Lungs

Radiological abnormalities in the chest are uncommon in patients infected with S. haematobium, despite the fact that S. haematobium eggs are found about twice as frequently in the lungs as S. mansoni eggs. In a previously reported personal series of over 15,000 patients of all ages, of whom at least 70% were known to be infected with S. haematobium, and all of whom had chest x-rays, there was not one patient in which a diagnosis of pulmonary schistosomiasis was entertained. In a similar smaller series reported from Zambia (Northern Rhodesia) of 255 cases, all known to have bilharziasis and all under the age of 30 years, there were no abnormal pulmonary findings. And yet it should be emphasized that, pathologically, every second case will show ova in the lungs.

Radiologically there are three distinct patterns which, although rare in clinical practice, may be significant. The first, the Katayama syndrome (Fig. 2.28 A), has already been described and the radiological changes in S. haematobium at this stage are identical to those of S. mansoni.

The second pattern is the reaction around the larvae either when they embolize a small vessel or die during treatment. This is a local immune reaction similar to others in the Loeffler syndrome. There is likely to be a peripheral blood eosinophilia. There will be scattered hazy foci of consolidation in both lungs, changing in both size and position at short intervals, and without any specific distribution. There is not likely to be any long-term result. There is no lymphadenopathy (Fig. 2.58).

The third pattern is often found by chance in the elderly patient when a routine chest radiograph shows a pattern of fine, generalized interstitial fibrosis, distributed equally throughout both lungs (Fig. 2.28 B); it is nearly always symmetrical and not confined to the lung bases. There are no abnormal clinical findings and in most patients the degree of dyspnea is no more than would be expected from the patient's age. The cardiac outline is normal and there is no cor pulmonale or clinical cyanosis. The microscopic findings are those of diffuse fibrosis with numerous eggs in the peribronchial regions; emphysema is not a marked feature. Even in endemic areas this is uncommon, but when seen it is typical, as is the striking disparity between the obvious radiological findings and the lack of clinical disability. Eventually, pulmonary hypertension and cor pulmonale may develop but in S. haematobium this is a later change compared with more rapid deterioration in S. mansoni infections.

Bilharziomas caused by S. haematobium do not appear to have been reported. It must be emphasized that the vast majority of patients with S. haematobium infections, even if lifelong, will have normal chest radiographs.

Fig. 2.28 A, B. S. haematobium does not prominently affect the lungs, but may be seen at quite different stages: A Katayama stage of an acute S. haematobium infection. This young adult had not previously been exposed to schistosomiasis when he bathed in a Central African lake 4 weeks before this radiograph. The day after swimming he noticed that his arms were "sun burnt" and 3 weeks later he developed an irritating cough and felt ill. He had a low fever and a poor appetite, and his blood showed a 20% eosinophilia. The chest radiograph shows an increase in vascular markings with a faint nodular pattern throughtout both lungs; the hila are prominent. There were no focal lesions and the findings were transient. There was an immediate clinical response to anti-schistosomal therapy and his chest radiograph returned to normal. B In the late stage of schistosomiasis the appearances are quite different. This elderly Zimbabwe African was known to have had S. haematobium infection for most of his life. He came to hospital because he fractured his leg; he was a little short of breath. Both lungs show marked interstitial fibrosis and there is enlargement of the main pulmonary arteries. Pulmonary hypertension has many causes and there is no way to distinguish schistosomiasis, nor, at this stage, will specific therapy have any effect.