Epidemiological patterns of hepatitis B virus (HBV) in highly endemic areasr

Edmunds, W. John; Medley, Graham; Nokes, D. James; O’Callaghan, Christopher J.; Whittle, Hilton; Hall, Andrew J.

doi:10.1017/s0950268800001497

Cited by 153 publications

(136 citation statements)

References 73 publications

(92 reference statements)

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“…for wild-type HBV infection (ii) estimating the degree of protection (φ) of the vaccine against the wild-type and then (iii) exploring the effect of different values of cross-immunity (c), coverage (ν) and relative transmissibility (α). Edmunds [25] estimates R ! l 5 using an age-independent model of serological HBV data in The Gambia.…”

Section: Equilibrium Model Analysismentioning

confidence: 99%

“…The dynamics of the original model [12,25] appear relatively robust to realistic parameter variation, e.g. recovery rates (σ and γ), the relative infectiousness of acute and carriers (η) and the form of the transmission matrix (β).…”

Section: Sensitivitymentioning

confidence: 99%

“…Asia compared to, for example, SubSaharan Africa. However pre-vaccination Taiwan appears to have had the highest known incidence of perinatal transmission, yet it has been estimated that more than 60 % of carriers were infected horizontally [25]. Moreover if population growth is low and families have on average only two children then it can be seen that vertical transmission alone can never produce a R !…”

Section: Sensitivitymentioning

confidence: 99%

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Predictions of the emergence of vaccine-resistant hepatitis B in The Gambia using a mathematical model

2000

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SUMMARYVaccine escape variants of hepatitis B virus (HBV) have been identified world-wide. A mathematical model of HBV transmission is used to investigate the potential pattern of emergence of such variants. Attention is focused on The Gambia as a country with high quality epidemiological data, universal infant immunization and in which escape mutants after childhood infections have been observed. We predict that a variant cannot become dominant for at least 20 years from the start of vaccination, even when using a vaccine which affords no cross protection. The dominant factor responsible for this long time scale is the low rate of infectious contacts between infected and susceptible individuals (we estimate the basic reproduction number of hepatitis B in The Gambia to be 1n7). A variant strain that achieves high prevalence will also take many years to control, and it is questionable whether emergence will be identifiable by sero-surveillance until of high prevalence. The sensitivity of the model predictions to epidemiological and demographic factors is explored.

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Section: Equilibrium Model Analysismentioning

confidence: 99%

Section: Sensitivitymentioning

confidence: 99%

Section: Sensitivitymentioning

confidence: 99%

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Predictions of the emergence of vaccine-resistant hepatitis B in The Gambia using a mathematical model

2000

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“…Expansion of the HBV survey database is most pressing in the developing world, where the burden of HBV associated liver disease, and the need for vaccine intervention, is highest [16]. In Africa, in particular, uncertainty remains in the relative importance of different routes of HBV transmission and in the underlying risk factors for infection especially for childhood horizontal transmission [16].…”

Section: Introductionmentioning

confidence: 99%

“…In Africa, in particular, uncertainty remains in the relative importance of different routes of HBV transmission and in the underlying risk factors for infection especially for childhood horizontal transmission [16]. Whilst there are numerous serological surveys reported in the literature, few have been designed to obtain data representative of the socio-behavioural and demographic structure of the community.…”

Section: Introductionmentioning

confidence: 99%

Seroepidemiology of hepatitis B virus in Addis Ababa, Ethiopia: transmission patterns and vaccine control

et al. 2003

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SUMMARYA community-based seroepidemiological survey of Addis Ababa, Ethiopia was conducted in 1994 to inform on the transmission dynamics and control of hepatitis B virus (HBV) infection. Venous blood from 4736 individuals under 50 years of age from 1262 households, selected using stratified cluster-sampling, was screened for HBV markers using commercial ELISAs. HBsAg prevalence was 7% (95 % CI 6-8), higher in males (9 % ; 7-10) than females (5 %; 4-6). HBeAg prevalence in HBsAg positives was 23 % (18-29), and less than 1 % of women of childbearing age were HBeAg positive. Overall HBV seroprevalence (any marker), rose steadily with age to over 70 % in 40-49 year olds, indicating significant childhood and adult transmission. Estimated instantaneous incidence was 3-4/100 susceptibles/year, higher in males than females in 0-4 year olds, and peaking in early childhood and young adults. The age at which 50 % had evidence of infection was around 20 years, and the herd immunity threshold is approximated at 63-77%. Addis Ababa is of intermediate-high HBV endemicity, with negligible perinatal transmission. Our main findings are the identification of a significant difference between males and females in the age-acquisition of HBV infection, and marked differences between age groups in HBV incidence rates. These results should target future research studies of underlying risk factors. Furthermore, we generate a crude estimate of the level of coverage of HBV vaccine that would be required to eliminate the virus from the study population.

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Preimmunization epidemiology of hepatitis B virus infection in South African children

et al. 1999

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The prevalence of hepatitis B surface antigen (HBsAg) was determined in a community-based, cross-sectional, age-stratified sample of children from 0 to 6 years of age (n = 2,299) from the Eastern Cape Province of South Africa. The purpose of the study was to investigate the epidemiology and the age of acquisition of hepatitis B virus (HBV) infection in children, thus providing a preimmunization baseline measure of this infection in the population targeted for HBV immunization in South Africa. Overall, 10.4% (95% CI, 9.2-11.7) of the children tested were HBsAg-positive. There was a high rate of positivity in the 0-6- and 7-12-month age groups at 8.1% (95% CI, 5.5-11.7) and 8.9% (95% CI, 6.1-12.7), respectively, suggesting a higher rate of early acquisition of this infection than previously reported in South Africa. The proportion of HBsAg-positive children increased significantly with increasing age (chi2trend = 5.9, df = 1, P = 0.02), reaching 15.7% in the 61-72-month age group. This is the highest rate of HBV infection reported in community-based children from South Africa, indicating a significant burden of this infection. The difference in HBsAg prevalence between urban and rural children was not statistically significant (chi2 = 0.32, df = 1, P = 0.57). There was also no difference in positivity between males (10.5%; 95% CI, 8.7-12.5) and females (9.8%; 95% CI, 8.1-11.7), (chi2 = 0.006, df = 1, P = 0.94). This study provides the most recent preimmunization, community-based baseline investigation of the epidemiology of HBV infection in children targeted for universal immunization in South Africa.

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Epidemiological patterns of hepatitis B virus (HBV) in highly endemic areasr

Cited by 153 publications

References 73 publications

Predictions of the emergence of vaccine-resistant hepatitis B in The Gambia using a mathematical model

Predictions of the emergence of vaccine-resistant hepatitis B in The Gambia using a mathematical model

Seroepidemiology of hepatitis B virus in Addis Ababa, Ethiopia: transmission patterns and vaccine control

Preimmunization epidemiology of hepatitis B virus infection in South African children

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