软脚瘟者。便清泄白。足肿难移者是也。即湿温。宜苍术白虎汤。不可轻下。
小儿亦易传染。人见惊搐发痉。误作惊治。与大人多仿佛也。故凡盛夏湿温之证。
即藏疫疠在内。一人受之。则为湿温。一方传遍。即为疫疠。所以疫疠之发。每每盛
于春夏者。以其湿热暑三气交蒸故也。盖春主厥阴肝木。秋主阳明燥金。冬主太
阳寒水。各行其政。惟春分以后。至秋分以前。少阳相火。少阴君火。太阴湿土。三气
合行其事。天本热也。益以日之暑。日本烈也。益以地之湿。三气交动。时分时合。其
分也风动于中。胜湿解蒸。不觉其苦。其合也。天之热气下。地之湿气上。人在气交
之中。无隙可避。故病之繁且苛者。莫如夏月为最。以无形之热。蒸动有形之湿。即
无病之人感之。未免为患。况素有湿热。或下元虚人。安得不患湿热之证乎。是以
湿热之证。最忌发汗。发汗则湿热混而为一。中气尽伤。多成死证。惟宜分解。先抉
中气。使中气徐领其表其里。上下分消。故多愈也。至若疫气。则邪正混合。邪极胜。
正极衰。转眼立毙。苦寒伤胃。温补助邪。如人中黄之类。方为合法也。夫伤寒之邪。
先行身之背。次行身之前。次行身之侧。由外廓而入。瘟疫之邪。则直行中道。流布
三焦。上焦为清阳。故清邪从之上入。下焦为浊阴。故浊邪从之下入。中焦为阴阳
交界。凡清浊之邪。必从此区分。甚者三焦相混。上行极而下。下行极而上。伤寒邪
中外廓。一表即散。疫邪行在中道。表之不散。伤寒邪入胃腑。则腹满便 。故可攻
下。疫邪布在中焦。散之不收。下之复合。此与治伤寒表里诸法。有何涉哉。
周禹载曰。按吴又可皆论寻常所有疫疠。喻嘉言止论天地不正之大疫。各极快
畅。不可执一。要知瘟疫有伤气。伤血伤胃之殊。故见证不同。治亦稍异。若入脏者。
则必不知人而死矣。大法以证为则。毋专以脉为据也。
绞肠瘟，表现为肠鸣、干呕、水样腹泻且排泄不通畅。治疗应采用探吐法，适宜使用双解散。
软脚瘟，表现为大便清稀、泻下白色黏液、足部肿胀难以移动的症状。这就是湿温病，适宜使用苍术白虎汤。不可轻易使用攻下法。
小儿也容易被传染。人们看到小儿惊厥抽搐、发生痉挛，误认为是惊风而按惊风治疗。这与大人的病情多有相似之处。因此，凡是盛夏时节发生的湿温病症，
体内都潜伏着疫疠之气。一个人感染它，就表现为湿温；一个地区广泛传播，就称为疫疠。所以疫疠的发作，往往在春夏季节最为盛行，这是因为湿热暑三种邪气交相蒸腾的缘故。大概春季由厥阴肝木主令，秋季由阳明燥金主令，冬季由太阳寒水主令，各自行使自己的职权。只有从春分以后到秋分以前这段时间，少阳相火、少阴君火和太阴湿土这三种邪气共同发挥作用。天气本热，加上日光的暑热；地表本烈，加上地气的湿气。三种邪气交互运动，有时分开有时合并。当它们分开时，风气在内部流动，克制湿气并解除蒸热，人不觉痛苦；当它们合并时，天的热气下降，地的湿气上升，人处于天地气交之中，无处可躲避。因此，病情繁杂且严重的，没有比夏季月份更厉害的。因为无形的热邪蒸动有形的湿邪，即使是健康的人感之，也难免受害，何况素来就有湿热，或者下元虚弱的病人，怎么能不患上湿热证呢？所以对于湿热证，最忌讳发汗。如果发汗，则湿热混合为一，中气完全受损，多导致死亡。适宜的方法是分解邪气，先疏通中气，使中气慢慢统领表里，上下分消邪气，所以大多能痊愈。至于疫气，则是邪正混杂，邪气极盛，正气极衰，转眼之间就会立即死亡。苦寒药会损伤胃气，温补药会助长邪气，如人中黄之类的药物，才是合法的治法。伤寒的邪气，先侵犯身体背部，其次侵犯身体前面，再次侵犯身体侧面，由外廓而入；瘟疫的邪气，则直接沿中道运行，流布于三焦。上焦属于清阳，所以清邪从上而入；下焦属于浊阴，所以浊邪从下而入；中焦是阴阳交界之处，凡清浊之邪，必定从这里区分。严重的会导致三焦混淆，上行至极则下行，下行至极则上行。伤寒邪气在外廓，一用解表法即可消散；疫邪行于中道，解表不能消散。伤寒邪气入胃腑，就会出现腹部胀满、大便不通（注：原文“便 ”此处疑为“便闭”或“便硬”，结合语境“故可攻下”，通常指便秘或实热积滞），所以可以使用攻下法。疫邪散布在中焦，发散则不收摄，攻下则邪气复合。这与治疗伤寒的表里诸法，有什么关系呢？
周禹载说：考察吴又可所论述的都是寻常常见的疫疠，喻嘉言只论述天地间不正的大疫，各自都非常痛快淋漓，不可固执一端。要知道瘟疫有伤气、伤血、伤胃的不同，所以表现出的症状不同，治疗方法也稍有差异。如果邪气进入脏腑，那么病人一定会神志昏迷而死。大原则是以症状为准，不要专门以脉象为依据。
Jiaochang Wen (Intestinal Plague) is characterized by borborygmus (intestinal rumbling), dry retching, and watery diarrhea with a sensation of incomplete evacuation. Treatment should employ the method of inducing vomiting to expel pathogens. The Shuangjie San (Double-Resolution Powder) is indicated.
Ruanjiao Wen (Soft-Legged Plague) is characterized by clear stools, discharge of white mucus, and swollen feet that are difficult to move. This condition is equivalent to Shiwen (Damp-Warmth). The Cangzhu Baizhu Tang (Atractylodes Macrocephala and White Tiger Decoction) is indicated. One must not lightly employ purgative methods.
Children are also susceptible to infection. When observing children experiencing convulsions and spasms, practitioners often mistakenly treat them as Jingfeng (Wind-Convulsion). This presentation bears many similarities to adult cases. Therefore, any Damp-Warmth syndrome occurring in midsummer harbors Yi Li (Plague Pathogens) within. If contracted by one individual, it manifests as Damp-Warmth; if transmitted throughout a region, it is termed Yi Li. Thus, the onset of plague pathogens is often most prevalent during spring and summer, due to the intermingling and steaming of Dampness, Warmth, and Summerheat. Generally, Spring is governed by Jueyin Liver Wood, Autumn by Yangming Lung Metal, and Winter by Taiyang Bladder Water, each exercising its own authority. Only from after the Spring Equinox to before the Autumn Equinox do Shaoyang Ministerial Fire, Shaoyin Sovereign Fire, and Taiyin Spleen Earth jointly exert their influence. Heaven is inherently hot, augmented by the summer heat of the sun; Earth is inherently intense, augmented by the dampness of the ground. These three qi interact, sometimes separating and sometimes merging. When separated, wind moves internally, overcoming dampness and resolving steaming, causing no distress. When merged, heavenly heat descends and earthly dampness ascends. Humans exist within this intersection of qi, with no refuge. Consequently, the complexity and severity of diseases are greatest in summer months. Formless heat steams and agitates formed dampness; even healthy individuals contracting this will inevitably suffer harm, let alone those with pre-existing damp-heat or deficiency in the lower yuan (kidney essence/origin). Therefore, for damp-heat syndromes, sweating is strictly contraindicated. Sweating causes dampness and heat to merge into one, completely damaging the Middle Qi (Spleen/Stomach energy), often leading to death. The appropriate approach is to resolve and separate the pathogens, first unblocking the Middle Qi, allowing it to gradually govern the exterior and interior, dispersing pathogens above and below, thus ensuring recovery. Regarding plague pathogens, however, evil and righteous qi are mixed; evil is extremely strong while righteous qi is extremely weak, leading to sudden death. Bitter-cold herbs damage the Stomach, while warm-tonic herbs assist the evil. Substances like Renzhong Huang (Human Midden Yellow) constitute the legal treatment. The pathogen of Shanghan (Cold Damage) first affects the back of the body, then the anterior, then the lateral aspects, entering from the exterior shell. The pathogen of Wenyi (Plague-Epidemic) travels directly along the central pathway, distributing through the Three Jiao (Triple Burner). The Upper Jiao belongs to Clear Yang, so clear pathogens enter from above; the Lower Jiao belongs to Turbid Yin, so turbid pathogens enter from below; the Middle Jiao is the junction of yin and yang, where clear and turbid pathogens must be distinguished. In severe cases, the Three Jiao become confused, with upward movement reaching extremity turning downward, and downward movement reaching extremity turning upward. Shanghan pathogens remain in the exterior shell and dissipate upon releasing the exterior; Wenyi pathogens travel in the central pathway and do not dissipate with exterior-releasing methods. When Shanghan pathogens enter the Stomach-Fu organs, abdominal fullness and constipation occur, making purgation applicable. Wenyi pathogens distribute in the Middle Jiao; dispersing them fails to gather them, and purging them causes them to recombine. How does this relate to the various exterior-interior methods used for treating Shanghan?
Zhou Yuzai stated: Wu Keyi discussed common epidemic plagues, while Yu Jiayan discussed only the great epidemics caused by abnormal heaven-earth qi. Both were thorough and cannot be viewed rigidly. One must understand that plagues differ in whether they injure Qi, Blood, or the Stomach, leading to different clinical manifestations and slightly varied treatments. If pathogens enter the Zang-Fu organs, the patient will lose consciousness and die. The general principle is to take symptoms as the standard, rather than relying solely on pulse diagnosis.