An attempt to study the economic loss arising from Schistosoma japonicum infection and the benefits derived from treatment.

From the northern and southern portions of Leyte Province, which are endemic for schistosomiasis, a total of 801 infected individuals were interviewed, examined, and classified into mild, moderate, severe and very severe forms of disease with an assumed loss of working capacity for each category. The frequency rate or number of spells of illness for the past year under observation were correlated with the degree of incapacity to get the total days lost per person per year. Following a series of computations, of which the disability rate was considered as the most important, a total of 45.4 days lost per infected person per year was arrived at. Treatment of the disease with praziquantel was carried out and the patients were followed up one year after treatment, at which time the same methodology was applied. The results show that the 45.4 days lost prior to treatment went down to 4 days lost. There was an economic gain of 41.4 days as a result of treatment. This can be expressed in terms of financial value if we consider half of the infected cases as breadwinners receiving a minimum wage. It should be noted that a number of assumptions in this study were made. It is, however, hoped that this work will serve as a guide and a starting point for others to carry out related studies on economic loss and subsequent economic benefits to justify budgetary requests/allocations for the implementation of various preventive and control measures.

Immunogenetic factors involved in the pathogenesis of distinct clinical manifestations of schistosomiasis japonica in the Philippine population.

Immunogenetic factors were studied in 60 patients with schistosomiasis japonica in the Philippines, of whom 15 were characterized by marked hepatosplenic lesions and 45 characterized by cerebral symptoms. Immune responsiveness of the patients to schistosomal antigen was measured by T cell proliferation in vitro, and their HLA-A and -B specificities were typed. All but one hepatosplenic patients showed strong immune responsiveness to the schistosomal antigen, whereas both low and high responders were observed in the cerebral patients. A significant association between HLA-B40 and high responders to the schistosomal antigen was observed (P = 0.0458), and this HLA specificity was increased in frequency in the hepatosplenic patients. HLA-B16 was not observed in the hepatosplenic patients, but was common in the cerebral patients (26.5%) (P = 0.0255), and this HLA specificity was commoner in the low responders than in the high responders. These observations suggest that an HLA-linked gene governs the clinical manifestations of human schistosomiasis japonica by controlling immune responsiveness of the infected hosts to the schistosomal antigen.