Encyclopedia of Health and Medicine

342 Infectious Diseases
called erythema migrans. The rash starts at the site
of the bite and looks somewhat like a bull’s eye
around the bite. The rash expands over five to
seven days, becoming large and raised, and may
burn or hurt. The rash may also spread to other
parts of the body.
Other symptoms may include
• FEVER
• HEADACHE
• MUSCLE aches and JOINT PAIN
• LYMPHADENOPATHY (swollen LYMPH nodes)
Though these symptoms, including the rash,
will go away without treatment, the infection
remains in the body and extends its involvement.
Untreated Lyme disease may cause
• NEUROPATHY (tingling and numbness in PERIPH-
ERAL NERVES), ENCEPHALOPATHY (disturbances of
BRAIN function), and MENINGITIS (INFLAMMATION of
the membranes that surround the brain and
SPINAL CORD)
• BELL’S PALSY (PARALYSIS of the facial muscles)
• arthritis (inflammation of the joints), particularly
in the knees and hips
• PALPITATIONS, dizziness, and changes in BLOOD
PRESSURE resulting from cardiovascular involvement
BLOOD tests confirm the diagnosis. Treatment
with ANTIBIOTIC MEDICATIONS eliminates the infection.
People who receive early diagnosis and treatment
nearly always recover quickly and fully.
When the infection has spread to multiple body
systems, residual effects may continue for several
months.
ANTIBIOTIC MEDICATIONS TO TREAT LYME DISEASE
amoxicillin
ampicillin
azithromycin
cefuroxime
doxycycline
Tick precautions when hiking or camping in
tick-infested areas are the most effective means of
preventing Lyme disease. Such precautions
include wearing long pants tucked into high boots
or socks to prevent ticks from attaching to the
lower legs, examining the entire body for ticks
after activities of possible exposure, and immediately
removing any attached ticks. Because early
treatment can avert serious complications, anyone
bitten by a tick who develops rash or flulike symptoms
should receive a medical evaluation for the
possibility of Lyme disease or for ANTIBIOTIC PROPHY-
LAXIS (preventive antibiotic therapy).
See also ROCKY MOUNTAIN SPOTTED FEVER.
malaria An illness that results from INFECTION
with one of four Plasmodium parasites: Plasmodium
malariae, P. ovale, P. vivax, and P. falciparum. Bites
from the female Anopheles mosquito spread the
infection from one person to another. Though
malaria has not occurred naturally in the United
States since the 1950s, travel to or immigration
from regions of the world where malaria is
endemic results in about 1300 cases of malaria in
the United States each year.
Malaria can be serious or fatal without treatment
and is a major cause of death worldwide,
particularly in developing nations with limited
access to medical resources. Malaria is particularly
devastating in the Sahara and sub-Sahara regions
of the African continent, where it claims the life of
one child every 30 seconds. Extreme poverty, lack
of medical resources, and environmental conditions
in which mosquito populations flourish converge
in these regions, maintaining an endemic
presence of malaria that is the most extensive in
the world.
Plasmodium parasites initially infect LIVER cells,
where they reproduce. They then migrate into
erythrocytes (red BLOOD cells), entering the blood
circulation. The INCUBATION PERIOD ranges from 8
days to several months, after which flulike symptoms
emerge that include
• FEVER and chills
• HEADACHE
• MUSCLE aches
• NAUSEA, VOMITING, and DIARRHEA
• JAUNDICE (yellow discoloration of the SKIN)
• tiredness or fatigue
Microscopic examination of a blood sample
shows the parasites, confirming the diagnosis.