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Taking the Bite Out of Insect- and Tickborne Diseases
transmit are often specific to the disease;
not all mosquitoes can transmit West Nile
virus, and different mosquitoes transmit
chikungunya virus.
“Further,” he adds, “persons living in
these areas may have more outdoor exposure to these bugs, and their dwellings may
not be adequately sealed to prevent the
mosquitoes’ entry. Once there is a large
population of persons or animal hosts
infected with agents (like dengue or West
Nile virus), these illnesses can proliferate
through these transmitting vector insects.”
But could that be changing? The
increasing temperatures and weather
changes, which includes a rise in precipitation, could allow for a shift or an expansion of disease-carrying insects’ territory,
says the Centers for Disease Control and
Prevention. More research is needed to
better predict if this will happen.
Other factors attributed to the rise of
transmitted vector-borne diseases include:
■M
igratory birds that carry disease
■A
n increase in the population of whitetailed deer, which carry disease transmitted by ticks
■H
ome construction in formerly unin-
How to avoid being bitten
The best way to stop the spread of vector-borne infections is to prevent insect and tick
bites in the first place. Follow these tips to avoid being exposed:
■ Remove
outside sources of standing water that provide a breeding ground for mos-
quitoes, such as birdbaths, planters and pet bowls.
■K
eep window and door screens in good condition.
■K
eep your yard free from piles of leaves, and mow the lawn often.
■A
void wooded, brushy or grassy areas that may be tick-infested.
■D
uring outdoor activities near where ticks and mosquitoes may live, wear light-colored
clothing so you can easily see and remove ticks and insects. Wear long sleeves and
long pants, tucking pant legs into your socks or shoes to cover skin. A hat helps, too.
■U
se an insect repellent on your skin or clothing. Repellents recommended for their
effectiveness include those containing DEET, picaridin, IR3535, permethrin and oil
of lemon eucalyptus. Avoid clip-on and wristband devices since they may not be as
effective as spray-on or rub-on DEET products. Use high-concentration DEET products
with care because some may cause neurological problems.
■ Check
your clothing and skin for ticks when you return indoors. Check pets, too.
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June 2015
habited wilderness areas where more
ticks and insects can be found
■ I nfected individuals who travel between
regions
■A
growing number of individuals with
compromised immune systems, which
makes them more susceptible to vectorborne infection
Who’s most at risk?
While reports of vector-borne infections
being transmitted in the United States
may garner media attention, such diseases
aren’t always easily transmittable. Lyme
disease spread by ticks, for example, has a
low transmission risk overall—including
in regions where Lyme is common.
“Individuals at greatest risk of developing symptoms and infection-related
complications include those who are 65
and older or have a weakened immune
system,” Dr. Davis says. “Persons with
chronic health conditions such as heart
and kidney diseases or on immunosuppressant medications may experience
more severe manifestations of disease.”
You’re also more likely to become
infected if you travel to regions where the
diseases are more common.
Below is a rundown of vector-borne
diseases that may pose a risk—albeit usually slight—to residents of North America and Puerto Rico.
■ Mosquitoes
West Nile virus usually pro-
duces mild or no symptoms
in healthy individuals. One
in five people have flulike symptoms and
skin rash. Sometimes fatigue and weakness can last for weeks or months. West
Nile virus is usually treated with overthe-counter pain relievers, but patients
with severe cases may be hospitalized
to receive intravenous f luids and pain
medication. In fewer than 1 percent of
cases, patients develop encephalitis or
meningitis.
THINKSTOCK
Not long ago, being bitten by a mosquito
didn’t mean much more than having to
deal with an itchy, swollen area of your
skin. These days, if you take certain news
reports to heart, a mosquito bite can leave
you with an infection you may never have
heard of until recently.
Despite the alarmist nature of the news,
your risk of contracting a vector-borne illness—infection spread by a bite from a
tick, a mosquito or another insect—is quite
low. But there is some truth behind the
news. Worldwide, more than 1 billion people are infected, and more than 1 million
die of diseases such as malaria and dengue
fever, transmitted by mosquitoes, according to the World Health Organization.
“Many insect-transmitted diseases like
dengue are most common in tropical and
subtropical countries that have lowerquality housing and inadequate diseaseprevention methods and healthcare,” says
Steven G. Davis, M.D., FACP, an infectious disease consultant at Baylor Medical
Center at Irving in Texas.
“The environment in these areas has
been most suitable for the proliferation of
particular insect vectors. These insects that
THINKSTOCK
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Chikungunya made the news last July
when two Florida residents were locally
infected by the virus, which is common in
parts of Africa and Asia and has recently
spread rapidly throughout the Caribbean.
Most infections of Americans are travel
related. Symptoms can include a fever,
headache, rash, muscle pain and debilitating
joint pain. They usually improve within a
week except for joint pain, which may linger
for months. Anti-inf lammatories can
relieve symptoms. Unlike most mosquitoes,
one of the species that transmits the chikungunya virus—called the Asian tiger mosquito—is active during the daytime.
Dengue fever has been reported over the
last 16 years in states such as Texas, Hawaii
and Florida. It produces high fever; severe
headache; severe eye pain; joint, muscle and
bone pain; rash; and mild bleeding. It’s usually treated with acetaminophen, rest and
fluids. Worsening symptoms that include
vomiting, abdominal pain and breathing
problems can cause circulatory system failure, shock and death if they’re not treated.
Encephalitis—inf lammation of the
brain—can cause flulike symptoms and
lead to seizures, coma and death if not
treated. Antivirals, anticonvulsants and
corticosteroids are used to treat the virus,
prevent seizures and reduce brain swelling.
■ Ticks
Lyme disease is perhaps the
best-known tickborne disease.
A bull’s-eye rash is a telltale sign
of infection, although it doesn’t appear in
every infected patient. Other symptoms
include fever, headache and fatigue. If
the infection isn’t treated, it can spread to
the joints. “Untreated Lyme disease can
also affect the heart and nervous system,
although it’s rarely ever fatal,” Dr. Davis
says. If caught early, Lyme disease is
highly treatable. Antibiotics are all that’s
usually needed to make a full recovery.
Rocky Mountain spotted fever produces
a spotted rash, as the name implies, but this
typically doesn’t show up until the sixth day
or later following the onset of symptoms,
and up to 15 percent of patients never
develop a rash. Other symptoms include
fever, nausea, vomiting, severe headache,
muscle pain and lack of appetite. “People
exposed to ticks in an endemic area require
prompt administration of an antibiotic like
doxycycline to prevent some tickborneassociated illnesses like Rocky Mountain
spotted fever to progress to a life-threatening form of the disease,” Dr. Davis says.
Colorado tick fever is so named because
up to 15 percent of campers in Colorado
have been exposed to the virus. The virus
is found less often in other states. It’s characterized by a fever that comes and goes,
rash, sensitivity to light and flulike
symptoms. Self-treatment with a
pain reliever is usually all that’s
needed. The illness typically goes away on
its own unless complications develop.
Southern tick-associated rash illness,
or STARI, transmitted by the lone star tick,
is sometimes mistaken for Lyme disease
since they both leave a red bull’s-eye mark.
As with most other tick-transmitted diseases, f lulike symptoms are common.
Doctors may treat the illness with antibiotics because of its resemblance to Lyme
disease, although it’s not known whether
antibiotics have any effect on STARI.
STARI symptoms tend to be less severe
than Lyme’s, and patients recover faster
than those with Lyme disease.
Babesiosis is transmitted by deer
ticks. Most cases occur in the Northeast
and upper Midwest. Healthy people who
contract babesiosis have either no or flulike symptoms. Prescription drugs are
available to treat the disease; most people
with no symptoms don’t need treatment.
Ehrlichiosis and anaplasmosis are
emerging infectious diseases in the United
States and other countries, says the
National Institute of Allergy and Infectious Diseases, with 1,761 cases reported
in 2010. Symptoms, if any, may resemble
those of the flu and are treated with antibiotics. If severe symptoms aren’t treated,
both diseases can be life threatening.
Powassan encephalitis can cause symp-
toms such as headache, fever, confusion,
partial paralysis and coma. No specific
treatment exists, but patients can benefit
from intravenous fluids, respiratory support and drugs to reduce brain swelling.
Tularemia appears in various ways,
depending on how bacteria enter the
body. Fever may be accompanied by skin
ulcers, lymph-gland swelling, eye irritation or inflammation, sore throat, mouth
ulcers, tonsillitis and, in rare cases, cough,
chest pain and difficulty breathing. Antibiotics can treat tularemia.
■ Triatomine
(kissing) bugs
Chagas disease causes more
disability and death in the
Western hemisphere than any
other parasitic disease. Chagas disease
that’s transmitted by insect is confined
to mostly rural areas in Mexico, Central
America and South America. In this country, blood-sucking triatomine bugs—also
called kissing bugs or cone-nose bugs—are
found mostly in the south, but infections are
rare. Early symptoms, if any, are similar to
those of the flu and may include swelling
around the bite or the eye area. Symptoms
can last a few weeks or months, after which
the disease goes into remission permanently
or reappears years or decades later. At that
time, 30 percent of infected individuals may
develop serious or life-threatening heart or
gastric complications. Drugs and other
treatments are used to kill parasites in the
blood and manage symptoms.
Don’t forget Fido
Humans aren’t the only ones who can
suffer adverse health consequences
related to insect bites. A mosquito bite
can infect your dog with the larvae of the
roundworm, triggering the life-threatening disease heartworm. The disease can
lead to damage to major organs, including the heart and lungs. Symptoms of
heartworm include fatigue, weight loss,
persistent cough and, as the disease progresses, a swollen belly. Drugs are available to prevent or control the disease.
June 2015
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