Toxoplasmosis
is an infection you can get from a microscopic parasite called Toxoplasma
gondii. Although the infection generally causes a mild, symptomless illness in
people with healthy immune systems, it's risky during pregnancy because the
parasite may infect the placenta and your unborn baby.
Researchers
estimate that of the over 4 million births in the United States each year, between
400 and 4,000 babies are born with toxoplasmosis (known as congenital
toxoplasmosis). This infection can be mild or severe, causing stillbirth,
long-term structural and neurological damage, and other devastating effects. The
good news is there's a lot you can do to avoid becoming infected in the first
place.
What is
toxoplasmosis?
A
single-celled parasite called Toxoplasma gondii causes a disease known as
toxoplasmosis. While the parasite is found throughout the world, more than 60
million people in the United
States may be infected with the Toxoplasma
parasite. Of those who are infected, very few have symptoms because a healthy
person's immune system usually keeps the parasite from causing illness.
However, pregnant women and individuals who have compromised immune systems
should be cautious; for them, a Toxoplasma infection could cause serious health
problems.
How do
people get toxoplasmosis?
A
Toxoplasma infection occurs by:
Eating
undercooked, contaminated meat (especially pork, lamb, and venison).
Accidental
ingestion of undercooked, contaminated meat after handling it and not washing
hands thoroughly (Toxoplasma cannot be absorbed through intact skin).
Eating food
that was contaminated by knives, utensils, cutting boards and other foods that
have had contact with raw, contaminated meat.
Drinking
water contaminated with Toxoplasma gondii.
Accidentally
swallowing the parasite through contact with cat feces that contain Toxoplasma.
This might happen by
cleaning a
cat's litter box when the cat has shed Toxoplasma in its feces
touching or
ingesting anything that has come into contact with cat feces that contain
Toxoplasma
accidentally
ingesting contaminated soil (e.g., not washing hands after gardening or eating
unwashed fruits or vegetables from a garden)
Mother-to-child
(congenital) transmission.
Receiving
an infected organ transplant or infected blood via transfusion, though this is
rare.
What are
the signs and symptoms of toxoplasmosis?
Symptoms of
the infection vary.
Most people
who become infected with Toxoplasma gondii are not aware of it.
Some people
who have toxoplasmosis may feel as if they have the "flu" with
swollen lymph glands or muscle aches and pains that last for a month or more.
Severe
toxoplasmosis, causing damage to the brain, eyes, or other organs, can develop
from an acute Toxoplasma infection or one that had occurred earlier in life and
is now reactivated. Severe cases are more likely in individuals who have weak
immune systems, though occasionally, even persons with healthy immune systems
may experience eye damage from toxoplasmosis.
Signs and
symptoms of ocular toxoplasmosis can include reduced vision, blurred vision,
pain (often with bright light), redness of the eye, and sometimes tearing.
Ophthalmologists sometimes prescribe medicine to treat active disease. Whether
or not medication is recommended depends on the size of the eye lesion, the
location, and the characteristics of the lesion (acute active, versus chronic
not progressing). An ophthalmologist will provide the best care for ocular
toxoplasmosis.
Most
infants who are infected while still in the womb have no symptoms at birth, but
they may develop symptoms later in life. A small percentage of infected
newborns have serious eye or brain damage at birth.
Who is at
risk for developing severe toxoplasmosis?
People who
are most likely to develop severe toxoplasmosis include:
Infants
born to mothers who are newly infected with Toxoplasma gondii during or just
before pregnancy.
Persons
with severely weakened immune systems, such as individuals with HIV/AIDS, those
taking certain types of chemotherapy, and those who have recently received an
organ transplant.
What should
I do if I think I am at risk for severe toxoplasmosis?
If you are
planning to become pregnant, your health care provider may test you for
Toxoplasma gondii. If the test is positive it means you have already been
infected sometime in your life. There usually is little need to worry about
passing the infection to your baby. If the test is negative, take necessary
precautions to avoid infection (See below).
If you are
already pregnant, you and your health care provider should discuss your risk
for toxoplasmosis. Your health care provider may order a blood sample for
testing.
If you have
a weakened immune system, ask your doctor about having your blood tested for
Toxoplasma. If your test is positive, your doctor can tell you if and when you
need to take medicine to prevent the infection from reactivating. If your test
is negative, it means you have never been infected and you need to take
precautions to avoid infection. (See below).
What should
I do if I think I may have toxoplasmosis?
If you suspect that you may have
toxoplasmosis, talk to your health care provider. Your provider may order one
or more varieties of blood tests specific for toxoplasmosis. The results from
the different tests can help your provider determine if you have a Toxoplasma
gondii infection and whether it is a recent (acute) infection.
What is the
treatment for toxoplasmosis?
Once a
diagnosis of toxoplasmosis is confirmed, you and your health care provider can
discuss whether treatment is necessary. In an otherwise healthy person who is
not pregnant, treatment usually is not needed. If symptoms occur, they
typically go away within a few weeks to months. For pregnant women or persons
who have weakened immune systems, medications are available to treat
toxoplasmosis.
How can I
prevent toxoplasmosis?
There are
several general sanitation and food safety steps you can take to reduce your
chances of becoming infected with Toxoplasma gondii.
Cook food
to safe temperatures. A food thermometer should be used to measure the internal
temperature of cooked meat. Do not sample meat until it is cooked. USDA
recommends the following for meat preparation.
For Whole
Cuts of Meat (excluding poultry)
Cook to at
least 145° F (63° C) as measured with a food thermometer placed in the thickest
part of the meat, then allow the meat to rest* for three minutes before carving
or consuming.
For Ground
Meat (excluding poultry)
Cook to at
least 160° F (71° C); ground meats do not require a rest* time.
For All
Poultry (whole cuts and ground)
Cook to at
least 165° F (74° C), and for whole poultry allow the meat to rest* for three
minutes before carving or consuming.
*According
to USDA, "A 'rest time' is the amount of time the product remains at the
final temperature, after it has been removed from a grill, oven, or other heat
source. During the three minutes after meat is removed from the heat source,
its temperature remains constant or continues to rise, which destroys
pathogens."
Safe Food Handling
Freeze meat
for several days at sub-zero (0° F) temperatures before cooking to greatly
reduce chance of infection.
Peel or
wash fruits and vegetables thoroughly before eating.
Wash
cutting boards, dishes, counters, utensils, and hands with hot soapy water
after contact with raw meat, poultry, seafood, or unwashed fruits or
vegetables.
Wear gloves
when gardening and during any contact with soil or sand because it might be
contaminated with cat feces that contain Toxoplasma. Wash hands with soap and
warm water after gardening or contact with soil or sand.
Teach
children the importance of washing hands to prevent infection.
If I am at
risk, can I keep my cat?
Yes, you
may keep your cat if you are a person at risk for a severe infection (e.g., you
have a weakened immune system or are pregnant); however, there are several
safety precautions to avoid being exposed to Toxoplasma gondii :
Ensure the
cat litter box is changed daily. The Toxoplasma parasite does not become
infectious until 1 to 5 days after it is shed in a cat's feces.
If you are
pregnant or immunocompromised:
Avoid
changing cat litter if possible. If no one else can perform the task, wear
disposable gloves and wash your hands with soap and warm water afterwards.
Keep cats
indoors.
Do not
adopt or handle stray cats, especially kittens. Do not get a new cat while you
are pregnant.
Feed cats
only canned or dried commercial food or well-cooked table food, not raw or
undercooked meats.
Keep your
outdoor sandboxes covered.
Your veterinarian
can answer any other questions you may have regarding your cat and risk for
toxoplasmosis.
Once
infected with Toxoplasma is my cat always able to spread the infection to me?
No, cats
only spread Toxoplasma in their feces for a few weeks following infection with
the parasite. Like humans, cats rarely have symptoms when first infected, so
most people do not know if their cat has been infected. The infection will go
away on its own; therefore it does not help to have your cat or your cat's
feces tested for Toxoplasma.