Biomedical Engineering Reference
In-Depth Information
identified species of Borrelia, capable of producing Lyme disease, will be
encountered in the near future. Lyme disease has been known to produce a
bewildering array of symptoms, particularly when it enters its chronic stage.
Thus, it has been confused with various chronic ailments and neurodegenera-
tive disorders of unknown etiology.
Relapsing fever is an infection characterized by recurring fevers often
accompanied by other systemic symptoms including fever, nausea, and rash.
It is caused by any of several genera of class Borrelia and is transmitted by
a tick or a louse. Tick-borne relapsing fever (TBRF) is transmitted by the
Ornithodoros tick, a genus in Class Argasidae, whose members are all
soft-bodied. It occurs in many areas of the world and is found in the United
States and Canada. Species associated with tick-borne relapsing fever are:
Borrelia duttoni, Borrelia parkerii,andBorrelia hermsii. Louse-borne relapsing
fever is caused by Borrelia recurrentis and occurs most often in Africa, Asia,
and Latin America.
Borrelia lonestari (Southern tick-associated rash illness or STARI) is prob-
ably the most redundant name in taxonomy, as it encompasses the abbreviation
STARI (loneSTARI) and its common geographic location (Texas, the Lone
Star state). Though the disease occurs in Texas, it can also be found in every
state between Texas and Maine.
Brachyspira pilosicoli, formerly Serpulina pilosicoli, is a colonizing spi-
rochete in the large intestine of pigs, and is occasionally found in humans. It
can produce diarrhea and rectal bleeding [47]. Brachyspira aalborgi accounts
for a small fraction (less than 1%) of cases of acute appendicitis.
Subspecies of Treponema pallidum are responsible for four diseases: syph-
ilis, pinta, bejel, and yaws. Syphilis, caused by Treponema pallidum (pallidum
variant), is transmitted sexually. It can also be transmitted from mother to infant
via transplacental infection or through physical exposure to the neonate during
its passage through the birth canal. Humans are the only animal reservoir
for syphilis. In adults, syphilis is a multistage disease, first appearing as a
primary skin lesion (chancre), followed weeks later by a rash and various sys-
temic symptoms (secondary syphilis), followed by a long latency period (years),
followed by a systemic illness affecting the brain, cardiovascular system,
and other organs (tertiary syphilis). The tertiary phase is non-infectious. Today,
syphilis is most common in developing countries [48].
Pinta, bejel, and yaws are non-venereal infections caused by subspecies
of Treponema pallidum (variants carateum, endemicum, and pertenue,
respectively). Each is primarily a skin disease that is spread by direct skin-
to-skin contact. Lesions beginning in the skin can spread to joints and bones.
Pinta occurs primarily in Central and South America. Yaws occurs primarily
in Asia, Africa, and South America. Most cases of bejel occur in the
Mediterranean region and Northern Africa and often involve the mouth and
oral mucosa, with mouth-to-mouth transmission.
Treponema denticola is a major cause of periodontitis.
