The molecular evolution of life on earth along with changing environmental, conditions has rendered mankind susceptible to endemic and pandemic emerging infectious diseases. The effects of certain systemic viral and bacterial infections on morbidity and mortality are considered as examples of recent emerging infections. Here we will focus on three examples of infections that are important in pregnancy and early childhood: SARS-CoV-2 virus, Zika virus, and Mycoplasma species. The basic structural characteristics of these infectious agents will be examined, along with their general pathogenic mechanisms. Coronavirus infections, such as caused by the SARS-CoV-2 virus, likely evolved from zoonotic bat viruses to infect humans and cause a pandemic that has been the biggest challenge for humanity since the Spanish Flu pandemic of the early 20th century. In contrast, Zika Virus infections represent an expanding infectious threat in the context of global climate change. The relationship of these infections to pregnancy, the vertical transmission and neurological sequels make these viruses highly relevant to the topics of this special issue. Finally, mycoplasmal infections have been present before mankind evolved, but they were rarely identified as human pathogens until recently, and they are now recognized as important coinfections that are able to modify the course and prognosis of various infectious diseases and other chronic illnesses. The infectious processes caused by these intracellular microorganisms are examined as well as some general aspects of their pathogeneses, clinical presentations, and diagnoses. We will finally consider examples of treatments that have been used to reduce morbidity and mortality of these infections and discuss briefly the current status of vaccines, in particular, against the SARS-CoV-2 virus. It is important to understand some of the basic features of these emerging infectious diseases and the pathogens involved in order to better appreciate the contributions of this special issue on how infectious diseases can affect human pregnancy, fetuses and neonates.

地球上生命的分子进化以及不断变化的环境条件使人类容易感染地方性和大流行性新兴传染病。某些全身性病毒和细菌感染对发病率和死亡率的影响被认为是最近出现的感染的例子。在这里，我们将重点关注三个对怀孕和幼儿期很重要的感染示例：SARS-CoV-2 病毒、寨卡病毒和支原体物种。将检查这些感染因子的基本结构特征，以及它们的一般致病机制。冠状病毒感染，例如由 SARS-CoV-2 病毒引起的，可能是从人畜共患的蝙蝠病毒进化而来，感染人类并引起大流行，这是自 20 世纪初西班牙流感大流行以来人类面临的最大挑战。相比之下，寨卡病毒感染代表了全球气候变化背景下不断扩大的传染威胁。这些感染与怀孕、垂直传播和神经系统后遗症的关系使这些病毒与本期特刊的主题高度相关。最后，支原体感染在人类进化之前就已经存在，但直到最近它们才被确定为人类病原体，它们现在被认为是重要的合并感染，能够改变各种传染病和其他慢性病的病程和预后。研究了由这些细胞内微生物引起的感染过程，以及它们的发病机制、临床表现和诊断的一些一般方面。最后，我们将考虑用于降低这些感染的发病率和死亡率的治疗实例，并简要讨论疫苗的现状，特别是针对 SARS-CoV-2 病毒的疫苗。重要的是要了解这些新出现的传染病和所涉及的病原体的一些基本特征，以便更好地理解本期特刊对传染病如何影响人类怀孕、胎儿和新生儿的贡献。