Table 2. Incidence rates of seroconversion and seroreversion per child year among children ages 0–11 years in Haiti, 1990–1999.
| Seropositivity cutoff * | 4-Fold change in IgG levels † | |||||||
|---|---|---|---|---|---|---|---|---|
| Pathogen | Child- years | Incident cases | Rate (95% CI) |
Child- years | Incident cases | Rate (95% CI) |
Ratio of cases | Ratio of rates |
| Seroconversion/boosting | ||||||||
| Giardia VSP-3 or VSP-5 | 269.6 | 108 | 0.40 (0.34, 0.48) | 277.2 | 120 | 0.43 (0.35, 0.54) | 1.1 | 1.1 |
| Cryptosporidium Cp17 or Cp23 | 109.3 | 70 | 0.64 (0.54, 0.77) | 241.0 | 204 | 0.85 (0.73, 0.97) | 2.9 | 1.3 |
| E. histolytica LecA | 283.7 | 97 | 0.34 (0.28, 0.42) | 297.1 | 107 | 0.36 (0.29, 0.45) | 1.1 | 1.1 |
| Salmonella LPS groups B or D | 132.1 | 75 | 0.57 (0.47, 0.68) | 226.8 | 149 | 0.66 (0.54, 0.80) | 2.0 | 1.2 |
| ETEC LT B subunit | 9.7 | 11 | 1.13 (0.75, 1.82) | 32.1 | 32 | 1.00 (0.70, 1.45) | 2.9 | 0.9 |
| Norovirus GI.4 | 213.0 | 80 | 0.38 (0.30, 0.47) | 254.3 | 107 | 0.42 (0.34, 0.53) | 1.3 | 1.1 |
| Norovirus GII.4.NO | 105.8 | 67 | 0.63 (0.51, 0.80) | 147.2 | 100 | 0.68 (0.54, 0.86) | 1.5 | 1.1 |
| Seroreversion/waning | ||||||||
| Giardia VSP-3 or VSP-5 | 441.6 | 91 | 0.21 (0.17, 0.25) | 290.9 | 127 | 0.44 (0.35, 0.54) | 1.4 | 2.1 |
| Cryptosporidium Cp17 or Cp23 | 586.1 | 29 | 0.05 (0.03, 0.07) | 273.5 | 171 | 0.63 (0.53, 0.74) | 5.9 | 12.6 |
| E. histolytica LecA | 395.2 | 43 | 0.11 (0.08, 0.15) | 310.4 | 67 | 0.22 (0.16, 0.27) | 1.6 | 2.0 |
| Salmonella LPS groups B or D | 544.3 | 25 | 0.05 (0.03, 0.07) | 344.5 | 89 | 0.26 (0.20, 0.32) | 3.6 | 5.6 |
| ETEC LT B subunit | 702.1 | 2 | 0.00 (0.00, 0.01) | 649.7 | 22 | 0.03 (0.02, 0.05) | 11.0 | 11.9 |
| Norovirus GI.4 | 464.9 | 28 | 0.06 (0.03, 0.09) | 362.2 | 56 | 0.15 (0.11, 0.21) | 2.0 | 2.6 |
| Norovirus GII.4.NO | 574.3 | 19 | 0.03 (0.02, 0.05) | 477.9 | 39 | 0.08 (0.06, 0.11) | 2.1 | 2.5 |
*Incident changes in serostatus defined by crossing seropositivity cutoffs.
†Incident changes in serostatus defined by a 4-fold increase or decrease in IgG levels (MFI-bg), with incident boosting episodes restricted to changes that ended above the seropositivity cutoff and incident waning episodes restricted to changes that started from above the seropositivity cutoff.