Host immune response in returning travellers infected with malaria

Area of Science:

• Immunology
• Infectious Diseases
• Travel Medicine

Background:

• Canadian-born (CB) travellers may experience more severe malaria than foreign-born (FB) travellers.
• Host immune responses, including cytokine and chemokine profiles, are hypothesized to differ between CB and FB malaria patients.
• Understanding these differences can aid in developing malaria biomarkers and therapeutics.

Purpose of the Study:

• To investigate differences in cytokine, chemokine, and endothelial activation profiles between Canadian-born and foreign-born travellers with malaria.
• To identify potential immune markers associated with malaria severity in different traveller groups.
• To explore age- and species-specific immune responses to malaria.

Main Methods:

• Analysis of blood samples from 186 travellers returning to Toronto between 2007 and 2011.
• Quantification of cytokine, chemokine, and angiopoietin concentrations using multiplex and ELISA assays.

Main Results:

• Canadian-born travellers had significantly higher Interleukin-12 (IL-12) (p40) levels compared to foreign-born travellers.
• Epidermal Growth Factor (EGF) levels were higher in foreign-born travellers.
• Plasmodium vivax infections showed distinct cytokine profiles (MCP-1, M-CSF) compared to Plasmodium falciparum, and older travellers (≥55) with P. vivax had elevated IL-6 and M-CSF.

Conclusions:

• Elevated IL-12 (p40) and reduced EGF in Canadian-born travellers may predict malaria severity.
• Immune markers like IL-6, M-CSF, and MCP-1 could be valuable for understanding age- and species-specific malaria responses.
• Regional variations in immune responses suggest differing malaria strains, particularly in West Africa.