although there is low background of local infection [18,19]. The endemic background in Western Europe is higher than in other developed zones, and is mainly associated with genotype 3 viruses and a potential reservoir in pigs [20–23]. Although the symptoms are generally mild, HEV infection is responsible for high mortality rates (up to 20%) in pregnant women, especially during the three first month of pregnancy [24–26]. HEV is endemic in regions where the water supply may be contaminated with animal waste, such as in Central Asia, the Middle East, and parts of South America and Africa. There have been major waterborne epidemics in refugee camps in Somalia [27] and Sudan [28], causing sickness and death. The groups of people at risk include those with liver disease, the elderly and the immunocompromised [29,30]. Thus, HAV and HEV are both food and waterborne pathogens. They share the same routes and mechanisms of spread and they both cause similarly severe epidemics. Although we conducted preliminary evaluations of food-borne viruses In Burkina Faso in 2005 and 2008, little is known about the prevalence of HAV and HEV in food [31,32]. The inhabitants of Ouagadougou are undoubtedly exposed to these viruses as a consequence of the socioeconomic situation, the hygiene standards and the nutritional habits marked by the consumption of street-vended products [32]. Indeed, an evaluation of the etiology of severe diarrhea in infants in Burkina Faso demonstrat- ed the involvement of rotavirus and adenovirus in these disease outbreaks. Both of these viruses are, like HEV and HAV, transmitted by the fecal-oral route [33,34]. Here, we report an analysis of the seroprevalence of HAV- and HEV-specific antibodies in the population of Burkina Faso. Materials and Methods Ethics statement This study was carried out according to the routine practices of the Regional Blood Transfusion Center of Ouagadougou (RBTC- O) and the Medical Center Surgical unit of Samadin (MCS), and was approved by the Ethics Committee for Health Research (ECHR): ‘‘Comite´ national d’e´thique pour la recherche en sante´ (CNERS). Ministe`re de la Sante´ 03 BP 7009. Ouagadougou 03, Burkina Faso’’. All subjects participating in the study signed a voluntary consent form after being given all the information necessary and sufficient to make an informed decision regarding their participation in this study. Study design and population The study was carried out between November 2010 and January 2011, and then in March 2012. The study population of blood donors and pregnant women was classified into represen- tative groups. Serum samples from 178 blood donors and 189 pregnant women attending the Medical Center of Samadin for prenatal HIV testing who were found to be fit to donate blood after the medical interview were used (367 samples in total). Blood samples were collected according to the international rules of blood donation as described by Rouger (2006) [35]. Sampling A volume of 5 ml of whole blood from each donor was obtained by venipuncture and collected into a dry tube. Blood samples were transported to the laboratory and kept at 4uC for overnight for sedimentation. The samples were then centrifuged at 3000 g for 10 min at 25uC. Sera were gently collected into cryotubes (NalgeneH) and stored at 22065uC until the serological analysis. Hepatitis A and E Viruses in Ouagadougou Serological tests All serum samples were analyzed for specific anti-HAV IgM and IgG using an immunochromatographic test (SD Bioline IgM/ IgG anti-HAV; Standard Diagnostics, Inc., Korea) according to the manufacturer’s instructions. This test has a sensitivity of 97.6% and a specificity of 98.0%. Serum samples were also screened for anti-HEV IgG by enzyme linked immunosorbent assay (ELISA) tests (DIA.PRO Diagnostic Bioprobe Srt, Italy or Beijing Wantai Biological Pharmacy Enterprise CO., LTD, China). Positive and negative controls were included in all the ELISA microplates. The results were scored as positive or negative according to the standard procedures recommended by the manufacturer. Data processing The data were processed, analyzed and plotted using Excel 2007 and GraphPad Prism 5.0d. 95% confidence intervals were calculated (CI95); Chi-2 and corrected P values were obtained using StatView 5.0 software (SAS Institute, USA). Results Seroprevalence of anti-HAV immunoglobulin The results of screening blood donors and pregnant women for anti-HAV IgM and IgG are shown in Table 1. Nine samples from blood donors did not give results that could be interpreted. The donor population included more men 69/91 than women 22/91, but the prevalence of anti-HAV IgG did not differ between women (18%, CI95 [2–34%]) and men (13%, CI95 [5–20%]). The seroprevalence of anti-HEV was slightly higher among pregnant women (23%, CI95 [14–31%]) than blood donors. The prevalence of anti-HAV IgM was similar for all three groups. The presence of anti-HAV IgM indicates a history of recent HAV infection, but as blood donors are questioned about clinical illness before blood is collected, any these infections were presumably asymptomatic. The prevalence of anti-HAV antibodies according to age is shown in Figure 1. The anti-HAV prevalence increased slightly from the ,25 age group to the .36 age group. Anti-HAV seroprevalence was high in the 46–55 years age group, whereas no positive cases were detected in the 56–65 years age group (data not shown). There were no significant differences between the age groups and no trend for a decrease or an increase of prevalence with age. Few subjects were anti-HAV IgM positive, and all positive subjects were ,25 or 36–45 years old. Seroprevalence of anti-HEV immunoglobulin Pregnant women and in blood donors were screened for anti- HEV IgG (table 2 shows the prevalence according to age and group). There was no significant difference between general prevalence in January 2011 and that found by subsequent analysis in March 2012. There is recent evidence from England and France that a new ELISA test (the Wantai kit) detects previously unrecognized cases of anti-HEV seropositivity. We therefore compared the values obtained with the Dia.Pro test and the newly available Wantai kit for the samples collected from the blood donor group in 2011. With the Dia.Pro test, 19.1% of 89 blood donor samples from 2011 were positive, whereas 14.6% of the same samples scored positive and 4.5% indeterminate in the Wantai test. We repeated the comparison in a new set of sera obtained in 2012 from blood donors and pregnant women. The distribution of optical density (O.D.) values obtained for the 189 samples with the Dia.Pro and Wantai tests are shown in Figure 2. Despite a large difference in the range of positive values between the two kits, the total number of positive samples was not very PLOS ONE | www.plosone.org 2 October 2012 | Volume 7 | Issue 10 | e48125