Dominique Noah Noah

Bio: Dominique Noah Noah is an academic researcher from University of Yaoundé I. The author has contributed to research in topics: Hepatitis B & Population. The author has an hindex of 9, co-authored 25 publications receiving 252 citations.

High Prevalence and Predominance of Hepatitis Delta Virus Genotype 1 Infection in Cameroon

Abstract: Antibodies to the hepatitis delta virus (HDV) were found in 17.6% of 233 hepatitis B virus surface antigen-positive subjects in Cameroon. Phylogenetic analyses showed the presence of HDV-1, HDV-5, HDV-6, and HDV-7 genotypes. These results enrich the limited data on HDV prevalence and molecular diversity in Cameroon.

A prominent role of Hepatitis D Virus in liver cancers documented in Central Africa.

Abstract: Hepatocellular Carcinoma (HCC) is one of the commonest cancers in Central Africa, a region with the unusual peculiarity to be hyperendemic for infections with Hepatitis B, C and D viruses. However, data estimating the respective proportions of HCC cases attributable to these viruses are still limited in this area. The current study was undertaken to determine the role of these viruses in HCC compared to non-HCC Cameroonian patients. A case–control study was conducted in the Gastroenterology Unit of Central Hospital of Yaounde in collaboration with Centre Pasteur of Cameroon. Blood samples of all HCC cases (n = 88) and matched control individuals without known liver disease (n = 85) were tested for serological markers of Hepatitis B, C and D viral infections using commercially available enzyme immune-assay kits. Hepatitis B and C viral loads were quantified for positive patients by real-time PCR using commercial kits. The mean age was 46.0 ± 18 and 42.1 ± 16 years old for HCC-patients and controls, respectively for a 2.3 Male/Female sex ratio. The prevalence of hepatitis B surface antigen, antibody to HCV and antibody to HDV were significantly higher in HCC patients (65.90, 20.26 and 26 % respectively) than in control patients (9.23, 4.62 and 1 %) (P < 2.5 10−5). The risk factors analysis showed that both HBV and HCV infections were strongly associated with HCC development in Cameroon with crude odds ratios of 15.98 (95 % CI 6.19-41.25) and 7.33 (95 % CI 2.09-25.77), respectively. Furthermore, the risk of developing HCC increased even more significantly in case of HBV and HDV co-infections with the odd ratio of 29.3 (95 % CI, 4.1-1231). HBV-DNA level was significantly higher in HBsAg-positive HCC-patients than in HBsAg-positive controls with (6.3 Log IU/mL and 5.7 Log IU/mL) respectively (P < 0.05). HBV and HCV infections are the mains factors of HCC development in Cameroon. Our results show that patients co-infected with HDV are at very high risk to develop HCC. An active surveillance program of patients and, foremost, an easier access to antivirals and primary prevention measures are crucial steps to reduce the incidence of HCC in this country. Due to the lack of truly efficient antiviral therapy, the fate of HDV-infected patients remains, however, particularly worrying.

Circulation of human influenza viruses and emergence of Oseltamivir-resistant A(H1N1) viruses in Cameroon, Central Africa

Abstract: While influenza surveillance has increased in most developing countries in the last few years, little influenza surveillance has been carried out in sub-Saharan Africa and no information is available in Central Africa. The objective of this study was to assess the prevalence of influenza viruses circulating in Yaounde, Cameroon and determine their antigenic and genetic characteristics. Throat and/or nasal swabs were collected from November 2007 to October 2008 from outpatients with influenza-like illness (ILI) in Yaounde, Cameroon and analyzed by two different techniques: a one-step real time reverse transcription-polymerase chain reaction (RT-PCR) and virus isolation in MDCK cells. Typing and subtyping of virus isolates was performed by hemagglutination inhibition (HI), and viruses were sent to the WHO Collaborating Centre in London, UK for further characterization and analyses of antiviral resistance by enzyme inhibition assay and nucleotide sequencing. A total of 238 patients with ILI were sampled. During this period 70 (29%) samples were positive for influenza by RT-PCR, of which only 26 (11%) were positive by virus isolation. By HI assay, 20 of the 26 isolates were influenza type A (10 H3N2 and 10 H1N1) and 6 were influenza type B (2 B/Victoria/2/87 lineage and 4 B/Yagamata/16/88 lineage). Seven (70%) of the H1N1 isolates were shown to be resistant to oseltamivir due to a H275Y mutation. This study confirmed the circulation of influenza A(H1N1), A(H3N2) and B viruses in the human population in Central Africa and describes the emergence of oseltamivir-resistant A(H1N1) viruses in Central Africa.

HBs antigene prevalence in blood donors and the risk of transfusion of hepatitis b at the central hospital of yaounde, cameroon

Abstract: Parenteral transmission of hepatitis B virus (HBV) during blood transfusion is not insignificant. Although blood transfusion safety has greatly improved over the last 15 years, the transfusion risk of HBV remains high in developing countries. In the context where blood transfusion safety is limited in some hospitals in Cameroon, the development of good and quality practice for blood donation, based on the use of the most sensitive techniques for the detection of infectious risk of blood donation should be a priority of health authorities. The aim of this paper is to document the epidemiology of HBV infection in the population of blood donors and to assess the risk of infection during blood transfusions at the Central Hospital Yaounde (CHY), Ca- meroon. Methods: During a seven months period, 1000 volunteer donors were recruited prospectively at the blood bank of the CHY. Those included in the study were people aged from 18 years to 55 years without any particular medical history. Data collection was done through an investigation form. Samples were first analysed at the CHY and then Centre Pasteur of Cameroon. Results: Of the 1000 samples tested 108 (10.8%) were positive for HBs Ag. The male and the female sex represented 83.1% and 16.9% respectively. According to the age groups, 56.2% were 18 to 27 years, 30.5% were 28 years to 37 years, 10.4% were 38 years to 47 years and 29% were 48 years to 55 years. The 892 negative sera were analyzed for total anti-HBc antibodies of which 75.78% were positive and 24.56% negative. The 676 samples positive for anti-HBc antibody were retested for HBs Ag using enzyme immunoassay with a confidence level of 95%, between 52 and 82 positive tests were still positive, a proportion that vary between 7.64% and 12.14% (9.89% ± 2.25%). Conclusion: The prevalence rate of 10.8% found in our series is consistent with data in Cameroon. The infectious risk of transmission of HBV among blood donors remains a major problem (9.89% ± 2.25%) related to the test used.

Droplet digital PCR detects high rate of TP53 R249S mutants in cell-free DNA of middle African patients with hepatocellular carcinoma.

Abstract: Hepatocellular carcinoma (HCC) is still a major killing malignancy in sub-Saharan Africa. Lifelong intoxication with aflatoxin B1 is considered as one of the primary causes of this situation. The role of aflatoxin in HCC from a given population is commonly estimated through the prevalence of R249S mutation of TP53, a hallmark for previous exposure to the mycotoxin. However, the role of AFB1 is barely known in large part of Africa. We conducted a survey on circulating cell-free DNA from 149 patients with HCC and 213 control subjects with and without liver diseases from Cameroon and Central African Republic using droplet digital PCR technique. We observed a mutation prevalence of 24.8% (n = 37/149) in patients with tumor and 5.6% (n = 12/213) in controls (P = 2.2E−07). Patients with mutations usually displayed significantly increased circulating alpha-fetoprotein (AFP) values, high hepatitis B virus (HBV) DNA loads as well as worsened values of blood cells count. Interestingly, the fraction of droplets positive for R249S was significantly larger in patients with liver cancer (15.3 ± 3.7%) than in controls (0.5 ± 0.3%, P = 7.1E−04). Our survey indicates that AFB1 is instrumental for HCC development in Middle Africa and that droplet digital PCR might be used in the region both to diagnose HCC and to conduct public health surveys on populations at risk of chronic aflatoxin intoxication.

Estimating the Global Prevalence, Disease Progression, and Clinical Outcome of Hepatitis Delta Virus Infection.

Abstract: _Background_ Hepatitis delta virus (HDV) coinfects with hepatitis B virus (HBV) causing the most severe form of viral hepatitis. However, its exact global disease burden remains largely obscure. We aim to establish the global epidemiology, infection mode-stratified disease progression, and clinical outcome of HDV infection. _Methods_ We conducted a meta-analysis with a random-effects model and performed data synthesis. _Results_ The pooled prevalence of HDV is 0.80% (95% confidence interval [CI], 0.63–1.00) among the general population and 13.02% (95% CI, 11.96–14.11) among HBV carriers, corresponding to 48–60 million infections globally. Among HBV patients with fulminant hepatitis, cirrhosis, or hepatocellular carcinoma, HDV prevalence is 26.75% (95% CI, 19.84–34.29), 25.77% (95% CI, 20.62–31.27), and 19.80% (95% CI, 10.97–30.45), respectively. The odds ratio (OR) of HDV infection among HBV patients with chronic liver disease compared with asymptomatic controls is 4.55 (95% CI, 3.65–5.67). Hepatitis delta virus-coinfected patients are more likely to develop cirrhosis than HBV-monoinfected patients with OR of 3.84 (95% CI, 1.79–8.24). Overall, HDV infection progresses to cirrhosis within 5 years and to hepatocellular carcinoma within 10 years, on average. _Conclusions_ Findings suggest that HDV poses a heavy global burden with rapid progression to severe liver diseases, urging effective strategies for screening, prevention, and treatment.

Systematic review with meta-analysis: diagnostic performance of the combination of pepsinogen, gastrin-17 and anti-Helicobacter pylori antibodies serum assays for the diagnosis of atrophic gastritis.

Abstract: Background The combination of pepsinogen, gastrin-17 and anti-H. pylori antibodies serological assays (panel test) is a non-invasive tool for the diagnosis of atrophic gastritis. However, the diagnostic reliability of this test is still uncertain. Aim To assess the diagnostic performance of the serum panel test for the diagnosis of atrophic gastritis. Methods Medline via PubMed, Embase, Scopus, Cochrane Library databases and abstracts of international conferences proceedings were searched from January 1995 to December 2016 using the primary keywords “pepsinogens,” “gastrin,” “atrophic gastritis,” “gastric precancerous lesions.” Studies were included if they assessed the accuracy of the serum panel test for the diagnosis of atrophic gastritis using histology according to the updated Sydney System as reference standard. Results Twenty studies with a total of 4241 subjects assessed the performance of serum panel test for the diagnosis of atrophic gastritis regardless of the site in the stomach. The summary sensitivity was 74.7% (95% confidence interval (CI), 62.0-84.3) and the specificity was 95.6% (95%CI, 92.6-97.4). With a prevalence of atrophic gastritis of 27% (median prevalence across the studies), the negative predictive value was 91%. Few studies with small sample size assessed the performance of the test in detecting the site of atrophic gastritis. Conclusions The combination of pepsinogen, gastrin-17 and anti-H. pylori antibodies serological assays appears to be a reliable tool for the diagnosis of atrophic gastritis. This test may be used for screening subjects or populations at high risk of gastric cancer for atrophic gastritis; however, a cost-effectiveness analysis is needed.

Hepatitis D Virus: Introduction and Epidemiology

Abstract: Hepatitis D is caused by the hepatitis D virus (HDV), a unique RNA pathogen that requires the hepatitis B surface antigen (HBsAg) to infect. Hepatitis D is transmitted by the parenteral route. The main susceptible group is patients with chronic HBsAg infection who become superinfected with the virus. Hepatitis D occurs throughout the globe, but control of hepatitis B virus (HBV) in the last two decades has consistently diminished the circulation of HDV in industrialized countries. However, hepatitis D remains a medical issue for injecting drug users (IDUs), as well as immigrants from endemic HDV areas, who are reintroducing the infection in Europe.