November 10 - Holobomolochus confusus

Here’s another ectoparasite of the European flounder, Platichthys flesus (Linnaeus, 1758) (Teleostei: Pleuronectidae). This time, it is Holobomolochus confusus (Stock, 1959) (Copepoda: Bomolochidae). The photo shows an adult female with 2 egg sacs. This specimen was isolated from the fish’s nasal cavity, which is the typical infection site. In comparison with other ectoparasitic copepods of the European flounder, i.e., Acanthochondria cornuta and Lepeophtheirus pectoralis, it is remarkably smaller, occurring less frequently and in lower numbers. This parasite is commonly found infecting the cod, Gadus morhua (Linnaeus, 1758) (Teleostei: Gadidae), and has also been reported from other species of fish.

For details, see the papers below:
1. Cavaleiro, F. I. & Santos, M. J. (2007) Survey of the metazoan ectoparasites of the European flounder Platichthys flesus (Linnaeus, 1758) along the north-central Portuguese coast. Journal of Parasitology 93, 1218-1222.
2. Cavaleiro, F. I. & Santos, M. J. (2009) Seasonality of metazoan ectoparasites in marine European flounder Platichthys flesus (Teleostei: Pleuronectidae). Parasitology 136, 855-865.

Contributed by Francisca I. Cavaleiro & Maria J. Santos, Universidade do Porto, Faculdade de Ciências, Departamento de Biologia, Rua do Campo Alegre, s/n, FC4, 4169-007 Porto, Portugal.

November 9 - Meloe franciscanus

Today's parasite is the larval stage of the blister beetle Meloe franciscanus. The beetle larvae are brood parasites that feed on eggs and the young of the solitary bee Habropoda pallida. The problem is, how do they get into the nest of a female bee on the first place? Well they do it by imitating the real thing. They gather into a swarm and climb to the tip of a grass stem. Once there, they clump together to form a small brown blob. While it might not look like much to you, but beetles give off a smell and produce vibrations that fool a male bee into thinking that the blob is one fine hottie. For the beetle larvae, it's a collective effort - the more of them there are in the blob, the more attractive they appear to a male bee. As soon as the bee comes into range expecting to get lucky, all the beetle larvae jump onboard. The experience leaves the bee slightly shaken, but unstirred, and he continue on his quest to find a female bee. However, once he does find a real female, he also ends up passing on his sticky hitch-hikers as a sexually transmitted infection. Once the beetles are all onboard the poor female, they cling on for dear life, eventually disembarking at her nest where they will be surrounded by all the food they'll ever need to grow up.

Photo credit: SFSU

Contributed by Tommy Leung.

November 8 - Baylisascaris procyonis

Baylisascaris procyonis is a nematode parasite, related to Toxocara canis. The adults live in the intestine of their hosts and lay eggs that pass out with the feces. If an animal swallows these eggs, the larvae hatch out in the intestine of this host and then one of two things can happen. If they find themselves in their final, i.e. definitive, host, then they will basically stay put - maturing into adults and beginning the cycle all over again. But, if the animal that swallowed them is not the definitive host, then well, things get a little messy. In these cases, the larvae leave the intestine and travel through the bloodstream, invading other tissues and usually making temporary homes in the central nervous system. If that host is a mouse, they can kill it or at the least cause it to act strangely, which can increase the chances of it being consumed by the definitive host. B. procyonis is a parasite of raccoons, and is very common in them (prevalence >70%). Recently, with raccoon populations expanding and coming into closer and closer contact with humans, people, especially children, are increasingly becoming accidentally infected with this parasite. Since we're not the definitive hosts, the larvae undergo visceral migrans and can cause very serious disease and even kill the human. There have been at least four reported deaths due to this parasite in the U.S. since 1980 and there is not currently an effective treatment.

You can read more about the human cases of B. procyonis here.

November 7 - Syngamus trachea

Syngamus trachea is a nematode known as the gapeworm, which infects birds such as chickens and turkeys. The name comes from the fact that they live in the birds' trachea and, when there are enough of them, they can cut off the airways, causing the bird to gape open their mouths. Females live in permanent conjoinment with males. When they lay eggs, the bird will cough them up and swallow them, and then they will pass out with its feces. Another bird may come along and ingest them or a snail or a worm may serve as an intermediate host.

November 6 - Otodectes cynotis

Many people who have had a dog or a cat as a pet are probably familiar with ear mites - infections that can cause your pet to have brown, cruddy material in their ears, shake their heads, and even itch frantically at their ears. Here's a close-up look at the culprits - Otodectes cynotis. These tiny arachnids are spread from animal to animal via direct contact and then take up residence in the ear canal. The adults lay eggs in the ears and then the mites hatch out and go through a larval stage and two nymphal stage before becoming mature. If left untreated, the mites can induce secondary bacterial or yeast infections, and, in rare severe cases, even deafness in the ear as well.

November 5 - Armillaria ostoyae

Yesterday, you met the smallest wasp known. Today meet one of the largest fungi known. Armillaria ostoyae is a species of parasitic fungus that is commonly known by the pleasant name of "Honey mushroom", but which causes the disease of both hardwood and coniferous trees called "Shoestring Rot." That latter name come from the appearance of rhizomorphs that the fungus can use to move between trees and infect them. Although relatives are edible and this fungus may be fine for most people to eat, others have experienced poisoning-type symptoms, thus you should probably avoid this one unless you really know what it is and that you are tolerant of it. This particular species is found in the Pacific Northwest and a few years ago, a colony of A. ostoyae in the Strawberry Mountains of Oregon was measured to be 2200 acres (8.9 square kilometers!) in size and was estimated to be over 2000 years old. That's one humongous fungus!
Photo from biopix.dk

November 4 - Camptopteroides verrucosa

Camptopteroides verrucosa is a species of fairyfly (family Mymaridae) - which is to say that it's not a fly at all, but rather a tiny little wasp. The very largest of these wasps only has a wingspan of 3 millimeters, so we are definitely talking tiny! Although not much is known about them, it has been observed that they can move and even mate underwater. The females inject their eggs into those of other insects and use an enormous variety of different hosts. These little parasitoids have recently been used in biocontrol efforts.

November 3 - Telogaster opisthorchis

Previously, we met Ribeiroia ondatrae, the trematode parasite which causes limb malformation in frogs. Now meet Telogaster opisthorchis, a trematode that causes malformation in fishes, specifically the larvae of Galaxias anomalus, a freshwater fish native to New Zealand which is only found in two catchment in the Otago region. If the metacercariae of T. opisthorchis happens to lodge themselves in the right spot, they can induce spinal deformities, resulting in "kinky" fish (see photo - the top fish is normal for comparison) that, like malformed frogs, are more susceptible to predation. As you can easily imagine, even without predation pressure, the survival of such malformed fish would be heavily compromised.

Interestingly, it has been found that the parasite combined with herbicide run-off has a synergistic effect on the fish larvae. While the trematode infection alone can induce the spinal deformities, exposure to the herbicide increases the severity of malformation. In addition, snail hosts that produce the cercariae - the infective stage of T. opisthorchis which infects the fish - also release more cercariae after exposure to moderate level of herbicide. Such an example illustrates how human activities can severely alter the dynamics of pre-existing ecological processes in the environment, such as those relating to the transmission of infectious diseases.

Reference:
Kelly, D.W., R. Poulin, D.M. Tompkins, and C.R. Townsend. 2010. Synergistic effects of glyphosate formulation and parasite infection on fish malformations and survival. Journal of Applied Ecology 47: 498-504.

Contributed by Tommy Leung.

November 2 - Heduris spinigera

Heduris spinigera is a species of parasitic nematode found in the stomach of a number of New Zealand's brackish water fishes. While this parasite was initially described decades ago, its lifecycle was only recently determined using a combination of both morphological and genetic identification techniques. This parasite uses a small crustacean as its intermediate host - the benthic amphipod Paracorophium excavatum. While this amphipod is consumed by many different species of fish, it seems that not all fish are equally suitable as hosts for H. spinigera. While their diets potentially expose them to H. spinigera, the nematode fails to become establish in these potential hosts, possibly due to factors such as host anatomy or physiology.

Like most parasites, H. spinigera is restricted to infecting a limited range of host species. Most parasites display some degrees of host specificity, and there are only very few parasites which can truly infect a wide range of different hosts. We now know that many species of parasites, which were previously believed to be host generalists, are actually cryptic species complexes, composed of morphologically similar but genetically distinct species, each infecting a different species of host.

Reference:
Luque, J.L., F.M. Vieira, K. Herrmann, T.M. King, R. Poulin, and C. Lagrue. 2010. New evidence on a cold case: trophic transmission, distribution and host specificity in Hedruris spinigera (Nematoda: Hedruridae). Folia Parasitologica 57: 223-231.

Contributed by Tommy Leung.

Link to paper here.

November 1 - Onchocerca volvulus

Onchocerca volvulus is a filarial nematode parasite of humans that causes the disease river blindness or onchocerciasis, primarily in Africa. These nematodes are transmitted by black flies, which release the larval nematodes with their saliva when they take a blood meal. The larvae mature in the human's subcutaneous tissue and mature in nodule structures. Females will produce over a thousand microfilarial larvae per day - these tiny larvae circulate in the blood, waiting to be picked up by another black fly. Although the mature worms can live in the host for over a decade, it is the larvae that truly produce the disease symptoms - and more specifically, it is their endosymbiotic Wolbachia bacteria that cause the distress. When microfilariae die and begin to degrade, the surface proteins that these bacteria produce cause the human immune system to react quite violently - and this can cause both severe skin issues as well as cause the cornea to become opaque, thus producing the characteristic blindness. Ivermectin, an antihelminthic drug is very effective against this disease.

Image is from this website.