StrategyPage has the backstory: Yes, reindeer who were frozen after the last anthrax outbreak got defrosted ad were the cause of the outbreak.
when the anthrax scare happened in 2002, my Oklahoma patients laughed and said if someone wanted to obtain anthrax bacteria, all they had to do is dig up their farmyards.
For thousands of years Anthrax was known as a livestock pest, regularly killing animals that grazed on land infested with Anthrax spores. The animals breathed in the spores as they pulled up grass and released the spores from the soil. Humans could get infected as well, usually by getting spores on a cut. This skin (cutaneous) form of Anthrax was fatal in up to 20 percent of the victims, depending on how potent the Anthrax strain was and how many spores got into the sore. People who worked with sheep's wool also got cutaneous Anthrax, as did those working with the hides of animals that grazed in areas containing Anthrax. In the 1970s, imported wool from an Anthrax area, improperly cleaned, infected a number of Americans.
the article then goes on to discuss anthrax as a bioweapon. It's not as easy as it seems. The major problem with Anthrax-as-a-weapon is delivering it. The spores, in their natural form, don't travel well in the air. "Militarizing" Anthrax consists of processing the spores so they don't clump together and thus can more easily float away in a breeze. And even this might not work well..
A couple of years ago, there was a huge outbreak of anthrax in Zimbabwe, that killed a bunch of elephants and other wild animals. Local officials stopped the outbreak by burning the carcasses of the dead aniimals instead of burying them or letting others eat them.
Even the most potent militarized Anthrax isn't that powerful. We know this from a military Anthrax accident in 1979. A Russian biological warfare plant outside the city of Sverdlosk accidentally released some militarized Anthrax. Thousands of people in the area were infected. But fewer than a hundred died. What was particularly discouraging to Russian military bioweapon scientists was that only one of the dead was of military age and he was already ill from other ailments. All of those that died from the Anthrax were old and usually sick.
apparently there is another outbreak there in 2015, that affected farm animals and killed some humans too. Apparantly the farmers were selling the meat to local butchers, and those who ate the meat caught it (this practice in the Philippines is common, and the meat is called "double dead meat).
There was also an outbreak during the 1970's, leading to conspiracy theories that the evil government only gave anthrax to the black cattle since the white farmers cattle didn't get it (uh maybe because they had been vaccinated? But never let facts stand in the way of a good conspiracy theory).
There has also been an outbreak in West Africa in recent years and some cases of cutaneous anthrax in human beings in Bangladesh.
Summary of Anthrax in African wildlife... it's been around for a couple of milleneum: BBC article notes it's presence in China 5000 years ago, may have been one of the ten plagues of Egypt (which affected all sorts of animals and also humans, whereas most diseases only affect one species) and that it was described by Virgil in ancient Rome. Presumably it was spread via humans since so it goes beyond what one expected if it was due to migrating animals.
And there is a trivia question about anthrax: Who invented the first vaccine against Anthrax?
Louis Pasteur. (maybe)
Pasteur then shifted his work focus to anthrax, which at the time was affecting cattle. In 1881, Pasteur performed a famous public experiment in which he injected one group of animals with an anthrax vaccine he had developed, and he did not vaccinate his second, control group. After a few weeks, both groups were injected with live anthrax bacteria, and all the vaccinated animals survived. Although Pasteur became famous for the development of the anthrax vaccine due to his public demonstrations, it is currently believed that a French veterinarian, Jean Joseph Henri Toussaint, actually is responsible for first creating this vaccine.