10/10

past, current, "conquered" plagues

THE plague

the plague sickness had 3 major human pandemics

• Justinian's plague
• black death + subsequent epidemics
• asia

this was the worst plague

• we know of these 3 bad episodes of this pandemic in historic times (written history)
• in prehistoric times, were probably also bad outbreaks
• killed people everywhere - in europe it came out of nowhere
  • it was feared bc of how quickly it killed people - ppl worried about being given their last rights from a priest before death

"the plague"

caused by yersinia pestis

• bacterium
• normally infects rodents (preferred by y pestis) - naturally circulate among wild rodents
  • occasionally will jump to humans + start causing disease in them
• unique feature of yersinia - can infect fleas - special property only few bacteria have
  • proliferate in fleas -> transmit to rodent/human when bitten by flea
• normally transmitted by fleas
• circulates btw rodents/humans VIA the flea (flea = vector)

bubonic, septicemic, pneumonic plague

• bit by infected flea - bacteria infected -> nearest lymph node = initial infection
  • local, intense infection site
  • manifest in 3 ways
    • bubonic plague - localized infection (near where initial infection occurred)
      • immune system try to keep pathogen/infection localized
    • systemic plague (septicemic plague)
      • immune system fails to keep local
      • spreads in body - usually by blood + grow + spread to all parts of body
      • chance of survival goes way down (likely 0 w/o antibiotics)
    • can get worse: infect lungs
      • pneumonic plague
      • infection progressed from blood to lungs
      • very fatal - can be fatal even w/ antibiotics
      • bad for community -> cough + spread + transmit pathogen to others directly = spreads easily
• if infected by someone else - if start in lung - very bad bc pathogen has head start
  • better to be infected by flea than a person.

"black death" - name bc tissue dies and gets black

plague + pestilence in london

• dont know how many ppl died in europe
  • estimate 1/4 to 1/3 of europe died
  • some parts were worse than others
  • most deaths in summer months (plague season)
  • scary bc ppl didnt know when it would come + didnt have good measures to fight it
  • last one - great plague of london - terrible

what was thought at the time to be cause of the plague?

• God punishing mankind for sins
• "pest maiden" in scandanavia
• jews accused of poisoning wells
• experts said it was caused by unusual alignment of planets

19th century (1880s) - germ theory of disease

17th century (1660s) - humans became aware of microbes

14th century (1350) - black death

humans didnt know microbes existed at the time

not until 17th century - became aware of their existence (far from even knowing it could cause disease)

the plague today

plague still around + infects people

easily treatabe if given antibiotics fairly quickly

more in subsahara africa + madagascar (there endemically, every year ppl get it)

can be blood-blood transmission - usually how ppl get it in the US if bitten by infected wild animal

draft genome

is same yersinia pestis still around?

• in last few years, dug up plague victims dates from london 1348-1350
  • recovered y pestis DNA from them
  • were able to recover enough to sequence entire genome of y pestis killing ppl in that 14th century
  • compared to genetic sequence with current y pestis today - they turned out to be the same
    • genetically the same as those hundreds of years ago

thus, less deaths due to other things - like public health measures to contain it, antibiotics, etc. = less ppl die/world not as impacted

= early episodes of plague truly caused by y pestis

GREAT INFLUENZA on 1918 - SPANISH FLU

estimated 25-50 million deaths

book on slide = definitive historical account

knew abt microbes 100 yrs ago + that they cause disease

at time, wasnt clear what was going on was caused by flu (virus)

flu virus cellular infection cycle

• hemagglutinin protein (H protein) - enables virus to attach to host cell
• neuraminidase (N protein) - required for release of progeny virus after the infected cell lyses

viruses infect cells

• THIS IS AN RNA VIRUS
  • for part of life cycle - genetic material goes to nucleus
  • simpler than HIV - doesnt involve genetic material integrating
• 2 surface proteins (mentioned above)
  • H protein and N protein
    • H protein - responsible for getting virion in the cell - initiates infection in cells
    • N protein - important for last stage of infection process - virion emerging from cell
  • these 2 proteins are the famous part of the virus
  • they determine how nasty flu virion will be
  • these vary among diff strains of flu virus
  • ex: caused by Spanish: H1N1
  • in 60s and 70s: their H and N proteins are slightly diff
  • 1918 was the worst one

each year 3 strains are chosen for selection in the flu vaccination for that year by WHO global influenza surveillance network

• chosen strains are H1N1, H3N2, and type B strains throught to most likely cause significant human suffering in the coming season
• flu emerges every year - get diff strain every year
  • happens bc of where it comes from - starts in wild or domesticated bird populations -> make way to domesticated birds -> jump to swine to humans OR can jump directly from chickens/birds to humans
  • making flu vaccine - try to predict which type of flu will come up each year
    • vaccine make neutralizing antibodies vs H1N1 (could possibly come up in a certain cycle)
    • they do these old ones AS WELL as making educated guesses on what might. come up in a new strain while making vaccine
    • difficult tot make vaccine bc dont know

flu very seasonal

based on symptoms - more in winter/near year time

flu went down drastically during covid bc of precautions

even partial protection may reduce viral load that lowers chance of getting severely sick as well as transmitted virus to others

how flu vaccine similar to covid one

• will not protect you from getting flu - can get if vaccinated - are just more likely to suffer less/less severe symptoms
  • same w/ covid

eradication of a human infectious disease

success - smallpox

• success story
• completely eradication/eliminated/wiped
  • bc vaccine extremely potent - prevents person from getting it
  • also bc only infects humans - entirely human population

near success

polio

• mainly affects children unter 5 years old
• 1 in 200 infections leads to irreversible paralysis and of those 5-10% die when breathing muscles are immobilized
• cases due to wild poliovirus have decrease by over 99% since 1988, from estimated 350,000 cases then to 33 reported cases in 2018
• as long as single child remainds infected, children in all countries are at risk of contracting polio
• failure to eradicate polio from these last remaining strongholds could result in as many as 200,000 new cases every year, within 10 years, all over the world
• in most countries, global effort has expanded capacities to tackle other infectious diseases by building effective surveillance and immunization systems

nigeria reaches 1 year without polio

• Today marks one year since Nigeria’s last reported case of wild poliovirus paralyzed a child. Final laboratory results on all specimens from acute flaccid paralysis cases and environmental samples for the full 12 month period are expected by September 2015. The Global Polio Eradication Initiative commends the hard work of the Nigerian government, partners, religious and community leaders, and health workers for such strong progress towards stopping polio.
• Neil Munshi in Lagos AUGUST 20, 2019 Nigeria is on the verge of being declared polio-free, which would mean the virus has been eradicated across Africa. Wednesday marks three years since Nigeria’s last documented case of polio, which was also the last case recorded in Africa. This means the continent can be certified free of the virus by the World Health Organisation-backed Global Polio Eradication Initiative once the remaining samples have been analysed. The milestone is an important achievement for Africa’s most populous country. “It is a big deal for Nigeria, for Africa and for the world,” said Tunji Funsho of Rotary International, the charity which has been at the forefront of the country’s fight against the disease.

wild polio eradicated in africa

• polio vaccune - attenuated (alive but w/o capacity of the wild type)
• this strain of polio to vaccinate humans can revert back and become partially pathogenic
  • = can cause symptoms in children if vaccinated

is measles next?

ASSIGNED READING ARTICLE

• some disease fighters want to eradicate the most contageous virus of all - but does a world still fighting polio have the stomach to try
• This article is the assigned reading - health professionals proposing to go after measles + eliminate it - is actually a big killer in parts of the world - prob could eliminate it, vaccines are good

mortality rates

Right after WWII, public health infastructure destroyed

- so in Germany, as infastructure rebuilt, saw decline

= selective data/cherry picking data

They leave info out

anti vaccine movements

1. Children with neurological disorders are often suffering from severe gastrointestinal distress and inflammation. A trigger of this inflammation and the resultant behaviors is the MMR vaccine.

We cite four published studies that support this position:

Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children

Lancet 1998 Feb 28

Wakefield AJ, Murch SH, Anthony A, Linnell J, Casson DM, [University Department of Medicine, Royal Free Hospital and School of Medicine, London, UK]

This study demonstrates that the MMR vaccine triggered autistic behaviors and inflammatory bowel disease in autistic children. Excerpt:

"Onset of behavioral symptoms was associated, by the parents, with measles, mumps, and rubella vaccination [MMR] in eight of the 12 children, with measles infection in one child, and otitis media in another… We identified associated gastrointestinal disease and developmental regression in a group of previously normal children, which was generally associated in time with possible environmental triggers."

Paper used by many groups to create mistrust in vaccines

- turned out to be a fraudulent paper

- made up data

- he had financial interest in the outcome

Paper retracted

Many studies have shown that the vaccine he claimed to cause autism (MMR)

- other studies failed to find associated btw autism and the vaccine

Some ppl say the thirmosol (contains mercury) was source of problem

• no longer used in medicine anyway