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- Volume 23, Issue 1, 2008
Southern African Journal of Epidemiology and Infection - Volume 23, Issue 1, 2008
Volume 23, Issue 1, 2008
Source: Southern African Journal of Epidemiology and Infection 23, pp 1 –2 (2008)More Less
The public health significance of hepatitis B virus (HBV) infection is frequently underestimated, as it takes many years for its complications to appear. However, hepatitis B ranks among the greatest health concerns globally, with over two billion people having evidence of exposure and at least 350 million people being chronic HBV carriers. Carriers often show no symptoms and are in many cases unaware of their condition. HBV infection in adults is often acute but selflimiting while, in contrast, younger persons are less likely to develop symptoms, but are more likely to become chronic carriers. This aspect is a vital cause for concern, since the chronic state potentially leads to death from liver cirrhosis or hepatocellular carcinoma (HCC) in later years.
Author Michael C. KewSource: Southern African Journal of Epidemiology and Infection 23, pp 4 –8 (2008)More Less
Hepatitis B virus infection, both acute and chronic, occurs commonly in the black population of South Africa, and chronic infection and its sequelae of cirrhosis and hepatocellular carcinoma are major public health threats. Chronic hepatitis B virus infection is rare in the other population groups, with the exception of the very small Chinese community. Prevalences of chronic carriage of hepatitis B virus in South African blacks are 5-16% in rural males, 8-9% in urban males, 4-12% in rural females, and 2.7-4% in urban females. The overall male to female ratio is 2.6 : 1.0. There are now three to four million South African blacks who are chronically infected with this virus. In rural black populations chronic hepatitis B virus infection is acquired very early in life, predominantly as a result of horizontal transmission of the virus, and by the age of 5 years carrier rates approach those seen in adulthood. Afurther slight increase occurs at school-going age and a greater increase at the time of becoming sexually active. Urban black carrier rates are significantly lower and the infection is acquired later in life. The decreased urban viral carriage rates occur mainly in the first generation born in an urban environment. Hepatitis B virus accounts for about 60% of clinically evident acute viral hepatitis among blacks and about 10% of chronic hepatitis and cirrhosis. It is the cause of the majority of the many cases of hepatocellular carcinoma that occur in black South Africans. The tumour is more common in males and in rural-born than in urban-born blacks. The close association between chronic hepatitis B virus infection and hepatocellular carcinoma holds true in rural and urban patients and males and females. The association is age-related, being closer in younger patients. Genotypes A and D of hepatitis B virus predominate in South African isolates, with genotype A and its subtype A having a particularly high hepatocarcinogenic potential.
The impact of the immunisation programme on vaccine-preventable diseases in South Africa : a review of progress over a 10- to 15-year periodAuthor Nthombenhle J. NgcoboSource: Southern African Journal of Epidemiology and Infection 23, pp 9 –13 (2008)More Less
Immunisation is the most cost-effective public health intervention currently available. No other undertaking, not even the development of antibiotics has had as much impact in lowering mortality. The Expanded Programme on Immunization (EPI) in South Africa has made significant progress in the control of vaccine-preventable diseases. South Africa has been declared free of wild poliovirus. The number of measles cases per year dropped from an average of 10,000 to 15,000 cases between 1980 and 1997 to an average of less than 100 confirmed cases per year from 1998 to 2006, with 830 cases during the worst measles outbreak. Haemophilus influenzae type b (Hib) cases have been markedly reduced and maternal and neonatal tetanus has been eliminated. Review of routine coverage data indicates a progressive increase in the routine coverage from 2000 to 2006, with 84% fully immunised coverage recorded at national level in 2006. Efforts of the immunisation programme are directed at maintaining a high routine coverage and improving the quality of routine data. The major challenges relate to : sustaining the achievements, introducing new vaccines, integrating with other child survival strategies, and gaining recognition. There is a need to strengthen the programme in order to sustain the achievements. EPI has a potential to contribute significantly to the fourth Millennium Development Goal, of reducing childhood mortality by two thirds by 2015, particularly when integrated with other child survival strategies.
Author M. Jeffrey MphahleleSource: Southern African Journal of Epidemiology and Infection 23, pp 14 –18 (2008)More Less
Human immunodeficiency virus (HIV) and hepatitis B virus (HBV) infections are both endemic in sub-Saharan Africa, warranting high priority efforts in prevention and control. In developed countries, both viruses are transmitted more or less at the same time, and primarily in teenagers and adults. Because the two viruses share major risk factors, a number of HIV-infected individuals will either have past exposure to, or be chronic carriers of HBV. In contrast, HBV is predominantly transmitted in childhood in sub-Saharan Africa; and the majority of inhabitants are already exposed to, or are chronic carriers of HBV by the time they become exposed to HIV for the first time. Nevertheless, there is frequent detection of HBV in HIV-infected individuals (and vice versa) in the region because both viruses are highly endemic. Although there is a limited number of data on the interaction of HIV and HBV in co-infected persons in the sub-Saharan region, reports from around the world have convincingly demonstrated that HIV co-infection can have a negative impact on the transmission, natural history, prevention and control, and treatment of HBV. The impact of HIV co-infection on HBV prevention and control includes, but is not limited to : increased prevalence of HBV in HIV-infected persons; increased HBV infectivity and transmission; accelerated need for HBV therapy due to rapid progression to active chronic hepatitis B; limitation in the choice of drugs (where possible, drugs causing cross-reactivity are avoided in highly active antiretroviral therapy (HAART) regimens until there is a need to treat both viral infections), particularly in the phase of expanding HAART programmes in the region; the need to perform HBV DNA testing in HBsAg-negative sera due to frequent detection of occult hepatitis B in HIV-co-infected persons; and finally, the need for administering additional hepatitis B vaccine doses and ascertaining levels of protective anti-HBs (antibodies against HBsAg) following hepatitis B vaccination.
Hepatitis B virus and human immunodeficiency virus co-infection : impact on transmission and natural history of diseaseAuthor Rosemary J. BurnettSource: Southern African Journal of Epidemiology and Infection 23, pp 19 –23 (2008)More Less
There is overwhelming evidence of a strong association between human immunodeficiency virus (HIV) and hepatitis B virus (HBV) infections in areas of low endemicity for both viruses, due to shared risk factors. There is also much evidence that HIVmodifies the natural history of HBV infection in these areas : co-infected individuals are more likely to be HBV chronic carriers, with higher levels of HBV infectivity, than HIV-negative individuals. Also, immunosuppression brought about by HIV infection reduces persistence of anti-HBs in previously immune and vaccinated individuals, and can cause HBV reactivation or reinfection in those previously exposed to HBV. Furthermore, HIV infection increases the risk of death from liver disease in HBV co-infected individuals, and this risk increases when these patients are treated with highly active anti-retroviral therapy. However, extensive research has found no convincing evidence that HBV impacts on the transmission and natural history of HIV infection. However, the growing body of literature from sub-Saharan Africa (where both HIV and HBV are endemic, and where the majority of the population have been exposed to HBV long before the time of reaching sexual maturity and being exposed to HIV) stands in sharp contrast with the above findings. In this region, it is clear that the prevalence of HBV in HIV-positive individuals is seldom significantly increased, especially in healthy individuals; and when it is significantly increased, it is not increased to the same extent as in HBV-naïve populations. Also, it is expected that these increases will be caused mainly by reactivation or re-infection.
Source: Southern African Journal of Epidemiology and Infection 23, pp 24 –28 (2008)More Less
Hepatitis B more than ever holds a prominent position among the most notorious infectious diseases on a global scale and remains an actual threat to the world population. However, not all countries or continents are equally affected. Sub-Saharan Africa for example is a high-endemic region, with carrier rates of hepatitis B surface antigen (HBsAg) 8% among certain population groups, representing a significant burden to the health and development of a number of societies.
Author Anna KramvisSource: Southern African Journal of Epidemiology and Infection 23, pp 29 –31 (2008)More Less
Genotypes A, D and E of hepatitis B virus (HBV) circulate in southern Africa. The prevalence of subgenotype A1, a segment of genotype A, and its high mean nucleotide divergence suggest that this subgenotype is endemic in South African blacks. We have fully characterised subgenotype A1 sequences and identified mutations or variations that could account for the high HBeAg-negativity and low HBV DNA levels, seen in carriers of the virus. These mutations or variations can reduce HBeAg expression at three levels. Firstly, at the transcriptional level, the core promoter mutations 1762T1764A, highly prevalent in isolates from hepatocellular carcinoma (HCC) patients reduce HBeAg expression. Secondly, at the translational level, mutations at 1809-1812 that alter the Kozak sequence of the precore/core open reading frame are stable traits of subgenotype A1 and affect HBeAg expression, at a level comparable to 1762T1764A. The presence of 1762T1764A, together with 1809-1812 mutations, reduced HBeAg expression in an additive manner. Thirdly, a G to T transversion at 1862 of the precore region affects HBeAg expression at the post-translational level, by interfering with signal peptide cleavage. Unique sequence alterations in the transcriptional regulatory elements and the HBV polymerase coding region were found in subgenotype A1. These, together with the mutations affecting HBeAg expression, may contribute to the pathogenesis of HBV-induced HCC, which has a high incidence in southern African blacks. In fact, we have shown a 4.5-fold increased risk of HCC in HBV carriers infected with genotype A, which is entirely attributable to subgenotype A1.
Source: Southern African Journal of Epidemiology and Infection 23, pp 33 –37 (2008)More Less
Hepatitis B virus (HBV) infection is a serious global health problem, with two billion people infected worldwide, and 350 million suffering from chronic HBV infection. HBV infections result in 500,000 to 1.2 million deaths per year caused by chronic hepatitis, cirrhosis, and hepatocellular carcinoma; the latter accounts for 320,000 deaths per year.
Source: Southern African Journal of Epidemiology and Infection 23, pp 38 –39 (2008)More Less
Hepatitis B virus (HBV) was first detected as the potential agent of hepatitis B with the aid of electron microscopy by David Dane in 1970. Today, a sensitive polymerase chain reaction (PCR) technique for the DNA encapsidated within this virus would be sufficient to detect HBV infections during the incubation period, the acute phase, and the recovery phase. In many cases, HBV DNA persists at low levels even after complete recovery despite cellular immunity and the presence of anti-HBs.
Author Erwin Van KerschaverSource: Southern African Journal of Epidemiology and Infection 23, pp 40 –44 (2008)More Less
Vaccination is one of the most efficient preventive measures. It saves a huge number of lives, more than any highly sophisticated and very expensive medical intervention. The injection followed by baby's cry is usually well known, but vaccination is much more than that. It is the development and implementation of an evidence-based medical programme, integrated in social organisation, legislation, and rules. It is the control and follow-up of the evolution of coverage and disease level in the population. It is a difficult procedure full of choices and decisions. After the introduction, giving an overview of the vaccination policy in Belgium and some critical factors that are threatening the objectives, data about hepatitis B in Belgium are resumed. As an example of a successful strategy, the vaccination strategy of Kind en Gezin/Child and Family is discussed. Finally, the 2003 increase of hepatitis B vaccination coverage in Flanders, using the Vaccination Database, is reported.
Source: Southern African Journal of Epidemiology and Infection 23, pp 45 –49 (2008)More Less
Different types of data are available to describe the epidemiology of HBV infection. Most industrialised countries have systems in place to register/notify cases of hepatitis B (acute hepatitis B disease : symptomatic/clinical cases only; all cases : symptomatic plus asymptomatic cases) to a centralised health authority. These surveillance systems allow the estimatation of the incidence of hepatitis B, which provides the best estimate for the risk for this condition.
Source: Southern African Journal of Epidemiology and Infection 23, pp 50 –52 (2008)More Less
Rotavirus gastroenteritis (RVGE) is the leading cause of severe diarrhoeal disease in infants and young children between 6-24 months of age world-wide. Prospective epidemiological studies have shown that already 20% of acute rotavirus gastroenteritis occurs during the first 6 months of life. It has recently been estimated that world-wide in children under 5 years of age, 611,000 (range 454,000-705,000) rotavirus-related deaths occur each year, with the majority of these deaths occurring in developing countries the Asian subcontinent, Africa, and Latin America. Every year in Africa, rotavirus is estimated to cause 170,000 to 210,000 deaths in children under 5 years of age and approximately 145,000 of these deaths occur in sub-Saharan Africa alone. In other low-income countries such as Bangladesh, rotavirus is estimated to cause 6,000-14,000 deaths each year in children under 5 years of age, whereas in India, up to a 100,000 deaths are recorded every year.
Source: Southern African Journal of Epidemiology and Infection 23, pp 53 –57 (2008)More Less
Infectious diseases lay a heavy burden upon public health in many parts of the world. The toll they take in terms of human suffering, social hardship, and economic cost is huge and as a consequence, preventing and combating them are keys to the development of the most affected regions.