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The transmission of epidemic diseases encompasses nine patterns. However, these do not extend beyond the categories of Exterior (Biao) and Interior (Li).

**Exterior-only presentation:** The symptoms include headache, body pain, fever, and pronounced aversion to cold (lin lin). There are no internal signs such as chest fullness, and appetite remains normal. This indicates that the pathogenic factor is transmitting outward and exiting via the muscle-surface. Favorable outcomes occur either through the resolution of macules (ban) or through sweating. Mild prescriptions can effect a cure. If sweating is incomplete and fever persists, Baihu Tang (White Tiger Decoction) is indicated. If macules fail to emerge fully and fever persists, Jubang Tang (Macule-Ascending Decoction) is indicated. If both macules and sweat appear but neither is thorough, the aforementioned decoctions should be combined.

**Interior-only presentation:** Symptoms are limited to stuffiness and oppression in the chest and diaphragm, with an urge to vomit but inability to do so, or vomiting without relief. Genti San (Melon Stamen Powder) is indicated. If the pathogen transmits to the middle and lower Interior, presenting with abdominal distension and fullness, absence of vomiting, dry stool constipation, heat-binding with peripheral flow (xie re pang liu), diarrhea accompanied by fever (xie re xia li), or fecal impaction in the large intestine, formulas from the Chengqi Tang (Gut-Purging Decoction) category are appropriate. If Interior syndrome recurs or occurs up to three times, treatment follows the preceding methods.

**Repeated Exterior resolution:** This indicates that the initial pathogenic factors were not fully cleared, and latent pathogens remain in the Membrane Source (Mo Yuan). Consequently, after three or four days, the previous fever returns, with a surging and rapid pulse. Upon resolution, those who should have macules will still manifest them, and those who should sweat will still sweat, leading to recovery. Treatment involving three rounds of Exterior resolution is extremely rare.

**Simultaneous Exterior and Interior transmission:** Initially, the pathogen lies dormant in the Membrane Source, occupying the Half-Exterior Half-Interior position, with both Exterior and Interior syndromes present. One must first unblock the Interior to eliminate Interior pathogens, allowing them to reach the Exterior. They are then expelled upward and outward through macules or sweat, following their natural tendency. If the disease recedes but fever remains, residual pathogens persist in the Membrane Source; Sanxiao Yin (Three-Draining Decoction) is indicated. If this pattern recurs once, twice, or thrice—though uncommon—it is treated according to the prior protocols.

Physicians often misunderstand cases involving repeated Exterior resolution followed by Interior purging, or complex simultaneous transmissions. Instead of understanding the pathology, they blame patients for poor self-care, while patients blame physicians for negligence. This mutual resentment is erroneous. It fails to recognize that this progression is inherent to the disease's momentum and nature.

**Exterior resolution followed by Interior purging:** Initially, only Exterior symptoms are present, with no Interior signs. Danyuan Yin (Origin-Reaching Decoction) is indicated. If meridian syndromes are involved, modifications based on the Three Yang channels should be applied. Subsequently, if the pulse becomes large and rapid, accompanied by spontaneous sweating and thirst, it indicates the pathogen has left the Membrane Source but has not yet fully exited the Exterior. Baihu Tang (White Tiger Decoction) is indicated to release the pathogen via sweating using acrid-cool dispersing methods, resulting in a calm pulse, cool body, and recovery. If fever persists after two to five days, Danyuan Yin (Origin-Reaching Decoction) is used again. If later symptoms such as chest fullness, abdominal distension, loss of appetite, irritability, and intense thirst develop, Rhubarb (Dahuang) is added to induce mild purgation.