Poxvirus Family: Poxviridae Subfamily: Chordopoxovirinae Class: Orthopoxvirus Genus : Poxvirus species: Smallpox (Variola) Special physical structures • Double-stranded DNA virus • Linear molecular structure with complex morphology • Unique enveloped large brick shaped • Obligate Intracellular Parasite Unusual genes or toxins Poxvirus is one of the largest viruses that contain several subfamilies such as cowpox, monkeypox, vaccinae, orf and molluscum to name a few with smallpox being the most endemic of all •Poxvirdae is one of the largest viruses and one that is a human pathogen that is deadly and was an epidemic that haunts medical professionals to this day • Smallpox virion consists of approximately 187,000 nueclotides which makes it one of the largest viruses to go through transcription and translation in the genetic code sequence • Smallpox virion has a helical nucleocapsid that resembles a dog bone or a dumbbell shapeOther unique characteristics • Smallpox is considered a category A agent, which can cause a widespread disease epidemic such as Anthrax, plague, botulism, tularemia, and viral hemorrhagic fevers • Ordinary form, confluent form, and hemorrhagic form History • Smallpox arrived with the European settlers to the New World in the early 1600s, which wiped out about 90% of American Indians but dates back to Egyptian times in B.C. • Edward Jenner’s discoveries in 1796 in the vaccination using cowpox lead the path to smallpox vaccination that eventually lead to the eradication of smallpox in 1980, the last case ever known was in Somalia, Africa in 1977 • The last outbreak in the United States was in 1949 Transmission & Life cycle Transmission of smallpox was person to person contact or by inhalation of the particles in the air of infected people or through the sharing of bedding /clothes • Viral multiplication is through transcriptase where the components of the virus are synthesized and assembled in the cytoplasm of the host cell and multiplies rapidly • Life cycle of the smallpox virus can be up to 14 days but quarantine for 17 days was previously used Symptoms • The outbreak of smallpox begins with a fever, an outbreak of a rash that is pus-filled and sores in the mouth that are filled with pus, vomiting, and body aches.The rash becomes crusted and eventually falls off leaving scars and can also cause blindness.
• It spreads quickly through the body, attacking the respiratory system, upper and lower extremities and evolve as postules on the skin that will eventually lyse • Variola major is the most fatal outbreak causing a blanket of pus-filled postules all over the body, internal and external , restricting oxygen Diagnosis • 10 days after exposure you can see a rash that develops into pus like blisters and begins to spread over large areas of the body. Treatment A vaccine within three to four days of exposure minimized the outbreaks during the epidemic up to 95% after vaccination • However, extreme side-effects may occur, including death which occurred 1-2:1,000,000 • Treated with a vaccine called vaccinia, which gives you the virus similar to smallpox in hopes that the immune system develops resistance to smallpox • The site of vaccination is your right upper extremity, which causes a blister that scabs and falls off leaving a scar • Vaccination with a two pronged (bifurcated) needle and repeated insertions with the sign of blood etermining a successful vaccination Prognosis • Poxvirus can kill 1 out of every three infected with smallpox • There are two forms of smallpox; Variola minor with a death rate of 1% or less and Variola major with Variola major having a 25% to 80% fatality rate and considered in medicine the most deadliest virus known to mankind. The World Health Organization eradicated smallpox in 1980 and Smallpox vaccinations were no longer required • Today, the World Healthcare Organization (WHO) holds the control to release the vaccination that will protect us from smallpox in case of a bioterrorist attack • Enough vaccines are available to vaccinate the entire United States with our population well over 300 million Disease control • Two locations where Variola virus is stored; The CDC (Center for Disease control) in Atlanta, GA and The State Research Center of Viriolgy in Koltsova, RussiaExtra • The use of smallpox as a bioweapon in a bioterrorist attack • November 21, 1736 Benjamin Franklin lost his 4 year old son to smallpox • George Washington has contracted smallpox in 1751 but survived • November 18, 1963 Abraham Lincoln contracted smallpox and survived but his valet wasn’t so fortunate References Tortora, Funke, and Case. Microbiology an Introduction, 10th ed Ch. 13.
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