Alright, I'll go on and take the analysis I made on this situation.
Once upon a time, there were elves and satyrs. Both the elves and the satyrs have what you call 'druids', being that can tap into their connection with nature. The elves used it for good, the satyr used it for bad. Eventually, the 'War of the Satyr' ensues. A small group of druids resolve to use the Pack totem. The Pack form is a totemic specialization that allows it's druids to turn into wolves and/or wolflike beings. (We are still waiting for confirmation on this.)
Now, it appears that from the point that the Druids of the Pack became worgen, they could spread their biological traits to other beings, like elves and maybe even the satyr(after all being corrupted elves). This was an undesirable trait and the worgen minds were locked up into a pocket dimension of the Emerald Dream, purposefully sent into a limbo of sorts.
Now, a possible explanation of how these druids could spread their curse is by means of two things. Firstly, they were feral creatures and the disease causes people to lose their mind, diseases being natural after all. Secondly, they aren't just feral, they are also connected to the nightmare and the curse is a manifestation of the Emerald Nightmare. And thirdly, all of the above; becoming feral equals being affected by the Emerald Nightmare.
This speculation is supported by the following quote;
The skies above the Nightmare are constantly clouded, creating a gloomy, depressing zone that weakens and deadens everything it touches. The beautiful green vegetation is twisted into brown decay, while ordinarily peaceful creatures are corrupted into shadowy, mutated versions of themselves known as Corrupted Ones. The Corrupted Ones are vicious and cruel, hunting anything they can, even after they leave the Nightmare’s affected zone.
Creatures twisted by the foul influence of the Nightmare mutate into evil, savage versions of themselves. The process can take minutes, hours or days depending on the creature, and some are never affected.
We know that worgens show the symptoms of these 'Corrupted Ones' and the ability to transfer their corruption doesn't seem as unlikely to me if you realize that the Nightmare is really so unpredictable and viral. That is just a theory of course.
However, what we should note is that before, worgen could not transmit the curse by their saliva. In fact, it seemed to cost some effort to transmit the worgen curse as I will explain below. What the worgens were capable of, though, is spreading a disease not unlike rabies. I think, and am quite sure, that this is the disease that affects Gilneans at first and are then cured from through alchemy, till they succumb again unless they are treated by the Druids of the Scythe.
Disease (Su): The saliva of a worgen carries a dangerous infection. When a worgen succeeds at a bite attack, the victim must make a DC 13 Fortitude save or contract a maddening disease. (Incubation period 1 day; damage 1d6 Charisma.)
As an infected subject’s Charisma drops, the victim slips deeper into a feral madness. This disease does not lower the victim’s Charisma below 1, and unlike normal disease, it continues each day until magically removed. The Fortitude saving throw is Constitution-based.
Now, Arugal found a way to take the Worgen Curse, which isn't much unlike the Satyr Curse and transfer it manually to other creatures. Supposedly, worgen magic wasn't stable enough to corrupt other beings fully while they were still bound to the ancient prison of the worgen. Arugal devised the 'Remedy of Arugal', also coined as 'Arugal's Folly'. He created bracers that stabilized the magics and enforced the transformation unto those that carry these bracers. In truth, they work the best at night, because the worgens are more powerful at night as well, but when strong enough, it can maintain the curse.
However, it seems that, after the Scythe of Elune was used, the barrier that prevented Arugal from spreading the curse completely, was weakened enough to let the curse spread on it's own again. This is how the worgen curse spread through eventually even Gilneas. This likely also explains how the curse was spread in the Wolfcult.
Finally, I'd like to conclude that the Scythe of Elune and Arugal's Folly share interesting parallels. The Scythe of Elune is mentioned to be able to spread the worgen curse to all of humanity and the elves. This makes it a very dangerous weapon, even a Weapon of Mass Destruction.