A fear is (apparently) laid to rest: Does using chopsticks cause disease? The answer is in this report:
“Use of chopsticks for eating and Helicobacter pylori infection,” W. K. Leung., J. Y. Sung., T. K. W. Ling., K. L. K. Siu and A. F. B. Cheng, Dig Dis Sci 44, 1999, pp. 1173-6.
See co-author Siu’s resume here.