Hepatitis B virus infection in Cameroon: a seroepidemiological survey in city school children

Sero-epidemiology of human immunodeficiency virus, hepatitis B virus and hepatitis C virus: a cross-sectional survey in a rural setting of the West region of Cameroon

INTRODUCTION

Human immunodeficiency Virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) are the three most common chronic viral infections worldwide, specifically in sub-Saharan Africa (SSA). This study aimed to determine the sero-epidemiology of HIV, HBV and HCV infections in a rural setting of the West region of Cameroon, a SSA country.

METHODS

We conducted a cross-sectional study from August 2 to 5, 2014 in the three health districts of the Menoua Division, West region of Cameroon. Sixteen villages were randomly selected. Participants were currently living in the Division at the time of the survey, and enrolled after they had provided a signed consent form. HIV screening used the "determine test" followed by Hexagon HIV for positive cases to the first assay. HBV and HCV were detected using DIASpot HBsAg and DIASpot HCV-Ab, respectively.

RESULTS

On the whole, 612 subjects consented to take part in this study, of whom 71.1% were females. Mean age of the study population was 45.3 ± 17.9 years. The seroprevalences of HIV, HBV and HCV infections were 1.0% (6/582), 4.5% (20/443) and 6.3% (23/365), respectively. The 41-50 years age group was the most represented among HIV-positive subjects. HBV prevalence was higher in the 21-30 years age group (13.4%), followed by the 51-60 years age group (7.8%), with a significant difference of prevalences among age groups (p = 0.002). All HCV-positive cases were above 40 years of age with a higher prevalence in the > 70 years age group (33.3%) followed by the 61-70 years age group (14.5%); there was a significant difference between the age groups (p = 0.001).

CONCLUSION

The seroprevalences of HIV, HBV and HCV infections in the Menoua Division of the West region of Cameroon were 1.0%, 4.5% and 6.3%, respectively. Preventive measures against these health threats need to be reinforced in this setting.

Hepatitis B serological markers and plasma DNA concentrations

Objectives:

To examine hepatitis B (HBV) serological markers and plasma DNA concentrations in a large group of untreated HBV/HIV-coinfected individuals in two sub-Saharan settings.

Design:

Baseline analysis of a randomized controlled trial.

Methods:

DART was a large trial of treatment monitoring practices in HIV-infected adults with advanced disease starting antiretroviral therapy at centres in Kampala or Entebbe, Uganda (n = 2317) and Harare, Zimbabwe (n = 999). HBV serological markers [antibody to HBV core antigen, HBV surface antigen (HBsAg), antibody to HBV surface antigen, HBV ‘e’ antigen (HBeAg), and antibody to hepatitis B ‘e’ antigen] and plasma HBV DNA viral load were measured retrospectively on stored baseline samples. Logistic regression was used to examine associations with baseline demographic and clinical factors.

Results:

The rate of HBsAg positivity was significantly higher in Zimbabwe than Uganda (12.2 vs. 7.7%, adjusted odds ratio = 1.54, P < 0.001) despite a similar prevalence of antibody to HBV core antigen (56.3 vs. 52.4%) in the two settings. Overall, HBsAg positivity was associated with male sex (adjusted odds ratio = 1.54, P < 0.001) but not with age, WHO disease stage, or CD4⁺ cell count. HBeAg was detected among 37% of HBsAg-positive patients, with higher rates among those with advanced WHO stage (P = 0.02). Also in HBsAg-positive patients, HBV DNA was undetectable in 21%, detectable but below the level of quantification in 14%, and quantifiable in 65%. A total of 96% of HBeAg-positive and 70% of HBeAg-negative patients had detectable HBV DNA; 92 and 28% of patients, respectively, had HBV DNA viral load more than 2000 IU/ml.

Conclusion:

High rates of HBV coinfection were observed, highlighting the importance of ensuring that coinfected patients receive an antiretroviral regimen, whether first-line or not, that is active against both viruses.

Epidemiological and molecular features of hepatitis B and hepatitis delta virus transmission in a remote rural community in central Africa

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) occur worldwide and are prevalent in both urban and remote rural communities. In a remote village in Gabon, central Africa, we observed a high prevalence of HBsAg carriage and HDV infection, particularly in children and adolescents. The prevalence of HBsAg differed significantly by gender and age, females being more likely than males to carry the HBsAg during the first 10 years of life, while the prevalence was higher among males than females aged 11-20 years. We also characterised HBV and HDV strains circulating in the village. The principal HBV strains belonged to genotype HBV-E and subgenotype QS-A3. Complete genome analysis revealed for the first time the presence of the HBV-D genotype in Gabon, in the form of an HBV-D/E recombinant. Molecular analysis of HDV strains and their complete genomic characterisation revealed two distinct groups within the dominant HDV clade 8. Molecular analysis of HBV and HDV strains did not reveal vertical transmission within the families studied but rather horizontal, intrafamilial transmission among children aged 0-10 years. Our findings indicate that HBV is transmitted in early childhood by body fluids rather than by sexual contact. Health education adapted to the different age groups might therefore help to reduce HBV transmission. Young children should be vaccinated to control HBV infection in areas of extremely high prevalence.

Prevalence of HBsAg and knowledge about hepatitis B in pregnancy in the Buea Health District, Cameroon: a cross-sectional study

BACKGROUND

Although infection with Hepatitis B Virus (HBV) remains a global public health problem, little is known about its epidemiology in pregnancy in sub-Saharan Africa. This study sought to determine the prevalence of, and identify factors associated with hepatitis B surface antigen (HBsAg) positivity among pregnant women in the Buea Health District (BHD) in rural Cameroon. We also assessed pregnant women's knowledge about hepatitis B.

METHODS

A cross-sectional, descriptive study was undertaken. Participants were evaluated using a structured questionnaire with clinical examination and were then screened for HBsAg using a commercial rapid diagnostic test. Assessment of knowledge was done using a hepatitis B basic knowledge summary score.

RESULTS

Of the 176 pregnant women studied, 9.7% (95% CI: 5.7%, 15%) tested positive for HBsAg. None of the risk factors assessed was significantly associated with HBsAg positivity. The hepatitis B knowledge summary score ranged from 0 to 12 with a mean of 1.5 (SD = 3.14, median = 0, IQR = 0 to 0). Only 16% of participants had scores greater than 6/12. The knowledge summary score of the participants was associated with the educational level (p-value = 0.0037).

CONCLUSION

The high prevalence of HBsAg (9.7%) among women of child bearing age suggests that vertical transmission of HBV may be a public health problem in Buea Health District. Knowledge of HBV among pregnant women was poor. We recommend that all pregnant women ought to be routinely screened for HBV and that health education on HBV should be provided to pregnant women especially during antenatal visits.

Hepatitis B virus exposure during childhood in Cameroon, Central African Republic and Senegal after the integration of HBV vaccine in the expanded program on immunization

BACKGROUND

More than 2 billion people worldwide have been exposed to hepatitis B virus (HBV). To prevent these infections, Senegal and Cameroon integrated the HBV vaccine into their Expanded Program on Immunization (EPI) in 2005, as did the Central African Republic (CAR) in 2008. We evaluated the prevalence of HBV exposure and infection after the integration of the HBV vaccine in the EPI.

METHODS

An observational cross-sectional study was conducted among the hospitalized children 3 months to 6 years of age in Cameroon, CAR and Senegal. Plasma was collected for the detection of anti-HBc, anti-HBs and hepatitis B surface antigen in children with anti-HBc and anti-HBs.

RESULTS

Between April 2009 and May 2010, 1783 children were enrolled, 19.4% of whom were anti-HBc positive. The percentage of children with anti-HBc was 44.4% among the children younger than 6 months, decreasing after 6 months to reach 18.8% at 12 months. This decline was followed by a rapid increase in anti-HBc positivity rate in CAR observed as early as 12 months of age compared with Cameroon and Senegal, where the anti-HBc increased between 18 and 36 months of age, respectively. The prevalence of hepatitis B surface antigen-positive children was significantly higher in CAR than that in Cameroon and Senegal (5.1% versus 0.7% and 0.2%; P < 0.001). Socioeconomic level, age and country were factors associated with the presence of anti-HBc.

CONCLUSIONS

Passive transfer of anti-HBc maternal antibodies versus HBV exposure could be differentiated as early as 12 months of age. The low prevalence of anti-HBc and hepatitis B surface antigen among children born after the integration of HBV vaccine in the EPI in Cameroon and Senegal suggests a positive impact of HBV vaccination.

Prevalence, correlates and pattern of Hepatitis B among antenatal clinic attenders in Yaounde-Cameroon: is perinatal transmission of HBV neglected in Cameroon?

BACKGROUND

Few studies have evaluated the prevalence of HBV in the general Cameroonian population or among antenatal attendants. The aim of this study was to determine the prevalence, correlates and patterns of Hepatitis B surface antigen among pregnant women attending antenatal care in Yaounde-Cameroon.

METHODS

This was a cross-sectional multicenter study carried out in a referral hospital and two secondary hospitals in Yaounde, the capital of Cameroon. The study lasted 15 months (March 2011 to June 2012), and recruited 959 pregnant women. Patient recruitment was consecutive. The HBsAg was tested using the Monalisa HBsAg Ultra ELISA kit. Other hepatitis B markers were equally tested.

RESULTS

The prevalence of hepatitis B infection (HBsAg) among antenatal clinic attenders in our setting was 7.7%. Amongst these women, just 5.4% were previously aware of their HBsAg status. The rate of HBV infectivity was high, with 28% of HBsAg positive women having evidence of HBeAg in their plasma, and up to 45.8% of these women lacking antibodies against hepatitis B e antigen (anti-HBe). About 41% of the pregnant women had had previous contact with HBV as evidenced by the positive status for anti-HBc.

CONCLUSION

The prevalence of hepatitis B among pregnant women in Cameroon is high, and the pattern tends towards high infectivity and therefore increased risk of perinatal HBV transmission. These highlight the need to step up preventive efforts against hepatitis B infection and perinatal HBV transmission in our community.

High prevalence of hepatitis B and syphilis co-infections among HIV patients initiating antiretroviral therapy in the north-west region of Cameroon

Hepatitis B virus (HBV) and syphilis co-infections contribute significantly to HIV-associated morbidity and mortality, but the burden of these diseases is not fully appreciated in sub-Saharan Africa, as prevalence data are scarce. Both infections often remain undiagnosed in resource-limited settings because routine testing is not a part of most of the national guidelines. Epidemiological studies provide important information on prevalence and risk factors for such co-infections and can provide guidance for clinical management and for the development of test strategies. We analysed data on baseline characteristics, CD4 cell counts, HBV and syphilis co-infection rates of 690 patients enrolling for antiretroviral therapy in rural Cameroon. The prevalence of both hepatitis B surface antigen (HBsAg, 12.6%, 95% CI 10.1-15.1) and treponemal antibodies (11.4%, 95% CI 8.9-13.7) was high, with significantly higher prevalences for both infections in men; detection of treponemal antibodies increased with age. Although liver enzyme elevations were common, they were not useful to identify HBsAg-positive patients. In this setting, routine serological screening for HBV and syphilis co-infection should be considered to avoid complications and ongoing transmission.

Hepatitis B and C: neglected diseases among health care workers in Cameroon

BACKGROUND

Healthcare workers (HCW) are at risk of acquiring blood-borne viral infections, particularly hepatitis B (HBV), hepatitis C (HCV), and HIV, especially in high endemic regions such as sub-Saharan Africa.

METHODS

Sera from 237 hospital workers in Southwest Cameroon were tested for anti-hepatitis B core antigen (anti-HBc), hepatitis B surface antigen (HBsAg), anti-hepatitis B surface antigen (anti-HBs), anti-HCV and (on a voluntary basis) for anti-HIV. Information on pre-study testing for HBV, HCV and HIV and pre-study HBV vaccination status was collected from these individuals.

RESULTS

The pre-study testing rate among participating hospital staff for HBV was 23.6% (56/237), for HCV 16% (38/237), and for HIV 91.6% (217/237). The pre-study HBV vaccination rate was 12.3% (29/237). Analysis of anti-HBc revealed that 73.4% (174/237) of the hospital staff had been infected by HBV. Active HBV infection (HBsAg positivity) was detected in 15 participants. Anti-HCV was found in four of 237 participants, HIV antibodies were detected in four of 200 participants tested.

CONCLUSION

HBV and HCV are neglected diseases among HCW in sub-Saharan Africa. The vaccination rate against HBV was very low at 12.3%, and therefore anti-HBc testing should be mandatory to identify HCW requiring HBV vaccination. Testing for HBV and routine HBV vaccination for HBV-negative HCW should be strongly enforced in Cameroon.

Low immune response to hepatitis B vaccine among children in Dakar, Senegal

HBV vaccine was introduced into the Expanded Programme on Immunization (EPI) in Senegal and Cameroon in 2005. We conducted a cross-sectional study in both countries to assess the HBV immune protection among children. All consecutive children under 4 years old, hospitalized for any reason between May 2009 and May 2010, with an immunisation card and a complete HBV vaccination, were tested for anti-HBs and anti-HBc. A total of 242 anti-HBc-negative children (128 in Cameroon and 114 in Senegal) were considered in the analysis. The prevalence of children with anti-HBs ≥10 IU/L was higher in Cameroon with 92% (95% CI: 87%–97%) compared to Senegal with 58% (95% CI: 49%–67%), (p<0.001). The response to vaccination in Senegal was lower in 2006–2007 (43%) than in 2008–2009 (65%), (p = 0.028). Our results, although not based on a representative sample of Senegalese or Cameroonian child populations, reveal a significant problem in vaccine response in Senegal. This response problem extends well beyond hepatitis B: the same children who have not developed an immune response to the HBV vaccine are also at risk for diphtheria, tetanus, pertussis (DTwP) and Haemophilus influenzae type b (Hib). Field biological monitoring should be carried out regularly in resource-poor countries to check quality of the vaccine administered.

A low proportion of HBeAg among HBsAg-positive pregnant women with known HIV status could suggest low perinatal transmission of HBV in Cameroon

BACKGROUND

Transmission of hepatitis B virus (HBV) from HBV-positive mothers to their infants is common and usually occurs when the mother is hepatitis B e antigen (HBeAg) positive and/or has a high HBV DNA load. In this study, we determined the prevalence of hepatitis B surface antigen (HBsAg) and HBeAg among pregnant women with known HIV status.

FINDINGS

A total of 650 pregnant women with a mean age of 26.2 years including 301 HIV-positives and 349 HIV-negatives were screened for HBsAg (Monolisa AgHBs Plus Biorad, France). Among the HBsAg-positives, HBeAg and anti-HBe were tested (Monolisa Ag HBe Plus Biorad, France). Overall, 51 (7.85%) were positive for HBsAg. The prevalence of HBsAg was not statistically different between HIV-positive and HIV-negative pregnant women [28/301 (9.3%) vs 23/349 (6.59%); p = 0.2]. None of the 45 HBsAg-positive samples was reactive for HBeAg.

CONCLUSIONS

Our study indicates a high prevalence of HBsAg with very low proportion of HBeAg in Cameroonian pregnant women. Since perinatal transmission of HBV is mostly effective when the mother is also HBeAg-positive, our data could suggest that perinatal transmissions play a minor role in HBV prevalence in Cameroon. In line with previous African studies, these findings further suggests that horizontal transmission could be the most common mechanism of HBV infections in Cameroon.

Hepatitis B and C virus infections in the three Pygmy groups in Cameroon

A high (11.8%) level of hepatitis B virus (HBV) infection was found among 524 Pygmies in Cameroon, whereas the extent of hepatitis C virus (HCV) infection in the same population was low (0.6%). Phylogenetic analyses showed cocirculation of two HBV genotypes, HBV-A3 and -E. Taken together, our results suggest different epidemiological scenarios concerning HBV and HCV infections in this population.

Detection and characterization of hepatitis B virus strains from wild-caught gorillas and chimpanzees in Cameroon, Central Africa

Previous epidemiological studies have reported a high prevalence of hepatitis B virus (HBV) infection in chimpanzees in Gabon and Congo, Central Africa. There is no data for this species from Cameroon. To date few cases of active HBV infection have been documented in gorillas and only one complete HBV sequence has been described from a wild-caught gorilla originating from Cameroon and housed in Germany. Since gorillas are apes found in Cameroon, we thus investigated the prevalence and genetic relationships of HBV infecting apes in this area. We subjected 185 wild-caught apes' plasmas, including 159 from chimpanzees and 26 from gorillas to ELISA screening for HBV surface antigen (HBsAg). Subsequently, we detected HBV DNA, sequenced the whole HBV genome and performed phylogenetic analysis. Eleven (6.9%) chimpanzees and 3 (11.6%) gorillas plasma were found HBsAg positive, of which 8 and 3 were positive for HBV DNA, respectively. Phylogenetic analyses revealed that the 3 new gorilla HBV sequences grouped together with the single available HBV sequence from gorilla. Evidence of recombination between HBV Pan troglodytes troglodytes and Pan troglodytes vellerosus was observed in two of the Cameroonian strains. Findings from our study show that HBV infection is endemic in wild-born gorillas and chimpanzees in Cameroon, and that there is evidence of recombination between HBV strains circulating in chimpanzees. We demonstrated the existence of gorillas' specific HBV strains distinct but related to those found in chimpanzees living in the same habitat in Cameroon, providing substantial evidence of species association of HBV in NHPs.

The underlying mechanisms for the "isolated positivity for the hepatitis B surface antigen (HBsAg)" serological profile

During HBV infection, four structural antigen/antibody systems are observed: hepatitis B surface antigen (HBsAg) and its antibody (anti-HBs); the pre-S antigens associated with HBsAg particles and their antibodies; the particulate nucleocapsid antigen (HBcAg) and anti-HBc; and an antigen structurally related to HBcAg, namely HBeAg and its antibody (anti-HBe). Through the examination of this antigen-antibodies system, hepatitis B infection is diagnosed and the course of the disorder may be observed. Isolated HBsAg seropositivity is a peculiar serological pattern in HBV infection observed some times in routine laboratory. In most cases is not clear how this profile should be interpreted neither its significance. This pattern, however, may be associated with some clinical and laboratorial situations of great relevance, some of which will be addressed in this article.

Epidemiology of hepatitis B virus in Africa, its genotypes and clinical associations of genotypes

Of approximately 360 million people in the world chronically infected with hepatitis B virus (HBV), 65 million reside in Africa. Thus, Africa, with 12% of the world's population, carries approximately 18% of the global burden of HBV infection, with hepatocellular carcinoma and cirrhosis accounting for 2% of the continent's annual deaths. Despite HBV being endemic or hyperendemic in Africa, there is a paucity of data on the genotypes and their distribution. Genotype A is found mainly in southern, eastern and central Africa. Most African genotype A strains belong to subgenotype A1, with subgenotype A3 found in western Africa. Genotype D prevails in northern countries and genotype E in western and central Africa. Ithas become increasingly evident that heterogeneity in the global distribution of HBV genotypes may be responsible for differences in the clinical outcomes of HBV infections and the response to antiviral treatment and vaccination. A limited number of studies have been published relating genotypes to clinical outcomes in African countries. Because observations from other regions of the world can not be extrapolated from one locale to another, the HBV strains circulating in Africa should be studied and related to clinical outcomes.

Seroepidemiology of hepatitis A, B, C, and E viruses infection among preschool children in Taiwan

Taiwan was a hyperendemic area for hepatitis A and B viruses (HAV and HBV) infection before late 1980s. To study the seroprevalence of hepatitis A, B, C, and E viruses (HCV and HEV) infection among preschool children in Taiwan, a community-based survey was carried out in 54 kindergartens in 10 urban areas, 10 rural areas, and 2 aboriginal areas randomly selected through stratified sampling. Serum specimens of 2,538 preschool children were screened for the hepatitis A, C, and E antibodies by a commercially available enzyme immunoassay and for HBV markers by radioimmunoassay methods. The multivariate-adjusted odd ratios (OR) with their 95% confidence intervals (CI) were estimated through the multiple logistic regression analysis. Females had a statistically significantly higher HAV seroprevalence than males. The seroprevalence of HCV infection increased significantly with age. The larger the sibship size, the higher the seroprevalence of HBV infection. Aboriginal children had a significantly higher seroprevalence of HBV and HEV infection and lower seroprevalence of HCV infection than non-aboriginal children. A significantly higher seroprevalence of HBV infection was found in rural children than urban children. There was no significant association between serostatus of HAV and HEV infection and between serostatus of HBV and HCV infection among preschool children in Taiwan. The poor environmental and hygienic conditions in the aboriginal areas might play a role in infection with HBV and HEV.

Seroprevalence of hepatitis B virus infection in individuals with clinical evidence of hepatitis in Goiânia, Goiás. Detection of viral DNA and determination of subtypes

The presence of serological markers for hepatitis B virus (HBsAg, anti-HBc IgM and Anti-HBc total) was investigated in the serum of 1,396 individuals who had clinical suspect of hepatitis. It was observed that 50.7% of the individuals were positive and, from the total of the studied individuals, 14.5% were positive for HBsAg. From these, 8.5% were also positive for anti-HBc IgM. The analysis in relation to gender showed a higher seroprevalence index among male individuals (p < 0.0001). It was observed the occurrence of subtypes adw2 (62.7%), ayw3 (23.5%), ayw2 (9.8%) and adw4 (3.9%). The viral DNA was detected in 61 (33.9%) HBsAg positive samples and in one sample positive only for anti-HBc total. These results indicate an important incidence of the HBV infection in this population, and reinforce previous studies regarding this virus in the central west region of Brazil.

Seroepidemiological survey of hepatitis B and C virus infections in Ghanaian children

The seroprevalences of hepatitis B virus (HBV) and hepatitis C virus (HCV) markers were evaluated in a random sample of 803 children attending school in Ashanti-Akim North district in Ghana in order to gain a better understanding of transmission patterns of these viruses, particularly horizontal transmission of HBV. This rural district is typical of 70% of the Ghanaian population. The overall seroprevalence of at least one marker of HBV infection was 61.2%, with rates increasing from 48% to 80% between the ages of 6-18 years (P < 0.001). The overall HBsAg seroprevalence was 15.8%, with the proportion of HBsAg positives amongst those with anti-HBc increasing from 39.3% in 6-7-year-olds to 51.8% in 12-13-year-olds. It appears that horizontal transmission during this age period was accompanied by a high rate of HBsAg carriage. Among those infected but not carriers, i.e., those HBsAg negative and anti-HBc positive, > 50% lacked detectable levels of anti-HBs, an unusual pattern of convalescent immune response to HBV. The overall seroprevalence of anti-HCV was 5.4% and did not differ significantly by age or gender. Anti-HCV seroprevalence was not associated with the presence of any HBV marker. A better understanding of the unusually high prevalences of HBV and HCV infections demonstrated in this population is likely to influence vaccination and blood transfusion policies and to stimulate further evaluations of these infections and their vehicles of spread in highly endemic regions such as sub-Saharan Africa.

Age- and sex-related study of HBV-DNA in HBsAg asymptomatic children from an endemic area (Cameroon)

A sero-epidemiological survey was carried out in Cameroon in January 1989 on a sample of 702 children of primary school age. A high HBV endemicity level was observed: 60.3% of the sera were positive to any HBV marker, 23.2% (163 sera) were HBsAg-positive. HBV-DNA positivity was observed in 38/163 (23.3%), thus showing a high level of infectivity among these carriers. Seventy-seven HBsAg-positive sera were tested for HBeAg/anti-HBe: 20 (26%) were HBeAg-positive 31 (40%) anti-HBe-positive, and 26 (34%) were negative for both. All sera were anti-HD-negative. Twenty-five per cent of HBeAg-positive sera were HBV-DNA-negative. This finding could be explained by a delayed HBeAg/anti-HBe seroconversion phase with fluctuant HBV-DNA. Only one case of HBV-DNA-positive anti-HBe-positive serum was observed. This study showed that HBV-DNA prevalence was significantly higher in boys (31.8%) than in girls (14.1%) (p less than 0.02). This difference was not observed for any HBV marker. We therefore conclude that in boys a prolonged HBV replicative phase might explain the observed high chronicity rate.