Analyses of the global distribution of chronic HBV infection have categorized regions based on HBsAg prevalence into low (<2%), intermediate (2%-7%), and high (≥8%) prevalence regions.20
Following Centers for Disease Control and Prevention (CDC) and American Association for the Study of Liver Diseases guidelines, the Minnesota Department of Health screens immigrants arriving from intermediate and high HBV prevalence countries for HBV infection. Hepatitis B virus testing of sub-Saharan African primary refugees arriving in Minnesota between 2004 and 2009, a substantial proportion of whom are Somalis, showed a mean HBV prevalence of 7% (www.health.state.mn.us
). Our finding of high adjusted HBsAg proportions in a sample of Somali immigrants is consistent with this. Importantly, we also found high proportions of anti-HCV positive test results among Somalis (10.3% in males and 6.7% in females). Hepatitis C virus RNA testing confirmed that 93% of Somalis with positive anti-HCV serologic test results had active HCV infection. The high anti-HCV positive rate found in Somali males is within the high prevalence category (>10%) of the global HCV distribution; however, in the global HCV distribution maps, Somalia is currently placed in the low prevalence category (1%-2.5%).21
Given the reported low HCV prevalence in Somalia and sub-Saharan Africa, unlike the recommendations for HBV testing, there has been no formal recommendation for screening immigrants from this region for HCV infection.
For both Somalis and non-Somalis, males almost always have higher proportions of both HBV and HCV infection than females. For all 3 markers, HBsAg, HBcAb, and anti-HCV, peak frequencies were in later age groups in Somalis compared with the control group. This may be due to several factors, including the epidemiology of these infections (mode of transmission and viral characteristics), biologic differences among races, and health disparities between Somalis and the control group. We found 11 individuals with chronic HBV who were 20 years or younger; it is plausible that these individuals were born outside the United States and did not receive HBV vaccination at birth. Although differences have been shown in chronic HBV rates among immigrants compared with Olmsted County residents, more work is needed to understand the extent of the HBV and HCV disparities in this immigrant population.16
Strategies designed to prevent and control viral hepatitis and its complications must also address significant disparities in morbidity and mortality associated with chronic HBV and HCV infections among different subpopulations in the United States.
In this study, we had expected to find that HBV infection was the major risk factor for HCC in Somalis, as is typically the case in sub-Saharan Africa. Indeed, the proportion of HBsAg in Somalis was higher than that of anti-HCV positivity (14% vs 10.0%), but the chronic HBV seropositivity rate in HCC patients was lower than that of HCV. Consequently, HCV seropositivity was found to have the strongest association with HCC in Somalis (OR, 31.3), making HCV the primary viral cause of HCC in this Somali sample. Although the OR had wide CIs due to the relatively small number of HCC cases, the association is so strong that it is likely to be validated in larger studies. Because of unavailability of HCV genotype in all 30 Somali HCC patients, it could not be conclusively determined whether a particular HCV genotype was more closely associated with HCC in Somalis. However, 6 of the 22 HCC patients with HCV infection had HCV genotype 4 infection and 2 had HCV genotype 3.
In addition to a high proportion of HBsAg-positive individuals, our study showed high rates of anti-HCV positivity in Somalis, confirmed by HCV RNA testing. The possible explanations for the high HCV infection rates are (1) transfusion of blood not screened for HCV, (2) hospital procedures performed without standard infection precautions, and (3) reuse of syringes and needles by paramedical workers. Epidemiologic studies in Egypt have shown an association between a history of receiving injections for the treatment of schistosomiasis and HCV infection.22
Similar risk factors may explain the spread of HCV infection in Somalia because during the 1970s and 1980s many people were vaccinated with the BCG vaccine, and needles and syringes may have been reused during the vaccination campaign.
In 2008, the CDC published recommendations for screening individuals for HBV infection,23
but there are no specific policies from the CDC, American Association for the Study of Liver Diseases, Minnesota Department of Health, or any other relevant agencies for HCV screening of immigrants. Although the significance of chronic HBV and HCV infections among at-risk people and different subpopulations in the United States has been recognized,24,25
immigrants or refugees are not yet specifically identified as being in a high-risk category requiring screening for HCV. Our new data show a high proportion of anti-HCV positivity, confirmed by HCV RNA, in Somali immigrants in Minnesota and a strong association with HCC in this population. In a substantial proportion of cases the diagnosis of HCV infection was made at the time of HCC diagnosis, and the opportunity to enroll patients in a surveillance program to allow detection of HCC at an early stage was missed. Consequently, only a few HCCs were detected during surveillance in this population. Significant differences were also observed in the HCV genotypes isolated from Somalis vs non-Somalis. Because there are a growing number of newly identified chronic HCV cases each year in Minnesota, it is important to confirm our observations in additional studies. In particular, this study is subject to potential selection bias because of the likelihood that individuals with clinically concerning elevations in levels of liver enzymes would preferentially be subject to screening. These individuals would also be more likely to have severe disease and a higher risk of HCC. It is important to perform population-based studies with random screening of the immigrant Somali population using both anti-HCV and HCV RNA testing to determine the true prevalence of HCV infection in the population. These additional studies could address other potentially significant factors not addressed in this study, including the relevance of time spent in Somalia or in refugee camps in neighboring states in determining the risk of HCV infection and the importance of aflatoxin exposure in determining risk of HCC. The Institute of Medicine also made 4 major recommendations to address the persistent transmission of HBV and HCV within the population and the incomplete identification and medical treatment of individuals with chronic viral hepatitis: (1) improvements in surveillance for HBV and HCV infections; (2) programs to improve knowledge and awareness, especially for at-risk individuals; (3) improvements in HBV vaccine coverage; and (4) improvements in access to services for viral hepatitis patients.24
If our findings are confirmed, it would be appropriate to recommend that immigrants and refugees from high-risk regions be screened for HCV on entry into the United States and that appropriate therapy for anti-HCV–positive individuals and/or regular surveillance for those at risk for HCC be instituted to reduce the long-term morbidity and mortality due to this virus.