Lurking Pathogens 3
Definition, History, Pathogenicity
In our last post, we did a quick and dirty review of Four Levels theory. This week, we will focus on Lurking Pathogens (Fú Xié, abbreviated further as LP), including a little bit of history and development.
Definition of LP
As detailed by the Warm Disease (Wēn Bìng) school, LP are exterior pathogenic factors which invade the body, producing few or no symptoms, then lie concealed somewhere in the interior until such time as they are provoked to appear by some additional disease-causing mechanism (Wen & Seifert, 2000). It is this delayed onset that is a chief characteristic of LP, in contrast to the immediate appearance of exterior symptoms in cold damage (Shāng Hán) or seasonal warm pathogen disease (Wēn Bìng) (Liu, 2005, p68).
Over the centuries, the term has grown less precise. Chace et al. (2007) note more modern usage, which includes any retained pathogenic factor, symptomatic or not, that remains latent for some time until it reveals itself through clinical manifestations. Some Chinese sources may even include any recalcitrant pathogen. For now, let’s stick with the Warm disease definition.
Historical development
The theory of LP dates back to the dawn of canonical Chinese medicine. The earliest mention is in the third chapter of the Yellow Emperor’s Inner Classic Basic Questions (Huángdì Nèijīng Sùwèn), likely from the Han period (c. 206 B.C.E-200 C.E.). It reads:
“If one was harmed in summer by summerheat,
in autumn this causes jie and malaria. [...]
If one was harmed in winter by cold,
in spring he will develop a warmth disease.”
(Unschuld & Tessenow, 2011, p. 79)
The actual usage of the term Fú Xié may have begun in the Yuán period during the 1300s, though some sources date it to the later Hàn, around the third century CE (Liu, 2005; Wen & Seifert, 2000). Much of the differentiation of LP came from Qīng-era physician Yè Tiānshì (1666-1745), who we mentioned in our Four-Level review last post. Following the Sùwèn passage above, Yè classified LP as either spring warmth (Chūn Wēn), which enters in the winter and comes out in the spring, or lurking summerheat (Fú Shŭ), which enters in summer and comes out in autumn or winter.
Ye’s classification is still the most orthodox view of LP, and the basic differentiation of heat and damp-heat given in some modern English-language TCM sources (Liu, 2005; Maciocia, 2022; MacLean et al., 2018), is, I believe, in line with this perspective. As LP theories continued to progress through the Qīng period, other ideas emerged, including discussion of the Kidney’s relation to LP, psychoemotional triggers of LP, and identification of LP associated with each of the seasons and each of the climatic factors (Liu, 1898; Liu, 2005). We at Clinical mulch think all of these ideas can be useful.
LP theory was not widely accepted until the latter half of the 1800’s. It remains minimally recognized even today; some commentators state LP do not exist (Bevin, 2013). Liu (2005) regards it as the next step in the evolution of warm disease theory.
The nature, etiology and pathogenicity of LP
The most commonly cited scenario of LP activation is that a season or two after the stealth pathogenic invasion, the patient comes down with a mild exterior pattern (frequently wind-cold) which, along with the usual chills and sniffles, triggers some unanticipated heat- or damp-heat-related interior signs. The exterior pattern resolves quickly but the interior signs remain for a prolonged period. The nature of the symptoms gives an idea of the location of the LP in relation to the Four Levels, as well as the state of the patient’s Zhèng Qì. If the symptoms are in the Qì level (Lung, Spleen, Fǔ organs), it indicates that the Zhèng Qì is relatively strong and thus gives a better prognosis. If the symptoms are in the Yíng or Xuè levels (Pericardium, Liver and Kidney), it means the Zhèng Qì has weakened and the LP is consuming the Yīn, Blood and Essence; accordingly, the prognosis is worse.
Since the LP are generally seen as having a warm nature (or if they are not warm per se, they obstruct the Qì dynamic and produce heat from stagnation), longer latency periods are correlated with more extensive damage to the Yīn aspects of the body and thus poorer outcomes (Liu, 2005).
In the next series installment, we will look more closely at the treatment principles, but the thumbnail version is that the progression or regression of the LP can be tracked according to changes in the levels at which the signs and symptoms appear. If the clinical picture shifts from Yíng level to Qì level manifestations, it indicates that the pathogen is being pushed toward the body surface and the prognosis is improving, where inward movement of pathogens from Qì to Yíng or Xuè level is a bad sign (Liu 2005).
As mentioned, typically a precipitating stimulus (such as wind-cold or wind-heat) needs to be present in order to express the LP. The triggers are not limited to exterior invasion: some of the factors that have been cited in the literature include the environmental growing of Yáng Qì in the springtime (Liu, 2005), emotional upset (Liu, 1898; Liu, 2005), dietary irregularities (Blalack & Chace, 2006; Liu, 2005) or the LP can just spontaneously appear (Bevin, 2013).
Given the variety of possible triggers, a question arises: how do we differentiate a LP from a regular interior heat or damp-heat pattern? It can be difficult, and Maclean (2018) says that some cases of LP are only identified in hindsight. An important clue can be the sudden appearance of heat or damp-heat signs and symptoms with no obvious trajectory, i.e. no interiorized exterior pattern, or history of long-standing interior disease. These can include low-grade fevers, significant fatigue, swollen lymph nodes, abnormal sweating and/or localized heat sensations, alternating chills and fever, etc. Maclean also includes a scenario of a “lingering pathogen”, with a history of more conventional pathogenic invasion (or possibly immunization reaction) in which the pathogen was never completely cleared. He says that the patient will often state something to the effect of “I’ve never been the same since… [the pathogenic invasion occurred]”. While this is strictly speaking distinct from the concept of LP, the treatment principle involved is basically identical, i.e. rooting out the pathogen, moving it toward more superficial levels if necessary and ultimately clearing it from the body.
Note: this newsletter is for information purposes only and is not intended as medical advice. Please seek the opinion of a health care professional for any specific medical issues you may have.
References
Bevin, M.-J. (2013). Lurking pathogens in springtime: Adventures in translation. The Lantern, 10(3), 22-27.
Blalack, J., & Chace, C. (2006). Lurking pathogens: A case study from the late Qing dynasty. The Lantern, 3(1), 31-37.
Chace, C., Blalack, J., & Schaefer, J. (2007). Lurking pathogens: Three modern approaches. The Lantern, 4(2), 17-27.
Liu, G. (2005). Warm pathogen diseases: A clinical guide. Eastland Press.
Liu, J.R. (1898). Fúxié xīnshū (New treatise on lurking pathogens). Retrieved June 3, 2022 from https://jicheng.tw/tcm/book/%E4%BC%8F%E9%82%AA%E6%96%B0%E6%9B%B8/index.html
Maciocia, G. (2022). The practice of Chinese medicine: The treatment of diseases with acupuncture and Chinese herbs. (3rd Edition). Elsevier Health Sciences (US).
Maclean, W., Lyttleton, J., Bayley, M., & Taylor, K. (2018). Clinical handbook of internal medicine: The treatment of disease with traditional Chinese medicine. Eastland Press.
Unschuld, P.U., & Tessenow, H. (2011). Huang Di Nei Jing Su Wen : An Annotated Translation of Huang Di's Inner Classic - Basic Questions: Volume 1. University of California Press.
Wen, J. M., & Seifert, G. (2000). Warm Disease Theory: Wen Bing Xue. Paradigm Publications.