Gene expression analyses reveal differences in children's response to malaria according to their age.

In Bandiagara, Mali, children experience on average two clinical malaria episodes per year. However, even in the same transmission area, the number of uncomplicated symptomatic infections, and their parasitemia, can vary dramatically among children. We simultaneously characterize host and parasite gene expression profiles from 136 Malian children with symptomatic falciparum malaria and examine differences in the relative proportion of immune cells and parasite stages, as well as in gene expression, associated with infection and or patient characteristics. Parasitemia explains much of the variation in host and parasite gene expression, and infections with higher parasitemia display proportionally more neutrophils and fewer T cells, suggesting parasitemia-dependent neutrophil recruitment and/or T cell extravasation to secondary lymphoid organs. The child's age also strongly correlates with variations in gene expression: Plasmodium falciparum genes associated with age suggest that older children carry more male gametocytes, while variations in host gene expression indicate a stronger innate response in younger children and stronger adaptive response in older children. These analyses highlight the variability in host responses and parasite regulation during P. falciparum symptomatic infections and emphasize the importance of considering the children's age when studying and treating malaria infections.

Immune gene expression changes more during a malaria transmission season than between consecutive seasons.

Plasmodium parasites, the causative organism of malaria, caused over 600,000 deaths in 2022. In Mali, Plasmodium falciparum causes the majority of malaria cases and deaths and is transmitted seasonally. Anti-malarial immunity develops slowly over repeated exposures to P. falciparum and some aspects of this immunity (e.g., antibody titers) wane during the non-transmission, dry season. Here, we sequenced RNA from 33 pediatric blood samples collected during P. falciparum infections at the beginning or end of a transmission season, and characterized the host and parasite gene expression profiles for paired, consecutive infections. We found that human gene expression changes more over the course of one transmission season than between seasons, with signatures of partial development of an adaptive immune response during one transmission season and stability in gene expression during the dry season. Additionally, we found that P. falciparum gene expression did not vary with timing during the season and remained stable both across and between seasons, despite varying human immune pressures. Our results provide insights into the dynamics of anti-malarial immune response development over short time frames that could be exploited by future vaccine and prevention efforts. IMPORTANCE: Our work seeks to understand how the immune response to Plasmodium falciparum malaria changes between infections that occur during low and high malaria transmission seasons, and highlights that immune gene expression changes more during the high transmission season. This provides important insight into the dynamics of the anti-malarial immune response that are important to characterize over these short time frames to better understand how to exploit this immune response with future vaccine efforts.

Characteristics of Hospitalized COVID-19 Patients at Admission and Factors Associated with Clinical Severity in Low- and Middle-Income Countries: An Observational Study.

Despite the numerous articles published on the clinical characteristics and outcomes of COVID-19 with regard to high-income countries, little is known about patients in low- and middle-income countries (LMIC) in this context. The objective of this observational, prospective, hospital-based multicentric study was to describe clinical features and outcomes of laboratory-confirmed COVID-19 patients hospitalized in each of the participating centers in Bangladesh, Guinea, Ivory Coast, Lebanon, Madagascar, and Mali during the first year of the pandemic (March 5, 2020 to May 4, 2021). The study outcome was the clinical severity of COVID-19, defined as hospitalization in intensive care unit or death. Multivariate logistic regression models were performed to identify independent variables associated with disease severity. Overall, 1,096 patients were included. The median age was 49.0 years, ranging from 38.0 in Mali to 63.0 years in Guinea. The overall clinical severity of COVID-19 was 12.3%, ranging from 6.4% in Mali to 18.8% in Guinea. In both groups of patients <60 and ≥60 years old, cardiovascular diseases (adjusted odds ratio [aOR]: 1.99; 95% CI: 1.13-3.50, P = 0.02; aOR: 2.47; 95% CI: 1.33-4.57, P = 0.004) were independently associated with clinical severity, whereas in patients <60 years, diabetes (aOR: 2.13; 95% CI: 1.11-4.10, P = 0.02) was also associated with clinical severity. Our findings suggest that COVID-19-related severity and death in LMICs are mainly driven by older age. However, the presence of chronic diseases can also increase the risk of severity especially in younger patients.

Plasma 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D Levels in Breast Cancer Risk in Mali: A Case-Control Study.

(1) Background: Breast cancer is the most prevalent cancer found in women in Mali. The aim of the current study was to determine the association between metabolites circulating in the blood, 25(OH)D and 1,25(OH)2D, and vitamin D levels with the risk of breast cancer in Malian women. (2) Methods: We conducted a prospective case-control study from August 2021 to March 2022. Control subjects were matched to cases according to age (within 5 years). The patients' clinical stage was determined by the oncologist according to the tumour-nodes-metastasis (TNM) classification system. (3) Results: We observed no differences in the mean 25(OH)D (p = 0.221) and 1,25(OH)2D (p = 0.285) between cases and controls. However, our findings indicate a more pronounced inverse association in the first level of plasma 25(OH)D, while the risk function decreases at higher levels. This observation takes strength with 1,25(OH)2D by a significant association between the first quartile and breast cancer as a risk factor (p = 0.03; OR = 71.84; CI: 1.36-3785.34). (4) Conclusions: These outcomes showed a possible association between 25(OH)D and 1,25(OH)2D in decreasing the risk of breast cancer.