Table 1.
Proportion of suspected (but not tested), laboratory-positive and negative CHIKV cases by demographic risk factors and clinical manifestations, as well as univariate prevalence ratio estimates comparing laboratory-positive cases and laboratory-negative suspected cases
| Demographic risk factor/clinical manifestation | Suspected (n)* | Positive (n) | Negative (n) | Prevalence ratio (95% confidence interval) |
|---|---|---|---|---|
| Median age (years) | 43.25 (880) | 45.99 (572) | 41.04 (248) | – |
| Female | 0.58 (551) | 0.60 (364) | 0.63 (165) | 0.96 (0.88–1.05) |
| Traveled 14 days before illness onset | 0.05 (35) | 0.07 (32) | 0.11 (21) | 0.83 (0.66–1.04) |
| Contact with recently ill household member | 0.25 (166) | 0.25 (103) | 0.17 (29) | 1.14 (1.02–1.27) |
| Pregnant | 0.02 (5) | 0.06 (12) | 0.02 (1) | 1.27 (1.06–1.51) |
| Fever ≥ 38°C† | 0.65 (460) | 0.77 (404) | 0.69 (152) | 1.14 (1.01–1.28) |
| Fever (2–7 days) | 0.71 (476) | 0.80 (362) | 0.75 (148) | 1.08 (0.95–1.24) |
| Arthralgia | 0.94 (826) | 0.94 (562) | 0.86 (214) | 1.45 (1.14–1.84) |
| Arthritis | 0.43 (317) | 0.44 (246) | 0.40 (94) | 1.06 (0.96–1.16) |
| Nausea/vomiting | 0.24 (141) | 0.21 (92) | 0.25 (46) | 0.93 (0.81–1.06) |
| Rash | 0.42 (274) | 0.33 (144) | 0.39 (74) | 0.93 (0.83–1.04) |
| Myalgia | 0.86 (622) | 0.93 (441) | 0.84 (165) | 1.46 (1.13–1.88) |
| Diarrhea | 0.16 (92) | 0.12 (54) | 0.25 (48) | 0.72 (0.60–0.87) |
| Fatigue/malaise | 0.22 (118) | 0.27 (117) | 0.35 (64) | 0.89 (0.79–1.00) |
| Headache | 0.70 (458) | 0.70 (316) | 0.67 (130) | 1.03 (0.92–1.15) |
| Chills/rigor | 0.57 (335) | 0.67 (299) | 0.58 (108) | 1.12 (1.00–1.25) |
| Eye pain | 0.35 (197) | 0.35 (140) | 0.35 (62) | 1.01 (0.90–1.13) |
| Anorexia | 0.36 (180) | 0.56 (231) | 0.50 (88) | 1.07 (0.96–1.20) |
| Unable to walk | 0.39 (263) | 0.44 (222) | 0.34 (72) | 1.14 (1.03–1.25) |
| Cough | 0.16 (103) | 0.11 (51) | 0.19 (40) | 0.78 (0.65–0.94) |
| Nasal congestion | 0.13 (78) | 0.07 (31) | 0.14 (27) | 0.74 (0.58–0.95) |
| Sore throat | 0.15 (96) | 0.10 (47) | 0.16 (33) | 0.83 (0.68–1.00) |
CHIKV = chikungunya virus. Statistically significant univariate prevalence ratio estimates are in bold.
*
Individuals suspected of CHIKV infection but without confirmed laboratory-test results.
†
Fever ≥ 38°C was marked “yes” only if the individual was febrile at the time of medical visit.