October 31 - Desmodus rotundus

The common vampire bat, Desmodus rotundus, seemed like a good parasite to feature on Halloween. These mammals derive all of their nutrition from the blood of other mammals, usually cattle, but sometimes other livestock and even sleeping humans. They sneak up on their hosts using a very quiet hopping motion and then slice open the skin with razor-sharp teeth, lapping up the blood that spills out. Vampire bats can only survive a few days without feeding, but have evolved a social behavior known as reciprocal altruism where a bat that feeds successfully one night may regurgitate some of its meal to a hungry roostmate. Later, the recipient may be the lucky one and return the favor to this donor. Vampire bats can be found in many places throughout the neotropics, but have sometimes been subjects of eradication campaigns because of the fear of rabies that they can spread.

October 30 - Philophthalmus gralli

Continuing our theme of nasty places to have worms, how about under the eyelid?! Flukes of the genus Philophthalmus are found in the conjunctival sac of the eyes of many species of birds and rarely in humans. In this case, a rhea (Rhea americana) in a zoo had an unusually heavy infection of several hundred flukes in each eye. The intermediate hosts are aquatic snails. When the cercariae escape from the snail, they encyst on vegetation or occasionally at the surface of the water and the cysts are ingested by the final host, where they hatch and migrate to the eye.

Contributed by Mike Kinsella, photo by Melanie Church.

October 29 - Megalodiscus temperatus

Megalodiscus temperatus is a digenean trematode belonging to the order Echinostomatiformes (Family Diplodiscidae). Diplodiscid flukes have a pair of posterior diverticula in the oral sucker, and the posterior sucker of these trematodes is about as wide as the greatest width of the body. Megalodiscus temperatus are common parasites of the rectum and urinary bladder of frogs. Eggs are shed from frog hosts, and miracidia hatch soon after the eggs reach the water. There is only one intermediate host for M. temperatus, snails of the genus Helisoma. Snails become infected when penetrated with miracidia, releasing cercariae into the water that subsequently encyst in the skin of frogs. Frogs regularly molt the outer layers of their skin, often ingesting the sloughed skin and the encysted metaceriae. Metacercariae excyst in the rectum, maturing in one to four months. Tadpoles can also become infected when ingesting cercaria. In this case, M. temperatus encysts in the stomach and excysts in the rectum of the tadpole. During metaphorphosis (tadpole intestines shorten considerably), M. temperatus migrates anteriorly then posteriorly again to the rectum.

Contributed by Jessica Light.

October 28 - Hysteromorpha triloba

Hysteromorpha triloba , a strigeid trematode is a strange looking and generally small parasite found in the digestive tracts of fish-eating vertebrates. The first intermediate host is a snail (e.g., Gyraulus hirsutus), and the second intermediate hosts are fishes of the families Cyprinidae (Abramis sp., Hyborhynchus notatus, Idus idus, Leuciscus sp., and Tinca tinca), Poeciliidae (Poecilia vivipara), and Siluridae (Ameiurus sp.). In the fish intermediate hosts, metacercaria encyst in the musculature (forming white cysts) and the parasite is passed on to the definite host when infected fish are eaten. Definitive hosts include herons, egrets, pelicans, and cormorants.

Other images can be found here.

Contributed by Jessica Light.

October 27 - Brachylaima thompsoni

Brachylaima thompsoni is a digenean trematode (Family Panopistidae – previously Brachylaimidae) that parasitizes shrews in North America. Similar to other trematode species, B. thompsoni has a complex life cycle and it parasitizes two intermediate hosts before parasitizing its shrew definitive host. Both the first and second intermediates hosts of B. thompsoni are terrestrial gastropods. Documented first intermediate hosts include Agriolimax agrestis, Zonitoides arboreus, Deroceras leave, and Ventridens ligera (sporocysts of B. thompsoni are found in the digestive gland of the first intermediate host). Free-living cercariae then infest the second intermediate host (potential hosts include Neohelix albolabris and Webbhelix), where metacercariae develop in the pericardium or kidneys. Definitive hosts such as Short-tailed Shrews (Blarina brevicauda), Elliot’s Short-tailed Shrew (Blarina hylophaga), and Least Shrews (Cryptotis sp.) become infected when feeding on parasitized gastropods. B. thompsoni is commonly found in the large intestine of its definitive host and eggs of this tremaode are shed in the shrew fecal material. The first intermediate host becomes infected by ingesting the eggs, starting the cycle over.

Contributed by Jessica Light.

October 26 - Echinorhynchus salmonis

Echinorhynchus species are acanthocephalan parasites belonging to the family Echinorhynchidae. Like other acanthocephalans we’ve already seen (e.g. Neoechinorhynchus emyditoides; Moniliformis moniliformis; Pseudocorynosoma constrictum, these thorny headed worms parasitize the intestines of fish and amphibians. The species shown here is probably Echinorhnychus salmonis, an acanthocephalan with a Holarctic distribution, occurring in fresh and brackish waters and commonly parasitizing salmoniform and other fishes (intermediate hosts include amphipods such as Monoporeia affinis). Echinorhynchus are often the topic of research projects including effects on host feeding ecology, anti-predator behavior, and host spawning. Here are two links about Echinorhynchus species:
First Site
Second Site

Contributed by Jessica Light.

October 25 - Aspidogaster conchicola

Aspidogaster conchicola is a trematode (Trematoda: Aspidogastrea) with a direct life cycle. Hosts include freshwater clams and snails (e.g., Viviparus species and Goniobasis livescens) and this particular one was found in Douglas Lake, Michigan, parasitizing a mussel belonging to the genus Ligumia. Hosts become infected when ingesting eggs of A. conchicola and adult worms can commonly be found in the mantle, pericardial, and renal cavities of their hosts. If parasite densities are high, A. conchicola may have negative consequences on host fitness. A. conchicola is the type species of the genus, and recently phylogenetic studies have found that A. conchicola is closely related to Lobatosoma species, resulting in a non-monophyletic Aspidogaster.

Contributed by Jessica Light.

October 24 - Lathraea clandestina

Today we have a pretty parasite - Lathraea clandestina, or the Purple Toothwort, is a parasitic plant that uses willows, poplars and alders as its hosts. Its name comes from the fact that its remnant, below-ground and chlorophyll-less leaves resemble teeth. These plants produce quite large fruits for their size, which burst when ripe, sending their tiny seeds off to be carried by rain or other moisture to new hosts. L. clandestina is found throughout Western and Central Europe and seemingly were recently introduced into the U.K. and Ireland.

October 23 - Trombidium holosericeum

The animal in the photo is not a parasite - but its offspring are. Like Eutrombicula alfreduggesi, Trombidium holosericeum is a mite that has parasitic larvae and nymphs. The larvae, commonly known as chiggers, can cause real distress to their hosts - including humans - as they feed. They do not crawl under the skin, nor do they feed on blood - what they do is attach themselves to the skin, pierce it. and inject enzymes that can break down the tissue. A hollow tube known as a stylosome forms - the chiggers will continue to "spit" in these enzymes and then suck up the nutrients. After about 3 to 5 days, they will drop off the host and transform into nymphs. They find a new host, feed in a similar way, and then drop off to molt into adults. The adults are not parasitic, but rather feed on plant juices or are predatory to other small arthropods.

October 22 - Lophoura brevicollum

Lophoura brevicollum is a parasitic copepod that infects the smooth grenadier Nezumia liolepis, a deep sea fish that is found in the bathypelagic depths, about 1200 metres (about three-quarters of a mile) down off the coast of Sinaloa, Mexico. The anterior of the parasite forms an anchor-like holdfast that is embedded in the back of its fish host. One of the more unusual morphological features of this parasite is a pair of peculiar tassels protruding from the abdomen, just in front of its elongated egg sacs. The function of these tassels is possibly related to the habitat of its host. Because L. brevicollum is an ectoparasite, it is exposed to the same environmental conditions as its fish host. In this case, it is the cold, dark surroundings of the deep sea. It has been suggested that the exotic brush-like protrusions of the copepod are adaptations to limited oxygen availability. The protrusions increase the copepod's body surface area to enhance oxygen uptake in the oxygen-poor environment of the bathyal zone.

Reference:
Gomez, S., Deets, G.B., Kalman, J.E., Morales-Serna, F.N. (2010) Lophoura brevicollum n. sp. (Copepoda: Siphonostomatoida: Sphyriidae), a parasite of the smooth grenadier Nezumia liolepis (Gilbert, 1890) (Pisces: Macrouridae) from the Eastern Pacific, and a new record and new host of Lophoura unilobulata Castro R. and Gonzalez. Journal of Crustacean Biology 30(1): 129-140.

Contributed by Tommy Leung.