气之所在也，如病在阳则身热而脉躁，病在阴则身寒而脉静，此其应也。病极则阴阳之气俱衰，
阴阳俱衰则卫气与邪气相离，故病得休，此其所以不发也，如明日卫气集与邪相遇，则复病也。
帝曰∶时有间二日，或至数日发，或渴，或不渴，其故何也？
帝承相离则休之意，问疟发时有间二日．或至数日，当其发也。有热甚而渴，有热不甚而不渴，其故何也。
岐伯曰∶其间日者，邪气与卫气客于六腑，而有时相失，不能相得，故休数日乃作也。
其间二日或数日者，邪气与卫气并寒于六腑，卫气入腑，周时
不能外出，而有时相失矣，有时相失，不能与病气相汤，故间二日，或休数日乃作也。
疟者，阴阳更胜，或甚，或不甚，故或渴，或不渴。
常有或渴或不渴之问，故日症者乃阴阳之气，更相胜也。或阳热之气过甚则渴，或阳热之气不甚，则不渴也。
帝曰∶论言夏伤于暑，秋必病疟，今疟不必应者，何也？
《生气通天论》云，夏伤于暑，秋为 疟，帝举以问，今疟有不必为是者，何也？
岐伯曰∶此应四时者也，其病异形者，反四时也，其以秋病者
寒甚，以冬病者，寒不甚，以春病者恶风，以夏病者多汗。
恶，去声。邪气伏藏而病疟，此应四时之升降出入者也，其病异形者，感一时之气而为疟，此反四
时也，其以秋时病疟者，冬伤于寒，阳气内藏，故寒不甚，以春时病疟者，春伤于风，气机始发，
故恶风，以夏时病疟者，夏伤于暑，腠理开，故多汗，此春夏秋冬，皆能病疟，所以明其不必应也。
帝曰∶夫病温疟与寒疟，而皆安舍，舍于何脏？
上文夏受水寒，秋伤于风，藏于腠理皮肤之中，发则先寒后热，名曰寒疟。温疟只言先伤于风，后伤
于寒，未言所受之时，未明所藏之处，帝欲详明温疟之由，故问温疟与寒疟，而皆安舍，舍于何脏，上文因
寒疟而及温疟，故寒疟详而温疟略，此问温疟而兼寒疟，故下文但论温疟，而不复言寒疟也。
岐伯曰∶温疟者，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。
上中，去声。藏如字，下同。温疟者得之冬，中于风寒，邪气藏于骨髓之中，至春则阳气大发，邪在
骨髓，气行经脉，故邪气不能自出，至夏因遇大暑，暑热上炎，则脑髓烁，暑行肌肉，则肌肉
消，暑开腠理，则腠理发泄，或有所用力，劳其形体，则骨髓之邪气，与汗皆出而为疟，此病邪藏于肾，其
气先从内之骨髓，而出于肌肉腠理之外也。如是者，大暑消烁阴虚而阳盛，阳盛则热矣。阳
热衰，则气复反入，既衰反入则阳虚，阳虚则寒矣，故先热后寒，名曰温疟。寒疟已悉于前，故不复论。
帝曰∶瘅疟何如？
因温疟而复问但热不寒之瘅疟也。
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。其气不反于阴，故但热
而不寒，气内藏于心，而外舍于分肉之间，令人消烁脱肉，故命曰瘅疟。
反，旧本误及，今改。瘅疟者，其人肺素有热，肺主气，肺热则气盛于身，肺气不能外出于皮毛，
则厥逆上冲。上冲者，中气实，而不能外泄也，肺热而实，因有所用力，劳其形体，则腠理
开，腠理在皮肤之内，分肉之间，因其开也。风寒复舍于皮肤之内，分肉之间，而发为疟病，发则阳气
盛，故先热，阳气盛而不衰，故但热不寒，则病瘅疟矣。上文温疟，气复反入，故先热后寒，瘅疟，
其气不反于阴，故但热而不寒，申明气不反阴，但热不寒者，邪热之气，内藏于心，而外舍于分肉之间，
令人消烁脱肉，是以气不反阴，但热不寒，故命曰瘅疟，所以详明瘅疟之所藏者如此。
帝曰∶善。
由瘅疟而推之，则上文少气烦冤，手足热而欲呕，亦火热之气内藏于心，帝故善之。
此一节，论寒疟温疟瘅疟之所由来，及治疟早晏之法也。
邪气所在部位不同，反应也不同：如果病在阳分，则身体发热且脉搏躁动；如果病在阴分，则身体发冷且脉搏平静，这是相应的表现。当病情发展到极点时，阴阳之气都会衰弱，阴阳俱衰导致卫气与邪气分离，所以疾病得以暂停，这就是为什么暂时不发作的原因。如果第二天卫气聚集并与邪气相遇，那么疾病就会再次发作。
黄帝说：有时疟疾隔两天发作一次，或者间隔几天才发作，有的口渴，有的不口渴，这是什么缘故呢？
黄帝承接上文“卫气与邪气分离则暂停”的意思，询问疟疾发作有时隔两天或几天，当它发作时，有的热势严重而口渴，有的热势不严重而不口渴，这是什么原因呢？
岐伯说：那些隔日发作的，是因为邪气和卫气客居在六腑中，两者有时不能同时到达，无法相互遭遇，所以要经过几天才能再次发作。
所谓隔两天或几天发作，是因为邪气与卫气一同寒凝于六腑，卫气进入腑中，一个时辰内不能外出，导致两者有时错开、不能相遇，因此隔两天，或者休息几天后才发作。
疟疾这种病，是阴阳之气互相胜负交替的结果，有时胜势严重，有时胜势不严重，所以有的口渴，有的不渴。
因为经常有人问起有的口渴有的不渴的情况，所以说疟疾是阴阳之气互相胜负的表现。如果是阳热之气过盛就会口渴，如果是阳热之气不盛，就不会口渴。
黄帝说：医论中说夏天被暑邪所伤，秋天必定患疟疾，现在疟疾不一定都符合这个规律，为什么呢？
《生气通天论》中说：“夏伤于暑，秋必痎疟”，黄帝引用这句话来提问，现在发现疟疾不一定都遵循这一规律，为什么呢？
岐伯说：这是顺应四时变化的情况。那些病症表现异常的，是违背了四时规律的。如果在秋季发病，是因为感受的寒气很重；如果在冬季发病，是因为感受的寒气不重；如果在春季发病，会有怕风的症状；如果在夏季发病，则会多汗。
“恶”读作去声。邪气潜伏藏匿而引发疟疾，这是顺应四时升降出入规律的情况；而那些病症表现异常的，是只感受一时之气而引发的疟疾，这是违背四时规律的情况。在秋季患疟疾的，是因为冬天受了寒邪，阳气内藏，所以寒气不重；在春季患疟疾的，是因为春天受了风邪，气机刚开始生发，所以怕风；在夏季患疟疾的，是因为夏天受了暑邪，腠理（皮肤毛孔）开放，所以多汗。这说明春夏秋冬四季都能导致疟疾，以此说明疟疾不一定非要顺应夏伤暑、秋病疟的规律。
黄帝说：关于温疟和寒疟这两种病，它们分别寄宿在哪里？寄宿在哪个脏腑？
上文提到夏天受水寒之气，秋天伤于风邪，邪气藏在腠理和皮肤之中，发作时先冷后热，称为寒疟。对于温疟，只说了先伤于风，后伤于寒，没有说明受伤的时间，也没有明确藏匿的地方。黄帝想要详细阐明温疟的成因，所以询问温疟和寒疟究竟寄宿在哪里，存在于哪个脏腑。上文因讨论寒疟而连带提到温疟，所以对寒疟讲得详细而对温疟讲得简略；这次询问温疟而兼带寒疟，所以下文只讨论温疟，不再重复谈论寒疟。
岐伯说：温疟这种病，是在冬天受到风寒侵袭，邪气藏在骨髓之中，到了春天阳气大发时，邪气不能自行排出，如果遇到大暑天气，脑髓被灼烧，肌肉消瘦，腠理开泄，或者因为用力劳作，邪气随着汗水一起排出，这种病邪藏在肾中，其气先从体内发出到体表。
像这种情况，会导致阴虚而阳盛，阳盛就会发热。当阳气衰退时，气又会重新返回体内，返回体内则导致阳虚，阳虚就会发冷。所以先发热而后发冷，称为温疟。
“中”读作去声。“藏”按原字读音，下同。温疟是由于冬天感受风寒，邪气藏在骨髓中，到了春天阳气大发，邪气在骨髓中，随经脉运行，所以邪气不能自行排出。到了夏天遇到大暑，暑热上炎，则脑髓被灼烧；暑气行于肌肉，则肌肉消瘦；暑气开启腠理，则腠理开泄。如果此时有所用力，劳累形体，那么骨髓中的邪气就会随着汗水一起排出而成为疟疾。这种病邪藏在肾中，其气先从体内的骨髓，而出于肌肉腠理之外。像这种情况，大暑消烁导致阴虚而阳盛，阳盛就会发热。阳热衰退，气又反向回归，既衰退又回归则导致阳虚，阳虚就会发冷，所以先热后冷，称为温疟。寒疟的内容前面已经详尽论述，所以不再重复讨论。
黄帝说：瘅疟（dān nüè，一种但热不寒的疟疾）是什么样的呢？
岐伯说：瘅疟这种病，是因为患者肺中素有热邪，热气充斥全身，气机厥逆向上冲撞，中焦气实而不能向外宣泄，再加上有所用力劳作，腠理开泄，风寒之邪便停留在皮肤之内、分肉（肌肉间隙）之间而发病。发病时阳气亢盛，如果阳气亢盛而不衰退，就会生病。这种气不返回阴分，所以只有发热而没有发冷。气内藏于心，外舍于分肉之间，使人肌肉消烁、身体脱瘦，所以命名为瘅疟。
“反”字，旧版本误写为“及”，现在改正。瘅疟的患者，肺中素来有热，肺主气，肺热则气盛于全身，肺气不能向外出于皮毛，就会导致气机厥逆向上冲撞。所谓上冲，是因为中气充实，不能向外宣泄。肺热且实，加上有所用力劳作，劳累形体，导致腠理开泄。腠理位于皮肤之内、分肉之间，趁着腠理开泄之时，风寒之邪再次停留于皮肤之内、分肉之间，从而引发疟病。发病时阳气亢盛，所以先发热；阳气亢盛而不衰退，所以只有发热没有发冷，这就形成了瘅疟。上文提到的温疟，气会反向回归体内，所以先热后冷；而瘅疟，其气不返回阴分，所以只有发热没有发冷。这里申述气不返回阴分、只有发热没有发冷的原因，是因为邪热之气内藏于心，外舍于分肉之间，使人肌肉消烁、身体脱瘦，正因为气不返回阴分、只有发热没有发冷，所以命名为瘅疟，如此详细阐明了瘅疟的藏匿之处。
黄帝说：好。
由瘅疟推究开来，那么上文提到的少气、烦闷冤屈感、手足发热且想呕吐等症状，也是火热之气内藏于心所致，所以黄帝对此表示赞同。
Where the pathogenic qi resides, the manifestations differ accordingly: if the disease is in the Yang aspect, the body will be hot and the pulse restless; if the disease is in the Yin aspect, the body will be cold and the pulse quiet. This is the corresponding reaction. When the disease reaches its extreme, both Yin and Yang qi decline. When both Yin and Yang qi decline, the Wei Qi (Defensive Qi) separates from the pathogenic qi, so the illness pauses. This is why it does not manifest at that moment. If the next day the Wei Qi gathers and encounters the pathogenic qi again, the disease will recur.
The Yellow Emperor said: Sometimes malaria occurs every two days, or after several days of interval. Some patients experience thirst, while others do not. What is the reason for this?
Continuing from the previous point regarding the separation of Wei Qi and pathogenic qi leading to a pause, the Yellow Emperor asked about the intervals of two days or several days between malaria attacks. He further inquired why, during an attack, some cases present with severe heat and thirst, while others have mild heat and no thirst.
Qibo replied: In cases occurring every other day, the pathogenic qi and Wei Qi reside in the Six Fu organs. There are times when they miss each other and cannot meet, thus requiring several days before the next attack occurs.
Regarding the intervals of two days or several days, this happens because the pathogenic qi and Wei Qi become stagnant and cold within the Six Fu organs. When the Wei Qi enters the Fu organs, it cannot exit within one double-hour period (Shichen), causing them to miss each other. Because they cannot meet the pathogenic qi, the interval lasts two days, or the patient rests for several days before the next attack.
Malaria is characterized by the alternating superiority of Yin and Yang qi. Sometimes the superiority is severe, sometimes it is not. Therefore, some patients feel thirsty, while others do not.
Since there is often inquiry into why some feel thirsty and others do not, it is stated that malaria involves the mutual superiority and inferiority of Yin and Yang qi. If the Yang-heat qi is excessively strong, thirst occurs; if the Yang-heat qi is not strong, there is no thirst.
The Yellow Emperor said: The treatises state that injury by summer-heat in summer leads to malaria in autumn. However, not all malaria cases follow this pattern. Why is this?
Citing the *Suwen: Lun Sheng Qi Tong Tian* which states, "Injury by summer-heat in summer leads to Jie Malaria (intermittent fever) in autumn," the Yellow Emperor raised this question, noting that current observations show malaria does not always adhere to this rule. Why is that?
Qibo replied: These are cases that conform to the Four Seasons. Those with atypical symptoms deviate from the Four Seasons. Cases occurring in autumn involve severe cold; those in winter involve mild cold; those in spring involve aversion to wind; and those in summer involve profuse sweating.
"Evil" (E) is pronounced with the departing tone. Pathogenic qi lying dormant causes malaria, which conforms to the ascending, descending, exiting, and entering of the Four Seasons. Atypical cases result from contracting qi of a single season, violating the Four Seasons' norms. Autumn malaria results from winter cold injury where Yang qi is stored internally, hence the cold is not severe. Spring malaria results from spring wind injury where the Qi mechanism begins to emerge, hence aversion to wind. Summer malaria results from summer heat injury where the Cou Li (pores/skin texture) open, hence profuse sweating. This demonstrates that malaria can occur in any of the four seasons, clarifying why it need not strictly follow the summer-heat/autumn-malaria rule.
The Yellow Emperor said: Regarding Warm Malaria and Cold Malaria, where do they lodge, and in which Zang organs do they reside?
Previously, it was mentioned that water-cold received in summer and wind injured in autumn hide within the Cou Li and skin, manifesting first as chills then heat, termed Cold Malaria. For Warm Malaria, it only stated initial wind injury followed by cold injury, without specifying the timing or location of storage. The Yellow Emperor sought to clarify the origin of Warm Malaria, asking where both Warm and Cold Malaria lodge and which Zang organs they affect. Since Cold Malaria was discussed previously alongside Warm Malaria, Cold Malaria was detailed while Warm Malaria was brief. Now, asking about Warm Malaria while including Cold Malaria, the following text discusses only Warm Malaria and omits Cold Malaria.
Qibo replied: Warm Malaria originates from wind-cold contraction in winter, with the pathogenic qi hiding in the Marrow. By spring, when Yang qi expands vigorously, the pathogenic qi cannot exit on its own. If met with intense summer heat, the brain marrow is scorched, muscles waste away, and the Cou Li open. If accompanied by physical exertion, the pathogenic qi exits along with sweat. This disease lodges in the Kidney, with its qi moving from the interior to the exterior.
In such cases, Yin deficiency and Yang excess occur. Yang excess leads to heat. As the qi declines, it returns inward; inward return leads to Yang deficiency, which causes cold. Thus, heat precedes cold, named Warm Malaria.
"Zhong" is pronounced with the departing tone. "Zang" is read as written, same below. Warm Malaria arises from winter wind-cold invasion, with pathogenic qi lodging in the Marrow. By spring, Yang qi expands, but the pathogen remains in the Marrow, traveling through the meridians, unable to exit spontaneously. In summer, intense heat scorches the brain marrow; summer heat travels through muscles causing wasting; summer heat opens the Cou Li. Physical exertion causes the pathogenic qi in the Marrow to exit with sweat, resulting in malaria. The pathogen lodges in the Kidney, moving from the internal Marrow to the external Muscles and Cou Li. Such intense summer heat consumes Yin, leading to Yang excess and heat. As Yang heat declines, the qi returns inward; declining and returning inward leads to Yang deficiency and cold. Hence, heat precedes cold, named Warm Malaria. Cold Malaria was fully discussed earlier, so it is not repeated.
The Yellow Emperor said: What about Dan Malaria (Feverish Malaria)?
Following the discussion of Warm Malaria, he asks specifically about Dan Malaria, characterized by heat without chills.
Qibo replied: Dan Malaria occurs in individuals who have pre-existing heat in the Lungs. Qi is abundant throughout the body, reversing upward and rushing against the center. The central Qi is full but cannot vent outward. Due to physical exertion, the Cou Li open, allowing wind-cold to lodge within the skin and between the muscle layers (Fen Rou). Upon manifestation, Yang qi becomes excessive. If Yang qi remains excessive without declining, disease ensues. The qi does not return to Yin, resulting in heat without cold. The qi stores internally in the Heart and externally in the Fen Rou, causing emaciation and wasting. Hence, it is named Dan Malaria.
"Fan" (return): Old editions erroneously wrote "Ji"; corrected here. Dan Malaria affects those with pre-existing Lung heat. The Lung governs Qi; Lung heat causes Qi abundance in the body. Lung Qi cannot vent outward through the skin and hair, leading to rebellious Qi rushing upward. Upward rushing indicates fullness in the center preventing external venting. With Lung heat and fullness, plus physical exertion weakening the form, the Cou Li open. Located inside the skin and between muscle layers, the opening allows wind-cold to re-lodge in the skin and between muscle layers, triggering malaria. Manifestation brings Yang excess, hence heat first. Since Yang excess does not decline, there is only heat and no cold, constituting Dan Malaria. Previously, Warm Malaria involved qi returning inward, causing heat then cold. Dan Malaria's qi does not return to Yin, causing only heat without cold. This clarifies that due to pathogenic heat storing in the Heart and lodging in the Fen Rou, causing emaciation, the qi does not return to Yin, resulting in only heat without cold, thus named Dan Malaria. This details the storage site of Dan Malaria.
The Yellow Emperor said: Excellent.
Inferring from Dan Malaria, the previously mentioned symptoms of shortness of breath, vexation/oppression, heat in the hands and feet, and desire to vomit are also caused by fire-heat qi storing internally in the Heart. Therefore, the Yellow Emperor approved this explanation.
This section discusses the origins of Cold Malaria, Warm Malaria, and Dan Malaria, as well as the principles of early versus late treatment for malaria.