(The text goes on to describe how a kind of literal 'soul' does not seem to be what is identified as lost by researching actual cases. This author then prefers to use indigenous words for the lost substance.)
Susto is a cultural illness, specifically a "fright sickness" with strong psychological overtones. Susto comes from the Portuguese and Spanish word for "fright" (i.e. sudden intense fear, as of something immediately threatening). A more severe and potentially fatal form of susto is called espanto (also from Spanish and Portuguese, meaning terror or intense fright). It is indigenously attributed to "soul loss" resulting from frightful or traumatic experiences. Among the indigenous peoples of Latin America, susto may be conceptualized as a case of spirit attack.
I've posted before about Susto, the condition of traumatic "fright sickness" that is said to cause a loss of spirit. While doing some recent research I came upon a few more remedies for the condition from the Spanish language Wikipedia.
The most common remedy is to make a "cleansing" of the affected with egg, lime, silver coins or herbs. One performs a "sweeping" with basil, pirú, ciruelillo, huele de noche, mirlo, epazote, malora, rue or any other plant which the healer chooses. Some people prefer to add these herbs to infusions to enhance the effect. Some people opt to smoke the person with copal, incense or some other plant. All the above procedures shall be accompanied by prayers. A variation of the "cleansing" uses chunks of rock alum, which after being rubbed on the body affected while praying, are thrown into the fire and, according to the fables, in the flames one can see who or what caused the fright. Another susto cure is by spraying the person with a mixture made with mescal (liquor) and Mechuda grass. For best results, this mixture should be ingested. If the fear is the result of the Earth being angry with someone because of their sins, it is necessary that the affected kiss as a sign of respect to him and asking for forgiveness. Another way is usually to go for a sucking (sucking specialist), who will take the patient to where the shock occurred. There, the sucker will suck, with a reed with his mouth or directly temples, wrists, elbows, knees and ankles of the patient. The "lifting of the Shadows" is a ceremony that is to go to the place where the affected "lost his soul" to capture it and place it in a baby chick, which will be taken immediately to the sick person. Once there, the soul of the bird is drawn through to the person.