Abstract:This article explores the common pathogenesis and transmission mechanisms of externally contracted febrile diseases. It points out that the invasion of external pathogens leads to the resistance of defensive Qi (wei qi) against pathogens, resulting in a struggle between the righteous and the evil, and the stagnation of Yang Qi, which manifests as a series of febrile disease symptoms. The pathogenesis is characterized by “stagnation-deficiency”. The transmission patterns of febrile diseases are summarized through the lens of “Qi and Blood – Body and Function”, categorizing the disease course into two stages: the Qi stage, which includes the Wei stage and is primarily characterized by functional disorders; and the Blood stage, which involves substantial damage and more severe functional disorders. The transformation mechanisms of severe externally contracted febrile diseases include excessive heat moving blood, heat obstructing the pericardium, excessive heat stirring wind, the desire for transformation being cut off, Shaoyin cold transformation, and the external loss of righteous Qi.
Throughout the development of Traditional Chinese Medicine (TCM) over the past two thousand years, various theoretical systems for the differentiation and treatment of externally contracted febrile diseases have emerged, primarily including the six meridian differentiation from the “Huangdi Neijing” and “Shanghan Lun”, the Wei-Qi-Ying-Blood differentiation proposed by Ye Tianshi, the Sanjiao differentiation by Wu Jutong, and the water-damp Sanjiao differentiation by Xue Shengbai, along with organ differentiation and Qi-Blood-Body Fluid differentiation. These differentiation theories discuss the evolution of symptoms and pathogenesis of externally contracted febrile diseases, providing important guidance for their treatment and making significant clinical contributions at different historical periods. However, it is regrettable that these differentiation theories have mostly remained distinct and have not formed a unified theoretical system, leading to a situation of “cold-heat opposition”. For instance, during the COVID-19 pandemic, there have been many debates regarding the etiology, classification, and treatment principles of the disease, with diverse academic viewpoints and macro-level explanations of symptoms and pathogenesis, resulting in a certain disconnection between traditional differentiation theories of externally contracted febrile diseases and the realities of COVID-19 infections. Currently, the academic community has not deeply revealed the essential characteristics of the transmission patterns of externally contracted febrile diseases, which has brought certain limitations to the study of these theories and their effective guidance in treating febrile diseases, thereby affecting the effectiveness and theoretical explanation of TCM in treating febrile diseases.In theory and practice, regardless of whether the cause is wind-cold, warm-heat, damp-heat, or warm-toxicity, the core pathogenesis of externally contracted febrile diseases caused by different pathogens is the invasion of external pathogens, the resistance of righteous Qi against evil, and the struggle between the righteous and the evil, leading to damage to Qi, Blood, Yin, and Yang. The evolution of the pathogenesis can manifest as a process from excess to deficiency, during which various common pathogenesis characteristics can be observed. Therefore, based on a thorough understanding of various common pathogenesis characteristics, exploring the transmission patterns of symptoms in externally contracted febrile diseases, analyzing the micro-pathogenesis of disease onset and transmission, and establishing a unified theoretical system for the differentiation and treatment of externally contracted febrile diseases is of significant theoretical and clinical value for promoting the development of the discipline of febrile diseases and effectively guiding their treatment. This article traces the physiological theories related to the human body and the pathogenesis of febrile diseases in the “Huangdi Neijing”, combined with discussions from Liu Wansu’s “Suwen Xuanji Yuanbing Shi” and other relevant works, proposing the “stagnation-deficiency” pathogenesis and the “Qi-Blood – Body-Function” transmission theory of externally contracted febrile diseases, and exploring the common pathogenesis and symptom transmission mechanisms of externally contracted febrile diseases, providing a theoretical basis for establishing a comprehensive and unified differentiation theory system for externally contracted febrile diseases.
1. Common Pathogenesis of Externally Contracted Febrile Diseases
The “Nanjing – Fifty-Eighth Difficult” states: “There are five types of cold damage: wind-cold, cold damage, damp-warm, febrile diseases, and warm diseases, each with different sufferings.” This indicates that externally contracted febrile diseases, also known as cold damage, are caused by the invasion of the six excesses. Here, cold damage can be understood in both broad and narrow senses; in a broad sense, it refers to all externally contracted diseases; in a narrow sense, it refers to the Taiyang cold damage syndrome caused by the invasion of wind-cold pathogens. Externally contracted diseases, regardless of the type of external pathogen involved, can exhibit febrile symptoms during the pathological process; their symptom transmission patterns often manifest as a process from excess to deficiency, with common pathogenesis including the two ends of “stagnation-deficiency”.
1.1 Defensive Qi as the Main Body Against Pathogens
TCM theory holds that defensive Qi (wei qi) is the main body of the human body’s resistance against pathogens, belonging to Yang. The “Lingshu – Ben Cang” states: “When the defensive Qi is harmonious, the flesh and muscles are relaxed and benefit… the five organs are not invaded by evil,” indicating that when the function of defensive Qi is normal, the five organs are not invaded by external pathogens.
When the six excesses invade the body, the righteous and evil struggle, manifesting a series of symptoms such as chills, fever, thirst, or lack of thirst, red tongue, floating pulse, or floating-tight, floating-slow, floating-rapid, etc. The “Suwen – Wind Theory” states: “When the wind Qi and Taiyang enter together, they travel through the pulse and disperse among the flesh, interacting with the defensive Qi; if the pathway is obstructed, it causes the muscles to swell and develop sores, and if the defensive Qi is stagnant and does not circulate, it leads to numbness within.” This indicates that the invasion of evil interacts with defensive Qi to cause disease.
In summary, when external pathogens invade, the main body of the body’s resistance is defensive Qi, and the struggle between the righteous and the evil is essentially the struggle between defensive Qi and external pathogens.
1.2 Stagnation of Defensive Qi Leading to Heat
Traditional TCM theory states that the heat symptoms of externally contracted diseases are caused by heat evil or external evil transforming into heat internally, i.e., “heat due to evil”, as Ye Tianshi mentioned in the “Ye Xiangyan’s Externally Contracted Warm-Heat” chapter: “The evil of cold damage lingers on the surface, then transforms into heat internally,” indicating that the initial stage of cold damage is on the surface, transforming into heat internally, resulting in Yangming interior heat syndrome. Liu Wansu, in discussing the pathogenesis of febrile diseases, proposed that “all six Qi arise from fire transformation” and “the transmission of the six meridians is all heat syndromes”, explaining the mechanism of heat symptoms in externally contracted diseases from the perspective of the six excesses transforming into fire, believing that the six Qi and six excesses transform into fire, thus causing heat symptoms.
In essence, whether it is wind-cold or warm-heat, after the invasion of the six excesses, the struggle with defensive Qi leads to stagnation of defensive Qi, excessive Yang Qi, and inability to disperse the stagnation, resulting in Yang stagnation and heat. The “Shanghan Zhi Ge – Shanghan Six Meridians Transmission” mentions: “Cold injures the form, cold injures the skin and hair, cold injures blood, cold injures nourishment. However, cold primarily closes and conceals, and the pores are tightly closed, causing Yang Qi to stagnate and unable to flow smoothly, leading to internal heat and dryness without sweating,” emphasizing the invasion of cold evil, the closure of the pores, and the stagnation of Yang Qi leading to body heat. Additionally, the “Suwen – Wind Theory” states: “When the wind Qi and Taiyang enter together, they travel through the pulse and disperse among the flesh, interacting with the defensive Qi… if the defensive Qi is stagnant and does not circulate,” and the “Suwen – Jade Machine True Storage Theory” states: “Therefore, wind is the leader of all diseases; now, when wind-cold invades a person, it causes the hair to stand upright, the skin to close, and leads to heat,” while Wu Youke’s “Warm Epidemic Theory – After the Resolution, Nourish Yin and Avoid Ginseng” states: “Epidemics are heat diseases; the evil Qi is internally stagnant, and Yang Qi cannot be announced, accumulating Yang into fire, and Yin blood is often struck by heat,” emphasizing that stagnation of Yang Qi leads to heat… Regardless of the organs, meridians, or the upper and lower parts, if there is any obstruction, it can lead to fever, indicating that all diseases with fever symptoms are due to stagnation. The above discussions clearly indicate that all diseases, including febrile diseases, exhibit fever symptoms, and their pathogenesis is due to the stagnation of Yang Qi and the closure of defensive Qi, which cannot be released, leading to heat. At the same time, different types of pathogens can cause varying degrees of stagnation, which also affects the body differently, resulting in different degrees of heat symptoms and disease outcomes.
1.3 Deficiency Due to Stagnation
In the development of externally contracted diseases, the heat-stagnation pathogenesis plays an important role. The invasion of external pathogens leads to the resistance of defensive Qi against evil, and the struggle between the righteous and the evil; when Yang Qi is abundant, heat arises, and when heat is stagnant and not released, the more Yang is stagnant, the more heat is generated. Excessive Yang leads to Yin diseases, damaging body fluids and resulting in insufficient body fluids; moreover, heat stagnation transforms into fire, which burns and consumes Qi and injures Yin. This can lead to deficiency of the organs’ Qi and abnormal Qi dynamics due to excessive fire consuming Qi, or it can cause rashes or bleeding due to the burning of the vessels, or damage to the Ying Yin and Yin blood, even leading to the depletion of true Yin. For instance, Wu Youke’s “Warm Epidemic Theory – After the Resolution, Nourish Yin and Avoid Ginseng” states: “Accumulated Yang becomes fire, and Yin blood is often struck by heat,” indicating that stagnation of Yang leads to transformation into fire, burning Yin blood and causing pathological changes such as blood heat, stasis heat, vessel damage, and depletion of Yin blood. Therefore, in the onset and transmission process of externally contracted febrile diseases, “stagnation-deficiency” is its fundamental pathogenesis.
In summary, after the invasion of the six excesses, the resistance of defensive Qi leads to stagnation of Yang Qi; defensive Qi belongs to Yang, and when Yang is stagnant, heat arises; excessive heat then damages the body’s righteous Qi, later manifesting as Yang deficiency, Qi deficiency, or Yin blood deficiency, with common pathogenesis including the two ends of “stagnation-deficiency”.
2 Transmission Mechanisms of Externally Contracted Febrile Diseases
Whether it is cold damage or warm disease, the evolution of the disease course manifests as a process from superficial to deep, from excess to deficiency. Ye Tianshi’s “Externally Contracted Warm-Heat” chapter proposes: “Generally speaking, after the Wei stage, we talk about Qi; after the Ying stage, we talk about Blood,” indicating that both cold damage and warm diseases can exhibit varying depths of Wei, Qi, Ying, and Blood.
2.1 Qi and Blood – Body and Function Theory
“Body-Function” is a pair of fundamental concepts in ancient Chinese philosophy. The body is the fundamental, internal component; function is the external manifestation of the body. In terms of the biological structure of the organism, the body refers to the material structure with specific life functions, while the relationship between Qi and Blood is the relationship between function and substance, with Yin blood constituting the organic structure, and its functions summarized as Qi and Yang. Therefore, the relationship between Qi and Blood can be summarized as the relationship between body and function. Theoretically, the Qi and Blood – Body and Function perspective can be used to explain the physiological functions of the body. For example, in the hand Taiyin lung, the lung itself is the tangible body; the lung’s function of governing Qi and controlling respiration is the function, and other organs can be similarly understood.
2.2 Transmission Patterns of Externally Contracted Febrile Diseases
As mentioned above, the normal physiological functions of the body can be summarized using the Qi and Blood – Body and Function theory; in the occurrence and development of febrile diseases, the transmission process of febrile disease symptoms can also be explained using the Qi and Blood – Body and Function theory. Ye Tianshi’s differentiation of Wei Qi Ying Blood divides febrile diseases into four stages, which can be further simplified in clinical practice into two stages: the Qi stage, which encompasses the Wei stage and is primarily characterized by functional disorders; and the Blood stage, which encompasses the Ying stage and is primarily characterized by substantial damage and more severe functional disorders. As Chen Guongsong stated in his “Warm Disease Theory Commentary”: “In summary, Wei corresponds to Qi, Ying corresponds to Blood; in terms of equality, Wei is the marker of Qi, Qi is the foundation of Wei, Ying is the commander of Blood, and Blood is the follower of Ying,” indicating that in the differentiation of febrile diseases, Qi can govern Wei, and Blood can encompass Ying.
In the onset of externally contracted febrile diseases, when the external pathogen invades the surface, the function of defensive Qi is disordered, diminished, or excessive, while also involving functional abnormalities of the organs, meridians, limbs, and orifices, manifesting as abnormal function; in the middle or critical stage of the disease, defensive Qi becomes excessive due to resistance against evil, leading to stagnation of defensive Qi and excessive heat, or Yang stagnation transforming into fire, with a fierce struggle between the righteous and the evil, consuming Yin blood, manifesting as damage to the body, as stated in the “Jingyue Quanshu – Rash” chapter: “If the evil poison is not resolved, it directly enters the Yin stage, stagnating and forming heat, leading to the depletion of fluids and blood,” indicating that the depletion of fluids and blood is essentially damage to the organs, meridians, limbs, and orifices, or it can lead to chaotic blood flow and bleeding, or the depletion of the organs leading to functional decline, or the righteous Qi wanting to escape, leading to a separation of Yin and Yang.
For example, in patients infected with the novel coronavirus, the initial symptoms may include chills, body aches, lack of sweating, and cough; chills are caused by the external pathogen obstructing defensive Qi, leading to a loss of warmth; due to Qi not being smooth, body aches are observed; the lung governs the skin and hair, and governs Qi belonging to Wei; when the pores and skin are obstructed, the lung Qi fails to disperse and regulate, resulting in symptoms such as chills, lack of sweating, and cough. Subsequently, symptoms such as fever, sore throat, and body aches may appear; fever is due to the stagnation of Yang Qi, and when Yang is excessive, heat arises, leading to fever or even high fever that does not subside, with defensive Qi obstructed, stagnation transforming into fire, and fire having a burning nature, leading to sore throat and body aches. In this stage, the evil stagnation transforms into fire, and the fire combines with the external evil, causing substantial damage to the body, manifesting as damage to the body, while also accompanied by more severe functional disorders; in severe cases, this can lead to death.
If the righteous overcomes the evil, in the later recovery stage of the disease, the pathogenesis may show that the evil retreats and the righteous is deficient, gradually moving towards recovery; however, residual evil may linger, leading to various abnormal symptoms, with the pathogenesis being residual evil lurking in the vessels, and the characteristics of the pathogenesis manifesting as body deficiency leading to functional abnormalities, with the nature of the symptoms being deficient.
3 Transformation Mechanisms of Severe Externally Contracted Febrile Diseases
Externally contracted febrile diseases, whether wind-cold or warm-heat, can worsen and present severe symptoms. Common severe symptoms in externally contracted febrile diseases include excessive heat moving blood, heat obstructing the pericardium, excessive heat stirring wind, Shaoyin cold transformation, and subsequently the external loss of righteous Qi and the failure of various organs, with the pathogenesis briefly described as follows:
3.1 Excessive Heat Moving Blood
In the extreme stage of externally contracted febrile diseases, Yang Qi is stagnant, leading to stagnation transforming into fire, burning the vessels, causing bleeding; the vessels lose their smoothness, and the fire heat transforms blood into stasis, obstructing the vessels, leading to bleeding; at the same time, excessive fire consumes Qi, leading to bleeding. As Wu Youke stated in his “Warm Epidemic Theory – After the Resolution, Nourish Yin and Avoid Ginseng”: “Epidemics are heat diseases; the evil Qi is internally stagnant, and Yang Qi cannot be announced, accumulating Yang into fire, and Yin blood is often struck by heat.”
3.2 Heat Obstructing the Pericardium
The pericardium is the palace of the heart, representing the heart’s commands and receiving evil on behalf of the heart. In the extreme stage of febrile diseases, excessive defensive Qi stagnates and obstructs the transformation into fire, injuring the heart vessels and body, leading to stasis heat obstructing the heart orifices, resulting in symptoms such as confusion, delirium, or unresponsiveness; fire evil can also injure the brain vessels and brain organs, leading to symptoms of loss of consciousness.
3.3 Excessive Heat Stirring Wind
In the extreme stage of febrile diseases, heat stagnation transforms into fire, and fire evil burns the tendons, leading to symptoms such as muscle spasms, frequent and forceful limb convulsions, or opisthotonos. In the later stages of febrile diseases, wind symptoms may also appear, with heat injuring true Yin, damaging the Yin of the liver and kidneys, leading to insufficient nourishment of the tendons, resulting in symptoms such as muscle twitching, spasms, or other internal wind symptoms.
3.4 Desire for Transformation Being Cut Off
The desire for transformation being cut off is mentioned in the “Warm Disease Differentiation – Original Disease” section: “In febrile diseases, if sweating occurs but the pulse is still rapid and panting, it indicates a recurrence of heat; if heat does not lead to sweating, it is because fire heat overcomes metal, leading to panting. Metal is overcome by fire, and the lung’s transformation source is cut off, leading to death.” The “Warm Disease Differentiation – Upper Jiao” section states: “In Taiyin warm diseases, if blood overflows from above, use Xihucao and Dihuang Decoction combined with Yin Qiao San. If there is a middle jiao disease, treat it according to the middle jiao method. If pink blood is vomited, it is untreatable; if blood overflows from above, with a pulse of seven or eight beats or more, and the face turns black, it is untreatable; one can use methods to clear the vessels and nourish Yin.” Vomiting pink blood is similar to the clinical manifestations of acute lung injury, pulmonary edema, and respiratory failure that may occur during novel coronavirus infections, such as acute respiratory distress syndrome. The pathogenesis of the desire for transformation being cut off is that metal is overcome by fire, which is essentially heat stagnation transforming into fire, with external evil and fire evil combining, injuring the lung Yin and lung vessels, leading to dysfunction in the lung’s ability to regulate water and the hundred vessels, causing blood and water to overflow, resulting in vomiting pink blood. The pathogenesis is primarily due to excessive defensive Qi, stagnation of Yang Qi, stagnation transforming into fire, with the fire’s burning nature damaging the lung body and depleting lung function. The method proposed by Wu involves clearing the vessels to clear heat, drain fire, and detoxify, while nourishing Yin to protect the vessels and Yin, i.e., protecting the lung’s substantive organ.
3.5 Shaoyin Cold Transformation
This syndrome is often seen in cold damage, as stated in the “Shanghan Lun”: “In Shaoyin disease, the pulse is fine and weak, and the patient only desires to sleep,” “In Shaoyin disease, the pulse is fine and cannot be induced to sweat, as Yang is lost; if Yang is already deficient, and the pulse is weak and hesitant, it cannot be purged,” “In Shaoyin disease, if there is aversion to cold and the body is curled up, with cold hands and feet, it is untreatable,” “In Shaoyin disease, if there is aversion to cold and the body is curled up, with a pulse that does not reach, and no agitation or restlessness, it is fatal,” “In Shaoyin disease, the pulse is fine and weak, desiring to lie down, sweating without agitation, desiring to vomit, and after five or six days, there is diarrhea, but restlessness and inability to sleep, it is fatal,” etc. Shaoyin cold transformation is often seen in the later stages of cold damage, with critical Yang deficiency of the heart and kidneys. Its pathogenesis includes two aspects: one is that the pathogenic evil (wind-cold) directly injures the Yang Qi of the heart and kidneys; the other is that the struggle between the righteous and the evil leads to stagnation of Yang Qi, excessive Yang heat, damaging Yin blood, and combined with excessive fire consuming Qi, thus injuring the Yang Qi of the heart and kidneys, or Yin damaging Yang, or both Yin and Yang being damaged, leading to critical Yang deficiency of the heart and kidneys or deficiency of both Yin and Yang in the later stages.
3.6 External Loss of Righteous Qi
The external loss of righteous Qi is seen in the extreme stage of febrile diseases, where heat stagnation transforms into fire, excessive fire injures Qi, and the fire heat obstructs, damaging the organs, meridians, limbs, and orifices, leading to depletion of the body and functional decline, manifesting as continuous sweating, fatigue, and a pulse that is deep, weak, and nearly absent, indicating a violent loss of Yang Qi, or a pulse that is scattered, large, and weak, indicating a loss of both Qi and Yin.
4 Conclusion
Throughout history, in the research and clinical practice of TCM regarding externally contracted febrile diseases, the debate between the cold damage school and the warm disease school has persisted. Even at the current stage, there are still numerous disputes regarding the differentiation and treatment of novel coronavirus infections, including epidemics, warm diseases, cold dampness, and cold damage, which have had a significant impact on the teaching and clinical practice of TCM regarding externally contracted febrile diseases. The fundamental reason for these academic disputes lies in the lack of a unified understanding of the etiology, onset, and pathological mechanisms of externally contracted febrile diseases, resulting in a long-standing opposition between the two disciplines.
The onset of externally contracted febrile diseases is primarily caused by the invasion of the six excesses; different pathogens can exhibit different clinical characteristics and affected areas, leading to various clinical manifestations, which is the basis for TCM differentiation and examination of causes. After the invasion of external pathogens, defensive Qi resists the evil, expelling the evil outward, or if the evil does not overcome the righteous, the disease resolves; if the evil cannot be expelled, defensive Qi stagnates, leading to a loss of warmth and chills; when defensive Qi rises to resist the evil, excessive Yang leads to heat, resulting in dysfunction of defensive Qi and the organs involved, with abnormal Qi dynamics, primarily manifesting as functional disorders, characterized by stagnation or chaos, belonging to the Qi stage. As the disease progresses further, excessive Yang stagnates, heat extreme transforms into fire, fire combines with evil, damaging the organs, meridians, limbs, and orifices, consuming Yin blood, leading to substantial organ damage, accompanied by more severe functional disorders, manifesting as body injury or depletion, functional chaos or decline, belonging to the Blood stage. In externally contracted febrile diseases, the progression from mild to severe is essentially a process from Qi to Blood, representing a transition from functional disorders to organic damage.
In summary, this article summarizes the classic works such as the “Huangdi Neijing” and “Shanghan Lun”, as well as the theories of Liu Wansu, Wu Youke, Ye Tianshi, and Wu Jutong, proposing the common pathogenesis of externally contracted febrile diseases as “stagnation-deficiency”; using the “Qi and Blood – Body and Function” theory to discuss the disease course and symptom transmission, and exploring the transformation mechanisms of severe symptoms in externally contracted febrile diseases, aiming to investigate the common pathogenesis, onset, and symptom transmission patterns of externally contracted febrile diseases, laying the foundation for subsequent discussions on a unified differentiation theory system for cold and warm diseases.
Author Information
Wei KaifengChief TCM PhysicianMD, Associate Professor at Nanjing University of Chinese Medicine, Master’s Supervisor, Director of the Warm Disease Research Department, Deputy Director of the Nanjing Integrative Medicine Research Center, Jiangsu Province 333 High-Level Talent, Vice Chairman of the Jiangsu Province TCM Infectious Disease Branch, and the sixth batch of national old TCM expert academic inheritors.
Yang JinProfessor
Professor at Nanjing University of Chinese Medicine, Doctoral Supervisor, Expert enjoying special government allowances from the State Council, concurrently serving as honorary professor at several TCM colleges. A national excellent teacher, one of the first hundred “National Teaching Masters” recognized by the Ministry of Education, a famous TCM physician in Jiangsu Province, and a guiding teacher for the academic experience inheritance of national famous old TCM experts. Formerly served as the Chairman of the Infectious Disease Branch of the Chinese Association of Traditional Chinese Medicine, and the leader of the Warm Disease discipline at Nanjing University of Chinese Medicine, a key discipline of the National Administration of Traditional Chinese Medicine and the Jiangsu Provincial Government.
References:Discussion on the Common Pathogenesis and Transmission Mechanism of Externally Contracted Febrile DiseasesWei Kaifeng, Yang Jin. Discussion on the Common Pathogenesis and Transmission Mechanism of Externally Contracted Febrile Diseases [J]. Journal of Nanjing University of Chinese Medicine, 2024, 40(3): 229-233