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Patient Zero | Radiolab

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Key Takeaways

  • Finding and eliminating novel viruses before they begin to spread is the most effective method to prevent a pandemic
    • E.g.: Establish call patterns in remote areas and identify unusually high number of calls to medical centers to determine when and where field investigations are necessary
  • “Typhoid” Mary Mallon was the first recorded asymptomatic carrier of typhus in the USA 
    • Hundreds of other typhus carriers were identified, many of whom were also cooks, yet only Mary was forcibly isolated and used as a media scapegoat. She remained under forced quarantine until her death.
  • According to a CDC study, patient zero for the AIDS epidemic was an airline steward named Gaetan Dugas who reportedly told his partners, “I’ve got gay cancer and now you’re gonna get it too”
  • By isolating the AIDS virus scientists discovered it entered America around 1966 and originated in humans around 1908 in South Eastern Cameroon
  • The Cut Hunter hypothesis is the best guess scientists have for how AIDS jumped to humans from chimpanzees
    • It hypothesizes that a Bantu man in Southeastern Cameroon hunting chimpanzees was most likely patient zero in 1908 and with transportation systems installed by colonization there was easy access to the rest of the world
  • AIDS in monkeys (also known as SIV) resulted from trillions of failures to become the perfect genetic combination and the AIDS epidemic as we know it

Books Mentioned

Intro

  • Judy Levitt is a professor emerita at the University of Wisconsin
  • David Quammen is a nature, travel, and science writer
  • Carl Zimmer is an author and journalist
  • Michael Warby is an evolutionary biology at the University of Arizona
  • Beatrice Hahn is a professor of medicine and microbiology at the University of Pennsylvania
  • Nathan Wolfe is a professor of human biology at Stanford University
  • Hosts – Sean Cole (@ittycity), Robert Krulwich (@rkrulwich) & Jad Abumrad (@JadAbumrad)

Typhoid Mary 

  • “Typhoid” Mary Mallon was the first recorded asymptomatic carrier of typhus in the USA 
    • George Soper, a sanitary engineer, traced typhus outbreaks in affluent families to one cook employed by all of them: Mary Mallon
  • Mary was quarantined in a cottage for three years in North Brother Island, NY with the public health department testing her three times a week for typhus
    • She was labeled an intermittent carrier because she only tested positive sometimes
  • Mary meanwhile sent her own feces samples to a private lab all of which test negative prompting her to sue the NYC government but lost  
    • George Soper himself said it was unconstitutional to forcibly quarantine her for years 
  •  The newly appointed health commissioner, released Mary on the condition that she can’t work as a cook 
    • Five years later, it was discovered that Mary had still worked as a cook so she was taken back to North Brother Island
    • “She was now a woman who could not claim innocence. She was known willfully and deliberately to have taken desperate chances with human life. She had abused her privilege. She had broken her parole.” – George Soper
  • Hundreds of other typhus carriers were identified, many of whom were also cooks, yet only Mary was forcibly isolated and used as a media scapegoat. She remained under forced quarantine until her death.
    • “It was more about making people feel safe than actually making them safe” Sean Cole

The Original Patient Zero

  • A CDC study of AIDS surveying the sexual partners of gay men is the first known usage of the term ‘patient zero’
  • Patient zero is officially identified from the CDC study as an airline steward named Gaetan Dugas who had sex with literally thousands of men
    • Gaetan would reportedly tell his partners after having sex that, “I’ve got gay cancer and now you’re gonna get it too” 
    • “My right to do whatever I want, my civil rights. I do as I please. I’ve got it, why shouldn’t they have it?” – Gaetan Dugas
  • “It was a very potent story. There’s no doubt. And he gave HIV to a lot of people, there’s no question about that. But what we do know is that he was not patient zero.” Carl Zimmer
  • In 1984 scientists isolated the virus and found that the AIDS virus replicates imprecisely leading to rapid mutations. 
    • “It turns out those errors – they happen at a predictable rate. You can kind of almost predict how many you’re gonna see in a year or five years.” – Jad Abumrad
    • You can use the virus’ genetic diversity as a clock to understand the history of the virus. The larger the diversity, the longer the virus has been around.
  • With the genetic clock data, scientists confirmed that AIDS entered America around 1966 when Gaetan Dugas was still a virginal adolescent
    • Scientists then traced AIDS from America to Haiti and then from Haiti to Africa
  • In Africa is where you find ZR59 and DRC60 — the two earliest known HIV positive humans
    • The ZR59 specimen was found in a blood tube from a hospital in the Democratic Republic of the Congo taken from a Bantu man in 1959
    • The DRC60 specimen was found by Michael Warby, an evolutionary biologist, in a bit of human tissue preserved in paraffin wax. 
  • Using these two samples the origin of AIDS in humans was dated to around 1908

 Cut Hunter Hypothesis

  • Scientists at the New England Primate Research Center discovered a virus in macaque monkeys so similar to AIDS it was named SIV, Simian Immunodeficiency Virus
    • Versions of SIV were then found in 40 different primate species and the closest match to HIV-1 was found in chimpanzees, specifically a small group in South Eastern Cameroon
    • The question was how and when did AIDS spillover from chimps to humans
  • The Cut Hunter hypothesis is the best guess scientists have for how AIDS jumped to humans
    • It hypothesizes that a Bantu man in Southeastern Cameroon hunting chimpanzees was most likely patient zero
  • He was butchering a chimp when he accidentally cut himself resulting in blood to blood contact due to the messy nature of field butchering
    • “What happens is that the virus in the chimpanzee blood found itself in an environment that was unexpected, that was alien to it but was not too much different from the biochemical environment it had been in — chimpanzee blood. It could function.”David Quammen
  • In 1908 colonization was still in swing so many transportation systems were being built and populations were exploding
    • The hunter could have easily transmitted the virus to a fisherman who then took it down one of many rivers into a city which would have been a launching pad to the world 

Chimp Zero

  • SIV originated as a combination of viruses from two different primate species
    • These entirely different viruses probably found each other in the stomach of a chimp
  • Chimpanzees in the wild hunt monkeys and the process is quite brutal; many times the monkeys are eaten alive by the chimps
    • “The chimps are literally covered in blood. They have blood on their face and their eyes. And from the virus’s perspective, this is spillover heaven.”Nathan Wolfe
  • Chimp zero likely caught the Red-capped Mangabey and Spot-nosed Guenon versions of SIV while hunting 
  • One of the viruses would have hijacked the polymerase enzyme to begin copying itself but the polymerase fell off mid-replication and began copying the second SIV virus resulting in single hybrid virus
    • 99.99% of the time nothing would happen because the chimp’s immune system would take care of it, but on rare occasions, the virus contains the perfect combination of genes to evade the chimp’s immune system and thrive
  • There were probably trillions of these hybrid viruses that failed to evade the chimp’s immune system and countless others that failed to make the jump to humans
    • It only takes that one perfectly designed virus to turn into something like the AIDS epidemic as we know it

Preventing Pandemics

  • Finding and eliminating novel viruses before they spread is the most effective method to prevent a pandemic 
    • AIDS had been spreading for around 70 years before it was even recognized
  • Nathan Wolfe is developing digital surveillance tools in remote places like the Congo to locate unusual medical activity
    • These places often don’t have roads or home electricity but they do have cell towers
    • He establishes normal call patterns and then identifies an unusually high number of calls to medical centers to determine when and where field investigations are necessary.
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