June 10 -Syphacia obvelata

This pinworm is commonly found in laboratory rodents such as mice and hamsters, as well as wild rodents. Because they are easy to maintain in these lab animals, they are often used as model organisms to study the biology of pinworms and to test anti-nematode compounds. This species, like some other pinworms, are capable of "retroinfection" - if the host's feces aren't moving quickly enough out, the eggs can hatch, mature, and just migrate back up the intestine to join their parents in churning out more eggs. Typically, though, the eggs are accidentally consumed by a rodent when it is grooming and go through the life cycle the normal way.. Ah, phew- that's comforting.

Image comes from this page.

June 9 - Orthohalarachne attenuata

Back in 1984, a 35-year old guy started feeling a pain in his eye and went to his doctor. The doctor looked under his eyelid and saw nothing. The next day, the pain was worse so he went back and asked the doctor to examine him again. During that visit, the doctor found - and removed - a single mite of the species Orthohalarachne attenuata. Ok, weird, but not that weird, right? Wrong. Orthohalarachne attenuata is a species of mite that normally is found in the nasal passages of fur seals, sea lions, and walruses. In seals, the mites can be both prevalent (as in almost every single seal has them) and abundant (as in more than 1000 mites per seal and in a few cases in one study, more than 2000!). These incredibly high infestations can cause problems for the seal's breathing, but can also do damage in the lungs and leave the seals susceptible to other infections, too. Transmission between seals occurs by -- sneezing on each other, of course. So, how did this young guy in California get a nasal mite in his eye? Turns out that two days before his first doctor's visit, he had visited Sea World - where he stood too close to some walruses and got sneezed on.

Photo contributed by Mike Kinsella. Documentation of the human case in this paper.

June 8 - Plasmodium floridense

In January, you read about Plasmodium minuoviride, a malaria parasite of lizards, and learned that over 100 malaria parasites use lizard hosts. Today’s parasite – Plasmodium floridense – is another of these lizard parasites. As you might have guessed from its species name, it was first described in Florida, but its distribution includes the southern United States, most of the Caribbean, as well as parts of Central America. It is known from roughly 30 lizard species (a high host number for this kind of parasite), with most of these belonging to the lizard genus Anolis.

Prevalence (the percentage of animals infected) of P. floridense varies greatly among these hosts, ranging 5 to 50%. The cause of this variation is unknown. Differences in host ecology might affect prevalence, because – for example – some lizard species occur in open areas and infected lizards might use heat from the sun to raise their body temperature (i.e., a “behavioral fever”). Likewise, a vector species may encounter some lizard species more frequently than others, based on differences in these lizards’ roosting preferences, thereby skewing the rates of infection. These and several other potential factors could be causing the variation in prevalence of P. floridense.

Anolis lizards make good subjects in which evaluate the factors affecting parasite prevalence. They have undergone a repeated pattern of adaptive evolution in the Greater Antilles, and based on their behavior, morphology, and ecology, these lizards can be categorized into one of several “ecomorph” types. The pattern on each island is very similar, as near to a replicated experimental design as an evolutionary biologist could hope. Preliminary research on Hispaniola has shown that P. floridense infections are found primarily in lizards of one ecomorph type, and ongoing work will determine if this pattern is consistent across other islands (Falk et al., unpublished).

Contributed by Bryan Falk.

June 7 - Diplozoon paradoxum

We normally think of parasites as rather despicable creatures - out for food and shelter and not caring who suffers in their quest. But today's parasite, the monogenean Diplozoon paradoxum, has at least one redeeming quality - it just might be the most monogamous organism on the planet. A young D. paradoxum, called a diplora, settles down on the gills of a fish and waits for a mate. If another one never comes along, then the single parasite will simply die (of loneliness?). However, if another comes along, the two worms actually fuse their bodies completely together and become adults, with one producing testes and the other producing ovaries allowing them to continually cross-fertilize. And that is how they will stay - forever.

Diplozoon is the official symbol of the Meguro Parasitological Museum in Japan - if you visit, you can even buy jewelry featuring the conjoined parasites.

The image comes from this site.

June 6 - Dermanyssus gallinae

Dermanyssus gallinae, or the red mite, is an ectoparasite of birds. They do not live on birds, but rather hop on them to feed on their blood at night, while they are sleeping. They can be major pests for chicken and other poultry farmers. They will occasionally take blood meals from mammals, even humans, if they work with or live near birds.

June 5 - Macracanthorhynchus hirudinaceus

Today's parasite has quite a handle of a Latin name - perhaps you'll prefer the common name - "Giant Thorny-Headed Worm of Swine." As that moniker suggests, this is an acanthocephalan, and like its relatives has a life cycle that alternates between an invertebrate and a vertebrate. The eggs of this parasites are eaten by beetles where they will develop into juveniles or cytacanths. These insects then get eaten by pigs (or occasionally dogs or even humans in very rare cases). The adults attach themselves to the small intestinal wall and can get quite large - up to 65 centimeters. The eggs pass out with the pig's feces and interestingly, if a bird accidentally eats them if they are on something that they're gobbling up, they pass right through unharmed to wait for the right (beetle) host.

June 4 - Lernaeocera branchialis

Life is about dealing with changes, but for Lernaeocera branchialis, some of those changes are pretty profound. This parasitic copepod starts out as a free-swimming nauplius, like other crustaceans. Then, it turns into a copepodid and seeks out an intermediate host, something slow and easy to find, like a flounder. It mates with an opposite-sex copepodid on this host and then sets off to find its final host, usually a cod or haddock. It then completely metamorphosizes into a large (4 cm), red, worm-like thing with a big egg sac and "antlers". Its head remains inserted into the gills of the fish where it feeds from the blood and pumps out new eggs.

The photo is from this site.

June 3 - Boschniakia hookeri

If you're hiking in western North America and look down and spot a pine cone sitting on its end, take a closer look - it might be Boschniakia hookeri, known as groundcone. These are species of broomrapes, holoparasitic plants with no chlorophyll that depend on plants like alders or huckleberries for water and nutrients. The part that looks like a pinecone can be brown or purple, yellow or red and this is the inflorescence. Native Americans/Canadians sometimes ate the stems of these plants as a snack.

June 2 - Rhinosporidium seeberi

Rhinosporidium seeberi is a bit of a mystery. It is found primarily in India and Sri Lanka and causes a disease known simply as rhinosporidiosis, which is an infection in the mucosal tissues of the nose, pharynx, and sometimes the eyes. The organism is a member of the group Mesomycetozoea, which are single-celled organisms thought to predate the split between animals and fungi. The natural history of these parasites is also not very well known - they are thought to occur in water and possibly soil and infect people when tissues are exposed when they bathe in common ponds. The image come from this website - if you're brave, open that link for some pictures of the infection in people.

June 1 - Compsilura concinnata

Gypsy moths are a notorious invasive species in the eastern U.S., causing massive damage to hardwood trees like oaks, aspens and apples. These moths were originally imported in the late 1860's by a biologist to try to breed disease-free silk-spinning caterpillars that then escaped and spread like crazy. (I remember being a kid when they first reached my hometown in northern New York - it was like a plague had descended on us!) In an effort to control them, a parasitoid fly, Compsilura concinnata, was introduced from Europe. Although the flies do help to some degree, they may have caused more damage than good because they also prey on native caterpillars. Part of this is because the gypsy moth is univoltine, that is it just undergoes one generation per year, but the flies are multivoltine. The flies use gypsy moth caterpillars for their first generation in the spring, but then when the gypsy moths are gone, the flies turn to other caterpillars for the rest of the warm months. The beautiful Luna Moths have been hard hit by these "control" agents.

The image is from this site and read more about the effect on luna moths here.