Table 1. Distribution of selected features among the total study population.
| Variable | Laboratory-confirmed patients, number (%) | Clinically-confirmed patients, number (%) | P-value | ||
| Occupation | |||||
| Outdoor activities | 178 | (62.7) | 69 | (58.9) | P > 0.05 |
| Other | 106 | (37.3) | 47 | (41.1) | |
| Likely place of acquisition of infection†‡ (LPIA) | |||||
| Northern | 102 | (55.7) | 42 | (53.2) | P > 0.05 |
| Western | 3 | (1.6) | 5 | (6.3) | |
| Southern | 72 | (39.3) | 29 | (36.7) | |
| Other | 6 | (3.4) | 3 | (3.8) | |
| Number of lesions | |||||
| Up to 2 | 251 | 88.4 | 108 | 93.1 | P>0.05 |
| More than 2 | 33 | 11.6 | 8 | 6.9 | |
| Type of lesion | |||||
| Typical lesion | 53 | 18.7 | 22 | 19.0 | P > 0.05 |
| Nodule | 67 | 23.6 | 29 | 25.0 | |
| Ulcerating nodule | 66 | 23.2 | 19 | 16.4 | |
| Ulcer | 74 | 26.0 | 34 | 29.3 | |
| Plaque | 19 | 6.7 | 10 | 8.6 | |
| All other | 5 | 1.8 | 2 | 1.7 | |
| Site of lesion | |||||
| Trunk | 21 | 7.3 | 10 | 8.6 | P > 0.05 |
| Head and neck | 95 | 33.4 | 42 | 36.2 | |
| Lower limbs | 21 | 7.3 | 16 | 13.8 | |
| Upper limbs | 147 | 51.8 | 48 | 41.4 | |
| Size of lesion | |||||
| Up to 2 cm | 197 | 69.4 | 72 | 62.1 | P > 0.05 |
| Above 2 cm | 87 | 30.6 | 44 | 37.9 | |
| Duration | |||||
| Up to 4 | 120 | 42.3 | 50 | 42.3 | 0.052§ |
| >4–8 minutes | 105 | 37.0 | 30 | 25.4 | |
| >8–12 minutes | 37 | 13.0 | 18 | 15.5 | |
| >12 minutes | 22 | 7.7 | 18 | 15.5 | |
| Onset typical* | |||||
| Yes | 273 | 96.1 | 108 | 91.5 | 0.026§ |
| No | 11 | 3.9 | 10 | 8.5 | |
| Definition of the edge of the lesion†‡ | |||||
| Well defined | 145 | 57.1 | 41 | 43.2 | 0.002§ |
| Ill defined | 109 | 42.9 | 55 | 57.9 | |
| Regularity of the lesion edge†‡ | |||||
| Regular | 205 | 67.2 | 70 | 63.0 | 0.018§ |
| Irregular | 100 | 32.8 | 51 | 37.0 | |
| Shape of the lesion†‡ | |||||
| Rounded | 222 | 73.8 | 80 | 64.0 | 0.030§ |
| Oval | 23 | 7.6 | 10 | 8.0 | |
| Irregular | 55 | 18.6 | 35 | 28.0 |
*Painless acne-form non-itchy lesions of < 2 mm size. †Total number of lesions (not cases) was considered. ‡Doubtful information and missing cases have been excluded. §Statistically significant P values (P < 0.05) in comparison with laboratory negative lesions or patients.