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Description:This photograph depicts a dorsal view of a male cayenne tick, Amblyomma cajennense. This tick specie is a known North, Central and South American vector of Rickettsia rickettsii, which is the etiologic agent of Rocky Mountain spotted fever (RMSF).

Note the large scutum, or “shield”, which unlike its female counterpart, covers the entire surface of this specimen’s dorsal abdomen. See PHIL 10870 and 10871, for an image depicting a dorsal view of a female A. cajennense tick. Like the female of the specie, the male also possesses four pairs of legs, placing it in the class of Arachnida, as are spiders and scorpions. Two of this specimen’s legs are tucked up underneath its abdomen.
Rocky Mountain spotted fever, like all rickettsial infections, is classified as a zoonosis. Zoonoses are diseases of animals that can be transmitted to humans. Many zoonotic diseases require a biological vector (e.g., a mosquito, tick, flea, or mite) in order to be transmitted from the animal host to the human host. In the case of RMSF, ticks are the natural hosts, serving as both reservoirs and vectors of R. rickettsii. Ticks transmit the organism to vertebrates primarily by their bite. Less commonly, infections may occur following exposure to crushed tick tissues, fluids, or tick feces.

High Resolution: Click here for hi-resolution image (30.39 MB)
Content Providers(s):CDC/ Dr. Christopher Paddock
Creation Date:2008
Photo Credit:James Gathany
Links:CDC – Div. of Viral and Rickettsial Diseases National Center for Zoonotic, Vector-Borne, and Enteric Diseases; Rocky Mountain Spotted Fever
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Copyright Restrictions:None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.