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hrlichiosis is a bacterial infection
caused by exposure to the bacteria Ehrlichia
chaffeensis, or E.
chaffeensis.
The ehrlichiosis bacteria is
transmitted via a bite from the lone star tick. It was named after the army
base where the first known person was infected in Fort Chaffee, Arkansas.
Although the condition was known to occur in animals, it
wasn't until the mid-1980s that the first cases
were reported in humans.
The condition is treatable with antibiotics but it
can be potentially deadly for people who have other health conditions, such
as HIV, or who have had an organ transplant.
Share on PinterestThe lone star tick
can cause ehrlichiosis through bites. The tick is native to the eastern U.S.,
as well as Mexico.
Ehrlichiosis is a condition that occurs as the result of a
bite from a lone star tick, or Amblyomma
americanum. This tick can transmit bacteria called E. chaffeensis, which is also known
as rickettsia.
The lone star tick is prevalent in much of the eastern
United States (U.S.) and Mexico. In the U.S., cases have been reported from
coastal New England to western Texas.
While the condition is not considered as serious as
tick-transmitted Lyme disease, some cases
have been life-threatening.
People are more likely to be infected with ehrlichiosis in
the spring and summer months, as they spend more time outdoors.
The bacteria Ehrlichia
ewingii can also cause ehrlichiosis in humans. This bacteria is
very similar to E. chaffeensis and
will cause similar symptoms.
Symptoms of ehrlichiosis begin about 1-2 weeks after an
infected tick has bitten a person. While there are some common symptoms
associated with the disease, they can vary from person to person.
Symptoms of ehrlichiosis include:
- chills
- confusion
- diarrhea
- eye redness
- fever
- headache
- malaise, or feeling generally
unwell
- muscle pain
- nausea
- vomiting
According to the Centers for
Disease Control and Prevention (CDC), an estimated 60 percent of
children will experience a rash as a result of ehrlichiosis, compared to 30
percent of adults.
If a rash does occur, it usually does not itch. The rash
does not typically appear on the face but may appear on the palms and the soles
of the feet. Sometimes, the rash can look like a sunburn and
cause swelling, peeling, and redness.
Not all people who are bitten by a lone star tick will have
the symptoms associated with ehrlichiosis. Some people will have no symptoms or
symptoms too mild to recognize.
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Ehrlichiosis may initially cause similar symptoms to other
diseases related to tick bites. Examples of these include:
- anaplasmosis
- Lyme disease
- Rocky Mountain spotted fever
Unlike Rocky Mountain spotted fever and Lyme disease,
ehrlichiosis is most likely to affect older adults or people with a weakened
immune system.
Additionally, a rash is much less common in ehrlichiosis
than in other tick-related diseases. However, the lone star tick can also carry
bacteria known to cause Rocky Mountain spotted fever.
Share on PinterestSome possible
symptoms of ehrlichiosis are headaches, fever, chills, and nausea.
Ehrlichiosis can be difficult to diagnose, as the affected
person may not know they have a tick bite and the condition's symptoms are
similar to other illnesses, such as the flu.
A blood test is available to check for antibodies, which the
immune system develops in response to a tick bite. However, these do not
usually appear until a week after the bite.
A doctor will usually begin by asking about a person's
symptoms, and when they started noticing the symptoms. It is important to
determine if a person has recently been bitten by a tick or has visited an area
where ticks are common.
A doctor will also likely order laboratory tests. These
tests check for:
- increased liver enzymes
- decreased platelet count
- decreased white blood cell
count
During the first week of illness, a doctor may test a
person's blood for tick-borne pathogens using a polymerase chain reaction or
PCR assay.
Doctors can also examine blood under a microscope for the
presence of morulae, which are collections of Ehrlichia bacteria in white blood cells.
A doctor would ideally diagnose a person quickly, but if
symptoms continue for longer than 7-10 days, a doctor may order a test for
antibodies to the Ehrlichia bacteria.
Other tests for ehrlichiosis include an indirect
immunofluorescence assay (IFA). This test is rarely used and requires multiple
blood samples at different times to test for the body's immune response to the
organisms.
Doctors will commonly prescribe the antibiotic doxycycline
to treat ehrlichiosis.
The earlier a person takes this antibiotic, the less likely
it is that the condition will have long-lasting effects. A doctor may prescribe
antibiotics without having blood test results, to ensure a person who has been
bitten by a tick gets prompt treatment.
If symptoms do not improve within 1-3 days after beginning
treatment, the person probably does not have ehrlichiosis. However, it is
important that the person takes the full course of antibiotics for them to be
effective.
In rare instances, such as due to allergies or pregnancy, a
person may not be able to take doxycycline. In these situations, a doctor may
prescribe a different antibiotic, called rifampin.
If a person has been bitten by a tick but is not
experiencing symptoms, doctors do not usually recommend taking doxycycline as a
preventive measure. Doing so may delay the onset of the condition, which can
make the treatment slower.
Doctors also prescribe doxycycline to treat other diseases
that occur due to tick bites, including Rocky Mountain spotted fever and
anaplasmosis.
If a person does not receive treatment and their symptoms
progress, they can experience complications that include:
- prolonged fever
- adult respiratory distress
syndrome
- blood clotting disorders
- seizures and coma
- meningitis
If these complications occur, a doctor will treat them in
addition to the underlying infection.
Share on PinterestWearing clothing
that fully covers the limbs can help a person avoid a tick bite. Wearing
light-colored clothing can make it easier to spot ticks.
Prevention of ehrlichiosis involves taking steps to avoid
getting a tick bite.
If people live in an area with lone star ticks, they can
help prevent ehrlichiosis by:
- wearing long-sleeved shirts,
long pants, and hats when camping or hiking
- wearing light-colored clothing
to make ticks easier to spot
- checking clothing and skin for
ticks after being outdoors
- tucking pants into socks to
make it harder for ticks to reach the skin
- checking pets for ticks after
returning from the outdoors
Exposure to fields and wooded areas puts a person at
greatest risk for getting a tick bite.
According to the CDC, ehrlichiosis is fatal in 1.8 percent of
cases.
However, serious complications and fatality are more common
in individuals with a weakened immune system. Cancer treatments, HIV, prior organ
transplants, and some medications can compromise the immune system.
The majority of people make a full recovery from ehrlichiosis,
especially if they received antibiotics in good time and took them as
instructed.
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