Caves Reported to have Relapsing Fever Vectors
Relapsing fever ticks are known from all the caves west of Red
Bud Isle in West Lake Hills, Travis County, Texas. Stay out of these caves, they
aren't worth the risk. Bill Elliott and Peter Sprouse got Relapsing Fever in
Little Black Hole, summer 1994.
by Alicia Wisener Gale
excerpted via OCR from The TEXAS CAVER June 1976
Borrelia Recurrentis is a spirochete that causes
Relapsing Fever. It is transmitted by soft ticks of the genus Ornithodoros and
it has recently been found in the body louse, pediculus humanus. Ticks
such as O. turicata, O. hermsi, O. parkeri, and O. talaje are the
most frequent vectors and are found all over the western US. The disease may be
transmitted directly through tick bite or indirectly through coxal fluid. These
ticks are fairly common inhabitants of caves.
Relapsing Fever symptoms are the same whether transmitted by
tick or louse. Three to ten days after transmission, the patient undergoes a
febril stage (fever) in which large numbers of Spirochetes are found in the
blood, and, in a fourth of those cases, in the urine as well. After
approximately 4 days, the fever declines as the number of spirochetes in the
blood also drop. During the next 3 to 10 days, an afebrile stage occurs during
which the organism becomes less motile and assumes bizarre forms. A second
febrile stage then occurs during which spirochetes reappear in the blood, but in
fewer numbers. There may be from 3 to 10 recurring febrile attacks which means a
disease lasting from as few as 21 days to as many as 140 days (5 months). In
fatal cases, Borrelia recurrentis may be found in the spleen and liver;
with hemorrhagic lesions in the gastrointestinal tract and kidney.
Diagnosis of the disease depends on isolation of the spirochete
from the blood either by darkfield microscopy, common microscopy, or animal
inoculation, or Agglutination Reactions with Proteus OXK agglutimins. B.
recurrentis is a flexible spiral organism from 8 to 30 microns in length
with 5 to 10 loosely wound spirals. The spirochete is a motile one that stains
well with Wrights, Giemsa, and other stains containing aniline dyes. Under the
electron microscope, a central axial filament surrounded by a protoplasm sheath
can be seen. Fibrils resembling flagella appear to arise from this axial
filament. Division is believed to be by transverse fission. B. recurrentis
grows well on chick embryo, but cultivation on artificial media is usually not
successful. The organism is a very viable one and remain virulent for many
months at refrigerator and even dry ice temperatures.
There is no immunization against relapsing fever at at the
present. Some recovered patients resist disease 2 to 5 years later, while others
remain resistant only so long as B. recurrens
remained in the tissues. Serum agglutinins and antibodies can be demonstrated
during the course of the disease and it is possible to follow the febrile and
afebrile phases through the varying reactivity of these antibodies. Besides the
body's natural defense through antibodies, certain drugs have proven useful.
Trivalent arsenical, particularly neoarsphenamine, were used until the advent of
penicillin and tetracycline. These drugs are useful only in very large doses
(i.e. 1 million units per day). The drugs of choice are chlortetracycline and
oxytetracycline. Exacerbation of symptoms frequently occurs following initiation
of drug therapy.