Table 1. Prevalence of anti-HAV IgG and IgM in pregnant women and blood donors. Men (n = 69) 9 (13%, CI95 [5–20%]) 2 (3%) 2 (3%) Serological markers IgG IgM IgG + IgM Blood donors Women (n = 22) 4 (18.2%, CI95 [2–34%]) 1 (4.5%) 1 (4.5%) doi:10.1371/journal.pone.0048125.t001 different; however, as for the previous comparison, samples scored as indeterminate in the Wantai test were positive in the Dia.Pro test (five sera). There was a very good correlation between the O.D. values for the two tests (Figure 3). Although the slopes were the same for the two groups, the correlation coefficient was higher for blood donors (r2 = 0.95) than for pregnant women (r2 = 0.71); indeed, the correlation for pregnant women showed a significant deviation from the linearity (Runs test p = 0.0092). Dia.Pro test data were used for all subsequent analyses of prevalence (Table 2). The anti-HEV IgG seroprevalence in female blood donors (11/47, 23%, CI95 [7–40%]) was not significantly different from that in male donors (23/131, 16%, CI95 [11– 24%]). The prevalence of anti-HEV IgG among pregnant women (11%, CI95 [7–16%]) was lower than that in the entire blood donor group (19% CI95 [13–25%]); the difference with the female blood donor (non pregnant) group was highly significant, with an Odds Ratio ratio of 2.3 (CI95 [1.7–3.24], x2 = 4.31, p,0.05). This may have been because the women blood donors were older than the pregnant women. This difference between pregnant women and blood donors remained significant when the data from the two sampling dates were analyzed independently. However, there was an unexpected large difference between the distributions of seroprevalence according to age in 2011 and 2012 (Figure 4A, 4B). In 2011 anti-HEV IgG seropositive blood donors were all in the ,25 and 26–35 age groups, and there were no seropositive in the older age groups; the decrease in seroprevalence with age was significant (x2 = 4.4 p = 0.038 (Figure 4A). This unexpected pattern was not found with the samples collected in 2012 which, by contrast, showed an increase of seroprevalence with age (but not significant x2 = 1.32 p = 0.257; Figure 4B). Hepatitis A and E Viruses in Ouagadougou Pregnant women (n = 100) 23 (23% CI95 [14–31%]) 2 (2%) 2 (2%) Figure 1. Distribution of anti-HAV IgG and IgM in blood donors according to age group. doi:10.1371/journal.pone.0048125.g001 PLOS ONE | www.plosone.org 3 October 2012 | Volume 7 | Issue 10 | e48125 Figure 2. Comparison of results of testing with IgG ELISA kits. A) Wantai kit B) Dia.Pro test. Number of samples per OD value class (blue bars); red line: cumulative % of value: 100% is the 180 tested samples. Negative control value is given by a vertical doted line and the cut-off value as determined for the kit is given by a vertical continuous line. Arrows in the Wantai graph (A) indicate the OD values for a group of people with sub-detectable IgG. doi:10.1371/journal.pone.0048125.g002 Discussion This study investigating the prevalence of anti-HAV and anti- HEV seropositivity in Ouagadougou is the first of its kind in Burkina Faso. For epidemiological purposes, blood donors can be considered to approximate to the healthy ‘‘general population’’. However, the age criteria for blood donation and the elimination of samples found to be positive for hepatitis B and C antigens or for HIV antibodies could lead to an underestimation of the prevalence of anti-HAV and anti-HEV seropositivity in the general population. The group of pregnant women was not