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Anoka County Multi-Jurisdictional All Hazards Mitigation Plan 78 4.2.1.5 Infectious Diseases/Vectors Pandemics occur when disease affects large numbers of the population worldwide. Epidemics occur when large numbers are affected in a more localized area such as a city, region, state, or nation. Pandemics have occurred three times in the world’s human population. The 1918-1919 Spanish Flu caused the highest number of deaths. India had 16 million deaths. The U.S. had 675,000 deaths. Worldwide, the estimated fatalities were 20 million to 50 million. The 1957-58 Asian Flu was identified in February 1957 in China. By June, it entered the U.S. Globally it caused a million deaths. In the U.S., 70,000 persons died. It was a Type A virus. The 1968-69 Hong Kong Flu caused four million deaths worldwide and 34,000 deaths in the U.S. It was a Type A virus. Influenza occurs every year and nations attempt to prepare for the “flu season” which brings one to two weeks of symptoms, even pneumonia and death. The cost in the U.S. is $71 to $167 billion annually. Some 36,000 in the U.S. and 250,000 to 500,000 worldwide die annually. Three types of influenza viruses exist: A, B, and C. Type A viruses are of most concern for humans, pigs, marine mammals and birds. Type B virus has been identified in the seal population and is fatal. Influenza C virus is associated with ticks. Influenza viruses are constantly evolving. The viruses undergo minor and major modifications through antigentic drift and antigentic shift. Antigentic drift is the mechanism responsible for creating small changes in the genetic composition of the virus. Antigentic drift occurs in Type A and B influenza. Antigentic shift describes significant changes in the genetic structure of the virus. It occurs only in type “A” when two different virus strains are simultaneously present in a host or after transmission of viruses from different hosts. The two viruses swap genetic material creating a “new” virus never before seen. The ability to jump species, the constant changes in the generic makeup of the influenza virus, the potential for vaccine loss, and the rapid spread of Flu viruses are some of the reasons influenza is always a threat to the world’s population. Avian flu was first discovered in Canada. It is estimated that 50% of wild ducks in Canada carry various forms of the flu. Highly infectious forms are destructive to domestic poultry causing a rise in food costs. Three strains of avian influenza viruses are known to jump the species barrier from birds to non-human animals to humans: A(H9n2), A(H7N7) and A(H5N1). A(H5N1) is the most lethal, causing death in 68% of humans infected with it. Coughing or sneezing, victims spew infectious droplets at a rate of 150 feet per second. Shaking hands or contact with contaminated public washrooms and doorknobs can spread the disease very quickly. Scientists expect that an Avian H5 Flu virus, which has swept through chickens and other poultry in Asia, will change genetically into a flu that can be transmitted to humans. It has emerged as a highly pathogenic strain of influenza virus that is affecting the entire western component of Asia. The CDC is preparing for a possible pandemic. Humans have no immunity to this new avian flu. Small Pox (variola major) was last seen in the US in 1949. The last naturally occurring case was in Somalia in 1977. Smallpox vaccination in the US ended in 1972 except for military personnel. When smallpox was considered eradicated worldwide, only two laboratories were designated to keep the virus. One lab was the CDC in Atlanta, Georgia, and the other lab was in Russia. When the USSR break-up occurred, the location of Russia’s smallpox virus became unknown. It was widely thought that at least four other countries received part of the virus.