Saturday, August 23, 2014

Answer to Case 316

Answer:  Larval ticks, Ixodes species

These little guys were a bit hard to make out due to their small size, but you can nicely see several characteristic features, including 6 legs (versus the 8 legs of nymphs and adults), and - if you squint - a U-shaped anal groove, consistent with Ixodes species.
As mentioned by FP in Burlington, VT, Borrelia burgdorferi, the agent of Lyme disease, is not transmitted tranovarially from mother to larva. Therefore, larvae are not infected and cannot transmit this bacterium to humans.  Larvae can become infected when they take their first blood meal, after which they molt into nymphs. Therefore, unlike larvae, nymphs ARE capable of transmitting B. burgdorferi to humans, and present a particular hazard due to their small size which makes them easy to overlook.

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