Ultrasonographical investigation of periportal fibrosis in children with Schistosoma mansoni infection: reversibility of morbidity twenty-three months after treatment with praziquantel. - Doehring-Schwerdtfeger,E.; Abdel-Rahim,I.M.; Kardorff,R.; Kaiser,C.; Franke,D.; Schlake,J.; Richter,J.; Elsheikh,M.; Mohamed-Ali,Q.; Ehrich,J.H. (Am J Trop Med Hyg, 1992)