Zampieri Fabio, Michieletto Fabio, Zanatta Alberto
University of Padua, Department of Cardiac, Thoracic, Vascular Sciences and Public Health, Padua, Italy.
University of Padua, Padua Medical School, Padua, Italy.
Int J Infect Dis. 2025 Apr;153:107836. doi: 10.1016/j.ijid.2025.107836. Epub 2025 Feb 6.
The history of the conception of evolution of virulence is well known. However, in this period following the COVID-19 pandemic, it may be useful to recap such a current topic. In public debate, it has often been heard that COVID-19 was destined to evolve into a less virulent form because it would be in the virus's interest to coexist with the human population. This concept can be defined as the "Myth of the Good Pathogen" and originated from Smith's "law of declining virulence." The successes achieved thanks to vaccinations and antibiotics led the medical community, between the 1940s and the 1970s, to argue that the battle against infectious diseases had been won. However, the AIDS pandemic brought back down to earth the scientific community in their speculations about plagues. Since the 1970s, biologists have advanced the "virulence transmission trade-offs theory," a new model according to which intermediate virulence maximizes pathogenicity as a result of a trade-off between virulence and transmission. The introduction of trade-off models represented a crucial change that replaced the binary logic according to which natural selection shaped adaptations, whereas maladaptation escaped selection. This change was fundamental for the introduction of a new perspective in medicine, namely, Evolutionary Medicine, which might be an essential tool not only for understanding the dynamics of epidemics but also for preventing and curing infectious diseases.
毒力进化概念的历史广为人知。然而，在新冠疫情后的这段时期，回顾这样一个当下的话题或许会有所帮助。在公众辩论中，经常能听到有人说新冠病毒注定会演变成毒性较低的形式，因为与人类共存符合病毒的利益。这一概念可被定义为“良性病原体神话”，它源自史密斯的“毒力下降定律”。20世纪40年代至70年代，由于疫苗接种和抗生素取得的成功，医学界认为与传染病的斗争已经胜利。然而，艾滋病疫情让科学界在对瘟疫的推测中回归现实。自20世纪70年代以来，生物学家提出了“毒力传播权衡理论”，这是一种新模型，根据该模型，由于毒力与传播之间的权衡，中等毒力会使致病性最大化。权衡模型的引入代表了一个关键变化，它取代了那种自然选择塑造适应性而不适应则逃避选择的二元逻辑。这一变化对于在医学中引入一个新视角——进化医学至关重要，进化医学可能不仅是理解流行病动态的重要工具，也是预防和治疗传染病的重要工具。
