Bacillus anthracis and Anthrax, a Disease of Herbivores and Humans, History, Vaccines Current Views. A simple bacillus, a soil resident, can cause a simple black ulcer on the skin, or it may spread through the entire body of a mammal and lead to death in a few days.
During the period 1875–1880 Europe was amazed and excited with the great microbiological findings of Koch and Pasteur. More news was soon to come from each researcher’s laboratory.
The Frenchman Louis Pasteur, a renowned chemist-microbiologist, had done much. There remained work to do – anthrax research was one.
Pasteur enlisted a trio of young, enthusiastic medical doctors, Roux, Chamberland and Therrier, who each admired and worshipped the noble “Docteur Pasteur”. They were obedient, but thoughtful masters of medicine. They brought to Pasteur’s laboratory some tools and skills Pasteur lacked:
- how to treat people, and animals, as patients.
- injection techniques.
- other useful medical procedures.
Anthrax a Disease of Herbivores Transmissible to Humans, Anthrax Signs and Symptoms
Imagine sheep, goats, cows and horses grazing, as herbivores do, and then, days or weeks later, the horror of seeing them stumble, fall and die bleeding from their mouths and noses. Autopsies of the deceased by veterinarians revealed livers and spleens blackened with hard, black lesions of anthrax. The disease was emotionally and financially devastating. Occasionally, humans would get ulcerative cutaneous anthrax (see photo below), or pulmonary and disseminated anthrax which was deadly, and reminded of the classic herbivore disease.
Anthrax Vaccine Studies and Anthrax Challenge Protection Experiment
The team began their studies by growing Bacillus anthracis in tubes and flasks and testing animals. Pasteur’s experience showed that aged cultures, grown at elevated temperatures of 42–52 degrees C, sometimes yielded weakened (i.e. attenuated) strains that did not kill animals. Chicken cholera was a prototype study, and the chickens who recovered were resistant to the most virulent (dangerous) strain they tested.
Soon an attenuated anthrax strain was found, and several animals were resistant to challenge. The big experiment began at the farm of Pouilly-le-Fort, France with 48 sheep, 2 goats and several cattle. They were divided into two groups. Roux inoculated 24 sheep, 1 goat and several cows with the anthrax vaccine; this was done twice in just under two weeks. The second group was unvaccinated. At the end of the third week Roux and Therrier injected equal-sized amounts of virulent anthrax into all the animals. Pasteur and his team returned to the laboratory home and two days later started out to the experimental farm. It was June 2, 1881, Pasteur and his team approached, and cheers and applause broke out from the crowd. Labelled and vaccinated animals moved about—all were healthy. The control, unvaccinated animlas were dead but for two, and these soon succumbed.
Modern Day Anthrax Research and Anthrax Vaccines
Pasteur’s vaccine worked well, but it was not a smooth road. Some lots of vaccine were contaminated and were ineffective, or lethal in their own right. Pasteur weathered the storm and survived by sheer will and determination as he sought out resolutions to the problems.
It is known now that Bacillus anthracis is a pathogen because it:
- has a special capsule that protects it from drying and host defenses.
- produces very resistant spores that permit survival for years without food or water.
- produces a factor for edema (swelling and fluid in tissue) and a lethal factor.
Today, there are new, useful anthrax vaccines thanks to Pasteur, Roux ,Chamberland and Therrier.
The human anthrax vaccine uses protective antigen from B. anthracis as the immunogen.
Vaccine developments required animals, but the benefits are millions of saved lives over the last 150 years. Vaccinated animals and people are now protected from anthrax. Many owe their lives to these early these studies of anthrax and rabies.
Consider veterinary medicine as an intelligent, important and rewarding career.