Epidemic Diseases in Chinese Medicine: History, Classification, and Smallpox in Ancient China

Epidemic diseases in Chinese medicine have been studied, named, and treated for more than three thousand years, making Traditional Chinese Medicine (TCM) one of the oldest continuous frameworks for understanding contagious illness. Chinese physicians recorded the conditions under which epidemics spread, classified diseases by symptom and cause, and developed preventive and therapeutic methods — from variolation against smallpox to herbal decoctions — long before microbial theory existed in Western medicine.

What does Chinese medicine mean by "epidemic disease"?

In Chinese medicine an epidemic disease is a contagious, widely transmissible illness, captured by a cluster of classical terms whose written characters each carry a distinct nuance. The three core words are Yi (疫), Wen (瘟) and Li (疠). Yi denotes a widespread, transmissible sickness that strikes many people at once; Wen points to febrile, "warm" pestilence; and Li conveys a violent, malignant pestilential quality. The pictographic roots of these characters reflect how ancient observers understood disease — as something that arrives, spreads, and afflicts a population rather than an isolated individual.

The distinction between "contagion" and "epidemic" in classical Chinese differs from modern usage. Ancient texts already grasped that contact with the sick spread illness, but framed the cause as an external pestilential influence entering the body rather than a living organism. This etymological and conceptual analysis matters for medical history research methodology, because the terminology shows that pre-modern Chinese medicine recognised transmissibility centuries before the germ was identified.

Why were epidemics so common in early China?

Epidemics were frequent in early China because of high population density combined with recurring drought, flood, famine and war — the exact circumstances Chinese physicians recorded as triggers. In-depth acquaintance with epidemic diseases in China began a long time ago, when Europeans still saw in them a sky-sent "universal pestilence for ancestral sins" and the like. Chinese doctors instead noted the material conditions under which outbreaks appeared, and observed that contact with the sick contributed to their spread.

The dense settlement pattern of China amplified transmission. Such concentration could only be compared in ancient times with Egypt, strung along the Nile on a narrow strip of fertile land.

Smallpox illustrates this historical prevalence. The earliest information about smallpox in China dates back to 1400 BC, when the epidemic was introduced from India, and its foci most often appeared in commercial centres, seaside towns and port cities — the nodes of trade where people and goods concentrated.

How did ancient China track epidemic mortality?

Ancient China developed a rudimentary form of epidemiologic statistics by counting the dead. Servants were placed at the city gates to tally the number of bodies carried out, while others gathered figures from undertakers on how many coffins they had sold. From these two independent counts a daily mortality rate was determined — an early example of cross-checking sources to measure an outbreak's severity.

How does Chinese medicine classify diseases?

Chinese medicine classifies disease along three lines, the oldest of which is anatomical:

• by individual parts of the body,
• by the nature of the ailments and their causes,
• by methods of treatment.

The classification by body parts is the most ancient. As early as the 14th century BC, diseases of the tongue, teeth, ears, eyes and head were described, with infectious and surgical conditions added a little later. A special chapter of the code of laws Zhou li preserves information from the 8th–5th centuries BC about:

• malaria,
• parsha,
• abscess,
• tumor,
• ulcer,
• rabies,
• arrow wounds,
• bone fractures.

That same source set out the basics of dietary therapy, medication and surgical treatment. About two and a half millennia ago, doctors of Chinese medicine already possessed a rational system for classifying disease — a structured framework that distinguished epidemic from non-epidemic, internal from external, and curable from hopeless.

How did TCM understand contagion before microbes were known?

TCM explained contagion through the interplay of righteous qi and pathogenic qi long before pathogenic microorganisms were named in Western medicine. The core theory pairs zheng qi (righteous, upright qi — the body's resistance) against xie qi (evil or pathogenic qi). When zheng qi is strong, an external pestilence cannot take hold; when it is depleted by famine, exhaustion or cold, xie qi invades. This is the Chinese-medicine equivalent of immune resistance, and it underlies why constitutional factors were thought to determine who fell ill in the same outbreak.

The defensive layer in this model is wei qi (defensive qi), sometimes rendered Nei Wei Qi, which circulates at the surface of the body and guards against external invasion much as the immune barrier does in modern terms. Climate was the other half of the picture: the doctrine of the Six Qi (六气) describes wind, cold, summer heat, dampness, dryness and fire as normal seasonal influences, which become the Six Evils (六淫) when excessive or untimely and turn pathogenic. Epidemic illness was understood as these external evils overwhelming a body whose defensive qi could not balance them.

A striking advance came in the 17th century, when the physician Wu Youxing proposed that epidemics were caused by li qi — a specific pestilential agent entering through the mouth and nose, distinct from ordinary climatic evils. His treatise Wen Yi Lun (Treatise on Warm Epidemics) anticipated microorganism theory by arguing that each epidemic had its own particular cause, a remarkably early step toward the idea of disease-specific pathogens that Western medicine would only confirm with the microscope.

How did TCM's febrile disease theory develop?

TCM's theory of epidemic febrile disease evolved across nearly two thousand years, from the Han Dynasty foundations to the mature warm-disease schools of the Ming and Qing dynasties. The foundational text is the Shang Han Lun (Treatise on Cold Damage, also translated Treatise on Febrile Diseases), written by Zhang Zhongjing around the end of the Han Dynasty. Zhang Zhongjing, who reportedly lost much of his own clan to epidemic disease, organised febrile illness into stages and prescriptions, giving Chinese medicine its first systematic epidemiology and founding the School of Exogenous Febrile Diseases.

Two distinct schools framed epidemic fevers. The earlier Shanghan tradition centred on cold plague — illness beginning with chills, aversion to cold and clear early symptoms attributed to cold damage. The later Wen Bing (warm disease) tradition, which crystallised in the Ming and Qing dynasties, addressed the warm epidemic: fevers driven by heat, with rapid onset, thirst and dryness. Distinguishing cold plague from warm epidemic by their opening symptoms became central to choosing the right treatment.

The classical canon underpinning all of this includes the Huang Di Nei Jing (the Yellow Emperor's Inner Classic) and the Nan Jing (Classic of Difficult Issues), which supplied the theory of qi, organs and the Six Qi on which later febrile-disease writers built. The formation of these febrile disease schools represents an accumulation of clinical experience over centuries — each generation of physicians refining classification and treatment against the epidemics it faced.

Plague: eight names and a focus on prevention

Ancient Chinese medicine gave plague eight names, each pointing to a symptom or causal factor and each carrying its own rationale:

1. shi-i — disease dependent on a known epidemic "gene";
2. wen-tsi — pestilence from contagious air;
3. shu-i — plague of rats;
4. luan-tsu-zhen — bubonic disease;
5. biao-sho — shooting snake (meaning rapid plague infection);
6. da-tau — lumpy disease;
7. hong-si-ding — affecting the skin;
8. yang-za-chuang — itchy wounds.

Prevention held the leading place in the fight against plague. Ancient Chinese doctors reasoned that the contagious agent of plague developed in the surface layers of soil, so that rats burrowing there were struck first; rats then infected cats, pigs and cattle, and from them humans.

Identifying plague-carrying rats and linking their mass death to human outbreaks was a genuine discovery of Chinese medicine. At the first reports of dying rodents, preventive measures were taken at once, and many chronicles describe whole villages abandoning their homes for higher ground.

Containment extended to diet and water. People stopped eating meat from animals, especially pigs; water sources were placed under public control with round-the-clock watch. Doctors widely prescribed laxatives (rhubarb), diaphoretics (ginger) and some diuretics. Where the disease brought hemoptysis, remedies containing tannin and a potassium iodide solution in sea water were recommended, while external treatment used rubbed leaves of wild chrysanthemum or a preparation of lime and calomel diluted in seawater.

Cholera: dry versus wet, and the role of acupuncture

Cholera was another ancient scourge in China, and the canonical Nei-jing — attributed by legend to Emperor Huangdi but more reliably dated no later than the 3rd century BC — not only mentions it but attempts to explain its etiology through "bad gases" rising from deep damp valleys. The text distinguishes two types, "dry" and "wet," the latter with vomiting and diarrhoea being the deadlier. At first symptoms, physicians prescribed compounds combining opium with astringents and adsorbents.

As a counter-irritant measure — a method with wide indications in TCM — doctors used rubbing and massage of the neck, back and abdomen, cauterization at specific points, and plasters. At the height of the disease they turned to stimulants such as camphor and ginger, and in the algid (collapse) stage they infused ginger with sugar, or ginger cooked in rice alcohol, into the patient's mouth.

Acupuncture was regarded as the last and most effective remedy for cholera. A vivid account comes from the missionary Archbishop Favie, an eyewitness whose story was relayed by V. V. Korsakov, a Russian doctor who lived many years in China:

A missionary fell down on the road in an attack of cholera. Two Chinese doctors came up to him and "stuck iron needles with fine yellow copper ears into his hands and feet. Blood did not show at the points of the pricks. Then they stuck a needle about an inch long under his knee. A drop of black blood appeared, "He is saved," said one of the doctors, "but we must continue the treatment." They began the injections again, and in a quarter of an hour the patient turned on his bed, where he was carried. Seeing this, one of the doctors said: "That is good, but precautions must be taken before he can be sent to his bed." They stuck four 8 centimeter long needles into his forearm, after which the patient was carried to Peking. All night he slept peacefully," Favie ends his story, "and the next day he was completely healthy.

Korsakov declined any firm conclusion and noted he had never witnessed the like himself. Modern acupuncture specialists such as Dr. Zhu Lian suggest the case was likely acute gastroenteritis taken for cholera, since there is no laboratory confirmation that acupuncture cures cholera. Camphor, meanwhile, was prescribed in cholera while liquids such as rice broth were strictly forbidden.

Smallpox: naming, prevention and early variolation

The two most common Chinese names for smallpox both carry descriptive elements: tian hua can be translated as "heavenly flowers," while dou means "peas," after the appearance of the rash. The "heavenly" name reflects how common the disease was in old China — so universal it seemed an inevitable destiny, which churchmen interpreted as the will of heaven.

Smallpox epidemics peaked in winter, and Chinese doctors offered a convincing explanation:

1. in summer, people are not so confined to their homes;
2. those dwellings are open to the "good wind" and to the sun, whose "fire" burns out the disease.

V. V. Korsakov gave the same account, adding that in summer warm clothes are folded away in separate rooms — and the role of garments in transmission was no secret to Chinese medicine. Korsakov substantiated natural ventilation and the bactericidal action of sunlight from genuinely scientific positions.

Smallpox is held to have reached China from India around 1400 BC, a plausible date given that the first writings about it date to 1120 BC, while around 250 BC Fei Zi-Tai wrote one of the best books on smallpox, treated as a classic for centuries.

The most significant contribution of Chinese medicine to smallpox control was variolation — deliberate inoculation with human smallpox material. The practice dates to the Song Dynasty (960–1279) (read more: China in the 12th century) and was reportedly first performed on the son of Prince Tshin Fiang, who had recently lost several children to the disease.

About a thousand years ago a detailed inoculation protocol was set down. Scabs of smallpox pustules were to be collected from strong children who bore the disease easily, dried, and stored in hermetically sealed, freshly fired porcelain vases for no more than six months. Variolation was performed in autumn or spring, on a "moderate" day — neither hot nor cold and windless — and only on entirely healthy children.

Inoculation was most often done by blowing powdered scabs into the nostrils. Alternatively a paper tampon soaked in a weak scab solution could be placed in the nostrils for three days, and rubbing scab powder into the skin is also mentioned, though the nasal route was always preferred. According to Chinese anatomy the nostrils are the "outer opening of the lungs," from which air is carried throughout the body. A further method dressed the child in the clothes of a sick person. Chinese medicine graded smallpox by its course into three types:

1. mild ("shun do"),
2. severe ("Jian Dou"),
3. and hopeless ("Ni Dou").

From the last, patients die within a day.

Because variolation was discovered so early, the literature describes comparatively few specific treatments for established smallpox beyond symptomatic ones. Special pomades and ointments containing gleet and bee honey were widely used to heal the pustule wounds.

Typhoid fever: prevention through boiled water

Chinese sources record comparatively little on typhus, though the division into typhus ("hungry") and abdominal (typhoid) forms was made very long ago. The relative rarity of typhoid fever in old China — despite overcrowding, mass poverty and polluted water — presents a paradox.

The explanation lies in a deep-rooted custom: the Chinese have long avoided raw water, always boiling it and drinking it as tea, and by tradition even wash with boiled water — a remarkably effective form of prevention.

Among the remedies for the disease, rhubarb and ginger stand out, the latter sometimes lowering temperature significantly. V. V. Korsakov records a case in which ginger induced a typhoid patient to sweat and his temperature fell from 41° to 37° — an early observation of the symptom-alleviating, diaphoretic action of a Chinese herb.

Dysentery: two main types and many subtypes

Chinese physicians long distinguished two main forms of dysentery:

1. fresh, marked by copious pink-coloured stools;
2. old, when the stools are bloody, mucous and purulent.

A further fourteen subtypes were described, differing in the quantity and character of the stool. For acute dysentery, tinctures of tea and decoctions of water-poppet root, ginger and nutmeg were prescribed internally. Chronic dysentery, with severe wasting and weakness, called for gentiana, aconite root, and additionally soaked ginger and sunflower.

The arsenal of animal-origin remedies in Chinese medicine extended to frog body powders, used among other things in the treatment of dysentery.

Diphtheria: insufflated powders and counter-irritation

Chinese medicine had no means of accurately recognising diphtheria, lacking modern bacteriological tools, so the diphtheria category sometimes absorbed other diseases with similar symptoms. Setting that aside, Chinese doctors developed original treatments that achieved good results. Most often they blew a complex powder into the patient's throat every two to three hours. One illustrative prescription combined:

• crushed pearls, 15 weight parts,
• gallstones of certain animals, 3 weight parts,
• urinary sediment, 11 weight parts,
• charred prunes, 7 weight parts,
• indigo scale,
• purified camphor,
• licorice root, 3 weight parts,
• borax, cinnabar, acetic acid copper, 11 weight parts,
• and other substances (ambergris, musk, soot), 1 weight part.

The powder was insufflated either through a rolled paper tube or with a metal insufflator — a vessel like a pocket sprayer or oil can, with thin, slightly convex side walls. Pressing the walls forced the powder out through a hollow tube up to 14 cm long, made of three nesting parts. While blowing the medicine down the throat, the doctor pressed the tongue down with a flat, short-handled spatula. As a counter-irritant measure in diphtheria, massage of the neck area was used.

Measles: a non-malignant disease with watched-for complications

Measles is described in detail in Chinese sources as frequently bringing sore throat, bronchitis, conjunctivitis, fever and sometimes diarrhoea. Though considered non-malignant, it called for special attention to the heart, liver and lungs, where complications often arise — an early instance of organ protection in TCM treatment.

Among the many measures used in measles, one particularly original remedy that addressed the disease by relieving some of its manifestations was a pulverised decoction of parsley seeds.

These represent the general principles, means and methods of Chinese medicine in treating several infectious diseases.

Malaria: clinical forms and the wormwood remedy

Malaria ranks first among the many non-infectious (vector-borne) diseases recorded in China, with a death from malaria noted as early as 44 AD. A fairly accurate clinical picture appeared in a dedicated book by the physician Wu-Qing of Su Zhao as early as 1641 (more information: China in the 17th–18th centuries).

Wu-Qing assigned a major etiological role, alongside wind, heat, cold and dampness, to the harmful vapours of marshy plains, which he held entered the body "through the entrance gate" — mouth, nose and pores. Crucially, he observed that contagion does not always cause disease; it does so only when favourable conditions are present, echoing the zheng qi / xie qi principle that susceptibility depends on the body's state. Chinese medicine distinguished malaria by its leading symptoms into the following forms:

• severe chills without fever;
• severe chills with slight fever;
• fever alone, without chills.

For attacks accompanied by headache, peppermint oil was rubbed on the temples, while the attacks themselves were treated with wormwood, oculus and tortoise shell, supplemented by antipyretic and tonic remedies according to the patient's condition.

Acupuncture was long regarded in China as a highly effective means against malaria, and is now acknowledged by scientifically trained physicians. Across the board, epidemic diseases were recognised in Chinese medicine far earlier than in many other traditions, and detailed recommendations for their prevention and treatment were developed.

How is TCM used against modern epidemics — SARS and COVID-19?

Traditional Chinese Medicine remains an active part of epidemic response in the People's Republic of China, integrated into national protocols during both the 2003–2004 SARS outbreak and the COVID-19 pandemic. During SARS — caused by a coronavirus — Chinese hospitals combined TCM with Western medicine to reduce fever duration and support recovery, building the clinical experience later drawn on for COVID-19. The same integrated approach was applied to outbreaks of H1N1 and H7N9 flu.

For COVID-19, caused by SARS-CoV-2, China's National Health Commission incorporated TCM formulas into its official diagnosis and treatment protocol, aiming to alleviate symptoms in mild cases, delay or prevent progression from mild to severe disease, protect organ function, and reduce mortality in severe and critical patients. A number of specific preparations were screened and deployed, and clinical trials were registered with the Chinese Clinical Trial Registry (ChiCTR), including:

• Qingfei Paidu decoction,
• Lianhua Qingwen medicine,
• Jinhua Qinggan granules,
• Huashi Baidu decoction,
• Xuanfei Baidu decoction,
• Xuebijing Injection.

The proposed mechanisms align TCM concepts with modern pharmacology: anti-viral action, anti-inflammatory and immunomodulatory effects, and restoration of balance and homeostasis. In TCM terms these support zheng qi and clear xie qi; acupuncture and herbal therapy are also used for immune-system support and for rehabilitation during recovery. Historically, similar warm-disease formulas were credited with reducing mortality during the 1918 Spanish Flu pandemic in parts of China, and the COVID-19 experience has renewed interest in the global epidemic-control potential of TCM as a complement to Western medicine. These claims continue to be studied; TCM is best understood as a complement to, not a replacement for, evidence-based medical care.

Further reading and related topics

The history of epidemic diseases in Chinese medicine sits within a wider body of scholarship that uses ethnographic and historiographical approaches to study traditional Chinese medical ideas. Readers interested in the broader field of Medicine can explore related material, while those drawn to the long sweep of Chinese history and culture may enjoy our sections on Travel and Stories. For the full range of subjects covered here, see the main index of articles on travel, nature, science and life.