Pernicious Polliwogs

Pernicious Polliwogs, various spp.

Status: Least Concern

While upon first glance it may appear that the Mossfell islands are a perfect gateway to the greater American continent, several factors have prevented the wholescale development and colonization of the islands since their discovery in 1034 CE. None so odd and ghastly as the pernicious polliwogs.

Pernicious polliwogs (family: Occultidae) are an offshoot of the order Anura which have adapted to a unique and ingenious lifestyle. Almost all members of the family Occultidae are obligate parasites for a duration of their lifecycle. It is believed that ancestors of the pernicious polliwogs were frogs which had adapted to surviving through the digestive tract of birds. This enabled these small frogs to disperse over a large range and colonize new habitats. Overtime, frogs which partook in a commensal relationship with birds disappeared, likely due to the potential for seabirds to eject eggs into ocean water which is inhospitable to tadpoles. In their place, frogs which favored the guts of terrestrial mammals were more successful. However, this relationship transformed from neutral commensalism  into a parasitism.

For most species of pernicious polliwog, the host needs to ingest contaminated food or water. Thanks to specialized mucus coatings, ingested eggs are protected from the acid and peristaltic movement of the stomach. Once eggs reach the small intestines, the polliwogs emerge from their eggs. Here the polliwogs begin to leech off of their host's digested nutrients, much like tapeworms. In order to avoid the host's immune response, polliwogs have developed a series of tricks. Some varieties such as the spotted stool frog (Viliranae veikindi - vile frog sickness) begin to incorporate host cellular signals onto their outer epithelium, essentially tricking their host's immune response into believing the parasite is part of their body. Others such as the candy flea (Ranabipes dulciamicus - sugary bipedal frog friend) insert specialized glands into their host's bloodstream which release immunosuppressing hormones such as cortisol. 

Most pernicious polliwogs have an ambulatory adult phase. The spotted stool frog adult is nearly identical in behavior, size, and shape to any common frog found on the American or European continent. Spotted stool frogs hatch from mucous cocoons after being defecated from their host. Outside of the host, they hunt, grow, and look for mates. After mating, spotted stool frogs lay their eggs in still water, ready to begin the cycle anew.

Some pernicious polliwogs have adapted to have an abrupt and vibrant adult phase. Candy fleas spend most of their time as an intestinal parasite. Once they have reached a final growth phase, the mucous cocoon is defecated by the host. The cocoon will then lay dormant until conditions are ideal for hatching, which at times can last up to two years. Through the cocoon, the candy flea can detect temperature, humidity, and if any other candy flea cocoons are nearby. Once conditions are met, cocoons simultaneously hatch in what is called a flea bloom. The tiny frogs resemble insects with glossy skins and erratic hopping movements. Adults are only the size of a pencil eraser. Candy fleas are also notable for having no front legs and no mouths. These anatomical features are superfluous to their adult tasks, and the energy to develop them is put to better use - flashy colors and big eyes to seek out mates. Their purpose in life is to breed fervently, excessively, and passionately until they expire. 

Lastly, some pernicious polliwogs have forsaken their adult ambulatory phase altogether. One example is the choking pepper worm (Dirofilariaforma blodsugu - dire worm-form bloodsucker). The choking pepper worm starts life as dormant seed-like eggs the size of a needle head. these eggs will then lump together with adequate conditions into what is called a hyperblastula. This hyperblastula is unique as it is an mucous amalgamation of several different frog eggs which work together to infect a host. Once the hyperblastula finds a host, it can enter through the skin or through the digestive tract (although the skin provides a greater chance of infection). The hyperblastula then disassociates once it enters the bloodstream of the host. In the bloodstream choking pepper worm polliwogs will feast on the host's blood supply. Once they reach a certain size (1 cm in length), the polliwogs will migrate to the host's alveolar-capillary interface. Here the parasites finish their sexual maturation into large female egg-depositing forms and small male fertilizing forms. The males swim into the female's enlarged cloaca and fertilize the eggs. Once fertilization is completed, the female inserts her cloaca through the alveolar-capillary interface and deposits her eggs. The presence of eggs in the lung alveoli causes irritation and the host to cough out the little brown-black eggs (often likened to pepper, and hence the name), continuing the vile cycle. 

Disease

In the modern day, cases are thankfully rare due to extensive water treatment. Infections generally present among lower socio-economic status individuals, those who do fieldwork, and hikers. Additionally, while many pernicious polliwogs can infect humans, humans are not the preferred host of pernicious polliwogs, and infections are often self-limited. With the three species that can infect humans (spotted stool frog, candy hopper, choking pepper worm), infection typically lasts 2 weeks and manifests with anemia (due to either vitamin B12 deficiency or blood loss), fatigue, anxiety, and the sensation of internal tickling or movement. Additionally, candy flea infection presents with extreme agitation and immunosuppression; choking pepper worm infection will always present with the coughing up of eggs; spotted stool frog infection will terminate with a bout of severe diarrhea. 

Treatment for these infections is thankfully easily available in the form of prescription "defrogger" tablets (Ranabendazole, Toadziquantel). These medications will cause adults and juveniles to be recognized by the body's defenses and eliminated. Other forms of treatment include rocking therapy. Pernicious polliwogs are sensitive to full-body rhythmic movements. Likely an adaptation to avoid ingestion by sea creatures or flying animals too small to be adequate hosts, rocking movements or changes in barometric pressure will cause premature release of mucous cocoons and eggs from the host's GI tract and eject potentially viable larvae into better conditions. It is also the one reason why parasitic polliwogs infections have been mostly limited to the archipelago. However, there have been incidental cases of parasitic polliwogs throughout the eastern United States and Canada, and these cases are only rising with increased air-travel.

Effects on Introduced species

Until fairly recently, pernicious polliwogs only infected animals endemic to the Mossfells such as ratatoskrs, solenouses, and ground sloths. However due to some species' flexibility with choosing their hosts, pernicious polliwogs have become a common illness among many farm animals and humans. Initial Norse records do not mention pernicious polliwogs until 1142 CE when several villages began to experience symptoms similar to choking pepper worm infection. Prior to the discovery of Human Transmissible Adenocarcinoma in nordic grave autopsies, some infectious disease experts erroneously hypothesized that the end of the Mossfell Norse Golden age may have been partly due to a widespread parasitic infection as some polliwogs began to adapt to human bodies. Viardrmen oral tradition includes many cautionary tales of drinking from water surrounded by colorful creatures and later falling into grave illness.

Later British and American colonists would encounter similar issues with pernicious polliwogs. British colonial accounts often detail the woes of losing the family's cow to vile frogs. The settlement of Henswyck was beleaguered by continuous waves of polliwog infections until proper sewer systems were installed in 1890. Reservoirs of still water in the Hvankji desert on Neffannafjall were known breeding grounds for pernicious polliwogs, and prevented large-scale settlement by farmers up until the 19th century. 

In the 1930's, massive campaigns to treat potential polliwog habitat succeeded in controlling the parasites. This enabled further development of the islands throughout the 20th century. However, these gains have proven temporary. With increasingly bizarre weather patterns, standing water is becoming more common across the islands throughout the year, resulting in a spread of the parasites once more. Alarmingly, some polliwogs have developed new abilities to infect some birds such as chickens and tyrduck, leading to concerns for many poultry farms. Additionally, encroaching development has resulted in human habitation overlapping with previously untreated areas of the islands. 

Another shocking concern is the potential spread of polliwogs out of the archipelago. Since the 1700's sporadic and self-limited infectious outbreaks have been documented on the North American continent. Currently human polliwog infections are still rare and easily treated, but it could only be a matter of time before these parasites establish permanent populations across the world and expose the horror of these parasitic frogs to the wider world.