. This is evident from the following (Torti, Lib. iii, Cap. i): " Primo necat hominem perniciosa intermittens potissimum tertiana (quartana etenim, aliave intermittens rariuscule in primo membro nostrse divisionis locum habere solet, ssepius vero in secundo, ubii ad continuitatem vergat et ad acquirendam acutiem)....."