Lactase deficiency in patients with intestinal schistosomiasis.

Sixty patients having schistosomiasis mansoni infection were studied for lactase deficiency by different methods including lactase assay in intestinal biopsies. Thirty patients suffering from simple intestinal (Group I) and 30 patients suffering from hepatointestinal (Group II) schistosomiasis were compared to 60 controls (Group III). Lactase deficiency was evaluated by symptoms of lactose intolerance, stool pH and osmolarity, oral lactose tolerance test (OLLT), oral lactose hydrogen breath test (OLHBT) and lactase activity (LA) in small intestinal biopsies. OLTT showed intolerance in 36.7% of Group I and 40% of Group II compared to 23.3% of the controls. OLHBT showed intolerance in 26.7%, 30% and 18% for the three groups respectively, indicating a significance in Groups I and II. Abdominal symptoms of hypolactasia had higher scores in the patient groups compared to the controls, and was even higher in Group I than Group II. The mean lactase activity measured by micromol/gm wet wt/min was not statistically higher in Group I but higher in Group II than the controls. No correlation was found between lactase activity in the mucosa and the symptoms of hypolactasia in Group I. Hence, other factors in intestinal schistosomiasis may affect lactose hydrolysis. The study showed also that OLHBT is the most sensitive, specific and efficient among the non-invasive tests.