Igeshenk, or "hidden green" in Tae na Lepidesn, is a Lepidosian culture-bound syndrome which is essentially a more extreme form of the 'cabin fever' experienced by other species.
Transmission & Vectors
Igeshenk can progress to the level of a mass psychogenic illness - with the stresses of dealing with victims increasing the risk of their caretakers to themselves being overcome - but large gatherings of Lepidosians (especially kin) tend to have a protective effect.
Igeshenk, as the name implies, is a psychological illness which is typically brought about because a Lepidosian has been cooped up alone and, importantly, somewhere far from natural greenery.
A suffer of igeshenk will gradually begin to show signs of acute stress, irrationality, claustrophobia, and sensations of choking or breathlessness as their isolation continues. With a long enough period of isolation, sufferers will become aggressive and endeavor to leave the confines of wherever they are trapped by any means necessary, often resulting in violence. The condition seldom reaches this final phase on Lepidos, as escaping to a nearby green place (i.e. a farm) will generally bring about an end to the issue in short order. As many Lepidosians are now spacefaring individuals alongside citizens of the Cobalt Protectorate, however, trying to escape can have disasterous consequences. Sufferers have been known to bite and claw their way through would-be rescuers (i.e. Cobalt Knights investigating distress calls) to reach airlock controls, sometimes even requiring the use of lethal force on the part of these rescuers to protect the rest of the crew on a stricken vessel.
Patients with igeshenk should not be confined unless doing otherwise would present a risk to others (i.e. aboard a spacecraft). Instead, those with the condition should be moved to a location with lots of greenery and, if possible, kept occupied with social activities. If neither such treatment is available (i.e. at a remote outpost), presenting the sufferer with facsimiles of these conditions (i.e. nature documentaries) may help slow the progression of the condition, though it is generally understood that the 'real deal' is the only true cure. For late-stage sufferers, sedatives or antianxiety medications may be administered to calm the patient down long enough to allow for other interventions.
Once a Lepidosian has suffered a bout of igeshenk, he or she is considered to be at significant risk for a relapse. The evidence for this risk is anecdotal rather than scientifc, as the disorder remains uncommon and sporadic; furthermore, a constructed experiment to prove such a risk would be highly unethical. Nevertheless, out of an abundance of caution, major regulatory bodies such as the Evermorn Strategic Colony Initiative will not post a previous sufferer to a small (less than a dozen crew members) spacefaring vessel in any mission critical role and will require ongoing evaluations by flight doctors in all other cases.
Igeshenk generally does not manifest if a Lepidosian is in the regular presence of other people, with kin or long-term friends offering the best protection. Similarly, the use of closed environmental life support systems (CELSS) featuring extensive hydroponics or aquaponics can make the 'hidden green' visible, similarly preventing the condition from manifesting. So long as both of these conditions are met, even vulnerable Lepidosians are essentially immune to this condition.
There is believed to be a genetic component to one's risk of contracting igeshenk, as some Lepidosians have a greater resistance to the condition than others and Lepidosian-human hybrid children have substantially better resistance overall. Igeshenk appears to be a uniquely Lepidosian phenomenon, as humans and other near-humans have different and more varied responses to extreme isolation.
While the culture-bound syndrome was rare before the Midnight, it has become a more common condition with the ecological destruction that followed in the wake of that conflict.