Large Diffusion of Severe Acute Respiratory Syndrome Coronavirus 2 After the Successive Epidemiological Waves, Including Omicron, in Guinea and Cameroon: Implications for Vaccine Strategies.

Background: We aimed to estimate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence among the general population in Conakry, Guinea and Yaounde, Cameroon after the coronavirus disease 2019 Omicron wave. Methods: We conducted population-based, age-stratified seroprevalence surveys in Conakry and Yaounde (May and June 2022). We collected demographic and epidemiologic information and dried blood spot samples that were tested for SARS-CoV-2 immunoglobulin G (IgG) antibodies using recombinant nucleocapsid and spike proteins with Luminex technology. Results: Samples were obtained from 1386 and 1425 participants in Guinea and Cameroon, respectively. The overall age-standardized SARS-CoV-2 IgG seroprevalence against spike and nucleocapsid proteins was 71.57% (95% confidence interval [CI], 67.48%-75.33%) in Guinea and 74.71% (95% CI, 71.99%-77.25%) in Cameroon. Seroprevalence increased significantly with age categories. Female participants were more likely than male participants to be seropositive. The seroprevalence in unvaccinated participants was 69.6% (95% CI, 65.5%-73.41%) in Guinea and 74.8% (95% CI, 72.04%-77.38%) in Cameroon. In multivariate analysis, only age, sex, and education were independently associated with seropositivity. Conclusions: These findings show a high community transmission after the different epidemiological waves including Omicron, especially among people aged >40 years. In addition, our results suggest that the spread of SARS-CoV-2 has been underestimated as a significant proportion of the population has already contracted the virus and that vaccine strategies should focus on vulnerable populations.

Interest of seroprevalence surveys for the epidemiological surveillance of the SARS-CoV-2 pandemic in African populations: Insights from the ARIACOV project in Benin.

BACKGROUND: Many SARS-CoV-2 seroprevalence surveys since the end of 2020 have disqualified the first misconception that Africa had been spared by the pandemic. Through the analysis of three SARS-CoV-2 seroprevalence surveys carried out in Benin as part of the ARIACOV project, we argue that the integration of epidemiological serosurveillance of the SARS-CoV-2 infection in the national surveillance packages would be of great use to refine the understanding of the COVID-19 pandemic in Africa. METHODS: We carried out three repeated cross-sectional surveys in Benin: two in Cotonou, the economic capital in March and May 2021, and one in Natitingou, a semi-rural city in the north of the country in August 2021. Total and weighted-by-age-group seroprevalences were estimated and the risk factors for SARS-CoV-2 infection were assessed by multivariate logistic regression. RESULTS: In Cotonou, a slight increase in overall age-standardised SARS-CoV-2 seroprevalence from 29.77% (95% CI: 23.12%-37.41%) at the first survey to 34.86% (95% CI: 31.57%-38.30%) at the second survey was observed. In Natitingou, the globally adjusted seroprevalence was 33.34% (95% CI: 27.75%-39.44%). A trend of high risk for SARS-CoV 2 seropositivity was observed in adults over 40 versus the young (less than 18 years old) during the first survey in Cotonou but no longer in the second survey. CONCLUSIONS: Our results show that, however, rapid organisation of preventive measures aimed at breaking the chains of transmission, they were ultimately unable to prevent a wide spread of the virus in the population. Routine serological surveillance on strategic sentinel sites and/or populations could constitute a cost-effective compromise to better anticipate the onset of new waves and define public health strategies.

Population-based sero-epidemiological investigation of the dynamics of SARS-CoV-2 infections in the Greater Accra Region of Ghana.

The coronavirus disease 2019 (COVID-19) pandemic devastated countries worldwide, and resulted in a global shutdown. Not all infections are symptomatic and hence the extent of SARS-CoV-2 infection in the community is unknown. The paper presents the dynamics of the SARS-CoV-2 epidemic in the Greater Accra Metropolis, describing the evolution of seroprevalence through time and by age group. Three repeated independent population-based surveys at 6-week intervals were conducted in from November 2020 to July 2021. The global and by age-groups weighted seroprevalences were estimated and the risk factors for SARS-CoV-2 antibody seropositivity were assessed using logistic regression. The overall age-standardized SARS-CoV-2 antibody seroprevalence for both spike and nucleocapsid increased from 13.8% (95% CI 11.9, 16.1) in November 2020 to 39.6% (95% CI 34.8, 44.6) in July 2021. After controlling for gender, marital status, education level, and occupation, the older age group over 40 years had a higher odds of seropositivity than the younger age group (OR 3.0 [95% CI 1.1-8.5]) in the final survey. Pupils or students had 3.3-fold increased odds of seropositivity (OR 3.2 [95% CI 1.1-8.5]) compared to the unemployed. This study reinforces that, SARS-CoV-2 infections have been significantly higher than reported.

High and Rapid Increase in Seroprevalence for SARS-CoV-2 in Conakry, Guinea: Results From 3 Successive Cross-Sectional Surveys (ANRS COV16-ARIACOV).

We conducted 3 successive seroprevalence surveys, 3 months apart, using multistage cluster sampling to measure the extent and dynamics of the severe acute respiratory syndrome coronavirus 2 epidemic in Conakry, the capital city of Guinea. Seroprevalence increased from 17.3% (95% CI, 12.4%-23.8%) in December 2020 during the first survey (S1) to 28.9% (95% CI, 25.6%-32.4%) in March/April 2021 (S2), then to 42.4% (95% CI, 39.5%-45.3%) in June 2021 (S3). This significant overall trend of increasing seroprevalence (P < .0001) was also significant in every age class, illustrating a sustained transmission within the whole community. These data may contribute to defining cost-effective response strategies.

Rapid Increase of Community SARS-CoV-2 Seroprevalence during Second Wave of COVID-19, Yaoundé, Cameroon.

We conducted 2 independent population-based SARS-CoV-2 serosurveys in Yaoundé, Cameroon, during January 27-February 6 and April 24-May 19, 2021. Overall age-standardized SARS-CoV-2 IgG seroprevalence increased from 18.6% in the first survey to 51.3% in the second (p<0.001). This finding illustrates high community transmission during the second wave of COVID-19.

High Prevalence of Anti-Severe Acute Respiratory Syndrome Coronavirus 2 (Anti-SARS-CoV-2) Antibodies After the First Wave of Coronavirus Disease 2019 (COVID-19) in Kinshasa, Democratic Republic of the Congo: Results of a Cross-sectional Household-Based Survey.

BACKGROUND: In October 2020, after the first wave of coronavirus disease 2019 (COVID-19), only 8290 confirmed cases were reported in Kinshasa, Democratic Republic of the Congo, but the real prevalence remains unknown. To guide public health policies, we aimed to describe the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) antibodies in the general population in Kinshasa. METHODS: We conducted a cross-sectional, household-based serosurvey between 22 October 2020 and 8 November 2020. Participants were interviewed at home and tested for antibodies against SARS-CoV-2 spike and nucleocapsid proteins in a Luminex-based assay. A positive serology was defined as a sample that reacted with both SARS-CoV-2 proteins (100% sensitivity, 99.7% specificity). The overall weighted, age-standardized prevalence was estimated and the infection-to-case ratio was calculated to determine the proportion of undiagnosed SARS-CoV-2 infections. RESULTS: A total of 1233 participants from 292 households were included (mean age, 32.4 years; 764 [61.2%] women). The overall weighted, age-standardized SARS-CoV-2 seroprevalence was 16.6% (95% CI: 14.0-19.5%). The estimated infection-to-case ratio was 292:1. Prevalence was higher among participants ≥40 years than among those <18 years (21.2% vs 14.9%, respectively; P < .05). It was also higher in participants who reported hospitalization than among those who did not (29.8% vs 16.0%, respectively; P < .05). However, differences were not significant in the multivariate model (P = .1). CONCLUSIONS: The prevalence of SARS-CoV-2 is much higher than the number of COVID-19 cases reported. These results justify the organization of a sequential series of serosurveys by public health authorities to adapt response measures to the dynamics of the pandemic.

Validation of Dried Tube Sample Format Quality Controls for the Monitoring of Viral Load and Blood Screening Assays.

HIV viral load (VL) and donor screening assays experience variation and require quaity assurance (QA). NRL sought to confirm a dried tube sample format (HIVDTS) sample type for use in quality control (QC) programs for HIV molecular testing. 50 µL of HIV supernatant at 1 × 105 copies per millilitre (copies/mL)) was dried for 48 hours at room temperature. Post-production and shipped integrity studies were undertaken. Dried HIVDTS was reconstituted in PBS buffer and tested in HIV VL (six participants) or blood screening assays (four participants). Results were entered into NRL's QC monitoring software (EDCNet™) for analysis. The mean of 224 VL results when HIVDTS QCs were tested in Biocentric HIV GENERIC Charge Virale assay was 4.54 log10 copies/mL, with the percentage coefficient of variation (CV%) ranging from 1.75 to 13.20%. The mean Ct value for HIVDTS QCs tested on Roche Cobas MPX assay results was 28.71 (range 28.33 to 29.14), with CV% ranging from 1.56 to 3.98%. The study confirms HIVDTS QCs can effectively monitor the performance of HIV molecular testing and offers a cheaper alternative to commercial QC samples that require cold-chain shipping on dry ice and UN3373 conditions.

High HIV burden and recent transmission chains in rural forest areas in southern Cameroon, where ancestors of HIV-1 have been identified in ape populations.

We studied HIV prevalence and genetic diversity in rural forest areas in Cameroon, where chimpanzee and gorilla populations infected with the ancestors of the different HIV-1 groups have been identified and transmitted to humans during the 20th century. A total of 2812 individuals were studied, 924 from south-central, 1116 from south-east and 772 from south-west Cameroon. Of 208 (7.4%) samples that were confirmed for HIV-1 infection all belong to HIV-1 group M. In all sites and in all age categories, HIV-1 prevalence was higher in women (160/1599 (10.0%)) as compared to men (48/1213 (4.0%)) with the highest prevalence in women aged between 25 and 34 years (>17%). For 188/208 (92.3%) HIV-1 positive individuals, a fragment of the pol gene was successfully amplified and sequenced. Phylogenetic analysis showed predominance of CRF02_AG (58%), a large diversity of subtypes (A, D, F2 and G), nine different CRFs and more than 12% URFs. Interestingly, 35/188 (18.6%) HIV-1 strains form 12 recent transmission chains. The majority of the clusters are composed of two (n = 8) or three (n = 3) sequences but one cluster included ten HIV-1 strains from women living in four different villages on a major road for logging concessions in the south-east (60 km distance). In the three regions of Cameroon where the ancestors of the four HIV-1 groups have been transmitted to humans, we observed a high HIV prevalence, especially in the southeast where HIV-1 M originated. Many factors allowing rapid establishment in the human population and subsequent rapid spread to urban areas of a new retrovirus or other pathogens of zoonotic origin are now present. Our study shows clearly that some rural areas should also be considered as hot-spots for HIV infection. Prevention efforts together with growing access to HIV diagnosis and antiretroviral treatment are urgently needed in these remote areas.

Short Communication: Nucleoside Reverse Transcriptase Inhibitors with Reduced Predicted Activity Do Not Impair Second-Line Therapy with Lopinavir/Ritonavir or Darunavir/Ritonavir.

Second-line therapy randomized trials with lopinavir/ritonavir question the value of resistance testing to guide nucleoside reverse transcriptase inhibitor (NRTI) selection. In this study, we investigated the association between baseline drug resistance and treatment outcome after 104 weeks of second-line therapy with NRTIs and either darunavir/ritonavir or lopinavir/ritonavir in West-central Africa. We did an observational analysis of data from 387 individuals in a randomized, open-label 2LADY trial in Burkina Faso, Cameroon, and Senegal. We modeled the association between RTI drug resistance mutations (DRMs) and virological failure (VF) (viral load [VL] <50 copies/mL) at week 104 using logistic regressions. Covariates included baseline VL and CD4+ count, demographic, and adherence data. Overall, 193 (49.9%), 150 (38.8%), and 44 (11.4%) individuals had, respectively, low/none (genotypic susceptibility score [GSS] <1), intermediate (GSS = 1), and high predicted NRTI activity (GSS >1) in their prescribed second-line regimen. The average number of DRMs by drug class, the proportion of individuals by GSS category, and the duration of first-line therapy were not associated with VF (p > .05). High VL at switch was the only consistent prognostic factor for VF after multivariate adjustment (p < .01). Suboptimal adherence, high predicted RTI activity, or low NRTI mutations were associated with VF (p < .05) when using higher end points for VF or in the intention-to-treat analysis. In conclusion, the use of RTIs with predicted reduced activity does not impair second-line protease inhibitor-based therapy. Therefore, HIV care in resource-limited settings should prioritize strategies to improve adherence and targeted VL testing over drug resistance testing for selecting NRTIs during a protease-based second-line switch.

Comparison of different nucleic acid preparation methods to improve specific HIV-1 RNA isolation for viral load testing on dried blood spots.

In resource-limited countries (RLCs), WHO recommends HIV viral load (VL) on dried blood spots (DBS) for antiretroviral therapy (ART) monitoring of patients living in non-urban settings where plasma VL is not available. In order to reduce the impact of proviral DNA interference, leading to false positive results in samples with low plasma VL, we compared three different nucleic acid preparation methods with the NucliSens (Biomérieux) extraction, known for its high recovery of nucleic acids on DBS. Paired plasma-DBS samples (n=151) with predominantly low plasma VL (≤10,000 copies/ml; 74%) were used. At the threshold of 1,000 copies/ml on DBS, 51% and 10% were misclassified as false positives or false negatives, respectively with NucliSens, versus 41% and 20% with m2000sp (Abbott), described as more specific for RNA recovery. DNase treatments of nucleic acid extracts and free virus elution (FVE) protocol before nucleic acid extraction, reduced the proportion of false positives to 0% and 19%, but increased the proportion of false negatives to 40% and 73%. More efforts are thus still needed to improve performance of VL assays on DBS to monitor patients on ART in RLCs and allow timely switch to more costly second or third line ART regimes.

Virologic Failure and Human Immunodeficiency Virus Drug Resistance in Rural Cameroon With Regard to the UNAIDS 90-90-90 Treatment Targets.

BACKGROUND: In rural Africa, data on virologic effectiveness of antiretroviral treatment (ART) are not sufficient to assess the gap with the UNAIDS 90-90-90 treatment targets. We investigated the prevalences of unsuppressed viral load and antiretroviral drug resistance and the profile of genotypic resistance mutations among patients routinely treated in rural Cameroon. METHODS: A cross-sectional study was performed in 2013-2014 among patients ≥15 years and on first-line ART for ≥6 months in a district hospital. Patients were offered free access to human immunodeficiency virus viral load testing. Genotypic drug resistance testing was done when the viral load was >1000 copies/mL. Multivariate logistic regression models were used to assess the relationship of unsuppressed viral load or antiretroviral drug resistance with sociodemographic and medical characteristics. RESULTS: Of 407 patients (women 74.9%, median age 41.8 years, median time on ART 29.2 months), 96 (23.6%; 95% confidence interval [CI], 19.5-28.0) had unsuppressed viral load and 74 (18.2%; 95% CI, 14.6-22.3) had antiretroviral drug resistance. The prevalences of unsuppressed viral load and resistance increased with time on ART, from 12.0% and 8.0% in the 6- to 12-month group to 31.3% and 27.1% in the >72-month group, respectively. All 74 patients with antiretroviral drug resistance were resistant to nonnucleoside reverse-transcriptase inhibitors, and 57 of them were also resistant to nucleoside reverse-transcriptase inhibitors. CONCLUSIONS: Our estimations were among the highest observed in the west and central African region. The proportion of patients with virologic failure should be divided at least by 2 to reach the UNAIDS 90-90-90 treatment targets.

In-depth analysis of HIV-1 drug resistance mutations in HIV-infected individuals failing first-line regimens in West and Central Africa.

OBJECTIVE: In resource-limited countries, antiretroviral therapy (ART) has been scaled up, but individual monitoring is still suboptimal. Here, we studied whether or not ART had an impact on the frequency and selection of drug resistance mutations (DRMs) under these settings. We also examined whether differences exist between HIV-1 genetic variants. DESIGN: A total of 3736 sequences from individuals failing standard first-line ART (n = 1599, zidovudine/stavudine + lamivudine + neviparine/efavirenz) were analyzed and compared with sequences from reverse transcriptase inhibitor (RTI)-naive individuals (n = 2137) from 10 West and Central African countries. METHODS: Fisher exact tests and corrections for multiple comparisons were used to assess the significance of associations. RESULTS: All RTI-DRM from the 2015 International Antiviral Society list, except F227C, and nine mutations from other expert lists were observed to confer extensive resistance and cross-resistance. Five additional independently selected mutations (I94L, L109I, V111L, T139R and T165L) were statistically associated with treatment. The proportion of sequences with multiple mutations and the frequency of all thymidine analog mutations, M184V, certain NNRTIS, I94L and L109I showed substantial increase with time on ART. Only one nucleoside and two nonnucleoside RTI-DRMs differed by subtype/circulating recombinant form. CONCLUSION: This study validates the global robustness of the actual DRM repertoire, in particular for circulating recombinant form 02 predominating in West and Central Africa, despite our finding of five additional selected mutations. However, long-term ART without virological monitoring clearly leads to the accumulation of mutations and the emergence of additional variations, which limit drug options for treatment and can be transmitted. Improved monitoring and optimization of ART are necessary for the long-term effectiveness of ART.

Field evaluation of an open and polyvalent universal HIV-1/SIVcpz/SIVgor quantitative RT-PCR assay for HIV-1 viral load monitoring in comparison to Abbott RealTime HIV-1 in Cameroon.

With the increasing demand of HIV viral load (VL) tests in resource-limited countries (RLCs) there is a need for assays at affordable cost and able to quantify all known HIV-1 variants. VLs obtained with a recently developed open and polyvalent universal HIV-1/SIVcpz/SIVgor RT-qPCR were compared to Abbott RealTime HIV-1 assay in Cameroon. On 474 plasma samples, characterized by a wide range of VLs and a broad HIV-1 group M genetic diversity, 97.5% concordance was observed when using the lower detection limit of each assay. When using the threshold of 3.00 log10 copies/mL, according to WHO guidelines to define virological failure (VF) in RLCs, the concordance was 94.7%, 360/474 versus 339/474 patients were identified with VF with the new assay and Abbott RealTime HIV-1, respectively. Higher VLs were measured with the new assay, +0.47 log10 copies/mL (95% CI; 0.42-0.52) as shown with Bland-Altman analysis. Eleven samples from patients on VF with drug resistance were not detected by Abbott RealTime HIV-1 versus two only with the new assay. Overall, our study showed that the new assay can be easily implemented in a laboratory in RLCs with VL experience and showed good performance on a wide diversity of HIV-1 group M variants.

Short Communication: High Viral Load and Multidrug Resistance Due to Late Switch to Second-Line Regimens Could Be a Major Obstacle to Reach the 90-90-90 UNAIDS Objectives in Sub-Saharan Africa.

In the context of lifelong antiretroviral treatment (ART) as early as possible and to end the HIV/AIDS epidemic as a public health treat by 2030, it is important to evaluate the potential risk of transmission of HIV-1 drug resistance (HIVDR) in resource-limited countries (RLCs). Since HIV transmission is driven by HIV-1 RNA viral load (VL), we studied the association between plasma VL and HIVDR profiles in 451 adults failing first-line ART from the 2LADY-ANRS12169/EDCTP trial in Burkina Faso, Cameroon, and Senegal. Median duration on first-line ART was 49 months (IQR: 33-69) and 91% patients were asymptomatic. Genotypic drug resistance testing was successful for 446 patients and 98.7% of them were resistant to at least one of the first-line drugs; 40.6% and 55.8% were resistant to two or three drugs of their ongoing first-line ART, respectively. The median VL was higher in patients with HIVDR to all ongoing first-line drugs than in those still susceptible to at least one drug; 4.7 log10 copies/ml (IQR: 4.3-5.2) versus 4.2 log10 copies/ml (IQR: 3.7-4.7), respectively (p < .001). The proportion of patients with HIVDR to all ongoing first-line drugs was highest (77.9% [95/122]) in patients with VL >5.0 log10 copies/ml. High rates of cross-resistance to other nucleoside reverse-transcriptase inhibitors were observed and were also highest in patients with high VL. Without improvement of patient monitoring to avoid late switch to second-line regimens, a potential new epidemic caused by HIVDR strains could emerge in sub-Saharan Africa and compromise all efforts to reach 90-90-90 UNAIDS objective by 2020.

African origin of the malaria parasite Plasmodium vivax.

Plasmodium vivax is the leading cause of human malaria in Asia and Latin America but is absent from most of central Africa due to the near fixation of a mutation that inhibits the expression of its receptor, the Duffy antigen, on human erythrocytes. The emergence of this protective allele is not understood because P. vivax is believed to have originated in Asia. Here we show, using a non-invasive approach, that wild chimpanzees and gorillas throughout central Africa are endemically infected with parasites that are closely related to human P. vivax. Sequence analyses reveal that ape parasites lack host specificity and are much more diverse than human parasites, which form a monophyletic lineage within the ape parasite radiation. These findings indicate that human P. vivax is of African origin and likely selected for the Duffy-negative mutation. All extant human P. vivax parasites are derived from a single ancestor that escaped out of Africa.

Deciphering morphological determinants of the helix-shaped Leptospira.

Leptospira spp. are thin, highly motile, slow-growing spirochetes that can be distinguished from other bacteria on the basis of their unique helical shape. Defining the mechanisms by which these bacteria generate and maintain this atypical morphology should greatly enhance our understanding of the fundamental physiology of these pathogens. In this study, we showed that peptidoglycan sacculi from Leptospira spp. retain the helical shape of intact cells. Interestingly, the distribution of muropeptides was different from that in the Escherichia coli model, indicating that specific enzymes might be active on the peptidoglycan macromolecule. We could alter the shape of Leptospira biflexa with the broad-spectrum ß-lactam antibiotic penicillin G and with amdinocillin and aztreonam, which are ß-lactams that preferentially target penicillin-binding protein 2 (PBP2) and PBP3, respectively, in some species. Although genetic manipulations of Leptospira spp. are scarce, we were able to obtain mutants with alterations in genes encoding PBPs, including PBP3. Loss of this protein resulted in cell elongation. We also generated an L. biflexa strain that conditionally expresses MreB. Loss of the MreB function was correlated with morphological abnormalities such as a localized increased diameter and heterogeneous length. A prolonged depletion of MreB resulted in cell lysis, suggesting that this protein is essential. These findings indicate that important aspects of leptospiral cell morphology are determined by the cytoskeleton and the murein layer, thus providing a starting point for a better understanding of the morphogenesis in these atypical bacteria.