Academic journal article Bulletin of the World Health Organization

Prevalence of Hepatitis C Virus Antibodies and Genotypes in Asymptomatic, First-Time Blood Donors in Namibia

Academic journal article Bulletin of the World Health Organization

Prevalence of Hepatitis C Virus Antibodies and Genotypes in Asymptomatic, First-Time Blood Donors in Namibia

Article excerpt

Voir page 970 le resume en francais. En la pagina 971 figura un resumen en espanol.

Introduction

Viral hepatitis is a major global public health problem (1). The discovery of hepatitis C virus (HCV) in 1989 ended a period of intensive research aimed at finding the agent responsible for 80% of transfusion-associated ("non-A, non-B") hepatitis cases (2, 3). HCV is transmitted primarily through blood or blood products or contact with infected tissue (blood transfusion, intravenous immunoglobulins, intravenous drug abuse and tissue transplantation). Other routes of HCV transmission have also been implicated (sexual, vertical and household contacts), which may account for a proportion of the sporadic cases associated with this agent (4). HCV is not as infectious as hepatitis B virus (HBV), but as many as 80% of infected individuals can become chronically infected and risk serious long-term sequelae, including cirrhosis, liver failure and hepatocellular carcinoma (5-7).

Current treatment of HCV infection is not highly effective (4), and at least 90% of patients who need treatment are unable to afford it (8). A globally applicable and fully protective HCV vaccine is not available and would be difficult to develop (9). Public health interventions, therefore, continue to be the only effective method of preventing HCV infection (1, 10). These include screening of blood and blood products, effective use of universal precautions and contraceptive barrier methods, destruction of disposable needles, adequate sterilization of reusable materials such as syringes, and promotion of health education on HCV infection and its prevention (11).

Any strategy to prevent HCV infection must be based on accurate data, including information about its incidence and prevalence. Such information is, at present, lacking, particularly in developing countries (10). Recent prevalence estimates by WHO suggest that 3% of the world's population (ca 170 million people) are currently infected with HCV (10) and are therefore at risk of developing liver cirrhosis and/or live:- cancer. HCV is encountered worldwide, with a relatively high prevalence in Japan and the Mediterranean region, where 0.5-1.5% of blood donors are HCV antibody-positive (12). In northern Europe, USA and Canada the prevalence among blood donors is lower, between 0.01% and 0.05% (5, 12).

HCV prevalence data from southern Africa are incomplete, since no surveys have been published for Angola and Namibia. Countries in southern and central Africa show a range of HCV prevalences from [is greater than] 10% (United Republic of Tanzania) to [is less than] 1% (Botswana, Zambia and Zimbabwe) (1). In South Africa, the prevalence of HCV infection varies widely in different geographical areas and among ethnic groups within regions, ranging from 0.41% to 3.84% in published studies on blood donors (13-15). Marked differences have also been shown in South Africa between urban and rural populations, with a higher prevalence in the former (1.7%) than in the latter (0.9%) (15).

The high HCV prevalences in these countries suggest that the infection may also be important in Namibia. Furthermore, hepatitis B virus (HBV) infection, which is thought to be transmitted in the same way as HCV, is endemic in Namibia. The HBV carrier rate, as determined by the prevalence of hepatitis B surface antigen (HBsAg), is 14.8% among Namibian blood donors (16) and can be as high as 17% among rural adult males (17), which suggests that the prevalence of HCV may also be high. Hepatocellular carcinoma, which is associated with both HBV and HCV infection, is the fourth most common cancer in Namibia (15). Although the magnitude of the interaction between HBV and HCV in hepatocellular carcinogenesis is uncertain (19), there appears to be a considerable increase in hepatocellular carcinoma for patients infected with both viruses (20). The Namibian Blood Transfusion Service (NBTS) currently has no policy or guidelines for mandatory screening of blood and blood products for HCV, although there is routine screening for HBsAg. …

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