Farewell to the God of Plague: Conquering schistosomiasis in China; the last mile

Mon9  Apr05:15pm(15 mins)
Where:
Stream 3 - Physics 0.15 Main

Authors

D P McManus4; C A Gordon4; P He3; G M Williams5; Y S Li4; Y Wang3; J Hu3; D J Gray1; A G Ross2; D Harn6
1 Australian National University, Australia;  2 Griffith University, Australia;  3 Hunan Institute of Parasitic Diseases, China;  4 QIMR Berghofer Medical Research Institute, Australia;  5 The University of Queensland, Australia;  6 University of Georgia, United States

Discussion

Schistosomiasis in the People’s Republic of China (PRC) goes back to antiquity but, in the last 65 years, the Chinese government has made great strides in its control so that elimination is now the final declared goal by 2020. The control strategy aims to eliminate the role of bovines and humans as the sources of infection for intermediate host snails as a pre-requisite for transmission interruption. Due to inadequacies in diagnosis and surveillance, Schistosoma japonicum infection rates are underestimated, and areas of transmission risk go undetected so the likelihood of elimination by 2020 is questionable.

We are evaluating (2016-2020) the National Schistosomiasis Control Programme in 16 sentinel villages  in the Dongting (Hunan province) and Poyang (Jiangxi province) Lakes areas of the P.R. China using newly developed and field-verified loop-mediated isothermal amplification (LAMP) (for oncomelanid snails)- and real-time polymerase chain reaction (PCR)-based (for humans and animals) diagnostic techniques alongside the currently implemented methods. In a pilot study, we evaluated the qPCR assay using 633 human stool samples collected from five villages in Hunan, Anhui, Hubei, and Jiangxi provinces, and 182 bovine (70 cattle and 112 buffalo) stool samples obtained from four villages in Hunan, Anhui, and Jiangxi provinces in the PRC. All stool samples were subjected to the miracidium hatching test (MHT) (a diagnostic procedure used in the National Schistosomiasis Control Programme) and the qPCR assay. Samples positive by MHT were subjected to either the Kato-Katz technique for humans, or the formalin-ethyl acetate sedimentation-digestionFEA-SD) procedure for bovines, to determine infection intensities. 

The qPCR assay exhibited a high level of sensitivity in the detection of S. japonicum infections. With both the human and bovine samples, a significantly higher prevalence was determined using the qPCR assay (11.06% humans, 24.73% bovines) than with the MHT (0.93% humans, 7.69% bovines). The animal contamination index (calculated using data obtained with the qPCR technique) for all positive bovines was 27, 618, 000 eggs per day, indicating a considerable amount of environmental egg contamination that would be underestimated using less sensitive diagnostic procedures. The qPCR assay we have tested is applicable for monitoring the Schistosomiasis Control Programme in the PRC and can be used as a future field diagnostic and surveillance tool in low-transmission zones where schistosomiasis elimination is targeted and for monitoring post-intervention areas to verify that elimination has been maintained.

            
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