Ascaris cerebrofoetida is an obligate parasite found in humansi and, rarely, a few of the great apes. Its relative ineffectuality infesting any species other than humans, clearly related to specific adaptations that support its exceptional virulence for our species suggest that perhaps it has exceptionally first evolved to infest humans and from there spread out towards other Hominidae, rather than the other way around seen in all other parasites.
The exact infection agent is disputed, primarily because infection pathway varies by gender. In females, the infection always begins through the traversal of the mucous membranes lining the nasal concha (proceeding to the sphenoid sinus, by far the most common pathway), the vocal folds or the lacrimal ducts by a stage IV parasite. This vaguely snailshell shaped organism burrows its way to the pons. The process lasts a few hours, and it is generally reported as extremely unpleasant itchiness, rarely painful. Generally a few dozen up to a maximally reported hundred foreign organisms migrate, creating a colony through the extension of special filaments (the hypha).
The colony generally becomes established within a few days to about one week. Once established it begins secreting an array of about five hundred hormones and other linked aminoacids, lipids and complex polysaccharides, most of which were not described before in any living species. It is generally accepted that these mimic or otherwise interact with the normal functioning of human metabolism. The specific mechanisms are not understood in most cases, although there have been advances made recently in documenting some possible mechanisms of action for VVb-1, 2 and 8 as well as MSI and FD-c, FD-d-13, FDX-a and b as well as some of the simpler VU and VUx compounds.
In a clinical perspective the net effect of these are observable changes in the affected individual. As far as behaviour is concerned, an almost complete shut-down of higher cognitive functions, with language use sharply limited to rarely more than thirty words and incomplete sentence structure ; poor impulse control, manifested variously as aggressivity (primarily sexual in nature) among peers as well as suicidal or more broadly destructive tendencies if isolated, and in most cases an intolerance of clothing and confined spaces. The victim prefers to breathe through the mouth and tends to suckle on small items almost constantly - often its own thumbs.
Various anatomical modifications are also visible : a marked enlargement of the breasts generally and of the nipple particularly, which becomes extremely sensitive. Lactation is permanent. The waist narrows significantly, with few recorded instances over seventeen inches, age irrespective. The so called Malinovski sign, an obdurate bump protruding half an inch from the skin, about three or four inches under the umbilicus or roughly halfway between the umbilicus and the tip of the pudendal cleft, not swollen nor painful, giving a chitinous, bony impression upon palpation is the definite mark of the presence of the parasite. The buttocks enlarge significantly, maintaining an otherwise uncommon round, firm appearance. Other moreover cosmetic changes are also commonly reported : narrower pores, a general "brightening" of the complexion, greatly elongated eyelashes, much greater activation of the usual vaginal lubricating glands (resulting in the so-called "drip").
The colony firmly established it sends runners through the spine, which then follow through the celiac ganglia and into the ovarian plexus. Once the ovaries are reached, the fruiting bodies of the colony become established. The follicles are individually pierced over time, the ovary therein contained "impregnated" by a specially adapted agent vaguely resembling Arabis pollen (three colpi, prominent surface structure) which results in structural modifications of the cell that eventually yield a stage I parasite, which is excreted into the environment along with other vaginal discharges. An infested female will yield a few thousand successful stage I parasites over her lifetimeii, marking this lifeform as one of the invertebrates with the lowest offspring factor.
The stage I parasite is not infectious to humans, requiring a maturation phase inside Drosophila melanogaster, where it turns to stage II. If the fly is swallowed by Vandellia cirrhosa, then the parasite can move on to stage III, which is infective to human males exclusively. The parasites do not migrate through the urethral lacerations caused by the parasitic catfish into the bloodstream, but instead merely follow the urethra, proceed through the epididymis into the testicles. While the pain caused by the V. cirrhosa infestation is described as "excruciating", once the tell-tale sign of the urethral burning and itching makes itself felt the fish can be disposed of. The A. cerebrofoetida infestation continues, restructuring the testicle over a period of weeks, which is subjectively perceived as extremely pleaurable by the victim - frequently described in primary literature as "nothing but pure bliss" and "the best orgasm ever, just going for weeks". Infected males produce large quantities of stage IV parasite, which are found in seminal discharges alongside spermatozoa.
On the biology involved it would rationally be expected that A. cerebrofoetida is an extremely rare infection - in fact there's no good reason for it to even exist in the first place. The transition from stage II to stage III is particularly problematic, seeing how the common fruit fly and the parasitic freshwater catfish have very little ecologic overlap, not to mention that the latter do not normally consume the former. However, because of the parasite's exceptional fit with particular human behaviours, it has in fact proven as the most successful parasite known, with 90% worldwide infestation levels projected within five years. Particularly in less developed countries, and among the economically marginalised, the infestation of a pubescent female is viewed as a significant benefit, notwithstanding her loss of intellectual acumen and life expectancy, because the accentuation of prized sexual dysmorphisms that the parasite promotes significantly increase her prospects of a good marriage or a lucrative webcam entertainment career. Poor families will often expend months of their income to secure an infection for a daughter in one of the numerous if illegal and insalubre "beautification clinics" constantly springing up all over the ghetto and generally the thirld world.
Males on the other hand generally find the intrinsic rewards of the infestation irresistible, and since attempts to promote legislation making infestation illegal for males, or to force quarantine of the sufferers have always met with fierce political opposition it is probable that the male infecting stage III A. cerebrofoetida is here to stay. The triviality of helping the parasite bridge its II-III gap is also a factor. Currently, V. cirrhosa is by a large margin the most commonly kept aquarium fish by the general public, and accounts for most of the recent revival in aquarism as a hobby. The common process involves obtaining dessicated vaginal secretions of an infected female, adding them to a bowl of cut up fruit and then feeding the inevitable flies to the fish. Within weeks the whole tank is ready to carry the infection over, usually resulting in a frat party (the so-called "Bleed of Brotherhood" or "BB" in juvenile slang). The fish is small and undemanding. Attempts to curtail its importation have so far not been successful.
It is noteworthy that even 100% male carrier status would not likely result in significant female exposure, for obvious reasons. A. cerebrofoetida infestation in females is more of a poverty mediated political problem than a bona fide medical problem, and should probably be addressed with financial, legal and political incentives and disincentives as a social behaviour rather than through medical means. A cure in any case seems a fair distance away, provided a cure can in fact be had. The parasite does not respond to any of the common vermifuges or fungicides, in any case not moreso than the host. Its eventual extinction is in any case a complicated political problem for the reasons stated.
How the parasite came to be is a baffling question. It seems improbable that it would have appeared naturally - not least because the V. cirrhosa clears it out of its system entirely within about five to ten weeks, provided no re-infection occurs. As the parasite does not have any dormant stages, nor any significant biological reservoirs, as it can not survive dry conditions in the slightest, lacking any sort of cystic form, it is not readily obvious how it could have arisen evolutionarily. There is currently substantial debate between the proposition of a "meteoric" (or generally, alien) source and the proposition of a "conspiratorial" source. Neither theory is widely supported in the larger medical community, leaving the origins of Ascaris cerebrofoetida a mystery for later generations.———
- Note that it is currently disputed whether this organism is a fungus or a nematode. At the present time it is classified as the latter, in spite of displaying a number of characteristics more neatly characteristic of fungi. [↩]
- Generally, an infected female will not survive past about the age of about thirty-eight, irrespective of the age of infection, although there are two known exceptions that survived to fifty-one and fifty-two respectively. [↩]