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the wilyman thesis on how smallpox is transmitted

I had another head-desk moment today, on reading a bit more of Judy Wilyman's PhD thesis (a bit at a time is quite enough). The document has quite a bit to say about smallpox. I've already noted the ill-considered statement that the vaccine has never been subject to clinical trials - a statement unaccompanied by any "now, I wonder why not?" explanation.

Incidentally, in commenting on that post, Tsu Do Nimh pointed out that there have been quite a few natural experiments that allow a comparison of morbidity and mortality between the vaccinated and non-vaccinated, beginning back in 18th-century Boston. In this instance the practice of variolation (using pus or scab material from someone recently infected) was used to protect people from smallpox; it was not as effective as modern vaccines and there were concerns that people still became ill and died. However, the comparative statistics are compelling. There were 3 outbreaks of smallpox in Boston, in 1721, 1764, & 1792, During those outbreaks the deaths per thousand cases of smallpox among the non-variolated ranged from 146 to 298. For the variolated group, deaths/1000 cases ranged from 9 to 20.

Wilyman must have missed this somehow.

But it gets worse. 

It's quite evident that Wilyman would prefer to attribute declines in rates of infection from diseases such as measles, polio & smallpox solely to 'environmental' factors, such as isolation of patients, along with better hygiene and nutrition. No-one would deny that these are important, but it's also worth noting that 1950s America (ie the US) had high standards of both hygiene and nutrition - and fairly high rates of morbidity and mortality from measles. Nonetheless, she claims (p128 of the thesis proper) for smallpox that 

isolation of the cases alone could have stopped the circulation of the virus and eradicated this disease
Why? Because, in her view
smallpox is only transferrable by direct skin-to-skin contact.
Now, while it's true that the main route of transmission is face-to-face contact (and not skin-to-skin - the World Health Organisation notes that the virus can travel in saliva droplets on the breath of an infected person), that's by no means the only route. As the Centres for Disease Control point out
Smallpox can also be spread through direct contact with infected bodily fluids or contaminated objects such as bedding or clothing. Rarely, smallpox has been spread by virus carried in the air in enclosed settings such as buildings, buses, and trains.

That information was extremely easy to find. It's surprising, to say the least, that the usual rigorous literature review required for a PhD thesis did not turn up the same information. And that the examiners didn't notice its absence.

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Here were my comments about the smallpox passage:
p. 105 "smallpox is only transferrable by direct skin-to-skin contact. It is not transmissible through the environment or until the symptoms appear. Therefore, isolation of the cases alone could have stopped the circulation of the virus and eradicated this disease. ... A vaccine for smallpox was in use for 150 years before the disease was finally eradicated by the isolation of cases in the mid-twentieth century."
This is an unwarranted conclusion.
First, the info about contagiousness is inaccurate. "Generally, direct and fairly prolonged face-to-face contact is required to spread smallpox from one person to another. Smallpox also can be spread through direct contact with infected bodily fluids or contaminated objects such as bedding or clothing. Rarely, smallpox has been spread by virus carried in the air in enclosed settings such as buildings, buses, and trains. ...
A person with smallpox is sometimes contagious with onset of fever (prodrome phase), but the person becomes most contagious with the onset of rash."
The symptoms of the prodrome phase of smallpox are similar to the flu: "The first symptoms of smallpox include fever, malaise, head and body aches, and sometimes vomiting. The fever is usually high, in the range of 101 to 104 degrees Fahrenheit. At this time, people are usually too sick to carry on their normal activities. This is called the prodrome phase and may last for 2 to 4 days."
http://www.bt.cdc.gov/agent/smallpox/overview/disease-facts.asp
Of course, people tried to control smallpox by isolation before variolation/vaccination became available.
But that wasn't effective.
Someone with smallpox might not be isolated before they transmitted the disease to anyone else. It wouldn't necessarily be clear they had smallpox. The virus might be transferred on their bedding. And, someone had to take care of the sick person.
Mortality from smallpox was already greatly reduced by the vaccine, when it was finally eradicated by tracking down individuals who had been exposed and vaccinating them. See "Smallpox and its eradication" http://apps.who.int/iris/handle/10665/39485
Also, it would be unethical to not vaccinate a person who had been exposed to smallpox and rely on isolating them instead! "Approximately one-third of people with smallpox died of the disease. Survivors were scarred for life. If the eye was infected, blindness often resulted." http://www.medicinenet.com/smallpox/article.htm

Thanks, Beth; my thoughts exactly. I was horrified to see Wilyman implying that the smallpox vaccine should have been submitted to clinical trials - as you say, completely unethical & should have been picked up prior to submission of the thesis.

She didn't actually say that the efficacy should have been tested by exposing people to smallpox, and maybe what she intended instead was to justify antivaccinationists, because she goes on to say "Consequently there is controversy surrounding the use of smallpox vaccine in the control of smallpox epidemics throughout the history of its use."
This is also a misrepresention.
According to the book "Smallpox and its Eradication",

There was a strong antivaccinationist movement in several countries, but this was based less on concern about the risks of the procedure than on moral and philosophical objections to compulsory vaccination."

The smallpox situation was an extreme version of the problems nowadays with vaccine-preventable diseases. Smallpox was a very dangerous illness; the vaccine was more risky than modern vaccines; and various governments made vaccination compulsory.
Also, one effect of vaccination was that variola minor (a less severe form of smallpox that had "only" a 1% mortality rate) became more common. Apparently people weren't so alarmed by variola minor, so that encouraged antivaccination attitudes.
Yes, the idea of a clinical trial where people would be deliberately exposed to smallpox is quite horrible. It's like the Nazi medical experiments on concentration camp inmates.

That book "Smallpox and its Eradication" is very informative and it's free on the WHO website.
But the link I gave doesn't work. To get the book, search for the title and click on the link to the WHO webpage for it.

Thanks, Beth - another one for my reading list.

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Recent Comments

  • Alison Campbell: Thanks, Beth - another one for my reading list. read more
  • Beth: That book "Smallpox and its Eradication" is very informative and read more
  • Beth: She didn't actually say that the efficacy should have been read more
  • Alison Campbell: Thanks, Beth; my thoughts exactly. I was horrified to see read more
  • Beth: Here were my comments about the smallpox passage: p. 105 read more