Evaluation of the role of Ancylostoma caninum in humans as a cause of acute and recurrent abdominal pain.

Ancylostoma caninum is responsible for cases with eosinophilic enteritis (EE) and unexplained abdominal pain with peripheral eosinophilia in man. Ninety-five patients with obscure acute or recurrent abdominal pain and ten asymptomatic healthy parasite free were subjected to thorough history taking, clinical examination, sonography, routine laboratory investigations and serotesting by IgG ELISA to detect antibodies to excretory/secretory (ES) antigens of adult A. caninum and by IgG and IgG4 Western blot (W.B.) to detect antibodies to Ac68 antigen. Eleven male patients (11.6%) (5 with acute abdomen, 3 diagnosed as appendicitis and 3 had recurrent mild to moderate abdominal pain) fulfilled the criteria of case definition of human enteric infection with A. caninum (G.I). The study also detected human hookworm infection in 14 patients (G.IIb) other parasites in 34 patients (GIIc) and 36 patients had no parasites (G.IIa). Although 3 patients from group I were diagnosed as appendicitis and were dealt with surgically, the pain recurred and mebendazole only put an end to the patient's complaints. The obtained appendices of these operated cases showed marked eosinophilic infiltration but no adult canine hookworms were detected. IgG ELISA was positive in 72.7%, 8.3%, 100%, 23.5% and 0% in groups and control respectively. IgG and IgG4 W.B. did not increase the sensitivity but IgG4 W.B. elevated specificity to 100% excluding those with HH infection (Group Iib) who showed 100% cross-reactions. Stool analysis was the only differentiation between these two types of hookworms. These findings confirmed the presence of human enteric infection with A. caninum as clinical entity in the study community and referred to its value in differential diagnosis of the obscure abdominal pain.