Prevalence and Incidence of, and Risk Factors for, HIV-1 Infection among Factory Workers in Ethiopia, 1997-2001
Mekonnen, Yared, Sanders, Eduard, Messele, Tsehaynesh, Wolday, Dawit, Dorigo-Zestma, Wendelien, Schaap, Ab, Mekonnen, Walelgne, Meless, Hailu, Mihret, Wude, Fontanet, Arnaud, Coutinho, Roel A., Dukers, Nicole H. T. M., Journal of Health Population and Nutrition
The prevalence of human immunodeficiency virus (HIV) infection in Ethiopia has increased rapidly over the past 15 years. The first cases of acquired immunodeficiency syndrome (AIDS) were diagnosed in hospitals of Addis Ababa, the capital city, in 1986 (1). Two years later in 1988, high rates of HIV prevalence were detected among long-distance truck drivers (13%) and commercial sex workers (17%) residing along the main trading road of the country (2,3). In 1989, only 4.6% of women attending antenatal-care clinics in Addis Ababa were HIVpositive (4), but by 2001, this proportion had increased to about 15% (5).
Heterosexual contact is the predominant mode of spread of HIV in Africa (6). Identification of the factors that facilitate this sexual transmission of the virus is, thus, of paramount importance in the search for more effective strategies for control of HIV. In Ethiopia, previous studies have focused on factors associated with the risk of HIV infection among sex workers (7,8), but little is known about the risk factors for the general population of the country (9). Incidence data are also lacking. In this study, we report the prevalence and incidence of, and risk factors, for HIV infection among factory workers participating in a prospective cohort study of HIV infection and disease progression at two sites in Ethiopia.
MATERIALS AND METHODS
Study population and procedures
The Ethio-Netherlands AIDS Research Project (ENARP) established two cohort sites in 1997 to study the incidence and progression of HIV infection in Ethiopia. One cohort is located in a fibre products factory at Akaki, a suburb of Addis Ababa, and the other one at Wonji, a sugar estate, 107 km southeast of Addis Ababa. Both the cohorts have followed the same procedures, which were detailed elsewhere (10) and summarized below.
At general information meetings, factory workers of both the sexes were invited to join the study, and they subsequently underwent HIV testing. After signing an informed consent form at the study clinics, participants received individual pre-test counselling by an experienced counsellor to determine what they knew of HIV transmission and its prevention and course of infection; how they perceived their personal HIV-infection risk; and how they might react to a positive or negative result upon HIV antibody testing. After pre-test counselling, the interviewers, matched by sex with subjects, collected data on sociodemographic characteristics, sexual behaviour, and medical history, using a structured questionnaire. Each interview was followed by a clinical examination performed by a medical doctor, before blood was drawn for laboratory analyses. Finally, all individuals were informed that results of their HIV test would be available 30 days later at the study clinics. Attending post-test counselling was optional, although an appointment date was given, in writing, to everyone. Participants thereafter came every six months to the study clinics for follow- up, at which the above procedures were repeated.
Blood samples were transported to the ENARP's laboratory at the Ethiopian Health and Nutrition Research Institute (EHNRI) on the day these were collected. Plasma samples were tested for HIV-1 antibodies by HIVSPOT (Genelabs Diagnostics, Singapore) and Vironiostika ELISA (Organon, Boxtel, The Netherlands). Positive results found with either or both the tests were confirmed by Western blot testing (HIV Blot 2.2 Genelabs Diagnostics, Singapore). Plasma samples were tested also for syphilis using the Treponema pallidum haemaglutination test (TPHA; Serodia-TP, Fujirebio, Tokyo, Japan) and, if results were positive, a further sample was tested using the rapid plasma reagin (RPR) test (RPR Slide-Test, Biomerieux, Marcy l'Etoile, France).
HSV-2 antibody testing was performed only at Akaki on a sub-sample of participants using gG1 and gG2- coated antigens in a commercially-available ELISA test kit (Gull Laboratory, Germany). …