on the one hand and their social, biological, or psychological resources on the other. The stressful stimuli to the child may be mental (stranger is perceived as a threat, malevolent or demanding), physiological (loud and/or high-pitched voice of the stranger that is hurting to the child's eardrum; strong smell of the stranger that irritates the child's nasal nerves), or physical (stranger has heavy hands or is taking up too much space). The stranger's act of gently placing his finger with his saliva to the child's arm, foot, or any particular part of the child's body, could make him more familiar to the child, and thus, reduce if not remove the stress. As the stranger keeps gently saying, "Pwera usog... pwera usog...," the child is made to feel and assured that he means no harm. The usog is said to be counteracted because the child is prevented from succumbing to an illness since the child is no longer in distress. Children or even adults who are shy or have weak personalities are more susceptible to usog in accordance with observations and theory. Some have observed that at times even praising a shy child by a visiting relative caused an usog. The saliva from the stranger, granted that he or she is healthy and consistent with his or her oral hygiene, is relatively clean and contains enough antimicrobial compounds such as lactoferrin, lactoperoxidase, and secretory immunoglobulin A which can help clear pathogens from the child and benefit the child against infection. Furthermore, human saliva has opiorphin, a newly researched pain-killing substance. Initial research with mice shows the compound has a painkilling effect of up to six times that of morphine. It works by stopping the normal breakdown of natural pain-killing opioids in the spine, called enkephalins. Opiorphin in human saliva is a relatively simple molecule, and the child's immune system may trigger a biochemical cascade (complement system) to produce other stress-reducing compounds. Usog can also, though less commonly, affect adults, and it may induce vomiting and stomach ache rather than fever. Supposedly, it can be prevented by stopping a stranger or visitor from greeting the person. Unlike "lihi", however, usog is not yet medically accepted. More than the superstitious folks, researchers dealing with Filipino Psychology say they have observed this phenomenon with regularity and suggest that this be added to the Psychiatric Disorders Handbook DSM-V. See also Evil eye Lihi Albulario Saliva