High SARS-CoV-2 Seroprevalence among Healthcare Workers in Bamako, Mali

In Mali, a country in West Africa, cumulative confirmed COVID-19 cases and deaths among healthcare workers (HCWs) remain enigmatically low, despite a series of waves, circulation of SARS-CoV-2 variants, the country’s weak healthcare system, and a general lack of adherence to public health mitigation measures. The goal of the study was to determine whether exposure is important by assessing the seroprevalence of anti-SARS-CoV-2 IgG antibodies in HCWs. The study was conducted between November 2020 and June 2021. HCWs in the major hospitals where COVID-19 cases were being cared for in the capital city, Bamako, Mali, were recruited. During the study period, vaccinations were not yet available. The ELISA of the IgG against the spike protein was optimized and quantitatively measured. A total of 240 HCWs were enrolled in the study, of which seropositivity was observed in 147 cases (61.8%). A continuous increase in the seropositivity was observed, over time, during the study period, from 50% at the beginning to 70% at the end of the study. HCWs who provided direct care to COVID-19 patients and were potentially highly exposed did not have the highest seropositivity rate. Vulnerable HCWs with comorbidities such as obesity, diabetes, and asthma had even higher seropositivity rates at 77.8%, 75.0%, and 66.7%, respectively. Overall, HCWs had high SARS-CoV-2 seroprevalence, likely reflecting a “herd” immunity level, which could be protective at some degrees. These data suggest that the low number of cases and deaths among HCWs in Mali is not due to a lack of occupational exposure to the virus but rather related to other factors that need to be investigated.

Short Communication: Genetic Variation in Human IL10 Proximal Promoter and Susceptibility to HIV-1 Infection in Mali, West Africa

It is now recognized that to fully understand the role of host genetic variation on susceptibility to HIV-1 infection, investigations must be extended to African populations. We sought to determine if genetic variation in IL10 are associated with HIV-1 infection in a West African cohort in Mali. HIV-infected and -uninfected individuals were genotyped for three common single nucleotide polymorphisms (SNPs) located at positions -592 (C/A), -819 (C/T), and -1082 (G/A) of the IL10 promoter. We found that the ATA haplotype, which has been previously associated with low IL-10 expression, was the most represented in the cohort. Although we observed a trend toward an increased frequency of ATA/ATA carriage in HIV-infected compared with -uninfected individuals, the difference was not statistically significant. Similarly, individual IL10 SNPs were not significantly enriched in the HIV-infected group, suggesting that IL10 genetic variants are not associated with HIV-1 in this West African cohort from Mali.

Use of sodium dodecyl sulfate to improve tuberculosis sputum smear microscopy

Sputum smear microscopy (SSM), the most widely available tool for tuberculosis (TB) detection, has limited performance in paucibacillary patients and requires highly experienced technicians. The objective of this study was to determine whether the addition of sodium dodecyl sulfate (SDS), a detergent that thins sputum, at 4% and 10%, improves the detection of acid-fast bacilli (AFB), the clarity of slides, and the biosafety of the technique. Thirty participants with presumptive TB were enrolled. Three independent, blinded technicians examined the slides. Regular sputum concentrated AFB smear and sputum culture were used as standard control methods. Sputum culture was also performed before and after 10% SDS addition for safety analysis. We found that neither SSM with SDS 4% nor SSM with SDS 10% improved the test's performance. However, slides with 4% and 10% SDS, compared with slides prepared without SDS, had significantly better clarity scores. The 10% SDS-prepared sputum samples were all culture negative. While adding SDS detergent does not improve the performance of SSM slides, it does improve the clarity and biosafety. Where experienced technicians are scarce, especially in low resource settings, use of SDS may enhance the ease of slide reading in sputum smear microscopy.

Mycobacterium africanum (Lineage 6) shows slower sputum smear conversion on tuberculosis treatment than Mycobacterium tuberculosis (Lineage 4) in Bamako, Mali

Objective

Ancestral M. tuberculosis complex lineages such as M. africanum are underrepresented among retreatment patients and those with drug resistance. To test the hypothesis that they respond faster to TB treatment, we determined the rate of smear conversion of new pulmonary tuberculosis patients in Bamako, Mali by the main MTBc lineages.

Methods

Between 2015 and 2017, we conducted a prospective cohort study of new smear positive pulmonary tuberculosis patients in Bamako. Confirmed MTBc isolates underwent genotyping by spoligotyping for lineage classification. Patients were followed at 1 month (M), 2M and 5M to measure smear conversion in auramine (AR) and Fluorescein DiAcetate (FDA) vital stain microscopy.

Result

All the first six human MTBc lineages were represented in the population, plus M. bovis in 0.8% of the patients. The most widely represented lineage was the modern Euro-American lineage (L) 4, 57%, predominantly the T family, followed by L6 (M. africanum type 2) in 22.9%. Ancestral lineages 1, 5, 6 and M. bovis combined amounted to 28.8%. Excluding 25 patients with rifampicin resistance, smear conversion, both by AR and FDA, occurred later in L6 compared to L4 (HR 0.80 (95% CI 0.66–0.97) for AR, and HR 0.81 (95%CI 0.68–0.97) for FDA). In addition we found that HIV negative status, higher BMI at day 0, and patients with smear grade at baseline ≤ 1+ were associated with earlier smear conversion.

Conclusion

The six major human lineages of the MTBc all circulate in Bamako. Counter to our hypothesis, we found that patients diseased with modern M. tuberculosis complex L4 respond faster to TB treatment than those with M. africanum L6.

Establishing Reference Ranges of Hematological Parameters from Malian Healthy Adults

INTRODUCTION

Measurement of immuno-hematological parameters has been historically helpful in the diagnosis and treatment monitoring of many infectious diseases and cancers. However, these parameters have not yet been established in many developing countries where patient care strongly relies on such low-cost tests. This study describes the immuno-hematological parameter ranges for Malian healthy adults.

METHODS

A cross sectional study was conducted from August 2004 to May 2013. We included 213 healthy volunteers (173 male and 40 female), aged between 18-59 years. Median, 2.5 and 97.5 percentile ranges for each immuno-hematological parameter are presented.

RESULTS

In our study population, the hematological parameters' ranges were mostly different to the universal established ranges. We found in our population a Median white blood cell (WBC) count of 5200 cells/μL [3237.5-11900], Red Blood Cell (RBC) count of 4.94 10^6 [3.56-6.17], hemoglobin (Hb) of 14.2 g/dL [12.2-17.38], platelet count (Plt) of 275 10^3/μL [145.4-614.4], lymphocytes 2050/μL [1200-3800], neutrophils 2200/μL [1040-6220]; monocytes 200/μL [100-660]; eosinophils 131/μL [0-1026]; CD4 902 cells/μL [444-1669] and CD8 485 cells/μL [0-1272]. We found significant gender differences in RBC, Hb level and MPV. However, RBC and Hb were higher in males median values compared to females (median values) (p<0.001), whereas the Mean platelet volume lower values (MPV) in males than females (P<0.047). The hemoglobin level for some West African countries (Mali, Burkina Faso, Togo, and Nigeria) ranged from 13.5 to 15.1 g/dL for males and 12 to 13 g/dL for females. However in East and Southern Africa, the values were anywhere from 14.1 to 16.1 for males and 11.2 to 14.4 for females.

CONCLUSION

Our data may help physicians to better define hematological abnormalities in patients. They may also be used to define new "normal hematological values" in Malian population or in the whole West African population.

Retrospective surveillance of HIV prevalence in blood donors can help in the selection of the best social group for blood donation in Mali

The National Centre for Blood Transfusion, Bamako, Mali has collected data that characterizes trend in HIV prevalence over 10 years by gender, age, occupation, marital status and donor category. These data help to describe national HIV prevalence and assist in formulating blood donation policies. Donations from 1993 to 2002 were categorized by donor age (decade), occupation (student, military and other), marital status (single, married and other), gender and donor status (volunteer, occasional and family). Comparisons were made using conservative estimates of donation frequency/donor category. Donations increased by more than 400%. By 1999, increased HIV prevalence in donations from women was consistently present. Donations from the age group of 30-39 years showed an increased prevalence beginning in 2000, which by 2002 was almost 10 times greater than in the low-prevalence (<20 years) group (5.9 vs. 0.6%). By 2000, both categories - students and military were less likely to be HIV positive than those from other occupational categories, and donations from married persons were less likely to be HIV positive by 1997. The highest prevalence was observed in the 'occasional' donor category, which increased to >14% by 2001; volunteer donation HIV positive peaked at 2.3% in 1999. HIV prevalence in blood donations in Bamako, Mali, demonstrates important trends from 1993 to 2002. The prevalence of > 14% in donations from occasional donors and significant trends by decade, gender, marital status and occupation argue for increased analysis of the blood donor population to improve blood safety and to understand the demographics of HIV infection in Mali.