Table 2.

Age-specific Anti-HEV Seroincidence in Rural Bangladesh Over 2 Surveillance Periods and Overall, 2003–2005^a,^b

Age Group, years	No.	%	Baseline Anti-HEV Prevalence, %	0–12 Months’ Seroincidence Estimates*				>12–18 Months’ Seroincidence Estimates				Overall Rates
				No. Susceptible	Losses, no.	Infections, no.	Rate/1,000 Person-Years	No. Susceptible	Losses, no.	Infections, no.	Rate/1,000 Person-Years	Total Infections/ Person-Years	Rate/1,000 Person-Years
1–10	265	23.4	3.8	255	30	3	12.6	222	7	7	65.1	10/346	28.9
11–20	247	21.8	19.0	200	22	4	21.4	174	4	7	83.1	11/271	40.6
21–30	177	15.6	28.8	126	14	6	51.7	106	7	5	100.0	11/166	66.3
31–40	159	14.0	41.5	93	6	9	105.3	78	3	3	80.0	12/123	97.6
41–50	118	10.4	27.1	86	6	16	213.3	64	5	0	0.0	16/106	151.3
51–60	74	6.5	29.7	52	1	5	102.0	46	1	4	183.9	9/71	127.2
≥61	94	8.3	28.7	67	5	6	97.6	56	3	0	0.0	6/89	67.6
Total	1,134		22.5	879	84	49	60.3	746	30	26	72.4	75/1,172	64.0

Abbreviations: anti-HEV, antibody to hepatitis E virus; WR-U, Walter Reed antibody units.

* P < 0.001 (log-rank test comparing infection rates between age categories).

^aThe incidence density is calculated as events per person-years: ((no. of infections)/(no. of nonevents + 0.5(no. of infections + no. of losses)) × 1,000. Nonevents: (no. susceptible − (no. of losses + no. of infections)).

^bSeronegative individual experiencing an increase in total anti-HEV immunoglobulin to ≥20 WR-U/mL.