Immunity and morbidity in schistosomiasis japonicum infection

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  • 1 International Health Institute, Brown University, Providence, Rhode Island; The Research Institute for Tropical Medicine, Alabang, The Philippines; Nanjing Medical College, Nanjing, China; Jiangxi Institute for Parasitic Diseases, Nanchang, China; University of the Philippines College of Medicine, Manila, The Philippines; The Provincial Health Office of Leyte, Palo, Leyte, Philippines; Schistosomiasis Control Service, Department of Health, Manila, The Philippines
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Schistosomiasis japonica differs significantly from Schistosoma mansoni infection in several epidemiologic, immunologic, and operational characteristics for control. Because of numerous nonhuman hosts, transmission remains high despite aggressive case finding and treatment of human cases. Diagnosis of infection using the Kato-Katz stool technique is less sensitive and specific in this than in other species of human schistosomes, making case finding and treatment a less effective approach to control. Clinically, morbidity induced by S. japonicum appears unrelated to intensity of infection, and is more severe than that of S. mansoni in terms of liver pathology and stunting of child growth and development. Both hepatic enlargement and fibrosis appear to be reversible and preventable with aggressive treatment but several operational characteristics for control of infection due to S. japonicum make the community impact of case-finding and treatment with praziquantel less pronounced than would have been predicted by the analysis of individual cases. In the Philippines, rebound morbidity following reinfection mandates short treatment intervals between screening and treatment to have a significant impact on morbidity, while in China inapparent infection (infection not diagnosed by a single stool examination) appears to be a common cause for persistent hepatic pathology. The authors conclude that for S. japonicum, mass treatment or targeted mass treatment is a more cost-effective approach than case-finding and treatment for control.

Author Notes

Authors' addresses: G. Richard Olds, Department of Medicine, G575, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH 44109-1998. Remigio Olveda, Bernadette Ramirez, and Rodrigo Romulo, Research Institute for Tropical Medicine, Alabang, Muntinlupa, Metro Manila, The Philippines, Guanling Wu, Nanjing Medical College, 140 Hanzhong Road, Nanjing, Jiangsu, People's Republic of China, Peter Wiest, Department of Medicine, Division of International Health, R422, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH 44109-1998. Stephen McGarvey, Geographic Medicine, The Miriam Hospital, 164 Summit Avenue, Providence, RI 02906. Gemiliano Aligui and Pierre Peters, Research Institute for Tropical Medicine, Division of Immunology, Alabang, Muntinlupa, Metro Manila, The Philippines, Shaoji Zhang and Jianhua Yuan, Institute for Parasitic Diseases, Nanchung, Jiangxi Province, People's Republic of China, Bruce Daniel, Stanford University School of Medicine, Department R, Stanford, CA 94305-5488. Prudencio Fevidal, Department of Health, Jaro, Leyte, The Philippines, Wilfred Tiu, College of Public Health, University of The Philippines, Manila, The Philippines. Ernesto Domingo, University of The Philippines, Taft Avenue, Manila 2801, The Philippines. Bayani Blas, Schistosomiasis Control Service, Department of Health, Manila, The Philippines.

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