Is it better to be a milkmaid?

In the early 18th century, Lady Mary Wortley Montagu would discover the inoculation process for smallpox while she was living in Turkey. She had lost a brother to the disease, and barely survived it herself. Smallpox in the 18th century was particularly virulent; the CDC says it had an average a 30% death rate for those who got it. The inoculation was done using actual scabs from people who had smallpox, inserting it under the skin through a cut. Lady Montagu had her son inoculated while in Turkey, and her daughter in England when she returned in 1721. She then campaigned to popularize the method in Europe.

But Edward Jenner gets all the glory, even today, because he developed a vaccine to replace the inoculation. Inoculation is an old idea — you take some likely material from a living victim of the disease, and put it in a person who hasn’t had it (similar to the convalescent plasma being tried today). But there is always a danger of actually giving the healthy person the disease. A vaccine uses a more benign substance to achieve the same immunity.

I was taught in college that the discovery of the smallpox vaccine came out of the realization that milkmaids didn’t get smallpox. This was apparently because in leaning their cheek on the cow while milking, they acquired cowpox, a very mild disease. The cowpox antibodies protected them from smallpox.

There is a wonderful mythology around Edward Jenner and his 1796 vaccine. It’s based on the story of a milkmaid he met when he was a boy, bragging about her lovely skin that would never be scarred by the pox.  Rather like the story of George Washington and the cherry tree, it was created by a later biographer. The real story is more ordinary. Nevertheless, milkmaids didn’t get smallpox.

I learned today that an old vaccine for tuberculosis may have some value in helping with the current virus. The New York Times article says:

The B.C.G. vaccine has an unusual history. It was inspired in the 1800s by the observation that milkmaids did not develop tuberculosis.

The active ingredient of the Bacillus Calmette-Guerin vaccine is Mycobacterium bovis, which was isolated from a cow in 1908. It was made into a proven vaccine by 1911, and is today used in areas with high tuberculosis danger.

Unlike the Jenner/smallpox tale, the story of BCG inspiration and milkmaids is harder to track down. I can find nothing in a verifiable source, other than popular/journalistic websites copying each other’s phrasing, to confirm the background of the discovery.  Closest I could get was a 2008 Russian article saying that milkmaids and others close to cattle could carry a latent infection that gives a false positive for a tuberculin skin test. I couldn’t find anything even saying that milkmaids didn’t get tuberculosis. Is this a case of people just mistaking one apocryphal tale for another?

But we know that Mycobacterium bovis is to Mycobacterium tuberculosis as cowpox is to smallpox — a similar, less deadly disease that protects against a more virulent one. The Lancet warns that it might not be effective against the current virus, and there might not be enough available, but it has helped people with similar respiratory diseases recover faster.

I’d still like to think that milkmaids would be safer.


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