by: Jenny Dorth
Variola Minor is also known as Variola alastrim and is another virus that causes smallpox, along with Variola Major. It belongs to the Orthopox subfamily of Poxviridae, has monopartite ds DNA with a capsid having complex morphology, and is enveloped. The name Variola is derived from a practice termed "variolation," which was the first effective, preventative method developed to provide protection from an infectious disease. Variolation is the practice of inhaling material from the dried pox scabs or inoculating this material directly beneath the skin. This method was effective, but had the disadvantage of producing smallpox when the material was active and not providing full immunological protection in some recipients. Nevertheless, this practice of variolation of both Variola Minor and Major were practiced in the 18th century in China, India, western Asia, and Europe.
The characteristic rash would appear first on the face, forearms and hands on the 3rd or 4th day after the onset of symptoms and within a day after that, it would have spread to the trunk and lower limbs. The lesions began as macules that became firm papules that were pustular. After about 8-9 days after the rashís initial appearance, the papules would dry up and crust over by 14 to 16 days. The rash was more prevalent on the face, forearms, and lower legs than the thighs, abdominal region, and upper arms. This clinical presentation describes what is known as ordinary-type smallpox, which was the most common manifestation of a variola minor infection.
Variola minor, like variola major, is highly infectious and could be spread through inhalation of the virus released from lesions into nasal secretions, and also through direct contact of scab material, though at a much lower rate of transmission. The initial site of infection was in the upper and lower respiratory tract. After an incubation period of 10-14 days (the same for variola major), variola minor would display an acute onset of a fever, malaise, headache, and backache.
In comparison with variola major, variola minor was usually discrete, presented itself clinically as ordinary-type smallpox, the toxemia was less, lesions were more superficial, and healing time was more rapid. Variola major had the potential to cause more clincially-severe outcomes such as hemorrhagic-type smallpox associated with bleeding from the skin and mucous membranes, severe toxemia and death, and flat-type smallpox characterized with severe toxemia. It isnít surprising that variola minor ultimately lead to a lower fatality rate than variola major, taking into account the fact that its clinical presentations were less severe. The fatality rate of variola minor was usually around 1%, while that of variola major could be from 20-30%.
Vaccines and Behavioral
Smallpox, caused by variola major and minor, was the first infectious human disease to be eradicated from the world! Efforts to vaccinate and contain the spread of this disease had been made ever since the 18th century with variolation techniques. Then came along Jenner, who used the cowpox virus to give the worldís first vaccination against smallpox. This was highly effective, but could cause later neurological sequealae, and so the standard vaccine that was used to eradicate smallpox was the vaccinia virus. Vaccinia virus either had its origins from a recombinational event between the cowpox or variola virus through serial passage or could be the representative of a long-since extinct virus. Arguably the greatest triumph of medicine was the eradication of this disease through extensive vaccination programs and surveillance methods. Now only laboratory workers that handle the variola virus continue to be vaccinated.
There was no treatment in wide use for smallpox. For most people infected, they just had to wait for the disease to run its course.
Variola minor should have no game action since its severity was less than that of smallpox and also because it is now extinct.
Although variola minor never caused severe disease in humans and it is now eradicated, it should still be considered an important human virus because it has valuable lessons to teach us about vaccination programs and eradication efforts.