Trends of blood-borne infectious diseases in a rural blood donation center of southeast Gabon (Koula-Moutou)

Introduction Blood-borne pathogens such as human immunodeficiency virus (HIV), hepatitis B and C (HBV and HCV) viruses and Treponema pallidum remain a major public health problem in sub-Saharan Africa. The purpose of this study was to assess the frequency and clinical implications of HIV, HBV, HCV and Treponema pallidum markers in blood donors in a rural area of Southeast Gabon (Koula-Moutou) from 2012 to 2017. Methods Hepatitis B surface antigen (HBsAg), anti-HIV, anti-HCV and anti-Treponema pallidum antibodies were screened using rapid diagnostic tests (RDTs). Results Of a total of 5,706 blood donors, 1,054 (18.5%) were seropositive for at least one infectious marker and 59 (5.6%) had serologic evidence of multiple infections. The overall seroprevalence of HIV, HBsAg, HCV, and syphilis was 3.1%; 5.9%; 6.2% and 3.3%, respectively. HIV, syphilis and HCV distributions were associated with neither the sex nor the age of the donors. Only HBsAg seroprevalence was significantly higher in donors of the age group 26-35 years old compared to donors of the age group 36-45 years (OR = 1.43 (95% CI: 1.01-2.04), P = 0.045). There was a significant increase in the frequencies of HIV and syphilis and a regression of HBsAg and HCV among blood donors. Conclusion This study presents the epidemiology of the main pathogens detected in blood donors in a rural area in Gabon. We found that the overall distribution of transfusion transmitted infectious diseases were lower than those observed in the general population but could be underestimated due to the use of RDTs in the screening process of the blood donations.


Introduction
Blood transfusion remains a challenging medical procedure in Sub-Saharan Africa (SSA) due to the high prevalence of infectious agents [1]. Several factors affect the safety of blood transfusion in Gabon.
These include chronic shortage of blood, high number of first-time donors, lack of qualified personnel and financial resources as well as elsewhere else in the continent [2]. While blood utilization is rising in rural areas due to the high incidence of infectious diseases such as malaria, typhoid fever, the screening of pathogenic agents is still performed using RDTs. Comparatively, in the big cities like Libreville, high-performance equipment are available, thus guaranteed a much safer blood safety environment. In a recent report, a prevalence of 7.28% for HBsAg was reported among firsttime donors in Libreville, whilst a 4.1%, 4.9% were reported in the general population for HIV and HCV infections respectively [3][4][5]. In a previous study conducted in Koula-Moutou, a rural area, the seroprevalences of 1.3%, 3.3%, 4.9% and 1.6% for HIV, HBV, HCV and syphilis were reported, respectively [6]. Given that little is known on the epidemiology of transfusion transmitted infections (TTIs) in rural areas of Gabon. We have set for this study the goal of assessing the distribution of HIV, HBsAg, HCV and syphilis serological markers among blood donors in a rural area (Koula-Moutou). This epidemiological data will serve as a springboard to advocate for a better screening of TTIs using more robust methods such as 4 th generation Enzyme-Linked Immunosorbent Assay (ELISA) and Nucleic acid testing's (NATs) which will improve local population heath.

Methods
Study population: A retrospective analysis of blood donor data from 2012 to 2017 was carried out at the Centre Hospitalier regional Paul Moukambi (CHRPM). Individuals aged 17 to 65 with a weight >50 kg were eligible for blood donations after completing a questionnaire to exclude previously transfused persons, pregnant women, people with signs of hepatitis or signs of any other infection, and those with risky sexual behavior in the three months prior to blood donation at CHRPM. All blood donations were tested for HIV, Hepatitis B surface (HBsAg), HCV and syphilis. The sociodemographic characteristics of the blood donors were recorded in a database and venous blood was collected in the blood bags following the standard procedure.
Determination of blood and rhesus groups: ABO and rhesus blood groups were determined using anti-A, anti-B, anti-AB and anti-D antisera (Cypress diagnosis, Belgium) according to the manufacturer's recommendations.   Table   2 and Figure 1).

Socio-demographic characteristics of blood donors and HIV
and HBsAg seroprevalence: Seroprevalence of HIV was 3.1% in blood donors. It was two-fold higher in 2016 and 2017 compared to 2014 (p = 0.015 and p = 0.003). It was not associated with sex or age of blood donors, although the age group 36-45 years with 2.9% was the least infected ( Table 3). The overall seroprevalence of HBsAg was 5.9% (338/5706). HBV seropositive donors were significantly 1.5 times higher in 2013 than in 2017. No difference was observed for HBV infection by comparing the other years to 2017. HBV infection was 6.2% in men and 4.7% among women, but the observed difference was not statistically significant (Table 3).

Sociodemographic characteristics of blood donors and
seroprevalence of HCV and syphilis: The overall seroprevalence of HCV was 6.2% (351/5706). This seroprevalence has varied annually. It was almost two-and-a-half fold higher in 2012, 2013, 2014, and 2016 than in 2017. HCV seropositivity was almost equal in women (6.3%) and men (6.1%) and was not associated with the age of blood donors ( Table 4). The overall seroprevalence of Syphilis was 3.3% (189/5706). This seroprevalence has varied annually between 2012 and 2017. It was two to three higher in 2012 and 2017 than in 2014. It was 3.4% for men and 2.9% for women. But the difference observed was not significant (p = 0.465). Syphilis was not associated with the age of blood donors even It was higher in blood donors > 45 years (Table 4).

Discussion
A significance differences exist in the frequencies of TTIs in blood donation between urban areas and rural areas in SSA which is mainly due to the profiles of the donors. In Gabon, the majority of blood donors in Koula-Moutou, a rural area, are FRD, whereas in urbans areas the number of VNRD predominates [6]. As expected in this study, we also found that all blood donations were collected from FRDs. This finding is also consistent with earlier studies that showed a predominance of family donors in SSA, reaching 75-80% of the total blood donors [2]. This predominance could be explained by many sociocultural factors which are still strong in rural areas.
Indeed, relatives, friends, neighbors and peers are important support for patients; therefore provide a direct source of blood collection. In addition of being more accessible, donations from FRD are inexpensive. In contrast, recruiting VNRD requires an establishment of a strong and often costly awareness and recruitment programs which are difficult to maintain because of the limited financial resources in blood centers [7,8]. The majority of blood donors were men (83.5%) compared to women (16.5%). This percentage of men is similar to those found in studies across Africa [9, 10]. Diverse medical contraindications might prevent women of donating blood including pregnancy, menstruation, breastfeeding, anemia and some cultural beliefs [9, 11-13]. The 17-35 age group (80.0%) was the most represented among blood donors. This high proportion of young blood donors has been found in most African countries, and this can be explained by the younger demographic structure of the African population [14]. In this study, 18.5% of blood donors were seropositive for at least one infectious marker.

The overall seroprevalence of transfusion-transmitted infection (TTI)
in Koula-Moutou blood donors is higher than that of 11.5% reported in a previous study in Ethiopia [ years which is consistent with a recent report in Gabon [3].
The overall seroprevalence of HCV in blood donors was 6.2%. It has seen annual variations, falling significantly between 2012 and 2017 from 6.5% to 2.9%. The HCV seroprevalence of 6.2% found in this study is higher than the seroprevalences of 1

Conclusion
This study presents for the first time the seroprevalence and the evolution of infectious markers in blood donors in a rural area of Gabon. This report showed both an increase in HIV and syphilis distribution, and a reduction in HBV and HCV which is inconsistent with national data and previous studies in urban areas.
What is known about this topic  Seroprevalence of blood borne pathogens are well  The seroprevalence of TTI found are lower compared to the seroprevalence described in previous studies in Gabonese blood donors from urban areas.
Universitaire de la Francophonie (AUF) and CHRPM for their financial support.