帝曰∶夫病温疟与寒疟，而皆安舍？舍于何脏？岐
伯曰∶温疟得之冬中于风寒，气藏于骨髓之中，至春则阳气大发，邪气不能自出，因遇大暑，脑髓烁，肌肉消，
腠理发泄，或有所用力，邪气与汗皆出。此病藏于肾，其气先从内出之于外也。如是者，阴虚而阳盛，阳盛则
热矣，衰则气复反入，入则阳虚，阳虚则寒矣，故先热而后寒，名曰温疟。
《生气通天论》、《阴阳应象大论》皆曰∶冬伤于寒，春必温病，是伏邪发于少阴经络也。故仲景论伏气
温病，必先喉痛，以少阴经脉循喉系舌本故也，然肾司冬令而主骨，此其邪入深，而云藏于骨髓，故至春阳气
虽大发，而邪气不能自出，因又遇大暑，其邪久伏，郁极而成热，烁髓消肌，腠理发泄，或有所用力以动阳，
其邪始与汗皆出。此因先藏于肾，从内出外，故其阴已虚，而阳邪盛，阳盛则热矣；盛极必衰，衰则邪气复反
入阴，入阴则阴盛阳虚，阳虚则寒矣。故先热而后寒，以其邪本温热，因入于阴而身寒，故名温疟，非寒邪也。
其寒疟之由，已详上文矣。
帝曰∶瘅疟何如？岐伯曰∶瘅疟者，肺素有热，气盛于身，厥逆上冲，中气实而不外泄，因有所用力，腠
理开，风寒舍于皮肤之内、分肉之间而发，发则阳气盛，阳气盛而不衰，则病矣。其气不及于阴，故但热而
不寒，气内藏于心，而外舍于分肉之间，令人消烁肌肉，故命曰瘅疟。
肺素有热者，以其阳盛于身也，阳盛则升气多而厥逆上冲，
中气实而不外泄，所以肺热也。因有所用力而腠理开，风寒乘虚客于皮肤分肉之间，以其阳盛，邪即化热，
心为君火，同气相召，故藏于心，而外舍于分肉之间，则消烁肌肉。其邪不及于阴，故但热而不寒，命曰瘅疟
也。大抵疟之发寒热者，以邪气出入阴阳，阴阳之气互争互并故也。然邪必随身中之气变化，故阳盛之人，邪
即化热，阳虚之人，邪易入阴，入阴则阴盛多寒，客阳则阳盛多热。瘅疟之邪，不及于阴，故但热而不寒也。
又有湿闭热伏之病，亦由阳气不振，或见其内热而投寒药，则湿邪愈闭而阳陷，乃至危殆矣。此阴阳强弱，
邪之浅深，不可不辨也。
Yellow Emperor asked: Where do the pathogens of Warm Malaria (Wen Nue) and Cold Malaria (Han Nue) reside? In which Zang organs are they stored?
Qi Bo replied: Warm Malaria arises from contracting Wind-Cold in winter. The pathogen hides within the Marrow (Gu Sui). When spring arrives, Yang Qi expands vigorously, but the pathogen cannot expel itself. If accompanied by intense summer heat, the brain marrow is scorched, muscles waste away, and Cou Li (pores/skin texture) open and sweat. Or, if physical exertion occurs, the pathogen exits along with the sweat. This disease resides in the Kidney (Shen), and its Qi moves from the interior to the exterior. In such cases, Yin is deficient while Yang is excessive; Yang excess generates Heat. When Yang declines, the Qi reverses and re-enters the interior; interior entry leads to Yang deficiency, and Yang deficiency generates Cold. Thus, it presents with fever first followed by chills, named Warm Malaria (Wen Nue).
Both *Su Wen: Lun Sheng Qi Tong Tian* and *Yin Yang Ying Xiang Da Lun* state: "Injury by Cold in winter leads to Warm Diseases in spring." This indicates that latent pathogens emerge from the Shaoyin (Lesser Yin) meridians. Therefore, Zhang Zhongjing discusses latent Qi Warm Diseases as necessarily involving sore throat, because the Shaoyin meridian circulates through the throat and connects to the root of the tongue. However, the Kidney governs the Winter season and controls the bones. Since the pathogen enters deeply, it is said to hide in the bone marrow. Thus, even though Yang Qi expands greatly in spring, the pathogen cannot exit spontaneously. If intense summer heat follows, the long-latent pathogen becomes stagnant and transforms into Heat, scorching marrow and wasting muscles. With Cou Li opening or physical exertion mobilizing Yang, the pathogen finally exits with sweat. Because the pathogen initially resided in the Kidney and moved from interior to exterior, Yin is already deficient while Yang pathogens are excessive; Yang excess generates Heat. Excess inevitably declines; upon decline, the pathogen re-enters Yin. Entry into Yin causes Yin excess and Yang deficiency; Yang deficiency generates Cold. Hence, fever precedes chills. Because the pathogen is essentially warm-hot, but causes coldness upon entering Yin, it is named Warm Malaria (Wen Nue), not caused by Cold pathogens. The cause of Cold Malaria (Han Nue) has been detailed above.
Yellow Emperor asked: What is about Damp-Heat Malaria (Dan Nue)?
Qi Bo replied: In Dan Nue, the Lungs (Fei) harbor pre-existing Heat, causing Qi to be excessive throughout the body. Rebellious Qi rushes upward, Middle Qi is full but fails to vent outward. If physical exertion opens the Cou Li, Wind-Cold lodges between the skin and muscle layers (Fen Rou), triggering the disease. Upon onset, Yang Qi becomes excessive; if this excess does not subside, illness persists. The pathogen does not reach the Yin level, so there is only fever without chills. The Qi stores internally in the Heart (Xin) and externally in the Fen Rou, causing muscle wasting; thus it is named Dan Nue.
"Pre-existing Heat in the Lungs" implies excessive Yang in the body. Yang excess leads to abundant ascending Qi and rebellious upward rushing, with full Middle Qi failing to vent, resulting in Lung Heat. Physical exertion opens Cou Li, allowing Wind-Cold to invade the skin and Fen Rou due to deficiency. Due to excessive Yang, the pathogen immediately transforms into Heat. The Heart is the Sovereign Fire; sharing similar nature, it attracts the pathogen. Thus, the pathogen stores in the Heart and lodges in the Fen Rou, wasting muscles. Since the pathogen does not reach Yin, there is only fever without chills, named Dan Nue.
Generally, malaria presenting with alternating chills and fever occurs because pathogens move between Yin and Yang, causing mutual contention and merging of Yin and Yang Qi. However, pathogens change according to the body's internal Qi. Thus, in those with Yang excess, pathogens transform into Heat; in those with Yang deficiency, pathogens easily enter Yin. Entering Yin causes Yin excess and much Cold; lodging in Yang causes Yang excess and much Heat. Dan Nue pathogens do not reach Yin, hence only fever without chills.
Furthermore, diseases of Dampness obstruction and latent Heat also arise from failing Yang Qi. If one sees internal Heat and administers Cold herbs, Dampness becomes more obstructed and Yang sinks, leading to critical danger. The strength of Yin and Yang, and the depth of pathogens, must be distinguished carefully.