Table 1.

Number of Vibrio cholerae Infections Among Household Contacts by Age and Baseline Titer^a

	Day 2 Titer ≤20			Day 2 Titer 40–80			Day 2 Titer ≥160
Age (Years)	N	N Infected	Percent Infected (95% CI)	N	N Infected	Percent Infected (95% CI)	N	N Infected	Percent Infected (95% CI)
<5	30	11	36.7 (21.9–54.5)	8	2	25.0 (3.2–65.1)	12	0	0.0 (0.0–26.5)b
5–15	100	33	33.0 (24.6–42.7)	47	8	17.0 (8.9–30.1)	81	9	11.1 (6.0–19.8)
≥16	172	39	22.7 (17.1–29.5)	144	29	20.1 (14.4–27.4)	232	22	9.5 (6.3–13.9)

Abbreviations: CI, confidence interval.

^aContacts were followed for 9 days (337 contacts) to 21 days (489 contacts) from enrollment for rectal swab data and for 21 days (489 contacts) to 30 days (337 contacts) for serum samples, depending on the cohort. Almost all contacts that developed V cholerae infection were diagnosed ≤10 days after enrollment (148 of 158; 97%). Confidence intervals represent the expected range if the study population was repeatedly resampled.

^bExact CI calculated using exact methods given small numbers.