What disease killed 300-500 million people worldwide but has since been eradicated from the human population?

Smallpox1157 BC; Egyptian pharaoh Ramses V mummy

has smallpox lesions.

Progression:RashPus-filled blistersDisfiguration and/or

blindnessDeath rate = 30%

Man with smallpox; Public Health ImagesLibrary. Source: CDC

Queen Elizabeth 1Had smallpox in

1562

Source: Google images

Take pus from a lesion and put into vein or scratch in arm of a healthy person.Amount of virus varied, and some would

die.George Washington had his army

“variolated” during America’s War of Independence

The first vaccine

Edward Jenner 1749 - 1823

Physician who heard milkmaids say they never got smallpox if they had cowpox

In 1796, put pus from cowpox into cut on boy; 8 weeks later exposed him to smallpox.

Slow acceptance, then widely adoptedVacca = latin word for “cow”

Vaccine made with cowpox virusCauses body to produce antibodies

that protect against smallpoxSide effects: red spot, pustules,

scabs, leaves a scar. Fever is common, swelling.

Fatal complications are rare:1 death per million vaccines

1967: WHO announces global smallpox eradication program.Still 15 million new cases a year then

1977: Last reported naturally occurring case in Somalia.Smallpox is the only disease totally

eradicated in humans

Virus kept in labs in US, Russia & FranceRussian scientists claimed they could make

smallpox in large amounts in “scatter bombs.”Later: Where did the Russian scientists go?May not know for days – until symptoms

happenToday 50% of U.S. never vaccinated

Routine vaccination discontinued in 1972Boosters needed at 10 years

After 9/11/01, 150 million vaccines ordered Controversial

Feb 2008:DoD switched to new

“biodefense vaccine.”Grown in lab cell

cultures (monkey kidney cells) instead of on cow skin.

Similar to old vaccine but advanced production capabilities.

Used only for those at “high risk”.

CDC emergency-stockpiled ~200 million

Goal: Develop a second generation smallpox vaccine

Ring around the rosy,A pocket full of posies,

Ashes… Ashes,We all fall down!

Written in London in 1665

Bubonic PlagueRing around the rosy = dark-ringed red

spots in the skin from infected flea bites.Pocket full of posies = belief that

disease carried by putrid-smell of the lesions made people carry posies close to their nose

Ashes…Ashes = Bodies were cremated (not the norm in those days)

All fall down = death60% of London died

Great fire of London finally killed the rats

The brown rat, house rat, sewer rat, Norway rat = carriers of Bubonic Plague

Gangrene caused by plague

Excessive sneezing of plague sufferers led Pope Gregory VII to coin “God Bless You” as a holy response when someone sneezes.

Plague (bacteria) infects both people & rodents.Fleas (vector) transmit to people.Infected people transmit by coughing, sneezing,

close talking

Came closest to wiping out the human race.50 million people died from 1347-1352

(~50-60% of Europeans)

San Francisco 1907-1908

After the 1906 earthquakeHomeless rats and homeless peopleAnti-rat campaign lasted 4 years

25 cents per rat

Plague does still exist in parts of the worldWHO reports 1,000 – 3,000 cases per yearUsually where infected rodents live close to

humansRecent outbreaks: Russia, China, Kenya, Zaire,

Bolivia

Have there been any human cases in the U.S.?

CDC

13 cases reported in Oregon (5 fatal) since 1970.

Mostly spread from fleas of infected rodents.

In the news over the summer.

WWII: Japanese army dropped plague-infected fleas over China.

Both US and Soviet Union developed techniques to aerosolize the Plague bacteria.Pneumonic Plague = most severe threat

Most deadly form – rapid symptoms and close to 100% fatality rate.

Vaccine (3 doses) is for bubonic plague onlyWith antibiotic treatment = 50% fatality rate

Because of delayed treatment

Caused by Salmonella – typhi (bacteria)Mostly spread through water

Also food and from other infected people10% death rate in early 1900’s

Clean water supply prevents typhoid; there is also a typhoid vaccine

Carrier = person who has a disease-causing organism on their skin or in their body.

Carriers may not be sick, but can spread disease if come in contact with others.

6 of 11 people in a house got typhoid fever in 1906

Bad water & food ruled out; Mary refused to be tested

Mary tested against her will when 22 more people got typhoid

Mary put into isolation, released after 3 years.