Original essay by: Qin Bo-Wei
Translated, introduction, & commentary by: Jason Blalack
This essay on lurking pathogens (also referred to as lingering, hidden, deep-lying, or latent pathogens) is particularly relevant in today’s era, where we have students and practitioners using the term to describe all sorts of chronic disorders. Qin suggests that the utility of the term may be questionable. Although Qin emphasises the lurking pathogen theory that came out of the warm disease tradition, his historical analysis and questioning can be applied to the general use of the term today. It should first be pointed out that Qin is known as one of the greatest synthesisers of Chinese medicine. He was renowned for his deep classical study and his ability to take an immense amount information and extract the commonalities. Qin made great efforts to systematically integrate ideas of the past. These essays come from this perspective.
[Qin’s essay] In the past, there have not only been disagreements between the practitioners and scholars of warm disease and cold damage, but also a controversy within the warm disease current itself, between the theory of newly contracted pathogens and lurking pathogens. I believe that there is a close relationship between the origin of this controversy and above-mentioned warm disease and cold damage one.
The name, lurking pathogen, principally comes from the Inner Classic (Nei Jing), where it says “if there is damage by cold in the winter, there will be a warm pathogen disease in the spring”, and “if there is sufficient essence, there will be no warm disease in the spring.” Therefore Wang Shu-He (王叔和) said, “if a cold pathogen strikes and disease immediately occurs, this is called cold damage. If there is no disease, and there is a cold toxin that is stored in the interstices of the flesh, when spring arrives it transmutes into a warm disease.”
After this, many differing opinions were put forth. For example, Pang An-Chang (庞安常) and Zhu Gong (朱肱) believed that “if in the winter one contracts the qi of a cold toxin, and it lurks and does not discharge, then when spring arrives and it encounters the warm qi, it transforms, creating a warm disease.”
Han Di-He (韩袛和) went a step further and believed that if one first contracts cold in the winter and then again contracts a new seasonal pathogen in the spring, then this causes the onset of disease. Other doctors such as Li Dong-Yuan (李东垣), Zhu Dan-Xi (朱丹溪), and Wang Hai-Cang (王海藏) had another view: that people who over-indulged in sexual activity or overwork weakened themselves until their Kidney water was insufficient to control the sprouting of wood qi in spring [and this ascending yang qi] therefore expresses itself as a warm disease.
Consequently Wang An-Dao (王安 道) points out two types of pathology involved in the onset of disease with a lurking pathogen. One is constrained heat that follows springtime yang as it ascends and spreads. The second is a new pathogen stirring up previously existing constrained heat in the interior. His analysis is that if there is aversion to wind or cold then this is a newly contracted pathogen stirring a lurking pathogen. If there is no aversion to wind or cold then this is a lurking pathogen discharging to the surface from the interior.
This idea was established, until Wang Shi-Shan (汪石山) clearly pointed out the demarcation of lurking pathogen and newly contracted disease theory. He believed that if there was damage in the winter from a cold pathogen but the disease developed in the springtime, this was a lurking pathogen warm disease. If during the springtime one was exposed to [abnormally] warm qi and immediately fell ill, this was a newly contracted warm disease.
When Ye Tian-Shi (叶天士) said “Warm pathogens are contracted in the upper part of the body, first attacking the Lungs, and they may be abnormally passed to the Pericardium”, this even more clearly indicated the cause and the pathodynamic of a newly contracted warm disease.
These are the general ideas of newly contracted and lurking pathogen theory. I believe that the progression from lurking pathogen to newly contracted disease is our forefathers’ gradual evolution in understanding of warm disease theory.
At the present, the question is whether both terms – newly contracted and lurking pathogen – should co-exist. Advocates for the term lurking pathogen argue that we definitely see symptoms of lurking pathogens in the clinic. Now I want to talk about my own clinical experience.
Lurking pathogen and newly warm disease both belong to heat type diseases; ancient and modern scholars agree. Here are some differences. A newly contracted warm pathogen disease develops immediately, a lurking pathogen warm disease does not. Newly contracted pathogenic diseases have exterior symptoms, lurking pathogen disease does not. Newly contracted diseases progress from the exterior to the interior, lurking pathogen diseases transmit from the interior to the exterior. Newly contracted diseases transmute very slowly, lurking pathogens transmute quite rapidly.
Clinically, is it really possible to make a clear diagnosis based on these parameters? I feel that it is very difficult. In addition, a lurking pathogen that is in the non-immediacy period of the disease has no symptoms. Furthermore, in the early stage of the onset of disease, lurking pathogens will often have many exterior symptoms, as well as rapid transmutations. In addition, newly contracted warm diseases can very quickly and immediately transform to an interior heat presentation.
On the other hand, from the source of lurking pathogen theory, the Inner Classic: “In the winter when there is damage by cold, then there must be a warm pathogenic disease in the spring.” Therefore up until this point, all spring warmth patterns are caused by lurking pathogens, and the principle idea for treatment is to clear internal heat. However, wind warmth has the acrid cool release exterior formulas, Sang Ju Yin (Mulberry Leaf and Chrysanthemum Drink) and Yin Qiao San (Honeysuckle and Forsythia Powder). Spring warmth also has the acrid cool release exterior formula, Cong Chi Jie Geng Tang (Scallion, Prepared Soybean, and Platycodon Decoction). Although the names of the formulas are different, they are the same in substance.
Yin Qiao San (Honeysuckle and Forsythia Powder)
Cong Chi Jie Geng Tang (Scallion, Prepared Soybean, and Platycodon Decoction )
Wind-Warmth (Newly contracted disease)
Spring-Warmth (Lurking pathogen)
Jin Yin Hua (Lonicerae Flos) & Lian Qiao (Forsythiae Fructus)
Lian Qiao (Forsythiae Fructus)
Jie Geng (Platycodi Radix)
Jie Geng (Platycodi Radix)
Bo He (Menthae haplocalycis Herba)
Bo He (Menthae haplocalycis Herba)
Dan Dou Chi (Sojae Semen preparatum)
Dan Dou Chi (Sojae Semen preparatum)
Jing Jie (Schizonepetae Herba)
Cong Bai (Allii fistulosi Bulbus)
Dan Zhu Ye (Lophateri Herba)
Dan Zhu Ye (Lophateri Herba)
Lu Gen (Phragmitis Rhizoma)
Zhi Zi (Gardeniae Fructus)
Niu Bang Zi (Arctii Fructus)
Gan Cao (Glycyrrhizae Radix)
Gan Cao (Glycyrrhizae Radix)
** Chart added for comparison. It does not appear in Qin’s original essay.
As for the location of lurking pathogens, some physicians thought that they were located in skin and muscles, some in the muscles and bones, and also some thought they were located in the shaoyin and triple burner.
Consequently they thought that the lurking pathogen could exit from the shaoyang, yangming, or shaoyin as well as from the blood and yin aspects.
However, the treatment is exactly the same for the interior “spring warmth” pattern [which was the original name for a lurking pathogen emerging in springtime froma winter exposure] and for that of “wind warmth” [which was the original name for a newly contracted warm pathogen in springtime]: in both cases one differentiates and treats based on the signs and symptoms.
Actually we can say that after a warm disease presentation has undergone a pattern differentiation of the triple burner and protective, qi, nutritive, and blood, that the distinction of a newly contracted pathogen and lurking pathogen patterns loses its practical significance.
Furthermore, regardless of whether the lurking pathogen spontaneously erupts, comes about from a newly contracted pathogen, or if people use contemporary language saying the patient’s disease is in a “latent period”, it seems a bit hard to fathom that a pathogen is lying in some undetermined location for a season or more. Consequently it is my opinion that the term, lurking pathogen, is not necessary in present day. However, we should admit that lurking pathogen theory did historically motivate the development of warm disease theory; it is a process of increasing understanding.
On the other hand, warm disease belongs to the scope of external diseases and we should also consider newly contracted diseases as such. However, due to internal factors, the onset of disease of a newly contracted warm pathogen can produceparticular transmutations.a For example, the Inner Classic pointed out “if there is storage of essence then warm disease will not occur in the spring.” Essence here refers to the body’s essential qi; hence a deficiency of essential qi is the cause of the onset of disease.
For another example of how internal factors can influence the onset of a newly contracted warm pathogen, the Revised and Expanded Discussion of Warm Diseases (Guang Wen Re Lun), points out that warm disease has “four damages” and “four insufficiencies.” The four damages are great consumption (大痨 da lao), great desire, major disease, and chronic disease. The four insufficiencies are exhausted qi, blood, yin, and yang. I believe that the four damages are human matters whereas the four insufficiencies are endowed from heaven. The four damages are temporary, whereas the four insufficiencies are constitutional.
If these four damages and four insufficiencies are present and coupled with a warm pathogen, then often the pathogen will enter even more deeply, due to a correct deficiency (正虚 zheng xu). Once the pathogen enters deeply, transformations occur and it is difficult to evict. Consequently, the sequence of one’s treatment method is different from a typical warm disease pathogen. In addition, Wang Meng-Ying ( 王孟英) said, you have to take extra care of children, after they get a warm disease, it can easily lead to internal heat. I consider these ideas related to what people call lurking pathogen warm disease.
Furthermore, in clinical application, if a patient with a newly contracted warm disease has a strong tendency towards internal heat, or they have yin aspect constitutional deficiency, their condition will transform to heat more rapidly than normal, and one will see very easily and quickly an internal pattern. This is similar to what people call lurking pathogen warm disease. Consequently, we don’t need the name lurking pathogen. However, the meaning of lurking pathogen as well as the experience of ancient doctors treating lurking pathogens still requires us to pay attention to it. Furthermore it is necessary for us to organise and summarise these ideas.
Jason’s commentary: Qin takes a somewhat controversial stance, asking us to look at the clinical implications and utility of the term lurking pathogen. We should ask, can we understand “lurking pathogen theory” just through our modern outline of Chinese medicine itself?
For example, Huang Qin (Scutellariae Radix) and Mu Li (Ostreae Concha) are said to address lurking heat in the interior, in the context of Chai Hu Gui Jiang Tang (Bupleurum, Cinnamon Twig, and Ginger Decoction). However, what is the value in naming this a lurking pathogen versus merely chronic interior heat?
As a further example, Xie Bai San (Drain the White Powder), written in 1119, is commonly described as treating lurking fire in the Lungs. However, the original author did not explain it in this fashion and it was later authors, such as Wang-Ang (王昂) in 1682, who initiated the use of this term. Many other explanations throughout history for this formula’s etiology have existed, such as constrained heat, constrained fire, and even simply Lung heat. Did Wang-Ang see something that others missed, or did he prefer a different set of terms to describe his clinical reality? Essentially though, historical ideas such as lurking heat in the nutritive aspect were used to make up core treatment strategies for a heat pathogen in the nutritive aspect. Thus, nowadays, the treatment principles and methods should be congruent.
Although I think Qin has an important point, there may be some benefit in using, or at least understanding, how classical doctors used the term lurking pathogen. For example, there are specific treatment ideas and theory, especially in the warm disease current, that may warrant further examination. Take for example those from the famous Qing dynasty physician Liu Bao-Yi (柳宝诒). The use of the term may give us a handle on a certain genre of warm disease treatment strategies.
Many such strategies quite simply do not appear in modern textbooks. Hence the more simplified our medicine becomes, the more important it is to dive into original texts. There is a fine line between condensing material and losing essential information. I think the consolidation and simplification that has occurred over the past 50 years has gone far beyond what Qin originally envisioned when he developed his synthesis of Chinese medicine. Therefore, we may benefit from reclaiming some of the complexity that once existed, even
from Qin’s era.
In today’s time though, the utility of the term needs to be questioned in a different manner. That is, the term lurking pathogen has become an en vogue term for describing any pathogen dormant in the body, or an illness that is reoccurring. Quite simply though, with such an approach, can’t any pathogen (e.g. cold, damp, heat, phlegm etc.) involved in a chronic condition be considered a lurking pathogen? Hence, one cannot assume that using lurking pathogen theory, medicinals, or formulas (developed historically) will be correct in such cases. Proper Chinese medicine differentiation is paramount and in most (lingering pathogen) instances one’s solution will most likely fall within the scope of basic Chinese medicine. Hence, I do not think that using the term as a general idea for a pathogen that lingers in the body is useful clinically.
Relating such conditions and formulas to lurking pathogens can actually steer us away from the proper treatment methods. For example, we often hear, and are taught, that Xiao Chai Hu Tang (Minor Bupleurum Decoction) is great for lurking pathogens. Consequently, when we see a patient who chronically gets sick or has a lingering problem we immediately jump to the class of formulas that “address” lurking pathogens.
A question to consider is, what formula is not good for “lurking pathogens” (as used in this general sense)?
A very large percentage of formulas are appropriate for chronic “lurking pathogen” conditions. Even the simple Gui Zhi Tang (Cinnamon Twig Decoction) is routinely used for pathogens that are lodged in the muscle layer for sometimes years at a time. Along the same lines, Xiao Chai Hu Tang (Minor Bupleurum Decoction) is appropriate for a cold pathogen lodged in, or constraining, the shaoyang. Hence, more important than labeling something as a lurking pathogen, is to ascertain the type of pathogen (cold, hot, damp, etc.) and location of the pathogen (e.g. shaoyin, membrane source, the minute collaterals at the blood level, etc.). This ultimately brings us closer to fundamental Chinese medicine diagnostics.
Because of this more modern broad convention, the term is currently overused and creates confusion when trying to put it into context of Chinese medicine’s historical usages. It is quite possible that we need a new term to define our modern interpretations to help differentiate them from historical usages. This is because, as we have seen, the meaning of the term lurking pathogen has become convoluted. This is not only within Chinese medicine’s past, but also due to our Western integration of the concept of “lingering” pathogens, such as viruses. Quite simply, people are using this single term in different ways. Nonetheless, we should constantly evaluate possible unique usages throughout history and in the modern-day clinic.
Footnotes: Actually Qin uses the term lurking qi (伏气 fu qi) throughout his essay. However within this paper I choose the more recognisable term lurking pathogen (伏邪 fu xie)。‚It should be noted that there are various English translations for this term lurking (伏 fu), such as hidden, deep-lying, or lingering.
 To elaborate further, many physicians such as Ding Xue-Ping, believe that a lurking pathogen must be hidden away for a warm pathogen heat disorder to manifest. However, how does one actually know that there is a pathogen hidden away, especially when there are no symptoms present beforehand? Hence when the patient actually becomes ill, how can one be certain that this is because of pathogen that has just been lingering unnoticed, versus a pathogen that just entered the body? As Qin points out, it is not easy to make such clinical determinations.
 Di Gu Pi (Lycii Cortex), Sang Bai Pi (Mori Cortex), Gan Cao (Glycyrrhizae Radix) and Jing Mi (nonglutinous rice).
This article was originally published in The Lantern, Volume VIII, Issue 2 – 2011, as part of a larger essay entitled gu. Three essays from Qin Bo-Wei.