How to eat parasites: a guide for the perplexed

Let's continue our cursed journey of learning all about parasites! Today we will learn how to eat parasites: what to eat, how to eat them, and what to avoid.

The main source I rely on is

Overstreet, Robin M., ‘Presidential Address: Flavor Buds and Other Delights’, Journal of Parasitology, 89.6 (2003), 1093–1107 <https://doi.org/10/dv2tdk>

Tapeworm diet

Kind of a meme really. The tapeworm diet idea is simple: if there's a tapeworm in your intestine, they would eat your food and get fat for you, so that you won't get fat.

Typical advertisement from early 20th century

While tapeworms usually do not make one sick, they can block the intestine if they get too big or too many, which is life-threatening. That, and they don't work that well for losing weight.

Also this delicious factoid:

The cysticerci of the pork tapeworm, Taenia solium, have been fed by unprincipled medical advisors to unwitting Hollywood actresses in the 1930s as "slimming pills," producing adults in the intestine (Russell-Hunter, 1979).

Unconfirmed report: 

Eating parasites for other than a dietary reason apparently reached a new extreme on KarKar Island just north of Madang along northern Papua New Guinea, where contestants inten- tionally ate parasites. On "Parasite Day," they took a pill treat- ment, and the one that expelled the heaviest load of worms was the winner. The description of this recent event was on the Internet, but when I tried to obtain the details, the site was apparently no longer in operation.

 Tasty whale parasite

Some parasitic copepods and probably other blood-feeding crustaceans that infest fishes and marine mammals are eaten. Probably the best-known case involves the pennellid Lernaeocera brachialis attached in the buccal or branchial cavity of various codfishes and whiting, with its anterior body portion penetrating into the ventral aorta, bulbus arteriosus, or ventricle of the heart. In the Arctic, blood-filled individuals provide a gastronomic treat for Inuits. These people, however, obtain an even larger parasite snack by eating Pennella balaenopterae, a poorly understood species that can grow to monstrous proportions. Specimens up to 30 cm long routinely embed deeply into the blubber of baleen whales, with the posterior of their bodies trailing free from the host. The plump and juicy body extremity is plucked from the host and eaten raw, and the "sweet" contents of the blood-filled neck are sucked out.

 Pennella balaenopterae is detailed here, which includes this illustration:

Pennella balaenopterae embedded on

the side of the porpoise's peduncle

Parasitic castrator in oyster

Pea crab in oyster

The oyster is blessed with not one, but two tasty parasites. The pea crab is a delicate little crab that lives in the oyster, eats its mucus and steals its food. 

Source

Info about oyster pea crab is easy to find online since they are very popular in parts of America, so I won't say more about them.

Botfly maggots

Botflies are nasty parasites that lay eggs in the pelt of mammals, which then hatch and eat the skin and blood as they mature, then they metamorphize, and crawl out as an adult botfly. 

According to Olayuk Naqitarvik (pers. comm. to Nikolas Konstantinou and George Benz), the Inuit out of Arctic Bay, northern Baffin Island, Nunavut, Canada, also consider the botfly maggots from the hide of caribou to be a special treat. They reportedly bite off the "heads" and eat the remainder. Presumably, they bite off the posterior spiracle, which superficially appears like a head. The Inuit consider the taste as "sweet."

Eating botfly maggots is very little different from eating non- parasitic insect larvae, which is common practice in many parts of the world. Because of inherent dangers of toxins and dis- agreeable taste, the insect larvae eaten by different peoples are typically geographically restricted to select species.

Maggots are also used (but not eaten) in making a kind of cheese "cazu marzu":

The cheese fly, Piophila casei, lays eggs in the cheese, and its larva promotes fermentation, allowing the fats to decompose and leaving a pungent goo that burns the tongue. Casu marzu is also produced with a goat milk-based soft cheese produced by farmers from the southeastern Piedmont mountains perme- ated with pale pink, small, fat, barrel-shaped maggots crawling throughout the cheese.

There's plenty of report on cazu marzu online, so I won't explain more.

In comparison, using mites for cheese is positively boring.

A different European product utilizes not flies but the cultured cheese mite, Tyrophagus casei, which is capable of causing dermatitis, introduced to German Altenburger cheese. The mite-infested product becomes covered by a gray powder, which consists of the mites, their molts, and their feces. Wheth- er the flavor results from a fly or a mite, the product is moving with the visible wriggling animals; numerous people enjoy it, and large quantities are eaten.

The "little livers" of deer

(Overstree, 2003)

The giant liver fluke of deer (Fig. 24), up to 8 cm long, represents well a widespread example of an edible digenean, primarily because of its large size. William Font (pers. comm.) tells about an undergraduate student (Tony) at University of Wisconsin Eau Clare, who, when dissecting the livers of white-tailed deer brought in by the student hunters during the middle of deer season, spoke about old timer deer hunters in northern Wisconsin who considered the best part of eating deer was eating the "little livers." Individuals of the giant liver fluke, Fascioloides magna, of white-tailed deer, mule deer, elk, and other herbivores of North America and northern Europe constitute the livers inside the livers. The fluke occurs in pairs or in some cases 3 or more in fibrous capsules in the liver parenchyma. Even though seldom is there much inflammation, the blood vessels in the capsule wall intercept the many small bile ducts that penetrate the walls. Hematin pigment from the partial digestion of host blood by the digenean in or on the mesentery, lymph nodes, hepatic tissues, and other organs typically allows one to know that a liver is infected. Usually fewer than 30 occur per deer but as many as 125 have been recorded (e.g., Foreyt, 1981). 

I have heard from different sources about the Cajun practice of eating the deer flukes in Louisiana. I recollect hearing about 30 yr ago that the flukes were double fried to produce a puffy specialty like pommes souffles, or "puffed potatoes," from Arnaud's, Antoine's, and Galatoire's restaurants in New Orleans or like beignets in carefully temperature-controlled cooking oil. Upon trying to get recent confirmation of this from Cajuns in Mississippi and Louisiana, I was unable, suggesting the custom was probably quite local and maybe no longer practiced. Nevertheless, the custom is apparently widespread, even though the recipes differ. The same recipe, however, may have been used to produce puffed-up "sweet meat" from Georgia where Elon E. Byrd told students and colleagues about the hunters frying and eating the delicacies. Other anecdotal stories include those of Native Americans in the Southeast preparing them as "little flapjacks." In any event, a scattering of people eat the fluke, and there is no documented case of this species infecting a human (Beaver et al., 1984).

To transfer the "life force" from 4-hooved prey to human hunter, elderly Lakota Sioux from the Rosebud Reservation in Nebraska and the older generation Sioux elsewhere throughout the Sioux Nation eat a portion of the liver of their game or of butchered domestic animals. They follow this practice with a careful inspection for large flukes such as F. magna, Fasciola hepatica, and apparently dicrocoelids. Typically, they cook the worms along with their eggs for breakfast (D. Holiday, pers. comm.).

Figure from Parasitology: A Conceptual Approach, page 222.

Tapeworms

Cestodes (tapeworms): Of all the parasites intentionally eaten by people, cestodes constitute the most eaten group.

Tapeworm infection helps you tell apart swordfish from shark meat

From a different point of view, I have heard from ichthyologists (e.g., C. Richard Robins, previously of the University of Miami, Rosenstiel School of Marine and Atmospheric Science) that seafood consumers dis- tinguish the swordfish (Xiphias gladius) from the less-desirable shortfin mako shark (Isurus oxyrinchus), often sold as sword- fish, by the discoloration, which in turn results from an un- known-to-them trypanorhynchean infection in the swordfish. Infected swordfish steaks are apparently considered tastier than the shark or uninfected swordfish, but the consumer does not recognize the reason for the discoloration. 

Tasty tapeworm nodules

During hot dry years in the midwest United States, when the water levels are low, an abundance of plerocercoids, at least of a proteocephalid, in the flesh of bull- heads, other catfishes, and perches reaches high levels. Local farmers catch these fish and skin them to eat. The worms are readily apparent in the flesh, usually in nodules. A portion of the fishers eat the worms or infected tissue as a delicacy, usually cooked, while others cull out the worms or discard the entire fish (D. Holiday, pers. comm.).

Living spaghetti 

Ligula intestinalis... easy to detect because of the swollen ventral portion of the host's body, are typically roasted or otherwise cooked. Thaddeus Graczyk (pers. comm.) related to me that people in Poland cooked specimens in a skillet, frying them on both sides. He also told me that he did not try them. They, according to the late Paul Beaver as well as lectures by Martin Ulmer, are or were also eaten in northern Italy and elsewhere throughout the Mediterranean area as "vermicelli vicente" (=living spaghetti) and were therefore probably the cestode called "noodles" by some. "Living spaghetti" was eaten raw by fishers in the Caspian Sea. As soon as they caught an infected fish, they would cut into the body cavity, remove the large plerocercoids, and immediately eat them (as read by Sherman Desser, University of Toronto, but neither of us could locate the article).

Why are worms tasty?

Short answer: because mature tapeworms are basically moving bags of gonads (sex organs). They don't need bones, or brains, or eyes, since they are literally floating in an ocean of food. Gonads (ovaries and testicles, for example), are similar to eggs and caviar: fatty, oily, and often sweet.

These plerocercoids have an abundance of food reserves that probably makes them especially nutritious as well as tasty. Some adult and juvenile cestodes temporarily can store as much as 20 to >50% glycogen, measured as dry weight. Lipid can account for 20% of the total worm and >30% dry weight of the parenchyma in gravid proglottids (Roberts and Janovy, 2000). Whether this fat is what makes them so tasty is un- known, but it may be the combination with the glycogen.

Bertiella esculenta, the "good to eat" parasite, and its tasty cousin Bertiella flanneryi

I found this parasite on the Parasite of the Day blog.

Today's parasite is one of two species in the genus Bertiella which are relished by native people of Papuan New Guinea. The name Bertiella esculenta should clue you in on that fact, as "esculenta" means "good to eat" in Latin. The other species, Beritella flanneryi, is named after Tim Flannery who first came across this practice of eating the worms. These tapeworms usually live in the intestine of the coppery ringtail possum (Pseudochirops cupreus), and fortunately for those who find them a gastronomic treat, because of the specialized structure of the possums gut, the worm is very host specific and is unable to survive in any other environment, including the human gastrointestinal tract.

(Overstreet, 2003):

An hors d'oeuvre considered a delicacy among the Atbalmin people of the high and mossy Star Mountains in the western part of Papua New Guinea abutting Irian Jaya is a thick and yellow tapeworm from the intestine of possums. Tim Flannery, who wrote Throwim Way Leg (1998), meaning "hit the road" in Melanesian pidgin, a language spoken in Papua New Guinea, was interviewed about "The strangest 'meals' I've ever eaten". During that interview, he indicated that a slight preparation of the worm was necessary, "You simply wipe the clammy beast between your fingers and pop it in your mouth." In his book, however, Flannery (1998) indicated that the young stepson of his native collecting assistant would turn the stomach of residents and scientists alike when he would pierce his fingernail into the intestine of a coppery ringtail possum (Pseudocheirus cupreus, also listed as Pseudochirops cupreus). He would open the intestine where a lump existed to allow the tapeworms to squirt out, remove the feces from the worms, and drop each writhing organism straight into his mouth. Concerned that the worms might be harmful to the boy, Flannery sent some specimens to Ian Beveridge, who named the species Bertiella fianneryi and assured him that because of the highly specialized gut of the possum, the worm would find the human intestine quite hostile.

Location of Atbalmin

Adult anoplocephalid Bertiella esculenta from the intestine of a coppery ringtail possum,
Pseudocheirus cupreus, being eaten by native of Papua New Guinea. From Flannery (1998).

According to the paper which named this species, The genus Bertiella (Cestoda: Anoplocephalidae) from Australasian mammals: new species, new records and redescriptions, (Ian Beveridge, 1985):

The specific name is given because the species is apparently regarded as a delicacy by certain tribes in New Guinea (Dwyer & Plowman, 1981), who remove them from the intestine, wrap them in leaves and cook them before eating.

Even bigger ones! Reaching up to 10 meters!

The extremely large tapeworms Moniezia expansa and Moniezia spp., anoplocephalids related to Bertiella spp., eaten by native peoples of New Guinea and other areas commonly infect domestic sheep, goats, and cattle in large numbers. One or more of these species are also eaten by some people, including those in northern Italy, but I do not know the details. According to Colin Dobson (pers. comm.), "Moniezia pie" was fried by the farmers and served as a delicacy. He had also heard about the tapeworm being eaten as spaghetti. Whether the same or other cestodes are or were the ingredient(s) of "tapeworm soup," also supposedly eaten by some Europeans, remains unknown to me. When I asked for confirmation and details of these customs with the Italian parasitologists Simonetta Mattiucci and Lia Paggi, neither was familiar with them. Perhaps these delicacies are enjoyed in isolated communities only or maybe they are no longer eate 

Beware of tasty pork

Pork infected with the cysticercus, also termed "measly pork," is considered by some to be more tasty than uninfected animals, at least when cooked. Presumably because of the improved taste, there have been times in Mexico when pork flesh infected with T. solium has gone for a higher price than noninfected meat (E. Foor, pers. comm., from lectures by Harold W. Brown, ASP President in 1960, Columbia University, and Martin J. Ulmer, ASP President in 1977).

Popping boba, salmon roe

Species of related cyclophyllideans in the genus Echinococcus also have intermediate stages that can infect various tissues in humans or a variety of herbivorous hosts and produce serious disease. Such infection in humans and other intermediate hosts occurs from the host eating eggs rather than from eating the fluid-filled hydatid cysts... Michael Burt (pers. comm.) recollects hearing that the first individual in a hunting party of different South American Indian groups to spear a cervid (the deer family) was given the honor -- if the animal had an infection of Echinococcus sp. -- to drink the fluid from the hydatid cyst.

This sounds just like the popping boba! Or salmon roe!

In conclusion

Using good sense and some biological information, one can enjoy a delightful morsel or enhanced meal from a variety of parasites, either raw or cooked. 

Bon Appetit!