Epidemiology of blood-borne viral infections : with special reference to Central America

Abstract: Viral diseases transmitted through blood and/or blood products continue to be a major health problem in developing countries. Much less is known about the distribution and transmission routes in these countries in development. The aim of the study was to compare the epidemiology and transmission routes of the human immunodeficiency virus type 1 (HIV-1), the hepatitis C virus (HCV), and the GB virus type C (GBV-C) or hepatitis G virus (HGV) in Sweden with developing countries in the Central American region. The genotypes of HCV present in Honduras were analyzed in eight patients using PCR, followed by direct sequencing of the core, envelope 2 (E2)/non-structural 1 (NS1), and NS5 regions. The major genotypes for HCV that are distributed world wide, such as la, lb, and 3a have been found present in Honduras. To estimate the distribution of HIV-1 subtypes in Honduras an EIA assay using synthetic peptides corresponding to five of the major subtypes (A to E) was used. The Honduran HIV-1 epidemic show a similar distribution of HIV-1 subtype B as the HIV-1 epidemics in most of the developed world. The presence of the recently identified GBV-C/HGV was compared in samples from Sweden and Honduras. A total of 224 Swedish and 163 Honduran samples were analyzed for the presence of the presumed blood-borne GBV-C/HGV by PCR. Also, from both Sweden and Honduras, 44 cases and 58 cases, respectively, of suspected viral hepatitis of unknown origin were included. GBV-C/HGV RNA was detected in healthy Swedish as well as in healthy Honduran population. Likewise, GBV-C/HGV RNA was detected in Swedish and Honduran population of individuals with risk to acquiring blood borne viral infections. Analysis of the NS3 region for GBV-C of all positive samples confirmed HGV origin. The presence and distribution of GBV-C/HGV is related to known risk factors for bloodborne viral diseases in both Sweden and Honduras. Further, the importance of GBV-C/HGV in causing viral hepatitis of unknown origin is limited. To further clarify blood products as a transmission route and a possible association between GBV-C/HGV and fulminant hepatic failure (FHF) a retrospective study was performed. A panel of 58 patients clinically diagnosed with an acute or sub-acute FHF was screened for both GBV-C E2 antibodies and GBV-C/HGV RNA. In this study, GBV-C markers were present in 36% of the patients, which is higher than in healthy Swedish subjects (3%). Despite the elevated prevalence of GBV-C/HGV in patients with FHF our data suggest that in many cases the presence of GBV-C/HGV be caused by the therapy with contaminated blood products. Thus, elevated frequencies of GBV-C/HGV are to be expected in patients subjected to multiple transfusions and blood products. In July of 1997 a high number of HCV infections were diagnosed in the hemato-oncology ward in the pediatric hospital of Managua, Nicaragua. One of the major treatment strategies used for these children is the periodical administration of blood and/or blood products. A study was undertaken to try to understand the nature of the epidemic and to compare the transmission routes of HCV and GBV-C/HGV. A total of 185 patients were tested for HCV and GBV-C/HGV markers. In total, 92 (50%) out of 185 children had ongoing HCV infections. In contrast, GBV-C infection was confirmed in 20 (11 %) out of 185 children. Additionally, 100 Nicaraguan blood donors positive for anti-HCV were screened for HCV-RNA. Thirty-five blood donors were HCV RNA positive but only 12 (110/0) were GBV-C RNA positive. A panel of 73 hospital personnel, who were anti-HCV negative, were screened for both HCV RNA and GBV-C RNA. Two individuals (3%) were found to be HCV RNA positive and eight (11%) were GBV-C RNA positive. HCV and GBV-C coinfected one of these. Genotyping was performed in 35 of the children by sequence determination of a NS5 region fragment. The analysis showed that the majority of the children 34/35 were infected by HCV genotype 1a, and one child was infected by HCV of genotype lb. Fifteen of the blood donors were also genotyped: six were la, six were 3a, two were 2b and one was 2c. The present data allows for several conclusions. Collectively, treatment with contaminated blood products and the effective nosocomial transmission of HCV, which has been reported in developed countries, may help to explain the presence of this epidemic. Taken together several similarities exist between the presence and transmission of HIV-1, HCV, and GBV-C/HGV between Sweden and Central America. The subtypes of HIV-1 and HCV are seemed to follow the worldwide distribution. The role for GBV-C/HGV in various types of hepatitis remains unclear. Interestingly, the transmission route for GBV-C/HGV and HCV seem to differ. The present study highlights the importance of introducing screening for HCV at both blood banks and in hospitals in the developing world. However, screening alone would most likely not have prevented the HCV epidemic at the pediatric hospital "Manuel de Jesús Rivera", Managua, Nicaragua.