Table 2. Participant characteristics.

	Positive controls (n = 391)	Negative controls (n = 139)
Age in years: Median (range)	41 (20–82)	43 (22–74)
Male %	43%	43%
Female %	57%	57%
Ethnicity
African %	33%	18%
Caucasian %	43%	77%
Indian %	14%	5%
Mixed race	10%	0%
Symptomatology
Asymptomatic n, %	48, 13.5%
Mildly symptomatic n, %	30, 8.4%
Moderately symptomatic n, %	169, 47.5%
Severe symptomatic n, %	109, 30.6%
Days post presentation n, %
0–7 days	77, 19.7%
8–14 days	69, 17.7%
15–21 days	48, 12.3%
22–30 days	48, 12.3%
31–40 days	35, 8.9%
41–50 days	29, 7.4%
>51 days	85, 21.7%