Amatigue Zeguime

Malaria transmission in the Sahel persists during the dry season despite low microscopic parasite prevalence, maintaining reservoirs that hinder elimination efforts. Understanding serological markers of Plasmodium falciparum gametocyte exposure may help identify hidden transmission reservoirs during low‑transmission periods. We conducted a cross‑sectional survey in Kéniéroba, Mali, at three time points representing key seasonal periods: December 2024 (end of rainy season), May 2025 (dry season), and August 2025 (rainy season). A total of 356 participants were enrolled across three age groups (5-8, 9-17, and ≥18 yrs). Parasitaemia and gametocytaemia were assessed by microscopy. IgG and IgM responses to clinically isolated late-stage gametocytes were quantified by ELISA, and seropositivity thresholds defined using malaria‑naïve controls. Microscopic P. falciparum infection prevalence remained stable across surveys (~13%), but gametocyte carriage declined from 5.7% in December to ~2% in May and August, whereas gametocyte density was higher in the latter months. IgG/IgM seropositivity exceeded 95% throughout, with IgM peaking in May, consistent with recent antigenic stimulation. Age‑stratified analyses revealed weak but statistically significant associations between antibody levels and gametocyte carriage restricted to children aged 5-8 yrs, while no associations were observed in older children or adults. In conclusion, serological analyses indicate widespread and seasonally variable exposure to P. falciparum in Kéniéroba, with consistently high IgG and IgM responses to gametocytes reflecting intense background malaria exposure and cross‑reactive immunity from asexual stages. Seasonal and age‑stratified patterns identify school‑aged children as an important reservoir sustaining transmission. Although overall correlations with gametocyte carriage were weak, age‑specific associations suggest an age‑dependent relationship between antibody responses and carriage.

: Lymphedema (LE) is one the most disfiguring chronic manifestations of lymphatic filariasis. Its management relies primarily on limb hygiene and local care. A previous study in Ghana demonstrating a beneficial effect of doxycycline on LE led to the current multicenter trial on the efficacy of doxycycline in filarial LE. A randomized placebo-controlled trial was initiated in two rural health districts in Mali. Patients with LE stages 1–3 were randomized to receive either doxycycline (200 mg/day) or placebo over a 6-week monitored treatment period and were then followed every 6 months for 2 years. Both groups received materials for limb hygiene that was carried out daily for the entire 2-year study. The primary endpoint was lack of progression in LE stage at 24 months. One hundred patients were enrolled in each study arm. The baseline sociodemographic characteristics of each group were largely similar. There was no significant difference at month 24 after treatment initiation in the number of subjects showing progression in LE stage between the two treatment arms (P = 0.5921). Importantly, however, the number of attacks of acute adenolymphangitis (ADLA) was reduced in both arms, but there was no significant difference between the two groups at any follow-up time point (all P >0.23). Doxycycline was well tolerated in those receiving the drug. When added to daily self-administered limb hygiene, a 6-week course of doxycycline (200 mg) was not superior to placebo in increasing the improvement associated with hygiene alone in LE volume, stage, or frequency of ADLA attacks over a 24-month period.

The interpretation of a laboratory test result requires an appropriate reference range established in healthy subjects, and normal ranges may vary by factors such as geographic region, sex, and age. We examined hematological and clinical chemistry parameters in healthy residents at two rural vaccine trial sites: Bancoumana and Doneguebougou in Mali, West Africa. During screening of clinical studies in 2018 and 2019, peripheral blood samples from 1,192 apparently healthy individuals age 6 months to 82 years were analyzed at a laboratory accredited by the College of American Pathologists for a complete blood count, and creatinine and/or alanine aminotransferase levels. Based on manufacturers’ reference range values, which are currently used in Malian clinical laboratories, abnormal values were common in this healthy population. In fact, 30.4% of adult participants had abnormal neutrophil levels and 19.8% had abnormal hemoglobin levels. Differences by sex were observed in those who were older, but not in those younger than 10 years, for several parameters, including hemoglobin, platelet, and absolute neutrophil counts in hematology, and creatinine in biochemistry. The site-specific reference intervals we report can be used in malaria vaccine clinical trials and other interventional studies, as well as in routine clinical care, to identify abnormalities in hematological and biochemical parameters among healthy Malian trial participants.