BACKGROUND Mycobacterium leprae and Toxoplasma gondii infections are both neglected tropical diseases highly prevalent in Brazil. Infection with certain parasite species can significantly alter susceptibility to other important pathogens, and/or influence the development of pathology. Here we investigated the possible influence of M. leprae/T. gondii co-parasitism on the manifestation of leprosy and its clinical forms. METHODS Participants (n = 291) were recruited in Campos dos Goytacazes city, Rio de Janeiro state, southeast Brazil, from August 2015 to December 2019 and clinically diagnosed for leprosy. Participants were selected based on the presence (patients) or absence (healthy controls) of the leprosy disease. Contacts of patients were also recruited for this study. Serum samples from patients (n = 199) with leprosy, contacts (n = 40) and healthy controls (n = 52) were investigated for levels of IgM and IgG anti-phenolic glycolipid-1 (PGL-1) by ELISA. Additionally, IgG antibody against soluble Toxoplasma antigen (STAg) was measured in sera samples from leprosy patients, contacts and healthy controls for Toxoplasma gondii serology by ELISA. Anti-PGL-1 IgG and IgM levels were compared using one-way ANOVA Kruskal-Wallis or Mann-Whitney, while Spearman test was used to correlate levels of IgG anti-STAg and IgM/IgG anti-PGL-1 from seropositive and seronegative individuals for T. gondii infection. The risk of T. gondii infection for leprosy disease was assessed using Fisher's test. RESULTS Levels of IgM anti-PGL-1 antibodies were significantly higher in multibacillary (MB) patients compared to paucibacillary (PB) patients (P = 0.0068). Higher IgM and IgG levels anti-PGL-1 were detected in patients with the lepromatous forms. The serologic prevalence for T. gondii infection was 74.9%. We detected increased anti-STAg antibody levels in leprosy patients (79.4%), reaching 88.8% within those with lepromatous form of this disease. The leprosy risk increase in T. gondii seropositive individuals was two-fold (odds ratio [OR] = 2.055; 95% confidence intervals [95% CI]: 1.18-3.51) higher than those seronegative, and considering the lepromatous leprosy risk this increase was even dramatic (OR = 4.33; 95% CI: 1.76-9.69) in T. gondii seropositive individuals. Moreover the leprosy risk in T. gondii seropositive individuals was weakly correlated to the levels of IgG anti-STAg and IgM/IgG anti-PGL-1. CONCLUSIONS Altogether, our results suggest that T. gondii infection may exert immunomodulatory properties that influence to the susceptibility of leprosy, mainly on its more severe clinical form. A better understanding of parasite immunomodulation can ultimately contribute to the development of medical applications.

中文翻译：

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弓形虫感染的血清学证据可能是巴西两种被忽视的热带病流行地区麻风麻风病发展的潜在风险。

背景技术在巴西，麻风分枝杆菌和弓形体感染都是被忽视的热带病。感染某些寄生虫物种会显着改变对其他重要病原体的敏感性，和/或影响病理的发展。在这里，我们研究了麻风杆菌/ T的可能影响。刚地寄生在麻风病的表现及其临床形式上。方法2015年8月至2019年12月在巴西东南部里约热内卢州的Campos dos Goytacazes市招募参与者（n = 291），并临床诊断为麻风病。根据麻风病的存在（患者）或不存在（健康对照）选择参与者。这项研究还招募了患者联系人。麻风患者（n = 199）的血清样本，通过ELISA研究了接触者（n = 40）和健康对照（n = 52）的IgM和IgG抗酚糖脂1（PGL-1）水平。此外，还通过ELISA在麻风病人，接触者和弓形虫血清学健康对照的血清样品中测量了抗可溶性弓形虫抗原（STAg）的IgG抗体。使用单向方差分析Kruskal-Wallis或Mann-Whitney比较了抗PGL-1 IgG和IgM的水平，同时使用Spearman检验来关联血清反应阳性和血清阴性的IgG抗STAg和IgM / IgG抗PGL-1的水平弓形虫感染的个人。使用费舍尔检验评估了弓形虫感染麻风病的风险。结果与多杆菌（PB）患者相比，多杆菌（MB）患者的IgM抗PGL-1抗体水平显着更高（P = 0.0068）。在麻风病形式的患者中检测到较高的IgM和IgG水平抗PGL-1。弓形虫感染的血清学患病率为74.9％。我们在麻风病患者中检测到抗STAg抗体水平升高（79.4％），在患有这种疾病的麻风病患者中达到了88.8％。刚地弓形虫血清反应阳性个体的麻风风险增加是血清阴性患者的两倍（几率[OR] = 2.055； 95％置信区间[95％CI]：1.18-3.51），而考虑到麻风病麻风风险增加在刚地弓形虫血清反应阳性的个体中甚至更为显着（OR = 4.33; 95％CI：1.76-9.69）。此外，弓形虫血清反应阳性个体的麻风风险与IgG抗STAg和IgM / IgG抗PGL-1的水平弱相关。结论总之，我们的结果表明T。刚地氏菌感染可能会发挥免疫调节特性，影响麻风病的易感性，主要是在更严重的临床形式上。对寄生虫免疫调节的更好理解最终可以促进医学应用的发展。