Drover's cough is the common name for a parasitic disease found in the Wilds.
The parasite - a small worm similar to roundworm http://www.parasitecleanse.com/roundworms.htm - is native to the Wilds. Typically its life cycle goes as so:
1. Produces eggs inside vulture's digestive tract. 2. Eggs are transmitted to water sources. 3. Secondary vector ingests the egg. 4. Larva hatch and seek out lungs, as oxygen-rich environment is needed for further development. 5. Adult worms crawl up the throat to be reflexively swallowed into the digestive tract and/or otherwise spread through the body. 6. Adult worms encyst within the secondary vector, typically within the muscle. 7. Secondary vector is eaten by the vulture. The vulture's unique digestive chemistry allows the worm to mate and produce eggs.
The native secondary vector is typically another species of bird. However, Wisent populations make ready hosts for this parasite. As long as meat is well-cooked there is no risk of infection this way. Wisents can also be fed the same drug (a low-level antibiotic) that workers often take to keep them uninfected. However this infection is typically associated with Wisent-herders and ranchers, hence its common name.
About eighty years ago it was the pet cause of the upper-class. Now all companies are required to give their workers daily treatment to prevent infection. Usually this takes the form of a pill though a liquid form is often mixed with drinks as overdose is very hard to come by (e.g., like a gin and tonic).
Although humans can also easily become a secondary vector, once off-world they cannot pass on Drover's cough to others. The parasite needs the unique bird species to continue its reproductive cycle. However cysts of worms often cause a general feeling of weakness. Occasionally this can lead to sudden and dramatic death if the worms wander off into the body at large (such as into the brain, heart, etc).
It is most recognizable by a persistent, occasionally bloodied cough, caused by the developing larva in the lungs - hence its common name of Drover's cough.
Levels of larva in the lungs vary with time. Through some mechanism not fully understood, the worms may be able to undergo a type of secondary asexual reproduction by re-entering the larval stage. This means that often an infected human will suffer 'attacks' of high parasite load, usually characterized by low blood oxygen and trouble breathing. Once the larvae mature and propegate throughout the body, the load lessens and the infected recovers, but it is generally accepted that Drover's cough is an ultimately fatal disease that can be long and lingering. It is viewed somewhat like AIDS or HIV in that respect.
There are some treatments but all of them are extremely harsh and there is a high chance of relapse. Most of them take the form of cures that kill larvae in the lungs, and are more or less poisons that attempt to kill the parasites before they kill the person. While killing all larvae can be accomplished, it often comes with permanent lung damage, and encysted adults remain unharmed.