Cowpox is a disease of the skin that is caused by a virus
known as the Cowpox virus.
The pox is related to the vaccinia virus, and got its name from dairymaids touching the udders
of infected cows. The ailment manifests itself in the form of red blisters and is transmitted by touch from infected animals to humans.
When the patient recovers from cowpox, the person is immune to smallpox.
The
cowpox virus was used to perform the first successful vaccination against a disease, smallpox, which is caused by
the related Variola virus. Therefore, the word
"vaccination" — first used by Edward Jenner (an English physician) in 1796 —[1]
has the Latin root vacca meaning cow, or from Latin
root vaccinia meaning cowpox. [2]
Origin
In
the years 1770 till 1791 at least six people had tested independently the
possibility of using the cowpox vaccine as an immunization for smallpox in
humans for the first time; among them the English farmer Benjamin Jesty, in Dorset,
in 1774 and the German teacher Peter Plett in 1791.[3]
Jesty inoculated his wife and two young sons and thus spared them probable
death by smallpox which was raging in the area in which they lived. His
patients who had contracted and recovered from the similar but milder cowpox
(mainly milkmaids), seemed to be immune not only to further cases of
cowpox, but also to smallpox. By scratching the fluid from cowpox lesions into
the skin of healthy individuals, he was able to immunize those people against
smallpox. It was reported that farmers and people working regularly with cows
and horses were often spared during smallpox outbreaks. More and more an
investigation conducted towards 1790 by the Royal Army showed that
horse-mounted troops were less infected by smallpox than infantry, and this due to a major exposure to the horse pox
virus (Variola equina), with similar traits with cowpox's one.
Jesty
did not publicise his findings, however, and credit was assumed by the
politically astute Dr. Jenner who performed his first inoculation, twenty-two
years later. It is said that Jenner made this discovery by himself without any
ideas or help from others. Although Jesty was first to discover it, Jenner let
everyone know and understand it, thus taking full credit for it.
The
virus is found in Europe, and mainly in the UK.
Human cases today are very rare and most often contracted from domestic cats.
The virus is not commonly found in cows; the reservoir hosts for the virus are
woodland rodents, particularly voles. It is from these rodents that domestic
cats contract the virus. Symptoms in cats include lesions
on the face, neck, forelimbs, and paws, and less commonly upper respiratory
tract infection.[4] Symptoms of infection with cowpox virus in humans
are localized, pustular lesions generally found on the hands and limited to the
site of introduction. The incubation period is nine to ten days. The virus is
prevalent in late summer and autumn.
Kinepox
is an alternate term for the smallpox vaccine used in early 19th century America.
Popularized by Jenner in the late 1790s, kinepox was a far safer method for
inoculating people against smallpox than the previous method, variolation, which had a 3% fatality rate.
In
a famous letter to Meriwether Lewis in 1803, Thomas Jefferson instructed the Lewis and Clark expedition
to "carry with you some matter of the kine-pox; inform those of them with
whom you may be, of its efficacy as a preservative from the smallpox; &
encourage them in the use of it..."[5]
Jefferson had developed an interest in protecting Native Americans from
smallpox having been aware of epidemics along the Missouri River during the previous century. One year prior to
his special instructions to Lewis, Jefferson had persuaded a visiting delegation of North American Indian Chieftains to be
vaccinated with kinepox during the winter of 1801-2. Unfortunately, Lewis never
got the opportunity to use kinepox during the pair's expedition as it had
become inadvertently inactive — a common occurrence in a time before vaccines
were stabilized with preservatives like glycerol or kept at refrigeration temperatures.
The
Cow-Pock—or—the Wonderful Effects of the New Inoculation! (1802), James Gillray caricatured recipients of the vaccine developing
cow-like appendages.
Cowpox
was the original vaccine of sorts for smallpox. After infection with the
disease, the body (usually) gains the ability of recognizing the similar
smallpox virus from its antigens and so is able to fight the smallpox disease
much more efficiently. The vaccinia virus now used for smallpox vaccination is
sufficiently different from the cowpox virus found in the wild as to be
considered a separate virus. [6]
- ^ Thomas Cooper Library, University of South Carolina: "Edward
Jenner and the Discovery of Vaccination", exhibition, 1996
- ^ http://www.merriam-webster.com/dictionary/vaccine
- ^ Plett PC (2006). "[Peter
Plett and other discoverers of cowpox vaccination before Edward
Jenner]" (in German). Sudhoffs Arch 90 (2): 219–32. PMID 17338405.
- ^ Mansell, Joanne K.;Rees,
Christine A. (2005). "Cutaneous manifestations of viral
disease". in August, John R. (ed.). Consultations in Feline
Internal Medicine Vol. 5. Elsevier Saunders. ISBN 0-7216-0423-4.
- ^ "Jefferson's Instructions to Lewis and Clark (1803)".
http://www.library.csi.cuny.edu/dept/history/lavender/jefflett.html.
Retrieved 2007-08-10.
- ^ Yuan, Jenifer The Small Pox Story
- Peck, David R. (2002). Or
Perish in the Attempt: Wilderness Medicine in the Lewis & Clark
Expedition. Farcountry Press. ISBN 1-56037-226-5.
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