SYMPTOM A TOLOGY 



1379 



presenting but few symptoms, and very liable to be overlooked, or 

 the attack may be ushered in by some other fever — as, for example, 

 malaria or dengue. We will first describe a typical attack with 

 mild or severe symptoms. 



Incubation. — The incubation period of enteric fever ranges in its 

 known extremes from three days to twenty-three days, or much 

 longer. The shortest known period— that is to say, the one with 

 three days' incubation — was exceptional, the infection being due to 

 swallowing a culture of virulent bacilli, and therefore it may be 

 excluded for ordinary purposes. It is by no means easy as a rule 

 to define the incubation period, and it is usual to agree with Murchi- 

 son, and to state that it is most commonly about two weeks (ten to 

 fourteen days), but that it is often less than this, and may possibly 

 be as short as four or five days; while, on the other hand, it is often 

 longer, and no definite maximal limit can be mentioned, because 

 the study of typhoid carriers has demonstrated that persons, appar- 

 ently in good health, may be infected with the bacillus, and it has 

 further been shown that these people may suffer from auto-infection, 

 all of which naturally complicate the question of the duration of 

 the period of incubation. 



We therefore conclude that the usual incubation period for enteric 

 fever is about two weeks. 



During this period the patient may apparently show no signs or 

 symptoms of the disease, though at times headache and general 

 malaise may be felt. 



0?^s^^.— Typically the onset is gradual, the patient attending to 

 his ordinary duties, though suffering more markedly from the 

 feeling of malaise and lassitude and from headache than during the 

 period of incubation, and associated with these symptoms there 

 may be constipation, or there may be diarrhoea with pains in various 

 parts of the body, but especially in the back, the iliac regions, or 

 the legs. At times there is a troublesome cough. The disinclina- 

 tion for exertion, mental or bodily, increases, as does the headache 

 and the pains, until the patient feels so ill that he consults his 

 medical attendant, when it is found that the temperature is raised 

 above normal (100° to 101° F. in the morning) ; that it is higher in 

 the evening (103° to 104° F.) than in the morning; that the pulse, 

 though accelerated (80 to 90 per minute), is relatively slow as com- 

 pared with the temperature, and may be dicrotic ; while the tongue 

 is coated on the dorsum, though red at the tip and along the margins; 

 the headache is generally frontal, and there may be thirst, vomiting, 

 or epistaxis, as well as abdominal tenderness and slight distension, 

 especially in the right iliac region. If the case is observed early, 

 a step-like rise of the temperature may be noted — that is to say, the 

 evening temperature is always slightly higher than that of the pre- 

 ceding evening — while the morning remission is less, until about the 

 third or fourth day, when the temperature reaches 103° to 105° F. 

 at night. 



The onsret, however, is often atypical in the tropics, the symptoms 



