The World of Viruses What do you know?

What is a virus? a microscopic particle that can infect living cells (very small – 10-300 nanometres long) can only reproduce inside a host cell very simple in structure: a protein coat and genetic information (DNA or RNA)

Virus Structure Helical shape found mostly in plants Ex. Tobacco mosaic virus HEALTHY UNHEALTHY

Virus Structure Icosahedral shape are symmetrical, almost spherical Shape of many common viruses such as the cold virus, herpes and polio Cold virus Polio virus

Virus Structure Complex (Bacteriophage) type of virus that feeds on bacteria reproduce by attaching to the bacterial cell and injecting genetic material into the cell

Infamous Viruses HANTA VIRUS Spread through rodents, mostly deer mice in urine, droppings or saliva Most cases have been in Southwestern states, has reached Canada seen in every province except Nova Scotia and PEI Humans can catch the illness if they breathe in particles of the droppings, saliva or urine that are in the air

NORMAL HANTA VIRUS - notice color

Infamous Viruses Con’t Machupo (Bolivian hemorrhagic fever) villagers began to experience fever, high pain, headaches, myalgia, and hemorrhaging 10-20% of cases resulted in death

The local people had started to cut down thick jungles to grow corn and vegetables leading to an explosion in the mouse population in 1950s In the early 1960s the mice began to invade the villages Field mice carried the virus and shed it in their urine which, as it dried, was swept into the air during cleaning and was inhaled

Marburg Virus A rare, severe type of hemorrhagic virus that affects humans and other primates First diagnosed in 1967 in Marburg, Germany and Belgrade, Yugoslavia 37 fell ill after working with African green monkeys or after caring for someone infected Passed through contact with fluid droplets, contaminated blood or tissues Depending on the outbreak the fatality rate can range from 25-100%

Yellow Fever A tropical virus that is spread to humans from infected mosquitoes Since the 17th century it has been a major and terrifying scourge across the Americas and Africa Starts as a fever, headache, and a sense of uneasiness, progressing within hours to chills muscle pains and vomiting After five days, internal bleeding begins and the liver malfunctions which leads to jaundice (yellowing) of skin and eyes

Controlled? Was controlled by vaccinations and widespread spraying of DDT There has been a dramatic re-emergence of Yellow fever since the 1980s, usually as a result of changes in the ecology of an area (cutting down large stands of forests)

Human Immunodeficiency Virus A virus that attacks the immune system The infection rate is now pandemic It has killed more than 25 million people since 1981 It is estimated that 0.6% of the world’s current population is infected Some villages have 8 of 10 people that are HIV positive. Millions of children will be orphans as a result. Some isolated cases were found in tissue samples dating as early as 1959, but think it may date back to as early as 1930s. Thought to have originated in wild chimpanzees from Cameroon

Other Deadly Viruses Ebola - related to Marburg virus, 50-90% mortality 1918 influenza virus - caused 500,000 deaths in USA Avian flu – the next epidemic?

Some other common viruses: Chicken pox, measles, mumps Mononucleosis Cold, influenza Hepatitis, genital warts, genital herpes Rabies Influenza virus Rabies