Développement d’un algorithme approprié pour le diagnostic de l'infection à VIH: Experience du Tchad

peer reviewe

Evaluation immuno-virologique de la trithérapie antirétrovirale par Triomune en première ligne, chez les patients VIH-1 adultes à N’Djaména, Tchad.

peer reviewedaudience: researcher, professional, studentDans cet article, nous avons évalué les taux des lymphocytes TCD4 et les charges virales chez des patients Vivant avec le VIH sous Triomune, à N'Djaména au Tchad. Cette évaluation a lieu au J0 avant le traitement et après huit (8) mois de traitement. Nous avons remarqué que le taux d'échec à la Triomune était de 43,75% (21/48)

New genotypic approaches for the monitoring of HIV resistance to antiretrovirals in resource limited countries. The example of Chad

Cette thèse traite la question de la prise en charge des personnes vivant avec le Virus de l’Immunodéficience Humaine (PVVIH) au Tchad. En effet, la lutte contre le VIH demeure jusqu’à présent un problème majeur de santé publique dans les pays au sud du Sahara et ce, malgré les avancées notables enregistrées depuis quelques années. Les ressources limitées pour la prise en charge des PVVIH dans ces pays ont pour conséquence l’émergence et la transmission des souches résistantes qui se traduit par la perte de l’efficacité du traitement administré. Un traitement antirétroviral est administré dans l’objectif d’obtenir et de maintenir une charge virale plasmatique indétectable, tandis que la prise en charge d'une situation d'échec virologique implique le plus souvent une adaptation du traitement en fonction des résultats, le contrôle régulier de la charge virale et des tests génotypiques de résistance. Or, la performance d’un test de résistance est influencée par ses propriétés intrinsèques (sensibilité et spécificité), la qualité et le type de l’échantillon à analyser, la connaissance de la prévalence de résistance et de la diversité génétique dans la population. En tout état de cause, les techniques de mesure de la charge virale et les tests de résistance standard nécessitent des infrastructures de laboratoire adéquats et du personnel bien formé. Toutes ces méthodes, pour utiles qu’elles soient, se révèlent être inadaptées sinon très onéreuses pour les pays à ressources limitées (PRL). C’est la raison pour laquelle, le développement et la mise en place au Tchad des nouvelles alternatives, fiables et moins coûteuses seraient à notre avis, la solution pour une meilleure surveillance épidémiologique de la résistance du VIH au traitement. Une évaluation immunovirologique a été faite chez 116 patients sous traitement à N’Djamena. Ont été mesuré chez ces patients, le taux de lymphocytes TCD4 et la charge virale avant le traitement (J0) et après huit mois de traitement (M8). Nous avons ensuite comparé trois techniques de mesure de la charge virale (Abbott RealTime, Cobas AmpliPrep/Cobas TaqMan et la méthode de l’ANRS) au laboratoire de Référence Sida du CHU de Liège. Le séquencage a été réalisé sur plasma et DBS pour déterminer la prévalence des mutations de résistances acquises et la diversité génétique. Enfin, nous avons déterminé les mutations ponctuelles de résistances sur DBS et plasma par la technique ASPCR (Allele-Specific PCR)

Use of Dried Blood Spot to Improve the Diagnosis and Management of HIV in Resource-Limited Settings

peer reviewedOver 75% of people infected with HIV live in countries where health resources are very limited for the diagnosis and biological monitoring of people infected by the virus. In resource-limited settings, the use of DBS is a valuable alterna- tive. It has provided technical and economical alternative to the collection of blood in the tubes for testing HIV infec- tion. The DBS can be kept for over a year, it is economical in storage space and facilitates storage conditions because it can be stored at room temperature. It is more discreet and easier to carry over liquid samples that require tubes and other appropriate materials. The amount is sufficient for certain analyses of DNA generally, but may be insufficient for the analysis of viral RNA if the viral load is low. Its disadvantage is often associated with small amounts of blood col- lected available for testing, and the difficulties encountered in laboratories to extract the maximum possibilities without material contamination. DBS can be stored at room temperature (25°C - 35°C), at 4°C, −20°C or even −70°C. With PCR, the DBS is a suitable medium for the diagnosis of patients infected with HIV, virological monitoring by the VL and even analyzing viral genotype. It is a handy stand for the collection, transport and analyses of biological monitoring of HIV infection. It is indeed very suitable for environments with limited accessibility where it is difficult for specialized laboratories to monitor these patients. The DBS is suitable for resource-limited settings.Nouvelles approches génotypiques pour le monitoring de résistance du VIH aux ARV dans les pays à ressources limitée

Portage vaginal et profil de sensibilité du Streptocoque du Groupe B Chez la femme enceinte à l'Hopital Gynéco-Obstétrique et Pédiatrique de Yaoundé (Yaoundé)

In order to obtain reliable data on vaginal carriage of Streptococcus agalactiae in pregnant women and to formulate a prevention program of neonatal Group B Streptococcus (GBS) disease, we carried out a prospective cross sectional study for 6 months. The general objective of the study was to evaluate the prevalence of vaginal carriage and the resistance profile of GBS. The study involved 142 pregnant women presenting for antenatal care in Yaoundé Gynecology-Obstetric and Pediatric Hospital (YGOPH). Participants were interviewed using a standard structure questionnaire. Low vaginal swabs were collected and cultured on specific media. A presumptive identification of isolates was made using standard bacteriological methods. Confirmative identification of Group B Streptococcus was done and antimicrobial sensitivity testing was performed. Among the 142 pregnant women GBS colonization was confirmed in 11 (7.7%). The rate of carriage was 3.8% in the first trimester, 7% in the second trimester and 11.1% in the third trimester. The predominant germ was Candida albicans with a frequency of 45.2% among the germs found in monomicrobial culture and Gardnerella vaginalis (77.8%) among the germs in polymicrobial culture, followed by Candida spp (11.8%), S. agalactiae (8.6%) and Escherichia coli (4.3%). The result of antimicrobial sensitivity testing showed that all the GBS strains were sensitive to major antibiotics drugs tested. The highest rates of resistance were found with gentamycin (100%) and Cefuroxim (81.8%). The vaginal carriage of GBS among pregnant women is still high. Thus, well-planned, prospective studies will be necessary to fully appreciate the magnitude of the problem of GBS in our hospitals

Virological response, HIV-1 drug resistance mutations and genetic diversity among patients on first-line antiretroviral therapy in N'Djamena, Chad: Findings from a cross-sectional study

Background: The national antiretroviral therapy in the Republic of Chad provides free of charge antiretroviral regimens and therapeutic monitoring for patients receiving antiretroviral therapy nationwide. For a successful programmatic uptake, these efforts merit to be supported by thorough assessments of antiretroviral therapy response and HIV-1 drug resistance surveillance, especially with risks of cross-resistance due to the gradual stavudine phasing out in such national settings. We therefore evaluated the virological response to antiretroviral therapy, HIV-1 drug resistance emergence and circulating HIV-1 clades in a Chad context. A cross-sectional and prospective study was conducted among 116 patients (41 [δ ± 6.87] years, 59% female) receiving first-line antiretroviral therapy for ≥ 6 months in Ndjamena, Chad, in 2011-2012, enrolled consecutively. To ensure accuracy, plasma viral load was concomitantly measured using Abbott Real-Time and Cobas AmpliPrep/TaqMan (v2.0), and virological failure defined as ≥ 1000 HIV-1 RNA copies/ml. Plasma from patients experiencing virological failure were processed for sequencing of HIV-1 protease-reverse transcriptase using the ANRS-AC.11 resistance testing protocol; drug resistant mutations were interpreted using the ANRS-AC11 algorithm; and phylogenetic analysis was performed using MEGA.v.6. Results: Majority of patients was receiving zidovudine plus lamivudine plus nevirapine (46%), stavudine plus lamivudine plus nevirapine (41%) and tenofovir plus emtricitabine plus efavirenz (11%), for a median time-on-treatment of 5 [IQR 4-7] years. The rate of virological failure was 43% (50/116), with 86% (43/50) sequencing performance. Overall, 32% (37/116) patients presented ≥ one major drug resistant mutation(s), with 29% (34/116) to nucleos(t)ide reverse transcriptase inhibitors (67% [29/43] M184V/I, 30% [13/43] T215Y/F, 19% [8/43] V75A/F/I/L/M, 9% [4/43] K70P/R/W, 9% [4/43] K219E/N/Q and 5% [2/43] A62V); 86% (37/43) to non-nulceos(t)ide reverse transcriptase inhibitors (30% [13/43] K103N/S/E, 26% [11/43] Y181C/V/F/L, 2% [1/43] L100I, 2% [1/43] F227L, 2% [1/43] P225H); and 2% (1/43) to protease inhibitors (M46I, I54V, V82S). Six HIV-1 subtypes were found: 30% circulating recombinant form (CRF02-AG), 30% J, 16% G, 9% A, 9% D, 5% F. Conclusions: In Chad, almost half of patients are failing first-line antiretroviral therapy after 5 years, with considerable drug resistant mutations at failure. Absence of K65R supports the use of tenofovir-containing regimens as preferred first-line and as suitable drug for second-line combinations, in this setting with significant HIV-1 genetic diversity. © 2017 The Author(s)

High prevalence of cervical high-risk human papillomavirus infection mostly covered by Gardasil-9 prophylactic vaccine in adult women living in N'Djamena, Chad.

BackgroundWe conducted in 2018 a descriptive, quantitative, population-based, cross-sectional survey estimating the prevalence of cervical high-risk human papillomavirus (HR-HPV) infection and associated risk factors among adult women living in N'Djamena, Chad.MethodsFive of the 10 districts of N'Djamena were randomly selected for inclusion. Peer educators contacted adult women in community-churches or women association networks to participate in the survey and come to the clinic for women's sexual health "La Renaissance Plus", N'Djamena. Medical, socio-demographical and behavioral informations were collected. HPV DNA was detected and genotyped in endocervical swab using Anyplex II HPV28 genotyping test (Seegene, Seoul, South Korea).Results253 women (mean age, 35.0 years; range, 25-65) including 3.5% of HIV-positive women were prospectively enrolled. The prevalence of HPV infection was 22.9%, including 68.9% of HR-HPV infection and 27.6% being infected with multiple genotypes, providing a total HR-HPV prevalence of 15.8% (95% CI%: 11.3-20.3). The most prevalent HR-HPV genotypes were HPV-58, HPV-35, HPV-56, HPV-31, HPV-16, HPV-45, HPV-52 and HPV-18. HPV types targeted by the prophylactic Gardasil-9 vaccine were detected in nearly 70% (67.5%) and HPV-58 was the most frequently detected. HIV infection was a risk factor strongly associated with cervical infection with any HPV [adjusted Odds ratio (aOR): 17.4], multiple types of HPV (aOR: 8.9), HR-HPV (aOR: 13.2) and cervical infection with multiple HR-HPV (aOR: 8.4).ConclusionThese observations highlight the unsuspected high burden of cervical HR-HPV infection in Chadian women, and point the potential risk of further development of HPV-associated cervical precancerous and neoplastic lesions in a large proportion of women in Chad. The high rate of preventable Gardasil-9 vaccine genotypes constitutes the rationale for introducing primary vaccine prevention against cervical cancer in young female adolescents living in Chad