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Variola major
- 1. Variola Major Smallpox Presented by: Sampson Akwafuo, UNT Computational Epidemiology
- 2. Outline Background Virology History and Epidemiology of Smallpox Symptoms Transmission Treatment Mitigation and Control Computational approaches to Smallpox Containment Bioterrorism threat
- 3. Background Also known as Smallpox Caused by a Variola major, a virus belonging to the family of poxviridae Very infectious and often leave scars and blindness Fatality rate of about 30%, can get to 50% in densely populated areas Incubation period is about 12 days
- 4. Virology of Variola Belongs to the genus orthopoxvirus, family poxviridae and subfamily chordopoxvirinae Single, linear, double-stranded DNA Molecules Replicates in cell cytoplasm Measure about 300 x 200 nm in size Shaped like bricks
- 5. History First appeared in Egypt in 10,000 BC 6th Century – Increased trade with China and Korea introduces smallpox into Japan. 7th Century – Arab expansion spreads smallpox into northern Africa, Spain, and Portugal. 11th Century – Crusades further spread smallpox in Europe. 15th Century – Portuguese occupation introduces smallpox into part of western Africa. 16th Century – European colonization and the African slave trade import smallpox into the Caribbean and Central and South America. 17th Century – European colonization imports smallpox into North America. 18th Century – Exploration by Great Britain introduces smallpox into Australia.
- 6. Epidemiology Up to 500 million persons died from smallpox in the 20th century Reduced the population of Cook Inlet in Southcentral Alaska by half in 1830 Killed half of Cherokee Indian population in 1738 Other introductions: (Facilitated Spanish conquest) Caribbeans 1507 Mexico 1520 Peru 1524 Brazil 1555 Total death: up to 1billion Last known case: 1975 (Bangladesh) (1949: LO in the USA) May 8, 1980: WHO declared the world free of Smallpox
- 7. Symptoms Early symptoms include: High fever Head and body aches Sometimes vomiting Rashes (small red spots) on the tongue and in the mouth. Spots change into sores that break open and spread large amounts of the virus into the mouth and throat. Rashes spreads to other parts of the body, forming sores The sores will later become pustules (sharply raised, usually round and firm to the touch, like peas under the skin). Rashes and scabs disappear after about 4 weeks
- 8. Transmission Airborne Route: Aerosol Person – to- person Hospital outbreaks from coughing patients Infectious material Saliva Vesicular Fluids Scabs Urine Conjunctival Fluid Blood May cross the placenta Does not occur through animals or insect
- 9. Treatment and Prevention Treatment Supportive care (No treatment has proven effective) Use of experimental antiviral (Cidofovir) Prophylaxis Vaccination (Most effective when given within 3days of exposure) Has serious side effects (some life- threatening)
- 10. Smallpox Eradication Statue “The eradication of smallpox shows that with strong mutual resolve, teamwork and an international spirit of solidarity, ambitious global public health goals can be attained," Dr Margaret Chan, Director-General, WHO (2010) Erected on 17th May, 2010 at WHO HQ to commemorates 30th anniversary of Smallpox eradication
- 11. Computational Approaches to Smallpox Containment Burke Et al created a model to simulate response scenarios in an event of smallpox bioterrorism attack Created different scenarios, population level, response level Setting up a computational model will help study effects of a potential outbreak and state of preparedness Parameters: Populations size, density, age, georgical location of health institutions, Case Isolation and Contact Tracing (Martin Eichner, 2003)
- 13. Smallpox and Bioterrorism Considered a very potential bioterrorism weapon, second to anthrax “Class A Bioterrorist Threats” (CDC, WHO) Could be very devastating; depreciated immunity against VM in the population British army used smallpox as a biological weapon against Pontiac Indians in 1763 (Phillip Ranlet, 2000) Impacts of an attack on a particular on a prticular geographic location maybe felt globally. “Human mobility and the worldwide impact of intentional localized highly pathogenic virus release” (Goncalves B. et al, 2014)
- 14. Mitigation and Control (of an eventual attack)! Emergency Response Preparedness: 3 major levels: Community-based planning Build Community Partnership, Identify Resources, Help People with Functional, Language or Cognitive needs Public Heath Response Activities Isolate case, surveillance, vaccination, information mgt and epidemiological investigation Health Care Facility response Activities Protection of staff, preventing further spread Modelling situations of eventual Bioterrorism attack and how response will be coordinated. Need for development of: a vaccine without significant adverse effects
- 15. References History of Global Smallpox outbreaks: https://www.cdc.gov/smallpox/index.html Whitley R. J: Smallpox: A Potential Agent of Bioterrorism. Antiviral Research. Elsevier:2003, Vol.57. Iss 1-2 Bioterrorism planning for Smallpox: https://www.cdc.gov/smallpox/bioterrorism-response- planning/index.html Thomson Prentice; Smallpox, Bioterrorism and WHO; WHO publications, Geneva, 2007 Burke D.S; Epstein J.M et al: Individual-based Computational Modelling of Smallpox Epidemic Control Strategies. Journal of the Society for Academic Emergency Medicine, 2006
Editor's Notes
- replicate in the cytoplasm of the cell rather than in the nucleus. In order to replicate, poxviruses produce a variety of specialized proteins not produced by other DNA viruses,