Slum and urban deprivation in compacted and peri-urban neighborhoods in sub-Saharan Africa

UN-Habitat estimates that 51.3% of the urban population in sub-Saharan Africa (SSA) resided in slums in 2020, and future projections indicate continued growth. However, limited information on the spatial distribution and evolution of slums in the region underestimates the challenges they present.This study investigates the use of urban morphology to map slums in 95 cities across Nigeria, Kenya, Ghana, and Malawi. The approach employed an unsupervised classification and a tree-based clustering framework, integrating morphological and socio-economic indicators, as well as comprehensive sampling points for slums.Our findings indicate that morphological clusters with compact, small buildings are indicative of a high prevalence of slums, with an accuracy rate of 83.6%. Moreover, these morphological slum clusters exhibit significant correlations with socio-economic indicators, exhibiting lower GDP and wealth index compared to neighbouring clusters. Notably, larger and older cities with morphological slum clusters demonstrate improved economic well-being and enhanced access to infrastructure.Our findings underscore the potential of utilizing urban morphology to comprehend the diversity and dynamics of urban slums and socioeconomic development. These results provide a foundation for large-scale identification of slums and urban deprivation, offering support for targeted solutions to address the challenges associated with slums in developing countries

HIV and SARS-CoV-2 infection in postpartum Kenyan women and their infants.

BackgroundHIV may increase SARS-CoV-2 infection risk and COVID-19 severity generally, but data are limited about its impact on postpartum women and their infants. As such, we characterized SARS-CoV-2 infection among mother-infant pairs in Nairobi, Kenya.MethodsWe conducted a nested study of 62 HIV-uninfected and 64 healthy women living with HIV, as well as their HIV-exposed uninfected (N = 61) and HIV-unexposed (N = 64) infants, participating in a prospective cohort. SARS-CoV-2 serology was performed on plasma collected between May 1, 2020-February 1, 2022 to determine the incidence, risk factors, and symptoms of infection. SARS-CoV-2 RNA PCR and sequencing was also performed on available stool samples from seropositive participants.ResultsSARS-CoV-2 seropositivity was found in 66% of the 126 mothers and in 44% of the 125 infants. There was no significant association between SARS-CoV-2 infection and maternal HIV (Hazard Ratio [HR] = 0.810, 95% CI: 0.517-1.27) or infant HIV exposure (HR = 1.47, 95% CI: 0.859-2.53). Maternal SARS-CoV-2 was associated with a two-fold increased risk of infant infection (HR = 2.31, 95% CI: 1.08-4.94). Few participants (13% mothers, 33% infants) had symptoms; no participant experienced severe COVID-19 or death. Seroreversion occurred in about half of mothers and infants. SARS-CoV-2 sequences obtained from stool were related to contemporaneously circulating variants.ConclusionsThese data indicate that postpartum Kenyan women and their infants were at high risk for SARS-CoV-2 infection and that antibody responses waned over an average of 8-10 months. However, most cases were asymptomatic and healthy women living with HIV did not have a substantially increased risk of infection or severe COVID-19

Detailed methods for stool viral RNA extraction, RT-PCR, and sequencing.

(DOCX)</p

SARS-CoV-2 serology and stool viral RNA results over calendar time.

Results of SARS-CoV-2 serology and quantitative real-time PCR testing of stool samples from Linda Kizazi participants that first tested seropositive and had ≥1 available stool sample collected between May 1-December 31, 2020. Anonymized ID numbers on y-axis for mothers (M) and infants (B). Grey circles indicate date of last seronegative serology test and orange circles indicate date of first seropositive sample. White triangles represent SARS-CoV-2 RNA-negative and red triangles represent RNA-positive stool samples. Calendar time is on the x-axis.</p

Incidence of SARS-CoV-2 infection in postpartum Kenyan women and their infants from May 1, 2020 to February 1, 2022.

Incidence of SARS-CoV-2 infection in postpartum Kenyan women and their infants from May 1, 2020 to February 1, 2022.</p

SARS-CoV-2 genomes sequenced from Kenyan stool samples.

Complete SARS-CoV-2 genomes were sequenced from six RNA-positive stool samples. (A) Phylogenetic analyses of 500 randomly selected SARS-CoV-2 global sequences, the Wuhan1 reference, and the two Kenyan stool-derived genomes (indicated in red) are shown. Clade labels are shown. (B) Next-generation sequencing data statistics of the six Kenyan stool samples. (TIF)</p

Detection of SARS-CoV-2 antibody among mothers and infants over time.

(A) SARS-CoV-2 antibody levels over time relative to the first seropositive time point (0 months). Individual patterns in infants (top) and mothers (bottom) are shown in grey. Grouped by maternal HIV status, running means are shown for HIV-uninfected women or HIV-unexposed infants in black and women living with HIV or HIV-exposed infants in red. Limit of detection denoted by dashed vertical line. (B) and (C) are Kaplan-Meier hazard functions for participants’ estimated time to loss of detectable antibodies stratified by maternal HIV status and infant HIV exposure, respectively. HEU = HIV-exposed uninfected, HUU = HIV-unexposed uninfected. The risk period for loss of detectable antibody begins at the participant’s first positive serology test and ends either at the time of loss of detectable antibodies (estimated as the midpoint between the last positive test and first negative test after a positive test) or at the time of the most recent positive test.</p

SARS-CoV-2 antibody levels over time in mother-infant Pairs.

OD ratios show SARS-CoV-2 antibody levels over time in pairs where both mother and infant were first SARS-CoV-2 positive at the same visit and had ≥1 sample available after initial antibody detection. Increased levels of antibody denoted by darker purple shading as shown in key. Positive antibody levels denoted by filled circle, equivocal levels by X, and levels below the limit of detection by empty circles. Mother-infant pairs in which the mother was living with HIV are shown on top with bold red IDs; HIV-uninfected and -unexposed pairs are shown below with black IDs. (TIF)</p

High temperature inhibits ascorbate recycling and light stimulation of the ascorbate pool in tomato despite increased expression of biosynthesis genes

Understanding how the fruit microclimate affects ascorbate (AsA) biosynthesis, oxidation and recycling is a great challenge in improving fruit nutritional quality. For this purpose, tomatoes at breaker stage were harvested and placed in controlled environment conditions at different temperatures (12, 17, 23, 27 and 31 °C) and irradiance regimes (darkness or 150 µmol m(-2) s(-1)). Fruit pericarp tissue was used to assay ascorbate, glutathione, enzymes related to oxidative stress and the AsA/glutathione cycle and follow the expression of genes coding for 5 enzymes of the AsA biosynthesis pathway (GME, VTC2, GPP, L-GalDH, GLDH). The AsA pool size in pericarp tissue was significantly higher under light at temperatures below 27 °C. In addition, light promoted glutathione accumulation at low and high temperatures. At 12 °C, increased AsA content was correlated with the enhanced expression of all genes of the biosynthesis pathway studied, combined with higher DHAR and MDHAR activities and increased enzymatic activities related to oxidative stress (CAT and APX). In contrast, at 31 °C, MDHAR and GR activities were significantly reduced under light indicating that enzymes of the AsA/glutathione cycle may limit AsA recycling and pool size in fruit pericarp, despite enhanced expression of genes coding for AsA biosynthesis enzymes. In conclusion, this study confirms the important role of fruit microclimate in the regulation of fruit pericarp AsA content, as under oxidative conditions (12 °C, light) total fruit pericarp AsA content increased up to 71%. Moreover, it reveals that light and temperature interact to regulate both AsA biosynthesis gene expression in tomato fruits and AsA oxidation and recycling