Table 2.
Seroprevalence of antibodies against Japanese encephalitis virus (JEV) and hepatitis E virus (HEV) in Luangprabang and Huaphan Provinces during October 2008–January 2009 (dry season months), Laos
| Population characteristic | JEV serology* | HEV serology | ||||||
|---|---|---|---|---|---|---|---|---|
| No. tested | JEV HI assay | No. tested | HEV IgG ELISA | |||||
| % Positive | 95% CI | P | % Positive | 95% CI | P | |||
| Province | ||||||||
| Luangprabang | 209 | 59.8 | 53.1–66.5 | < 0.001 | 209 | 12.4 | 7.9–17.0 | 0.402 |
| Huaphan | 189 | 83.6 | 78.3–88.9 | 189 | 15.3 | 10.2–20.5 | ||
| Collection date | ||||||||
| October 2008 | 14 | 78.6 | 54.0–100.0 | 0.275 | 14 | 14.3 | 0.0–35.3 | 0.001 |
| November 2008 | 113 | 70.8 | 62.3–79.3 | 113 | 21.2 | 13.6–28.9 | ||
| December 2008 | 107 | 64.5 | 55.3–73.7 | 107 | 2.8 | 0.0–6.0 | ||
| January 2009 | 164 | 75.0 | 68.3–81.7 | 164 | 15.9 | 10.2–21.5 | ||
| Breed | ||||||||
| Indigenous | 367 | 70.6 | 65.9–75.2 | 0.987 | 367 | 14.4 | 10.8–18.1 | 0.370 |
| Exotic | 10 | 70.0 | 35.4–100.0 | 10 | 10.0 | 0.0–32.6 | ||
| Cross-breed | 11 | 72.7 | 41.3–100.0 | 11 | 0.0 | – | ||
| Age (months) | ||||||||
| 4–6 | 28 | 78.6 | 62.4–94.8 | 0.637 | 28 | 3.6 | 0.0–10.9 | 0.161 |
| 7–12 | 169 | 71.6 | 64.7–78.5 | 169 | 16.6 | 10.9–22.2 | ||
| > 12 | 193 | 69.9 | 63.4–76.5 | 193 | 13.0 | 8.2–17.7 | ||
| Production type | ||||||||
| Penned | 206 | 77.2 | 71.4–83.0 | 0.001 | 206 | 13.1 | 8.5–17.8 | 0.919 |
| Free range | 167 | 60.5 | 53.0–68.0 | 167 | 14.4 | 9.0–19.7 | ||
| Mixed | 6 | 100.0 | – | 6 | 16.7 | 0.0–59.9 | ||
*
All serum samples collected in Luangprabang and Huaphan Provinces were not reactive in the JEV IgM ELISA.
HI = hemagglutination inhibition; ELISA = enzyme-linked immunosorbent assay; CI = confidence interval.