Autopsy studies of urinary schistosomiasis have clearly shown that the disease (anatomic and physiologic derangements) caused by Schistosoma haematobium has a biphasic progression. The “active” phase is characterized by active oviposition in the lower urinary tract with consequent egg excretion in the urine and bulky inflammatory masses. After oviposition declines or ceases, calcified eggs in fibrotic masses persist as does the sequela, obstructive uropathy, but significant numbers of eggs are not excreted in the urine; this is the chronic “inactive” phase of the disease. Autopsy studies indicate that the presence of schistosomal obstructive uropathy is directly related to lower urinary tract egg burden, regardless of the phase of “activity” of the disease.
The authors of the recently published article, “Evaluation of schistosomal morbidity in subjects with high intensity infections in Qalyub, Egypt,” have acknowledged this biphasic nature of urinary schistosomiasis in their population-based clinicoepidemiologic study.