Usefulness of a fourth generation ELISA assay for the reliable identification of HCV infection in HIV-positive adults from Gabon (Central Africa)

Background/Objectives Guidelines for optimized HCV screening are urgently required in Africa, especially for patients infected with HIV, who sometimes show false positive or false negative reactivity in anti-HCV antibody assays. Here, we assessed the usefulness of a fourth-generation HCV Ag-Ab ELISA for the identification of active HCV infection in HIV-positive patients. Methods This cross-sectional study was conducted between 03/2010 and 01/2013 and included 762 Gabonese HIV-positive adult patients. The results of ELISA (Monolisa HCV Ag-Ab ULTRA, Bio-Rad) were compared with those obtained by RT-PCR (gold standard). The optimal ELISA signal-to-cutoff (S/CO) ratio to identify patients with active hepatitis C (positive HCV RNA) was determined. Specimens were further tested by the INNO-LIA HCV core assay (Innogenetics) and the Architect HCV Ag kit (Abbott) to define the best diagnostic strategy. Results Sixty-seven patients tested positive for HCV (S/CO ratio >= 1) by ELISA. Of these, 47 (70.1%) tested positive for HCV RNA. The optimal S/CO associated with active HCV infection was 1.7. At this threshold, the sensitivity of ELISA was 97.9%(95% confidence interval (CI) 90.0-99.9%), its specificity was 91.3% (95% CI 85.0-95.5%), and HCV seroprevalence rate was 7.3% (56/762) (95% CI 5.6-9.4%). Among 57 HCV-seropositive patients with available INNO-LIA results, false reactivity was identified in 14 (24.6%), resolved HCV infection in two (3.5%), possible acute HCV infections in nine (15.8%) and likely chronic HCV infections in 32 (56.1%) patients. HCV core Ag was undetectable in 14/15 (93.3%) specimens that tested negative for HCV RNA whereas it was quantified in 34 (out of 39, 87.2%) samples that tested positive for HCV RNA. Conclusions Our study provides comprehensive guidance for HCV testing in Gabon, and will help greatly clinicians to improve case definitions for both the notification and surveillance of HCV in patients co-infected with HIV

Travel Med Infect Dis

Background Toxoplasmosis is a zoonosis caused by the protozoan Toxoplasma gondii. In immunocompetent patients the infection is usually benign. However, cases of severe and even lethal primo-infections are regularly reported in South America. In contrast, data from tropical Africa are fragmentary. Methods Data for French cases of severe toxoplasmosis acquired between 2013 and 2018, in tropical Africa and among immunocompetent patients were collected retrospectively in 2018. Results Four male patients with a mean age of 34-years were identified. All infections originated in West or Central Africa. The clinical presentations were heterogeneous: two patients had severe disseminated toxoplasmosis, of which one presented with chorioretinitis associated with myositis and the other with febrile pneumopathy; one patient presented with post-infectious acute cerebellar ataxia and the final case had general symptoms and skin manifestations. The diagnosis of acute toxoplasmosis was confirmed by serology in four patients. Molecular diagnosis confirmed T. gondii infection in three patients with Africa 1 as the dominant genotype. The infection was cured with anti-infective treatment in all four patients. Ocular sequelae were reported in the two patients with chorioretinitis. Conclusions Imported cases of severe toxoplasmosis in immunocompetent patients are rare in France. However, this aetiology should be evoked rapidly in a patient with a severe infectious syndrome who has recently visited or originated from tropical Africa

Phyloepidemiological analysis reveals that viral divergence led to the paucity of SIVmus/gsn/mon infections in wild populations

Human immunodeficiency virus subtype-1 (HIV-1) is the result of cross-species transmission of simian immunodeficiency virus from chimpanzees (SIVcpz). SIVcpz is a chimeric virus which shares common ancestors with viruses infecting red capped mangabeys and a subset of guenon species. The epidemiology of SIV infection in hominoids is characterized by low prevalence and uneven geographical distribution. Surveys in Cameroon indicated that two closely related members of the guenon species subset, mustached guenons and greater spot-nosed guenons, infected with SIVmus and SIVgsn respectively, have also low rates of SIV infections in their populations. Compared to other monkeys, including red capped mangabeys and closely related guenon species, such an epidemiology is unusual.By intensifying sampling of geographically distinct populations of moustached and greater spot-nosed guenons in Gabon, and including large sample sets of mona guenons in Cameroon, we add strong support that the paucity of SIV infections in wild populations is a general feature of this monophyletic group of viruses. Furthermore, comparative phylogenetic analysis reveals that this phenotype is a feature of this group of viruses infecting phylogenetically dispirate hosts, suggesting that this epidemiological phenotype results from infection with these HIV-1 related viruses rather than a common host factor. Thus, these HIV-1 related viruses, SIVcpz and the guenon viruses which share a common ancestor with part of the SIVcpz genome, have a distinct epidemiology to that found in other African primate species. $\textbf{IMPORTANCE}$: Stable virus-host relationships are established over multiple generations. The prevalence of viral infections in any given host is determined by various factors. Stable virus-host relationships of viruses that are able to cause persistent infections and exist with high incidences of viral infections are generally characterized by a lack of morbidity prior to host reproduction. Such is the case for cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infection in humans.SIV infections of most African primate species also satisfy these criteria, being found at a high prevalence, with rare cases of clinical disease. By contrast, SIVcpz, the ancestor of HIV-1 infection in humans, has a different epidemiology and it has been reported that these animals suffer from an AIDS-like disease in the wild. Here we conclusively demonstrate that viruses which are closely related to SIVcpz and infect a subset of guenon monkeys show an epidemiology resembling that of chimpanzees