Worm therapy

Leeches and maggots have a history of use in medicine - for blood-letting or wound cleaning, respectively (and both have FDA approval for modern medical use). Recent reports have suggested potential usefulness for another creepy-crawly.

Filarial nematode worms are particularly nasty mosquito-borne parasites that take up residence in the lymph nodes. The worm is endemic to many tropical and sub-tropical countries and causes elephantiasis - the enlargement of limbs and genitals (and for guys thinking this doesn't sound so bad, the genitals can get so big that they interfere with regular physical activity. Pictures here), as well as less obvious internal damage. However, areas with high rates of filarial worm infection tend to have lower rates of inflammatory bowel disease, arthritis and other inflammation-caused ailments. This is thought, in part, to be caused by ES-62 - a glycoprotein secreted by the worm that has anti-inflammatory properties.

Scientists in Glasgow are now looking for a way to develop ES-62 into a better, non-heart-attack-inducing, anti-inflammatory.

Don't worry though - I don't think they plan on treating with live worms.

Are your bugs sexy?

Do parasites alter sexual behaviour?

While some parasites clearly manipulate the behaviour of their host to enhance their ability to spread to new hosts (think of alteration of limbic function by rabies leading to biting behaviour or reduced fear from predators in many instances), do they ever alter sexual behaviour?

There is evidence that many organisms discriminate against mates that are parasitized. It has even been proposed that positive selection for bright colours, large appendages, elaborate feathers/fur/etc is a surrogate for selecting mates who can support such useless extravagances... and are therefore free of parasites.

Rats have been shown to be able to identify parasitized individuals by smelling their urine, and avoid mating with them as a result. Female rats appear to prefer the scent of males that are free of lice over lice-infested males.

So do parasites ever lead to increased mating success? Snails (Biomphalaria glabrata) exposed to to Schistosoma mansoni respond by increasing their reproductive output. This is an adaptive response that enhances reproduction before the parasite causes host castration. Makes you wonder how they know?!

Milk-weed leaf beetles (Labidomera clivicollis) also increase their reproductive effort in response to parasitism by a sexually transmitted mite Chrysomelobia labidomera. This is where things get interesting. When a parasite is sexually transmitted, making it's host more promiscuous and/or more sexually attractive would be a great strategy.

Just imagine how rabies might effect its host if it were sexually transmitted...

Candiru

If you watched Grey's Anatomy last night you've probably seen the penis fish. You're also probably a girl. What they left out of the explanation, is that the Vandellia cirrhosa is in fact just as happy to swim up a vagina, or in fact any opening/orifice. It is a type of parasitic catfish that usually lodges itself in the gills of other fish and feeds on their blood. There is no reported case in pubmed, other than it is a gift to urology (?), but natives living on the amazon fear it (understandably so). However, reports of the fish swimming in the urine stream into the penis outside of the water are an urban legend. But if you are submerged , then beware. I'm scared of channel catfish myself...