27 June 2016

HEALTH - Vaccine Debate Part One: The History

(Variolation - pbs.org NOVA)
Vaccine history is unexpectedly fascinating and complex.

It is older than Louis Pasteur finding a vaccine (and cure) for rabies in 1885, older even than Edward Jenner’s 1798 use of cowpox to confer smallpox immunity.

Humans have been using infected material to inoculate domesticated animal populations, and themselves, for much longer than the practice has been documented.

The history of vaccination, and of the symbiotic interplay between human and veterinary medicine, offers insight into yet another way that our relationship with domestic animals enhances our lives.

Veterinary vaccines protect human health by limiting the spread of zoonotic diseases – those diseases, such as rabies, that can be transmitted from animals to humans – and there is a long history of the two fields of medicine learning from one another.

Farmers and nomadic herders, like the Tulani in Africa, have inoculated herd animals against diseases such as sheep pox for centuries. Animal inoculation was mentioned in the notes of European explorers and colonizers in Africa as early as the 16th Century.

There is evidence of human variolation, which is a similar type of inoculation via infectious material, in China at 1000 CE, and in 1706 a British minister learned of variolation against smallpox in Turkey.

Although the origins of the practice are not known, it is likely that human variolation was a result of applying successful veterinary techniques to human health care.

Variolation was effective but unpredictable. Smallpox variolation involved introducing infected human material taken from smallpox scabs or the fluid in pustules into healthy humans, often via an open vein. Although it offered solid immunity, there was a significant risk of post-inoculation mortality.

Smallpox vaccination, in contrast, used cowpox to inoculate humans, and this procedure, which was pioneered by Edward Jenner (1749-1823), was much safer. It was also less effective over time, and though the post-inoculation mortality rate was lower, revaccination was often necessary.

The history of smallpox vaccination perfectly demonstrates how human and animal vaccination have overlapped and intertwined.

Variolation likely started among animals, and was transferred to humans, and the development of vaccination as a safer alternative to variolation happened simultaneously among human and veterinary physicians.

The practice of vaccination itself went through multiple iterations including using humans as vaccine reservoirs, then back to using cows as the vaccine source, and many attempts to transport the vaccine outside of a living body.

This complicated interplay between human and animal medicine continues throughout vaccine history, and extends even into our current context.

Louis Pasteur expanded the understanding of viruses and vaccines, and worked with veterinarians and livestock farmers to develop his first two virus vaccines - against fowl cholera and anthrax. He eventually turned his attention to rabies, and this work would not have been possible without his collaboration with veterinarians.

These collaborations continue today.

When a disease affects both human and animal populations, sometimes the human vaccine comes first and sometimes the animal vaccine does, but there is always collaboration happening between the two fields of medicine.

The history of inoculation among both animals and humans extends further back than most people realize, and so do the controversies surrounding vaccine use.

Part two in this series will look at vaccine controversies, from anti-vaccination arguments in the 1880’s to today.

By Tiffany Sostar
Tiffany is a writer, editor, academic, and animal lover who came late to her appreciation of pets. At 18, a rescue pup named Tasha saved her from a depression and she hasn't looked back. She has worked as the canine behaviour program coordinator for the Calgary Humane Society, and was a dog trainer specializing in working with fearful and reactive dogs for many years. She doesn't have any pets right now, but makes up for it by giving her petsitting clients (and any dogs she comes across on her frequent coffee shop adventures) extra snuggles.

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