Biology subjects

Phiri, M.

Publications and source records attributed to Phiri, M..

3 recordsLinked to original sources

bioRxiv2025

Evaluation of plasma anti-CS3 and anti-LTB IgG avidity among Zambian children vaccinated with ETVAX

BackgroundEnterotoxigenic Escherichia coli (ETEC) remains a major cause of diarrheal disease in low- and middle-income countries (LMICs). To curb ETEC related diarrhoea, several candidate vaccines are in development, with ETVAX(R) being the most advanced. Although immunogenicity studies have primarily focused on measuring antibody titres, assessing antibody avidity offers additional valuable insight into antibody quality and immune maturity. This study assessed anti-CS3 and anti-LTB IgG avidity in Zambian children to better understand vaccine-induced antibody responses in an endemic setting. MethodsChildren aged 6-23 months (n=60) received three quarter-doses of ETVAX(R) with dmLT adjuvant on days 0, 14, and 90. Plasma samples collected at baseline (V1), seven days after the second dose (V5), and seven days after the third dose (V7) were analysed by limiting antigen dilution ELISA to calculate avidity indices (AI). Naive classification was performed using titre-based thresholds (20th percentile of baseline titres) and avidity-defined naivety (AI < 0.5). Receiver operating characteristic (ROC) analysis was used to evaluate the discriminatory performance of avidity indices against titre-defined naive status. ResultsBaseline avidity was detectable for both CS3 and LTB, consistent with prior natural exposure. Mean CS3 IgG avidity decreased from 0.7 at baseline to 0.6 after the third dose (p<0.001), while LTB IgG avidity showed transient decreases but no net gain. Naive classification at baseline revealed that 9/60 children had titres but low avidity (functional naivety), and 6/60 had waned titres but high avidity. Only one child was naive by both criteria for CS3, and none for LTB. ROC analysis demonstrated moderate discrimination for CS3 (AUC=0.65; optimal cut-off AI=0.36) but poor discrimination for LTB (AUC=0.30). ConclusionIn this endemic population, ETVAX(R) induced strong antibody titres but minimal changes in avidity over time with inter-individual differences, while ROC analysis highlighted the need for context-specific thresholds. These findings show the need for both antibody titre and avidity assessment in vaccine evaluations in endemic settings.

immunology↗

bioRxiv2025

Synthetic Substitutes as a Conservation Tool: Evaluating Synthetic Leopard Fur for Demand Reduction and Species Recovery

Providing synthetic substitutes is a widely promoted strategy to shift consumer demand away from wildlife products derived from threatened species. Yet, there is little evidence on whether such product substitution interventions effectively prevent illegal or unsustainable harvesting and contribute to the recovery of threatened populations. Drawing on the Furs For Life (FFL) Zambia initiative, which supplied synthetic furs known as "Heritage Furs" to replace leopard skins traditionally worn during Lozi royal ceremonies in Western Zambia, we present an evaluation designed to test both the effects and causal mechanisms of substitution. Guided by the EMMIE framework, commonly used in crime prevention evaluation, we triangulated data from semi-structured questionnaires, law enforcement patrols, court records, camera trap monitoring, and stakeholder interviews conducted between 2018 and 2024. Qualitative analysis using the General Elimination Method was employed to assess plausible alternative explanations for leopard recovery. By 2024, adoption of synthetic furs among leopard fur users exceeded 80 percent, while self-reported ownership of authentic leopard furs declined by 70 percent. At the same time, patrol detections of leopard poaching incidents decreased, and camera trap density estimates increased from an average of 2.7 to 3.8 leopards per 100 square kilometers across the focal landscape. An integrated mechanism of change, derived from stakeholder perspectives, indicates that while substitution reduced demand, concurrent and reinforcing effects of counter-poaching and counter-trafficking operations were critical to leopard recovery. This study provides the first empirical link between a demand reduction initiative based on synthetic substitutes and measurable species population recovery.

ecology↗

bioRxiv2018

Dust or disease? Perceptions of influenza in rural Southern Malawi

BackgroundInfluenza virus infections cause between 291 243 and 645 832 deaths annually, with the highest burden in low-income settings. Research in high-income countries has examined public understanding of influenza, but there is little information on views and behaviours about influenza in low-income countries. We explored communities ideas about the severity, causes, prevention and treatment of influenza in Chikwawa district, Malawi.\n\nMethodsWe conducted 64 in-depth interviews with parents of children aged <5 years, and 7 focus groups with community health workers, parents, and traditional healers. Data were analysed thematically and using a framework matrix to compare views between groups.\n\nResultsRespondents held varied ideas about influenza, and many were uncertain about its causes and treatment. Some parents, traditional healers and health workers thought influenza was not severe because they felt it did not cause death or limit activities, but others disagreed. Many saw influenza as a symptom of other conditions, especially malaria and pneumonia, rather than as a disease of its own. Most mentioned dust as the main cause of influenza and believed influenza could be prevented by cleaning the home thoroughly. Treatment seeking for influenza followed different stages, usually starting with home remedies followed by purchasing drugs from groceries and then visiting a health centre. Seeking a clinician tended to be triggered by severe symptoms like high fever or difficulty breathing, and suspicions of malaria or pneumonia. Community health workers provide health education for communities, but some lacked understanding of influenza.\n\nConclusionOur findings suggest uncertainty about the causes and control of influenza among parents and varied levels of understanding among health providers. Strengthening the capacity of community health workers to provide relevant information about influenza prevention and treatment could address parents interest in further information and support informed health seeking and engagement with future influenza interventions.

pathology↗