Serum Neopterin as an Immunological Biomarker in Cutaneous and Visceral Leishmaniasis: A Cross-Sectional Study in Some Parts of Iraq

Abstract

     Leishmaniasis is a serious neglected public health problem in many tropical and subtropical regions, including Iraq. Leishmaniasis mainly appears as local cutaneous skin lesions or invasive internal visceral parts. A complex host immune response to Leishmania infection complicates effective diagnosis and disease monitoring. Recognition of biomarkers improves prognosis and is essential for early detection and for monitoring treatment. T helper-1 immune activation during leishmaniasis is initially regulated by interferon-γ stimulation, as evidenced by neopterin synthesis. This study investigates serum neopterin levels, a biomarker indicative of cellular immune activation, in patients with cutaneous and visceral leishmaniasis. For the assessment of neopterin levels. From December 2024 to April 2025, 62 cutaneous and visceral subjects were selected from different parts of Iraq, males and females of different ages, before starting any treatment. Blood samples were examined using sandwich ELISA to measure the neopterin levels which showed that both CL and VL patients had noticeably higher (p<0.05) neopterin mean values of (2.5±1.2, 3.65±1.8) ng/ml, respectively, when compared to the control subjects mean value, which was 1.81±0.6 ng/ml. Furthermore, neopterin levels were significantly higher in VL subjects than in CL subjects. The increased levels observed in both types of leishmaniasis highlight the activation of the cellular immune response triggered by the parasite. According to the present results, neopterin can be considered a potential biomarker for leishmaniasis early prediction, which may indicate immunological processes during infection, either for the cutaneous or visceral form of the disease. Future, large-scale studies are warranted, as geographical and time constraints limit the current findings.