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Salem Health: Infectious Diseases & Conditions, 2nd Edition

Toxoplasmosis

by Laurie Rosenblum

Category: Diseases and conditions

Anatomy or system affected: All

Definition

Toxoplasmosis is an infection caused by a tiny organism called a protozoan. Many people are infected with this protozoan, but few people have any related symptoms or problems.

Causes

Toxoplasmosis is passed from animals to humans. People can contract it by touching contaminated cat feces or something that has had contact with cat feces, such as soil or insects; by eating undercooked, infected meat; and by touching one’s mouth after touching contaminated meat. In rare cases, receiving a blood transfusion or an organ transplant can lead to the infection.

A pregnant woman who gets toxoplasmosis for the first time has a 15 to 60 percent chance of passing it to her fetus. Active infection usually occurs only once in a person’s life, although the protozoan remains inactive in the body. If a woman has become immune to the infection before getting pregnant, she will not pass the condition to her fetus.

Risk Factors

People at risk for having symptoms from toxoplasmosis are infants born to women who are first exposed to toxoplasmosis just before becomingpregnant or during pregnancy; people with weakened immune systems fromconditions such as human immunodeficiency virus infection, acquired immunodeficiency syndrome, and cancer; and those who have had an organ transplant.

Symptoms

Most people do not have symptoms, but those who do may experience swollen lymph nodes, a fever, fatigue, a sore throat, muscle aches and pains, and a rash. People with weakened immune systems may develop toxoplasmosis infections in multiple organs. Infection is most common in the brain (encephalitis), eye (chorioretinitis), and lung (pneumonitis). Symptoms may include a fever; seizures; a headache; visual defects; problems with speech, movement, or thinking; mental illness; and shortness of breath.

In infants, the severity of symptoms depends on when during pregnancy the mother became infected. If infection occurs during the first three months of pregnancy, the fetus is less likely to become infected, but if the fetus does becoming infected, symptoms will be much more severe. The fetus is more likely to become infected during the last six months of pregnancy, but symptoms will be less serious. Toxoplasmosis can also cause miscarriage or stillbirth.

About one in ten infants born with toxoplasmosis has severe symptoms, including visual defects because of eye infections (chorioretinitis), enlarged liver and spleen, jaundice (yellow skin and eyes), pneumonitis, myocarditis (inflammation of the heart), brain malformations, mental retardation, cerebral palsy, and seizures. Many infants infected with toxoplasmosis who seem healthy at birth may develop problems months or years later. These include visual defects, hearing loss, learning disabilities, and seizures.

Screening and Diagnosis

A doctor will ask about symptoms and medical history and will perform a physical exam. Blood tests are done to look for antibodies produced by the body to fight the toxoplasmosis. Other lab tests are done to look for the protozoan itself. Pregnant women who are infected will undergo prenatal tests, including ultrasound and amniocentesis, to determine if the fetus is infected.

Treatment and Therapy

People who are healthy and not pregnant do not need treatment. Symptoms usually disappear within a few weeks or months. People with a weakened immune system are treated with antitoxoplasmosis medicines for several months. If a pregnant woman is infected but the fetus is not, the woman is usually given the antibiotic spiramycin. This medicine can decrease the chance of the fetus becoming infected by about 60 percent.

Fetuses with confirmed toxoplasmosis infections are treated by giving the pregnant woman a combination of the following medications: spiramycin, pyrimethamine, sulfadiazine, and folinic acid. These drugs can reduce the severity of, but not eliminate, a newborn’s symptoms. Once born, the infant will be given different combinations of medicines.

Prevention and Outcomes

Women who are pregnant or considering becoming pregnant should consult a physician about having ablood test to determine if they are immune to toxoplasmosis (which would indicate a previous exposure). If not immune, women should take the following steps to avoid sources of toxoplasmosis: Avoid eating raw or undercooked meat (if one touches raw meat, avoidtouching one’s eyes, mouth, or nose); wash one’s hands and cutting boards, knives, and sink with soap andwarm water; and wash all raw vegetables and fruits.

One should also avoid emptying a cat’s litter box; avoid children’s sand boxes because they are often used by cats as a litter box; avoid feeding a cat raw or undercooked meat; and keep one’s cat indoors to prevent it from hunting rodents or birds that could be infected. Also, when gardening, one should wear gloves; keep one’s hands away from one’s eyes, mouth, and nose; and wash one’s hands when finished. These steps also apply to persons with weakened immune systems.

Further Reading

1 

Ambroise-Thomas, Pierre, and Eskild Petersen, eds. Congenital Toxoplasmosis: Scientific Background, Clinical Management, and Control. New York: Springer, 2000.

2 

American Congress of Obstetricians and Gynecologists. “Perinatal Viral and Parasitic Infections.” ACOG Practice Bulletin, no. 20 (2000). Available at http://www.acog.org.

3 

Despommier, Dickson D., et al. Parasitic Diseases. 5th ed. New York: Apple Tree, 2006.

4 

Joynson, David H. M., and Tim G. Wreghitt, eds. Toxoplasmosis: A Comprehensive Clinical Guide. Rev. ed. New York: Cambridge University Press, 2005.

5 

Martin, Richard J., Avroy A. Fanaroff, and Michele C. Walsh, eds. Fanaroff and Martin’s Neonatal-Perinatal Medicine: Diseases of the Fetus and Infant. 2 vols. 8th ed. Philadelphia: Mosby/Elsevier, 2006.

6 

Parker, James N., and Philip M. Parker, eds. The Official Patient’s Sourcebook on Toxoplasmosis. San Diego, Calif.: Icon Health, 2002.

Web Sites of Interest

Center for the Evaluation of Risks to Human Reproduction

http://cerhr.niehs.nih.gov

Centers for Disease Control and Prevention

http://www.cdc.gov/parasites

Companion Animal Parasite Council

http://www.capcvet.org

March of Dimes

http://www.modimes.org

National Center for Emerging and Zoonotic Infectious Diseases

http://www.cdc.gov/ncezid

Women’s Health Matters

http://www.womenshealthmatters.ca

See also: AIDS; Antibiotics: Types; Cats and infectious disease; Childbirth and infectious disease; Diagnosis of protozoan diseases; Encephalitis; Fecal-oral route of transmission; Fever; Food-borne illness and disease; HIV; Parasitic diseases; Parasitology; Pregnancy and infectious disease; Prevention of protozoan diseases; Protozoan diseases; Toxocariasis; Treatment of protozoan diseases; Zoonotic diseases.

Citation Types

Type
Format
MLA 9th
Rosenblum, Laurie. "Toxoplasmosis." Salem Health: Infectious Diseases & Conditions, 2nd Edition, edited by H. Bradford Hawley, Salem Press, 2020. Salem Online, online.salempress.com/articleDetails.do?articleName=Infect2e_0560.
APA 7th
Rosenblum, L. (2020). Toxoplasmosis. In H. B. Hawley (Ed.), Salem Health: Infectious Diseases & Conditions, 2nd Edition. Salem Press. online.salempress.com.
CMOS 17th
Rosenblum, Laurie. "Toxoplasmosis." Edited by H. Bradford Hawley. Salem Health: Infectious Diseases & Conditions, 2nd Edition. Hackensack: Salem Press, 2020. Accessed December 14, 2025. online.salempress.com.