Wednesday, September 5, 2012

Reduviid Bites

“How blessed are some people, whose lives have no fears, no dreads; to whom sleep is a blessing that comes nightly, and brings nothing but sweet dreams.”
Bram Stoker- Dracula

The hemiptera family of insects of which the reduviids are an important group, along with such familiar insects as stink bugs, are an important vector in tropical medicine.  Of the reduviids, the Triatoma are the most important, in that they transmit Trypanosoma cruzi, which is the cause of Chagas' Disease.  These bugs usually hide in the cracks of walls, in the thatching of the roofs and in and under furniture, and only come out at night.  

Reduviid bites are usually unremarkable, with very little in the way of dermatologic manifestations,  but they fall into four broad categories:  papular lesions similar to other insect bites, small vesicles which act as a sort of hypersensitivity reaction, large urticarial lesions with lymphangitis and, finally the erythema multiforme like reactions we see here, which can be either nodular or bullous.  Often these are ascribed to spider bites, but they are not.

The patients rarely remember being bitten, in that the bugs are usually resting on bed linens or the like, rather than on the victim's skin, and use a sucking mouthpart which secretes an anesthetic.  They drink the blood while the patient sleeps, feeding for up to fifteen minutes at a time.  They excrete the trypanosome in their feces, which can be rubbed into the eye, causing a swollen eye called Romaña's Sign.  

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