763 Tropical Biomedicine 37(3): 763–777 (2020) Prevalence of enteroparasitic infections and related hormonal and immunological repercussions that may compromise students’ physical performance Nunez, P.R.M. 1,2 , Honorio-França, A.C. 3 , Geiger, S.M. 2 , Guedes, M. 2 , Fagundes, D.L.G. 3 , Magalhães, A.M. 3 , Gomes, M.A. 2 and França, E.L. 3* 1 Education Faculty, Federal University of Mato Grosso do Sul - Campo Grande, MS, Brazil 2 Department of Parasitology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil 3 Institute of Biological and Health Science, Federal University of Mato Grosso, Barra do Garças, MT, Brazil * Corresponding author e-mail: dr.eduardo.franca@gmail.com Received 5 November 2018; received in revised form 31 March 2020; accepted 1 April 2020 Abstract. The aim of this study was to evaluate the prevalence of enteroparasitic infections in students and their hormonal and immunological repercussions on physical development. Students of basic education of both sexes were evaluated. Parasitological stool tests were performed using the Hoffman and Kato-Katz methods. The students were divided into two groups: a control group (negative parasitological examination, N=25) and an infected group (positive parasitological test, N=25). Anthropometric variables (height, weight, and BMI), concentrations of hormones (melatonin and cortisol), cytokine/chemokine levels (IL-1β, IL-6, IL-8, IL-10, IL-12, IL-17 and TNF-α) and physical performance (aerobic capacity, upper- and lower-limb muscle strength and abdominal performance) were evaluated. The prevalence of parasitic infection among the students was 7.98%. No anthropometric differences were observed among the groups. IL-2 and TNF-α levels were higher and IL-8 levels were lower in serum from students who were positive for parasitic infection. Serum from students who were positive for parasitic infection showed higher levels of melatonin than that from parasite- negative students. No differences were observed in cortisol levels. Students who were positive for parasitic infection presented greater lower-limb strength and lower abdominal performance than parasite-negative students. In the parasitic infection group, IL-12 was positively correlated with melatonin. In the parasitic infection group, IL-8 showed a positive correlation with aerobic capacity, while IL-17 and TNF- α showed a positive correlation with abdominal performance. These data suggest that parasitic infections determine the profile of inflammatory cytokines and that melatonin may be involved in the control of this process to minimize tissue damage. Additionally, students’ difficulty in practising physical exercises can be an indication of enteroparasitic infection. INTRODUCTION Despite advances in the control of infant morbidity and mortality and in basic care, there are still several health problems in practically all urban areas of Brazil, with greater intensity among the vulnerable populations of the peripheral territories. The lack of infrastructure increases the epidemiological complexity, favouring the emergence of new diseases and the resurgence of old endemics, including parasitic infections (Hijjar et al., 2005). Weight-height deficit and anaemia are the main causes of morbidities associated with childhood enteroparasitic infections. Parasitic infections may compromise nutritional status due to reduced food intake and/or increased nutrient loss (Ostan et al., 2007; Araújo Filho et al., 2011). Thus, helminth and protozoal infections have been associated with a number of adverse