The novel virus, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), and the associated Coronavirus Disease 2019 (COVID-19) represent a pathogen to which human beings have limited to no evolved immune response. The most severe symptoms are associated with overactive inflammatory immune responses, leading to a cytokine storm, tissue damage, and death, if not balanced and controlled. Hypotheses within Evolutionary Medicine, including the Hygiene/Old Friends Hypothesis, provide an important lens through which to understand and possibly control this overactive immune response. In this article, we explore the role that infection with soil-transmitted helminths (STHs; i.e. intestinal parasitic worms) may play in dampening SARS-CoV-2 symptoms and mitigating the worst COVID-19 outcomes. Specifically, STHs stimulate the immunosuppressive and regulatory T-helper 2 (T_H2) branch of the immune system, which decreases ACE2-receptor expression (i.e. receptors SARS-CoV-2 uses to infect host cells), balances the inflammatory T_H1/T_H17 branches of the immune system triggered by SARS-CoV-2 infection, and reduces inflammation through the release of anti-inflammatory/regulatory cytokines. Because STHs are common and affect the most vulnerable and marginalized members of society, it is especially important to consider how these parasites may impact COVID-19 outcomes. Areas experiencing endemic STH infections are often characterized by a lack of preventative infrastructure and medical care, which may further exacerbate risk of SARS-CoV-2 infection and COVID-19 development. For this reason, we also explore biocultural factors that contribute to disease outcomes for both SARS-CoV-2 and STH infections. Biocultural and Evolutionary Medicine perspectives on COVID-19 are crucial for understanding the global impact of the disease.

中文翻译：

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老朋友遇到新敌人：免疫启动寄生虫在降低 COVID-19 发病率和死亡率方面的潜在作用

这种新型病毒——严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 和相关的 2019 年冠状病毒病 (COVID-19) 代表了一种人类对其没有进化出免疫反应的病原体。最严重的症状与过度活跃的炎症免疫反应有关，如果不平衡和控制，会导致细胞因子风暴、组织损伤和死亡。进化医学中的假设，包括卫生/老朋友假设，提供了一个重要的视角，通过它来理解并可能控制这种过度活跃的免疫反应。在本文中，我们探讨了土源性蠕虫（STH；即肠道寄生虫）感染在抑制 SARS-CoV-2 症状和减轻最坏的 COVID-19 结果方面可能发挥的作用。具体来说，STH 刺激免疫系统的免疫抑制和调节性 T 辅助细胞 2 (TH ₂ ) 分支，从而降低 ACE2 受体表达（即 SARS-CoV-2 用于感染宿主细胞的受体），平衡炎症性 T _H 1 /T _H 17 由 SARS-CoV-2 感染触发的免疫系统分支，并通过释放抗炎/调节细胞因子来减少炎症。由于 STH 很常见，并且影响社会中最脆弱和边缘化的成员，因此考虑这些寄生虫如何影响 COVID-19 的结果尤为重要。发生地方性 STH 感染的地区通常缺乏预防性基础设施和医疗护理，这可能会进一步加剧 SARS-CoV-2 感染和 COVID-19 发展的风险。因此，我们还探讨了导致 SARS-CoV-2 和 STH 感染疾病结果的生物文化因素。COVID-19 的生物文化和进化医学观点对于理解该疾病的全球影响至关重要。