Symptomatology
The period of incubation is usually given as from two to three weeks. In the experimentally produced cases of the American Red Cross Commission, the incubation period varied from five to thirty days; thus with intravenous injection of blood it varied from five to twenty days, and with inoculation of scarified areas with louse faeces the period was between seven and eleven days.
The onset is quite abrupt with headache, dizziness and pain on motion of the eyeballs. There is pain also in the back and limbs. The conjunctivae are injected. The fever rises rapidly to 102°-104°F. and falls rather abruptly to normal at about the fourth day. In most of the cases a secondary rise occurs so that we may have a saddle-back type of temperature chart.
The temperature charts tend to be grouped in three classes: (1) Those with a short febrile course of a few days, followed by a fall to normal, with or without a subsequent rise; (2) those with a more or less sustained type of fever, extending over five or six weeks without distinct relapses, and (3) those more typically of a relapsing type, with five or six distinct febrile periods.
In more than one-half of the cases there occurs an eruption of small (2 to 4 mm.) erythematous spots, which disappear on pressure. They are usually located on chest, back or abdomen, appear on the second day of the fever, and fade out by the fourth day. Constipation and anorexia are usually noted. The spleen is often somewhat enlarged. There is frequently a trace of albumin in the urine, but it is not accompanied by casts. The cutaneous hyperaesthesia over the shins is a prominent feature, but the same disturbance of sensation may be complained of over the ulna or fibula. Usually we find a leucocytosis but many cases show a normal white count or even a slight leukopenia. During the apyrexia there is an increase in mononuclear percentage. The pulse is rather slow for the temperature.
Diagnosis
Notwithstanding the intensive study given this disease during the war, we do not seem to have any constant or reliable laboratory test.
In some of the cases where muscle pains of the neck are marked there may be a stiffness of the neck that is suggestive of cerebro-spinal fever. Similarly, pain of the abdominal muscles may cause a suspicion of appendicitis and lead to an unnecessary operation.
The onset of trench fever is very like that of dengue or influenza.
In epidemic jaundice, the occurrence of the jaundice and marked albuminuria should differentiate.