In the era of Wen Bing or warm diseases (think: smallpox) the introduction of epidemic heat toxins as a form of Du was concurrent with the idea of a latent (or even fetal) heat pathogen. The differences are subtle, but important:
Du is characterized as a malignant spread of non-conscious and non-consciousness altering heat or fire vector which scorches tissues, causes malignancy, mutation, malformation, and destruction of the tissue. Latent heat pathogens can often live with us our whole life, and while it probably shortens life, we have no specific proof. Maybe the only example is that staph or strep recurrent can damage the heart valves and that might shorten life. Latent heat does, however, cause a series of life-altering maladies and nuisances of health ranging from spasm to headache to balance issues, autoimmune conditions, and general unwellness and lack of full vitality. However, because of the presence of heat, the person seems energetic. It isn’t the same as a spiritual heat and robustness. It is an uneasy heat presence.
Practically speaking, the difference in the red petechiae of the tongue is subtle. Latent heat produce small, usually pale or very dark red, or even faint red dots on the tongue, usually the sides. Du, if it produces petechia at all, produces wide, bright, even bubbling petechia, and the tongue can begin to take on a scorched appearance, which never happens with latent or fetal heat pathogens.
In the treatment of each, the herbal formulas are different, but share some common flower type herbs, such as dandelion or chrysanthemum. But they are from different families. And with latent heat, we don’t use scorpion or snake, etc. to treat. Also we don’t use as toxic herbs for purging, and instead focus on light, acrid or spicy herbs, aromatics, etc. to “vent” the heat.
Both are cases where acupuncture is not completely sufficient to treat, but requires herbs.
If you have red petechia on your tongue, consider the above info as informative, and you have a yellow flag, but there is nothing yet saying you require immediate medical attention. But if you have Du poison, like heavy metals etc., you do need to immediately begin to rid yourself of these tissue-damaging chemicals.
There is one more condition regarding Du you should know about and that is internally produced organ toxins, such as high liver enzymes. Liver Fire could manifest as poison, but usually doesn’t, unless the organ begins to die, slowly or quickly. Then the poisons can really spread internal to the body, even into the brain, and destroy the psyche, body, spirit, and even one’s karma and fortunes. So please take these issues very, very seriously.