More on STDs

At the same party AC mentioned, conversation naturally turned from herpes to other STDs - namely gonorrhea. (Don't you wish you could have been there?) Most people are probably familiar with Kramer's portrayal of the disease on Seinfeld:



In addition to the burning he describes, infection may also be accompanied by a urethral discharge (sometimes known as gleet). And no, you can't get it from a tractor (but possibly from a blow-up doll). You can, however, get it in non-genital sites such as the throat or eye. Throat infections may be asymptomatic, but common symptoms include redness and soreness. Gonococcal eye infections result in conjunctivitis, as well as a possible discharge.

While gonorrhea is primarily sexually transmitted - so much so that it's presence in children is almost always taken as a sign of sexual abuse - non-sexual transmission (such as from shared towels, rectal thermometers, or even caregiver hands, but not riding a tractor in your bathing suit) does occur. Still, it kind of makes you wonder about that lab pink eye outbreak.

STDs, drinking games and sexomnia

During a party over the weekend some younger colleagues took part in a drinking game called "flippy cup". Now the game was innocent enough but we wondered about the potential for transmission of herpes viruses (HSV, EBV) via drinking games. Interestingly we were not the first to notice a possible link, as you can read here in a college newspaper about herpes being passed around as a result of a "beer pong" tournament. The article even quotes a CDC report indicating a 230% increase in infection as a result of cup sharing. There goes to show that two girls shouldn't share one cup. In a related train of thought, the subject of alcohol-induced sexsomnia came up, perhaps as another vector for STD transmission. Apparently some people suffer from sleeping masturbation. As usual, pubmed comes to the rescue with a nice case report:

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...