Table 1. Prevalence of previous chikungunya virus infection, determined by detection of IgG, by demographic and clinical characteristics, Salvador, Brazil, November 2016–February 2017.

Characteristic	No. participants	No. positive (prevalence, %)	p value
Sociodemographic
Sex
M	761	93 (12.2)	0.60
F	1,011	116 (11.5)
Age, y
5–14	396	41 (8.1)	0.35
15–39	921	104 (11.9)
≥40	455	63 (14.9)
Skin color
Nonwhite	1,662	199 (12.0)	0.39
White	110	10 (9.1)
Household per capita income in US$/day*
≤5.50	1,429	171 (12.0)	0.69
>5.50	340	37 (10.9)
Education
Illiterate	76	14 (18.4)	0.06
Literate	1,696	195 (11.5)
Occupation/work
Yes	604	60 (9.9)	0.08
No	1,164	148 (12.7)
Residence located in an unpaved street
Yes	1,003	139 (13.9)	0.02
No	767	70 (9.1)
Type of residence construction
Plastered wall	1,447	154 (10.6)	0.04
Unplastered wall	211	33 (15.6)
Wood or other material	106	21 (19.8)
Residents per household
1	145	13 (9.0)	0.31
2–3	676	89 (13.2)
4–5	608	60 (9.0)
≥6	340	5 (13.5)
Clinical: reported symptoms†
Fever and arthralgia
None	1,212	111 (9.2)	<0.01
Only fever	322	38 (11.8)
Only arthralgia	89	20 (22.5)
Both, not simultaneous	40	7 (17.5)
Both, simultaneous	96	32 (33.3)
Myalgia
Yes	222	42 (18.9)	<0.01
No	1,548	167 (10.8)
Rash
Yes	216	50 (23.2)	<0.01
No	1,554	158 (10.2)
Pruritus
Yes	206	46 (22.3)	<0.01
No	1,563	163 (10.4)
Presumptive clinical diagnosis
Chikungunya
Yes	48	24 (50.0)	<0.01
No	1,724	185 (10.7)
Dengue
Yes	111	21 (18.9)	0.02
No	1,661	188 (11.3)
Zika
Yes	147	38 (25.9)	<0.01
No	1,625	171 (10.5)

*Data not shown for 3 participants.
†Reported symptoms with onset after January 2015.