Prevalence and risk factors of HTLV-1/2 and other blood borne infectious diseases among blood donors in Yaounde Central Hospital, Cameroon

Introduction Transfusion-transmissible infectious microorganisms including bacteria and viruses are among the greatest threats to blood safety for the recipient. The prevalence and risk factors of HTLV-1/2 and other blood borne infectious diseases were determined among blood donors in Yaounde Central Hospital, Cameroon. Methods Design: cross sectional study. Setting: The blood bank unit of Yaounde Central Hospital, Cameroon. Subjects: a consecutive sample of 265 apparently healthy adult blood donors. Investigations: Search for the presence of hepatitis B surface antigen (AgHBs) and antibodies to human T-lymphotropic virus type 1 (anti-HTLV-1/2), human immunodeficiency virus (anti-HIV), hepatitis C virus (anti-HCV) and syphilis and to determine the epidemiological correlates, if any, in the occurrence of HTLV infection. Results 77 (29.05%) of the blood donors had serological evidence of infection with at least one pathogen and 4 (5.2%) had dual infections with HTLV-1/2. The overall prevalence of HTLV-1/2, HIV, HCV, HBV and syphilis were 5.7%, 5.3%, 2.6%, 11.7%, 3.8% respectively. Surgical history (Chi2=4.785; P=0.029), scarification (Chi2=6.359; P = 0.012), piercing (Chi2 = 16.353; P = 0.000) and intravenous drug use (Chi2 = 15.660; P = 0.000) were identified as risk factors for HTLV-1/2 infection. Conclusion A relative high prevalence of viral infections and syphilis was recorded among the study participants especially for HTLV-1/2 for which none blood donation is routine screened in our set up. Therefore, a routine screen of blood prior to transfusion should include anti-HTLV-1/2 tests.


Introduction
The risk of viral and bacterial infections constitutes the major cause of transfusion related morbidity and mortality. Although the risk of transfusion-transmitted infections today is lower than ever due to the current efforts and strategies that have greatly helped reduce transfusion-associated risks [1], the supply of safe blood products remains subject to contamination with known and yet to be identified human pathogens [2,3]. According to UNAIDS (1997), up to 4 million blood donations worldwide are not tested each year for human immunodeficiency virus (HIV) and few are tested for hepatitis B and C viruses [4]. In sub-Saharan countries, blood safety remains an issue of major concern in transfusion medicine where national blood transfusion services and policies, appropriate infrastructure, trained personnel and financial resources are inadequate. Data on blood donors screening have revealed a high prevalence for the presence of viral and bacterial markers indicative of HBV, HIV, HCV and syphilis infections [5]. Similarly, those infections have been reported to be prevalent in Cameroon [6] and the screening of blood donors for HB surface antigen (HBsAg), HCV, HIV and syphilis antibodies is henceforth a routine practice in the blood banks [7].
Although a priority is given to screen blood for antigens and antibodies of the cited infectious agents in our set up, continuous monitoring of the magnitude of transfusion-transmissible infections among blood donors is important for assessing the occurrence of infections in the blood donor's population and for estimating the epidemiology of the diseases in the community. Aside from HIV, HCV, HBV and syphilis, a number of other infectious agents transmitted by transfusion of blood products have been described.
Human T cell lymphotropic viruses I is (HTLV-I) associated with adult T cell leukemia and HTLV-associated myelopathy/ tropical spastic paraparesis [8]. Both retroviruses (HTLV-1/2) have been attributed a role in the increased risk for developing severe asthma, respiratory and urinary tract infections, uveitis and dermatitis [9][10][11][12]. The global epidemiology of HTLV varies widely with prevalence rates up to 10% in certain areas in Japan, and up to 5-6 % in countries of the Caribbean, the Sub-Saharan Africa, and areas in the Middle East and South America [12]. In our set up, no priority has ever been given to screen blood donors for antibodies to HTLV-1/2 [7] thereby making blood transfusion unsafe for blood recipients.
Thus, evaluation of data on the prevalence of these transfusion transmitted infectious agents among blood donors is important for estimating the risk of transfusion and optimizing donor recruitment strategies to minimize infectious diseases transmission due to these viruses namely HTLV-1/2. Therefore, this study was conducted to determine among blood donors at the Yaounde Central Hospital in Cameroon, the seroprevalence of HTLV, HIV, HCV, HBsAg, and syphilis and to determine the epidemiological correlates, if any, in the occurrence of HTLV infection.

Methods
This was a cross sectional and prospective study which was carried

Results
As shown in Table 1

Discussion
This study aimed at determining the prevalence and risk factors of HTLV-1/2 and other blood borne infectious diseases among blood donors in the Yaounde Central Hospital of Cameroon. According to WHO recommendations, the minimum requirement for all donor blood should include screening for HIV, HBV and syphilis [6]. A national strategy of infectious disease screening of donated blood is well implemented in the blood bank unit of the Yaounde Central Hospital in Cameroon and includes the testing for HIV, HBV, HCV, and T. pallidium. Screening for HTLV-1/2 is not routine in this center thus the anti HTLV-1/2 test that was used in this study was purchased. In our study, the overall prevalence of HTLV-1/2, HIV, HCV, HBV and syphilis were 5.7%, 5.3%, 2.6%, 11.7%, 3.8% respectively. This result is in agreement with those reported in Africa [6,7,13,14]. The prevalence of HBV was remarkedly high among the study population. It has been extensively reported a very large burden of HBsAg infection in all sub-Saharan African regions with carrier rates ranging from 9 to 20% [14]. Our finding may be due to the low hepatitis B vaccine coverage rates in the study set up. This study illustrates the current transfusion transmissible risk of the screened infectious agents in Cameroon and raises serious concerns regarding the safety of the blood supply in our community, even after the screening of donors for infectious agents. There is still a potential risk of transmitting viral infections during the serologic window period i.e. the period of early infectivity when an immunologic test is non-reactive [15]. Therefore, the absence of infectious agents in the blood of apparently healthy individuals may not be sufficient to ensure lack of circulating pathogens.
In a study conducted in India by Bhattacharya et al [16], it was observed that out of the 1027 HBsAg negative blood samples  [17] and Santos et al [18], age was found to be a risk factor for HTLV-1 infection. A potential explanation for this association was that increasing age provides a greater length of exposure to events that might result in acquiring the virus, such as sexual activity, intravenous drug use or blood transfusion [18]. The difference in the size of the study population may explain the discrepancy with our result. In this study, we observed that individuals with surgical history, scarification, piercing and who used intravenous drug are at higher risk for HTLV-1/2 infection. This result is in agreement with Page number not for citation purposes 4 the finding of Blattner [19] who demonstrated that HTLV-1 is transmitted by routes involving transfusion and needle sharing.

Conclusion
This study illustrates the current transfusion transmissible risk of HTLV-1/2, in the study set up. The data also reveal that individuals with surgical history, scarification, piercing and who used intravenous drug are at higher risk for HTLV-1/2 infection. From these observations, we recommend routine screening of blood donor for HTLV-1/2 antibodies.

Competing interests
The authors declare no competing interests.

Authors' contributions
Michel Kengne conceived, designed, financed the study and produced the first draft of this manuscript. Dorine Carol Wouado Tsata and Thérèse Ndomgue performed the sample collection, the laboratory assays and the data analysis and interpretation. Julius Mbekem Nwobegahay corrected the research proposal before the study and did a thorough review of the manuscript. All authors have revised the manuscript in its current form.

Acknowledgments
Special thanks are due to the Director of the Yaounde Central Hospital who granted the research authorization for this study. Table 1: Sociodemographic characteristics of the study subjects and correlates with HTLV-1/2 infection Table 2: Prevalence of blood borne pathogens among blood donors Table 3: Factors associated with HTLV-1/2 infection