Symptoms of Toxoplasmosis

toxoplasmosis symptoms
© Verywell, 2018

Toxoplasmosis is not a disease we hear all that much about, but one that will affect nearly one of every 10 Americans at some point in their lives. Symptoms of toxoplasmosis tend to be mild and may include muscle pain, fever, fatigue, headache, and swollen lymph nodes, sometimes lasting for weeks. However, in the vast majority of cases, there will be few, if any, obvious signs of infection.

The disease really only become serious when it is passed from mother to child during pregnancy or when it occurs in people with advanced HIV infection. In both cases, Toxoplasma gondii, the parasite that causes the disease, can reap severe damage to the brain, eyes, lungs, and other major organs. Within this population of people, if not addressed, toxoplasmosis can lead to severe physical and mental disability and even death.

Frequent Symptoms

In people with normal immune systems, up to 90 percent of cases of toxoplasmosis will be entirely asymptomatic (without symptoms). As such, most people will not even be aware that they’ve been infected.

If acute symptoms do appear, they will most often be mild and may include:

  • Low-grade fever (lower than 100.4o F)
  • Headache
  • Fatigue
  • Swollen lymph nodes (lymphadenopathy)
  • Muscle aches (myalgia)
  • A general feeling of unwellness (malaise)

While symptoms rarely get worse, they can sometimes persist for weeks on end.

Moreover, because the symptoms are so non-specific, they can easily be mistaken for other illnesses, such as the flu, infectious mononucleosis, or even Lyme disease. While acute toxoplasmosis can be differentiated to some degree by the absence of certain symptoms (such as a cough, sore throat, or rash), it can only be confirmed with a blood test or an analysis of cerebrospinal fluid or a tissue sample.

Once an infection has occurred, the body's immune defenses will gradually bring it under control. The disease will then move in a latent phase in which the parasite forms a cyst, known as a bradyzoite, on different parts of the body (including the brain, heart, eyes, liver, and lungs). Unless the immune defenses are compromised, the bradyzoites can remain in a dormant state for a lifetime.

Congenital Symptoms

While T. gondii is typically transmitted by contaminated food or by accidental hand-to-mouth contact with cat feces, it can also be passed from mother to child during pregnancy.

The condition, known as congenital toxoplasmosis, affects as many as one of every 10,000 pregnancies in the United States, according to a report from the American Academy of Pediatric’s Committee on Infectious Diseases. While most cases are caused when a mother is newly infected during pregnancy, others may be the result of a reactivation of a past infection (most often in mothers with HIV).

Risk of Birth Defects

While the risk of T. gondii transmission tends to increase during the latter stages of pregnancy, the potential harm may be greatest during the early part of the first trimester. This is when the fetal stem cells are just starting to specialize and develop into cells of the brain, heart, and other organs.

Damage during this early stage of development can be catastrophic. In rare instances, it can lead to an irreversible birth defect known as microcephaly (in which the baby is born with an abnormally small head and brain) and macrocephaly (where the baby is born is born with an abnormally large head and brain).

Common Symptoms

Congenital toxoplasmosis can also increase the risk of miscarriage and stillbirth. Nearly 50 percent of cases will result in premature birth accompanied by low birth weight, most often when the baby has been infected before the 24th week of gestation.

Infants with severe toxoplasmosis will usually have symptoms at birth or develop them within the first six months of life.

Most of the symptoms will be related to a triad of complications commonly seen in severe cases, including hydrocephalus ("water on the brain"), chorioretinitis (inflammation of the choroid and retina of the eye), and intracranial calcification (abnormal deposits of calcium in the brain due to the infection).

Symptoms can include:

  • Jaundice (yellowing of the skin and eyes)
  • Vomiting
  • Diarrhea
  • Feeding problems, including difficulty swallowing (dysphagia)
  • Blurring and vision problems
  • Hearing loss
  • Speech problems (dysarthria)
  • Problem with walking, coordination, and motor skills
  • Developmental delays
  • Intellectual disability (mild to severe)
  • Seizures

Complications With HIV

Toxoplasmosis rarely affects people with intact immune symptoms. It is only when the immune system is compromised that the more serious features of the disease can appear. While this can happen to organ recipients or people undergoing cancer treatment (both groups of whom are treated with immune suppressive drugs), the group most affected are those diagnosed with AIDS.

Toxoplasmic Encephalitis

AIDS is defined as the stage of HIV infection in which a person has less than 200 CD4 T-cells (a type of white blood cell central to the immune defense). As such, a condition like toxoplasmic encephalitis (toxoplasmosis of the brain) is considered AIDS-defining, as it rarely seen outside of an AIDS diagnosis.

The brain is, in fact, the organ most affected when T. gondii reactivates. It is the site where bradyzoites not only proliferate but persist, often for the lifetime of the host. Without the immune defenses to protect itself, the brain and central nervous system can be severe and sometimes irreversibly harmed.

Symptoms of toxoplasmic encephalitis include:

  • Headache
  • Fever
  • Muscle weakness
  • Confusion
  • Speech and memory problems
  • Seizures
  • Personality changes
  • Dementia
  • Schizophrenia
  • Coma

Other Disease Complications

The brain is not the only organ that can be affected by toxoplasmosis. If T. gondii reactivates in the eye (ocular toxoplasmosis), it can cause blurring, redness, eye pain, excessive tearing, blind spots (scotomas), and extreme light sensitivity.

Reactivation in the lungs (pulmonary toxoplasmosis) can manifest with fever, shortness of breath (dyspnea), wheezing, chest tightness, and a non-productive cough.

If left untreated, toxoplasmosis in people with HIV will almost invariably lead to death.

When to See a Doctor

Since most people will not know they have toxoplasmosis, they will unlikely seek care and, in most cases, really won't need to.

However, if you are pregnant and have been diagnosed with a current infection, you will need to see a doctor to determine if your baby has been infected. This may involve an amniocentesis (in which a needle is used to remove fluid from the amniotic sac to check for infection) or an ultrasound (to check for symptoms such as hydrocephalus).

If a positive diagnosis is received, you will be prescribed antibiotics sometime during the second trimester to reduce your baby's risk of complications. If you have HIV, you may be started earlier.

Sources:

Centers for Disease Control and Prevention (CDC). "Parasites - Toxoplasmosis (Toxoplasma Infection)." Atlanta, Georgia; July 10, 2014.

Lee, S. and Lee. T. "Toxoplasmic Encephalitis in Patient with Acquired Immunodeficiency Syndrome." Brain Tumor Res Treat. 2017; 5(1): 34-36. DOI: 10.1479/btrt.2017.5.1.34.

Maldonado, J. and Read, S. "Diagnosis, Treatment, and Prevention of Congenital Toxoplasmosis in the United States." Pediatrics. 2017; 139(2): e20163860. DOI: 10.1542/peds.2016-3860.

McAuley, J. "Congenital Toxoplasmosis." J Pediatric Infect Dis Soc. 2014; 3(Suppl 1): S30- S35. DOI: 10.1093/jpids/piu077.

Park, Y. and Nam. H. "Clinical Features and Treatment of Ocular Toxoplasmosis." Korean J Parasitol. 2013; 51(4): 393-399. DOI: 10.3357/kjp.2013.51.4.393.