Toxoplasmosis and pregnancy

Toxoplasmosis is an infectious disease caused by a parasite (an organism that depends on or is sustained by a host organism). Toxoplasmosis is found in humans, most birds and many different types of mammals. For humans, this common infection usually does not cause symptoms. If you contract toxoplasmosis while you're pregnant, however, your unborn child may develop serious medical problems. Miscarriage, premature birth or stillbirth are also possible.

In the United States, toxoplasmosis is considered one of the most prevalent infectious diseases. In fact, in some populations more than 50 percent of people have been infected.


Causes/associated factors
Toxoplasmosis is caused by the parasite Toxoplasma gondii. Members of the cat family are the only hosts that excrete eggs formed by the parasite. When a cat is infected (by eating undercooked meat or infected mice, for example), the parasite lives in the cat's intestines and produces egg cells. For up to two weeks, these egg cells enter the environment through the cat's feces. After one to five days outside the cat's body, the egg cells are capable of infecting other animals or humans. The egg cells can survive in a favorable environment such as warm, moist soil for more than a year.
If ingested, the egg cells develop and infect tissues throughout the body, sometimes forming protective cysts. In healthy people and animals, the immune system stops the infection but the cysts remain in body tissues such as the brain, heart and muscles. In turn, this tissue can be a source of infection if it's later ingested or transplanted.

You develop immunity to the toxoplasmosis parasite after having an initial infection. Unless you have a weak immune system, a second bout with the infection is rare.


Transmission
You can be infected with toxoplasmosis in a variety of ways, such as:
touching the feces of an infected cat (which may contain the organism), handling litter boxes improperly, playing in sandboxes or yards where cats have left stools, or drinking water contaminated with cat feces
through contact with insects, such as flies or cockroaches, that might have been exposed to cat feces or ingested foods contaminated by cat feces
eating raw or undercooked meat from infected animals (especially pork, lamb and wild game), drinking unpasteurized milk (especially goat's milk) or eating raw or undercooked eggs. (Infected meat cannot cause an infection if it's cooked adequately, smoked or cured.)
through a lab accident
rarely, through a blood transfusion or organ transplant
If the initial infection occurs during pregnancy, you can pass the infection to your unborn baby through your blood, which circulates through the placenta. Other modes of transmission may also exist, but are currently unknown.

The incubation period (time from exposure until symptoms appear) ranges from five to 23 days.


The pregnancy connection
Again, if you contract toxoplasmosis for the first time during pregnancy, the infection can cross the placenta and affect your developing baby. Rarely, this can happen if you contracted toxoplasmosis before conception. The risk for this type of transmission is greater if your immune system is not functioning normally. In the United States, as many as 4,000 infants may be born with congenital toxoplasmosis each year.
The risk of transmission is highest during the third trimester (about 60 percent), but this is associated with the least severe form of toxoplasmosis. On the other hand, the risk for transmission is lowest in the first trimester (10 to 15 percent), but this leads to more severe disease. The mother's symptoms are often mild or nonexistent. Most babies born with toxoplasmosis show no symptoms at birth but may develop potentially serious problems later.


Signs/symptoms
Women who develop toxoplasmosis for the first time during pregnancy generally have no symptoms. If symptoms appear, they may include:
swollen lymph nodes, especially in the neck
fatigue
muscle or joint pain
sore throat
rash
fever
enlarged liver and spleen
rarely, visual changes due to retinitis (inflammation of the retina, the light-sensitive tissue found at the back of the eye that sends nerve impulses to the brain)
rarely, encephalitis (inflammation of the membrane covering the brain)
Toxoplasmosis may lead to miscarriage, premature birth or stillbirth. At birth, most infants infected with congenital toxoplasmosis often have no symptoms. If symptoms are present at birth, they may include:

low birth weight
enlarged liver and spleen
jaundice (yellowing of the skin or whites of the eyes)
anemia (a condition marked by a decreased number of red blood cells or hemoglobin, a protein in red blood cells that contains iron)
rash
feeding problems
seizures
hydrocephalus (fluid accumulation in the brain)
microcephalus (an abnormally small head)
A child born with congenital toxoplasmosis may eventually develop:

visual impairment due to retinitis
hearing disorders
developmental delays
mental retardation
seizures

Diagnosis
To determine if you have been infected with toxoplasmosis, your blood can be tested for antibodies (compounds that help to neutralize or destroy what the body perceives as foreign substances in the blood) to the toxoplasmosis organism. Your doctor may recommend antibody testing before you become pregnant to see if you're immune to toxoplasmosis. If you test negative, you can be retested during pregnancy if you've been exposed to the infection. If the second test is positive, you'll be diagnosed with toxoplasmosis. During the initial infection, the parasite may also be detected in your blood.
If you contract toxoplasmosis for the first time up to six months before conception or during pregnancy, testing blood from the fetus or the umbilical cord can help your doctor determine if the baby is infected. Ultrasound (using sound waves to create an image of internal body parts) may be used to detect any changes in the baby's brain or other abnormalities caused by the infection. In some cases, amniocentesis (withdrawing amniotic fluid, the fluid that protects the fetus in the womb, for examination) is recommended. If the fetus is diagnosed with toxoplasmosis, the doctor may do a series of computed tomography scans (CT scans; computer-generated, cross-sectional pictures of internal body parts) to determine the extent of the infection.

Unfortunately, there are no reliable tests to determine if a cat is passing the egg cells in its feces.


Treatment
If you develop an infection during pregnancy, the doctor may prescribe spiramycin, which may help prevent the infection in your baby. If your baby contracts the infection, a combination of medications that includes a sulfonamide drug, pyrimethamine and folinic acid will be prescribed. This combination of medications is alternated with spiramycin every three weeks until the end of your pregnancy to help treat the infection in your baby. Of course, treatment my vary depending on your particular situation and further research developments.
After the baby is born, he or she will be given the combination of a sulfonamide medication, pyrimethamine and folinic acid for one year or until it's certain that he or she does not have congenital toxoplasmosis.


Prevention
To prevent toxoplasmosis, keep the following suggestions in mind.
Avoid contact with cat feces. If you have a cat, ask someone in your household to change the litter box daily and routinely disinfect it with hot (almost boiling) water. Remind the person to wear gloves and wash his or her hands thoroughly after the chore is finished.

If you have a cat, don't feed it raw meat and keep it indoors to discourage hunting.

Don't bring a new kitten or cat into your home. It's not necessary to get rid of a cat you already have, however. Studies have shown that most women who've had a cat for a while are already immune to toxoplasmosis.

Avoid handling stray cats and kittens.

Protect play areas and sandboxes from cat feces.

Wear gloves when gardening, and wash your hands after having contact with soil or sand in case it's been contaminated with cat feces.

Peel or thoroughly wash fruits and vegetables before eating in case they've been in contact with soil contaminated with cat feces.

Wash your hands before preparing food or eating.

Do not drink unpasteurized milk (especially goat's milk) or eat raw or undercooked eggs or meat (especially pork, lamb and wild game).

Be careful when handling raw meat, poultry, seafood and unwashed fruits and vegetables. Avoid touching your face. When finished, always wash your hands, kitchen surfaces and utensils thoroughly with hot soapy water.

To kill Toxoplasma cysts, cook meat thoroughly to an internal temperature of at least 160°F. It should no longer be pink in the center.

Keep flies and other insects that may have been exposed to cat feces away from your food.