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War Surgery and Medicine

CHAPTER 13 — Pyrexia of Unknown Origin

page 574

Pyrexia of Unknown Origin

AN inquiry was made in August 1943 by Colonel J. R. Boyd into the relative frequency of the non-committal ‘diagnosis’ PUO. The term was essentially a provisional diagnosis which lasted only until such time as the correct nature of the illness had been elucidated by clinical examination. It was a handy way of classifying many fevers which, in the early stages, might resemble any one of many different feverish conditions, and where an early definite diagnosis would be largely guesswork. There were two main groups.

The first group was a comparatively large one and was made up of all those short-term fevers whose onset and clinical course presented no special distinguishing features and where the whole illness was over and recovery complete in a matter of perhaps twenty-four to ninety-six hours. These cases were held and treated in forward medical units and returned direct to duty without further evacuation down the line. The provisional diagnosis thus became the final diagnosis and was registered accordingly in the Field Medical Card 3118.

The second group consisted of those cases which remained feverish for more than four or five days. Some more serious condition had to be thought of and they were evacuated to the base hospital for investigation. They represented a considerable number, but in most of them diagnosis was readily made with the facilities available in hospital. The minority were the unexplainable few who remained undiagnosed after the exhaustion of almost every accessory aid to diagnosis.

In our base hospitals we made it a rule not to give a definite name to any case of fever unless and until clinical evidence completely justified the diagnosis. Furthermore, it was our practice in all such cases never to make a final diagnosis of PUO without having first excluded, by repeated physical examinations and the help of all relevant laboratory tests, malaria, relapsing fever, the enteric group of fevers, tuberculosis, meningitis, and septicaemia. Influenza was usually fairly easily excluded.

It was said that sandfly fever had to some extent taken the place of PUO as a ready diagnosis, and that in this way the total cases page 575 of PUO registered were less than they should have been. This affected the position in two ways, and it was possible that the one cancelled out the other. It had to be admitted that not infrequently an early diagnosis of sandfly fever had to be corrected later on in the light of fresh evidence, and this lent support to the contention that the diagnosis might have been too readily made. As a matter of fact the clinical picture of sandfly fever was not just as clean-cut and easy to distinguish with certainty as textbooks depicted it. Nevertheless, the converse was also probably true. Except in the presence of an epidemic, many medical officers hesitated to diagnose sandfly fever, preferring to label the case PUO. Colonel Boyd was inclined to think that the boot was on the other foot, and that the majority of the short-term fevers which recovered before diagnosis was made were, in fact, cases of phlebotomus fever (sandfly fever).

In 2 NZEF, between June 1941 and December 1942, a large number of cases of PUO were dealt with in forward medical units.1 Some 364 of these were able to return direct to their units without being evacuated farther than to a Field Ambulance or Casualty Clearing Station. The diagnosis of PUO was registered on the Form 3118 and was the only diagnosis. Of a considerable number whose illness was of sufficient duration or severity to make evacuation to hospital advisable, only in 25 was it found impossible to make a diagnosis, and the final diagnosis remained PUO.

Of the 364 cases returned to their units, 44 had blood films examined by a mobile laboratory unit with negative findings. In 47 per cent the fever lasted approximately three days; in 49 per cent approximately five days, and in only 4 per cent did it last longer than five days.

Eighty-five per cent of the cases occurred during the summer months, June to October. The incidence thus appeared to be seasonal, and suggested a relationship to atmospheric temperature and insect life. The incidence in different units appeared to be fairly evenly distributed.

Clinical Features

Three-day Fever: The onset was usually sudden with generalised aches and pains; frontal headache; soreness of the eyes or pain on lateral movement of the eyes. Severe backache was not infrequent, and sweating was common.

Five-day Fever: The symptoms were very similar, but the course was more prolonged, and loss of appetite was more complete.

page 576

Although a few blood films were examined to exclude malaria and relapsing fever, only a very few white blood counts were done. Although the impression was that leucopenia was the commoner finding, the estimations were too few in number to permit of any definite conclusions being drawn.

Over five days: In those cases where the fever lasted over five days, some were six, some eight, and some ten-day fevers. There was nothing distinctive in the clinical features, but the patients were more ill. Some looked almost like cases of typhoid, but suddenly the illness came to an end.

In none of the three groups was there any respiratory symptoms, and this was one of the main features which differentiated these short-term fevers from influenza.

In only 2.7 per cent of the cases was the spleen palpably enlarged. In none was neck rigidity a feature.

The cases which had to be evacuated to hospital, and in which a diagnosis was made later, consisted of a great variety of different conditions. The commonest were otitis media, sinusitis, prostatitis, pyelitis, rheumatic fever, catarrhal enteritis, bacillary dysentery and infective hepatitis.

Of the 25 cases which remained undiagnosed when recovery was complete, 5 were well by the time the base hospital was reached, and in another 5 the temperature became normal before time permitted full investigations to be made. In these cases only blood film examinations and white blood counts had been done.

In the remaining 15 the fever, calculated from the day of admission to hospital, lasted from seven to twenty-five days, and in one case there was intermittent fever for seven weeks. In each of these cases full investigations were made: repeated blood films; total and differential blood counts; agglutination reactions; cultures from blood, stools, urine; sedimentation rate; and, where indicated, the chest was X-rayed, the histamine test and icterus index done, and in some the Weil-Felix test.

Complete physical examinations were repeated regularly. One feature which the cases all had in common was a leucopenia with a slight relative diminution of polymorpho-nuclear cells. The total count was in no case higher than 7200. The usual was about 4000–5000 with 50–60 per cent of polymorphs.

In such cases it seemed clear that we should continue to adopt the honest course of making no definite diagnosis and that the term PUO was the most fully descriptive one.

In 2 NZEF in the period July 1941 to December 1945 there were 2848 admissions to medical units with a diagnosis of PUO, and these made up 3.55 per cent of all sick admissions.

1 It was not possible to obtain accurate figures of the total number.