Lake Area Schistosome Infection Prevalence Of High-risk Groups, The Assessment Of The Effect Of Chemotherapy And Immune Status

Objective To clarify and evaluate the prevalence of schistosomiasis infection and the immunity of the on board fishing population in the Dongting Lake for proposing a scientific basis on the study of more effective control methods.Methods Inquired and physically examined (DPE) the fishing residents of the Fishing Village of Lujiao Town in Yueyang for schistosomiasis infection; treated the patients with PZQ; stool examination methods were applied to detect the pathogens in stool specimen; B-ultrasonic examination was used to determine the pathological changes of liver and spleen; flow cytometry was used to detect the CD4+ and CD8+ T cells; turbidimetry analysis and ELISA methods were performed to detect total IgA,IgM,IgG and specific antibody to SEA in serum. The intensity of infection and pathological changes in the liver and spleen, the levels of different class of antibodies and the CD4+/CD8+ ratio in different kinds of population and their interrelationship were analyzed by SPSS 10.0 statistical software.Results 1. The number of the investigated population amounted to 279. The stool egg positive rate was 68.1%(EPG X±SD=207±567) in 163 persons, and the positive rate of the serological detection was 88.0%(IHA). The rate of liver and spleen damage was 77.4%(82/106); 2. Six months later by stool re-examination, the infection rate of the population with chemotherapy was 35.4%, 37.7% lower than the population without chemotherapy; 3. The CD4+/CD8+ ratio of the endemic population was significantly lower than the heathy people of the non-endemic region. And the decrease in the CD4+/CD8+ ratio was more distinct in the stool egg positive population than the negative ones. 4. A marked increase in the total IgM and specific IgG were present in the group of stool positive population; 5. The decrease in the CD4+/CD8+ ratiowas more outstanding following the increase of the intensity of infection, and the hepatosplenomegaly or the severity of the damages of the liver and spleen. A few months after the chemotherapy, the decrease in the CD4+/CD8+ ratio did not recover evidently,- 6. Among the population with light intensity of infection, the CD4+/CD8+ ratio was in direct proportion to the levels of the anti-SEA IgG, but in inverse proportion to the levels of total IgM and IgG in serum.Conclusion For the first time, it was ascertained that there existed high parasitological positive rate, heavy intensity of infection, high rate of the liver and spleen damage and the general decrease of the CD4+/CD8+ ratio in the fishmen of the East Dongting Lake; and it was found that the decrease in the CD4+/CD8+ ratio of the population infected with schistosome was more significant with the increase of the infection intensity and the pathological changes of liver and spleen. The low CD4+/CD8+ ratio was consistent with the decrease in the specific antibody responses in lightly infected population.