Badi Mata is a female deity worshiped by some tribes in India, like the Saharia, Kamar etc. The worshipers believe that her wrath causes people to suffer from the small pox disease. The worshipers sacrifice goats to appease her.

Another similar deities are: Chhoti Mata who is associated with chicken pox and Sendri Mata who is associated with measles.

The clinical definition of smallpox is an illness with acute onset of fever equal to or greater than followed by a rash characterized by firm, deep seated vesicles or pustules in the same stage of development without other apparent cause. If a clinical case is observed, smallpox is confirmed using laboratory tests.

Microscopically, poxviruses produce characteristic cytoplasmic inclusions, the most important of which are known as Guarnieri bodies, and are the sites of viral replication. Guarnieri bodies are readily identified in skin biopsies stained with hematoxylin and eosin, and appear as pink blobs. They are found in virtually all poxvirus infections but the absence of Guarnieri bodies cannot be used to rule out smallpox. The diagnosis of an orthopoxvirus infection can also be made rapidly by electron microscopic examination of pustular fluid or scabs. All orthopoxviruses exhibit identical brick-shaped virions by electron microscopy. If particles with the characteristic morphology of herpesviruses are seen this will eliminate smallpox and other orthopoxvirus infections.

Definitive laboratory identification of variola virus involves growing the virus on chorioallantoic membrane (part of a chicken embryo) and examining the resulting pock lesions under defined temperature conditions. Strains may be characterized by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. Serologic tests and enzyme linked immunosorbent assays (ELISA), which measure variola virus-specific immunoglobulin and antigen have also been developed to assist in the diagnosis of infection.

Chickenpox was commonly confused with smallpox in the immediate post-eradication era. Chickenpox and smallpox can be distinguished by several methods. Unlike smallpox, chickenpox does not usually affect the palms and soles. Additionally, chickenpox pustules are of varying size due to variations in the timing of pustule eruption: smallpox pustules are all very nearly the same size since the viral effect progresses more uniformly. A variety of laboratory methods are available for detecting chickenpox in evaluation of suspected smallpox cases.

The overall case-fatality rate for ordinary-type smallpox is about 30 percent, but varies by pock distribution: ordinary type-confluent is fatal about 50–75 percent of the time, ordinary-type semi-confluent about 25–50 percent of the time, in cases where the rash is discrete the case-fatality rate is less than 10 percent. The overall fatality rate for children younger than 1 year of age is 40–50 percent. Hemorrhagic and flat types have the highest fatality rates. The fatality rate for flat-type is 90 percent or greater and nearly 100 percent is observed in cases of hemorrhagic smallpox. The case-fatality rate for variola minor is 1 percent or less. There is no evidence of chronic or recurrent infection with variola virus.

In fatal cases of ordinary smallpox, death usually occurs between the tenth and sixteenth days of the illness. The cause of death from smallpox is not clear, but the infection is now known to involve multiple organs. Circulating immune complexes, overwhelming viremia, or an uncontrolled immune response may be contributing factors. In early hemorrhagic smallpox, death occurs suddenly about six days after the fever develops. Cause of death in hemorrhagic cases involved heart failure, sometimes accompanied by pulmonary edema. In late hemorrhagic cases, high and sustained viremia, severe platelet loss and poor immune response were often cited as causes of death. In flat smallpox modes of death are similar to those in burns, with loss of fluid, protein and electrolytes beyond the capacity of the body to replace or acquire, and fulminating sepsis.

Usog or balis is a topic in psycho-medicine in Filipino Psychology (but considered just as a Filipino superstition in Western Psychology) where an affliction or psychological disorder is attributed to a greeting by a stranger, or an evil eye hex. It usually affects an unsuspecting child, usually an infant or toddler, who has been greeted by a visitor or a stranger.

In some limited areas, it is said that the condition is also caused by the stranger having an evil eye or "masamang mata" in Tagalog, lurking around. This may have been influenced by the advent of the Spaniards who long believed in the "mal de ojo" superstition.

Once affected, the child begins to develop fever, and sometimes convulsions. Supposedly, the child can be cured by placing its clothing in hot water and boiling it. In most other places, to counter the effects of the "usog" the stranger or newcomer is asked to put some of his or her saliva on the baby's abdomen, shoulder or forehead before leaving the house. The newcomer then leaves while saying: ""Pwera usog... pwera usog..."" The saliva is placed on the finger first, before the finger is rubbed on the baby's abdomen or forehead. The stranger is never to lick the child. The practice is that the stranger or visitor is asked to touch his or her finger with saliva to the child's body, arm or foot (""lawayan"") to prevent the child from getting overpowered (""upang hindi mausog"").

One theory (Kristina Palacio) explains "usog" in terms of child distress that leads to greater susceptibility to illness and diseases. There are observations that a stranger (or a newcomer or even a visiting relative) especially someone with a strong personality (physically big, boisterous, has strong smell, domineering, etc.) may easily distress a child. Thus, the child is said to be "overpowered" or "nauusog" and thus may feel afraid, develop fever, get sick, etc.

In "usog", the child's distress is the consequence of the child's failure to adapt to change. It is, in medical terms, the consequence of the disruption of homeostasis through physical or psychological stimuli brought about by the stranger. Technically, the condition results from the child-environment interaction that leads the child to perceive a painful discrepancy, real or imagined, between the demands of a situation 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.

Running amok, sometimes referred to as simply amok or gone amok, also spelled amuk, from the Malay language, is "an episode of sudden mass assault against people or objects usually by a single individual following a period of brooding that has traditionally been regarded as occurring especially in Malay culture but is now increasingly viewed as psychopathological behavior". The syndrome of "Amok" is found in the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-IV TR). The phrase is often used in a less serious manner when describing something that is wildly out of control or causing a frenzy (e.g., a dog tearing up the living room furniture might be termed as "running amok".)

In 1849, amok was officially classified as a psychiatric condition based on numerous reports and case studies that showed the majority of individuals who committed amok were, in some sense, mentally ill. The modern DSM-IV method of classification of mental disorders contains two official types of amok disorder; beramok and amok. Beramok is considered to be the more common of the two and is associated with the depression and sadness resulting from a loss and the subsequent brooding process. Loss includes, but is not limited to, the death of a spouse or loved one, divorce, loss of a job, money, power, etc. Beramok is associated with mental issues of severe depression or other mood disorders. Amok, the rarer form, is believed to stem from rage, insult, or a vendetta against a person, society, or object for a wide variety of reasons. Amok has been more closely associated with psychosis, personality disorders, bipolar disorder, and delusions.