Study | Â | Number of positive | Mild | Moderate | Severe |
---|---|---|---|---|---|
Tai, 1998 [21] | Â | 540 | 484 | 43 | 13 |
Zhao, 2001 [26] | Â | 153 | 98 | 39 | 16 |
Tao, 2001 [27] | Â | 57 | 44 | 11 | 2 |
Chen, 2003 [29] | Â | 866 | 367 | 157 | 342 |
Zhou, 2007 [32] | Male | 1295 | 963 | 240 | 92 |
 | Female | 1636 | 1229 | 304 | 103 |
Zhu, 2008 [35] | Â | 129 | 129 | 0 | 0 |
Qiu, 2010 [37] | Symptomatic group | 178 | 66 | 73 | 39 |
 | Asymptomatic group | 1301 | 855 | 320 | 126 |
Deng, 2010 [39] | Â | 25 | 25 | 0 | 0 |
Total (proportion) | Â | 6180 (100%) | 4260 (68.93%) | 1187 (19.21%) | 733 (11.86%) |