to antibiotic therapy is often a diagnostic measure.
People who have human ehrlichiosis show
marked improvement in symptoms within 24 to
36 hours of beginning doxycycline treatment.
Most people recover fully with appropriate treat-
ment. Though some people develop mild illness
with few symptoms and fully recover without
treatment, untreated human ehrlichiosis can
become very serious very quickly because the
attack on the white blood cells compromises
immune function.
The risk for Ehrlichiainfection in the United
States is highest during the summer months (May
through October) when people are hiking and
camping in areas where ticks thrive. Measures to
prevent tick bites include wearing protective
clothing (such as long pants tucked into socks) or
using an appropriate insect repellent and checking
the SKINcarefully for ticks or signs of bites after
being in wooded areas.
See also GRANULOCYTE; MACROPHAGE; MONOCYTE;
ROCKYMOUNTAIN SPOTTED FEVER.
human papillomavirus (HPV) A family of more
than 100 strains of VIRUS, various strains of which
cause common WARTS, genital HPV infection, and
CERVICAL CANCER.
HPV and Common Warts
The strains of HPV that cause common warts are
mildly contagious and are more likely to spread to
different locations on a person’s body rather than
to other people. These strains include
- HPV-2, HPV-4, and HPV-7, which cause the
raised, rounded warts commonly found on the
hands and fingers - HPV-3 and HPV-7 cause flat, round warts that
typically grow on the face and backs of the
hands - HPV-1, which causes plantar warts on the plan-
tar surfaces, or soles, of the feet
Common warts typically do not cause symp-
toms other than their appearance, which people
tend to find cosmetically displeasing. Numerous
products and methods are available to remove
them. Over time, most warts left on their own
gradually recede and disappear as the IMMUNE SYS-
TEMdispenses with the virus that causes them.
Plantar warts, because they are on the walking
surface of the foot, often become painful. Plantar
warts are also more commonly spread among peo-
ple, typically via exposure in locker rooms and
shower rooms where people walk barefoot.Genital HPV Infection
Genital HPV INFECTIONis the most common of the
SEXUALLY TRANSMITTED DISEASES(STDS) in the United
States, causing new infection in over 5 million peo-
ple each year. More than 20 million people cur-
rently have HPV infections. More than 40 strains of
HPV cause genital HPV infection. These strains are
contagious among people and spread via sexual
contact (vaginal intercourse, anal intercourse, and
oral sex). Some strains produce no symptoms.
HPV-6 and HPV-11 produce fleshy growths,
often called genital warts, at the sites where the
virus enters the body. Commonly genital warts
grow on the tip of the PENIS, on the VULVAand at
the opening of the VAGINA, and around the ANUS.
Genital warts may also grow within the vagina
and on the CERVIXin women and on the SCROTUM
in men. Genital HPV may infect the MOUTHand
THROATthrough oral sex, though this is much less
common than genital infection.
Women may first learn they have genital HPV
infection during a ROUTINE MEDICAL EXAMINATION
when the health-care provider detects genital
warts inside the vagina and on the cervix. The
gynecologist may perform COLPOSCOPY, an exami-
nation of the interior vagina with a specialized
microscope, for further diagnostic assessment and
to remove tissue samples (biopsy). Genital warts
turn white after a few minutes when dabbed with
a mild acetic acid solution (vinegar), providing the
doctor with a quick diagnostic assessment. Labora-
tory examination of tissue samples from the
growths can confirm the diagnosis.
Because genital warts continue to grow, which
both cultivates and sheds the virus, doctors rec-
ommend treatment to remove them. Treatment
options include medications, cryosurgery (freez-
ing), electrocautery (burning), and laser therapy.
Genital warts tend to recur, however, as long as
the HPV infection remains present in the body.336 Infectious Diseases