Marina was 26 weeks pregnant when she had her routine prenatal blood test. The results showed an alteration in antibodies for toxoplasmosis. She had never heard much about it, only vaguely knew that "it had something to do with cats." At the appointment, several questions came to mind: is this serious? Is my baby at risk? Should I have gotten rid of my cat? This report brings together the answers that she, and anyone in the same situation, needs to hear.

"The data and clinical case cited in this article are fictional and are merely illustrative, serving to facilitate understanding of the topic addressed."

What is toxoplasmosis

Toxoplasmosis is an infection caused by a parasite called Toxoplasma gondii. It is one of the most common parasitic infections in the world. In many countries, a good portion of the adult population has had contact with this parasite at some point in their lives, often without ever realizing it.

The parasite completes part of its life cycle inside cats, but contamination of people usually happens in other ways, which we will detail shortly.

How we get contaminated

The main forms of transmission are:

  • Eating raw or undercooked meat (mainly pork, lamb, and game meat), which may contain cysts of the parasite.
  • Eating poorly washed fruits, vegetables, and legumes, contaminated by soil or water with feces from an infected cat.
  • Having contact with contaminated cat feces, either when cleaning the litter box or when working in the garden soil.
  • Drinking contaminated water, something rarer, but possible in regions without adequate water treatment.
  • In much rarer situations, blood transfusion or organ transplant.

Important to make clear: direct contact with the cat (petting, sleeping near it) does not transmit the disease. The risk is in the animal's feces, especially when it is young and has had a recent infection.

In a healthy person: what usually happens

In the vast majority of people with a properly functioning immune system, toxoplasmosis goes almost unnoticed. About 80 to 90% of cases cause no symptoms at all.

When signs appear, they tend to be very mild and similar to a light viral infection:

  • Fatigue
  • Low fever
  • Headache
  • Muscle pain
  • Swollen glands (lymph nodes), mainly in the neck

These symptoms usually disappear on their own within a few weeks, without need for treatment, and the person develops a kind of "immune memory" that protects them from new infections by the same parasite.

The situation changes for people with low immunity (for example, undergoing cancer treatment, living with uncontrolled HIV, or using immunosuppressive medications). In these cases, the infection can be more serious and affect the brain, eyes, or lungs, requiring close medical follow-up.

Why pregnancy changes everything

During pregnancy, the concern is not so much about the mother's health, which usually follows the mild pattern described above, but about the possibility of the parasite crossing the placenta and reaching the baby. This is what is called congenital toxoplasmosis.

The risk of transmission to the baby varies depending on the stage of pregnancy:

  • Early in pregnancy (first trimester), the chance of the parasite passing to the baby is lower, but if it happens, the consequences tend to be more severe.
  • Late in pregnancy (third trimester), transmission is more frequent, but the effects tend to be milder.

This is why, contrary to what may seem intuitive, the greater risk of damage is not always linked to the time of highest chance of transmission.

A reassuring point: if the woman already had contact with the parasite before becoming pregnant (which shows up on the blood test), she is normally already protected, and the risk to the baby in this pregnancy is quite low.

What can happen to the baby

When the infection passes to the baby, the picture is quite variable. Some babies are born without any apparent signs, and the problem is only noticed later, sometimes years later. Others may present, right at birth:

  • Visible changes on brain imaging tests, such as calcifications
  • Accumulation of fluid in the brain (hydrocephalus)
  • Inflammation of the eye's retina (chorioretinitis), which can affect vision
  • Head smaller than expected (microcephaly)
  • Jaundice, enlarged liver and spleen

In more serious and less frequent cases, there can be pregnancy loss or stillbirth. It is important to stress that, with proper prenatal follow-up and early diagnosis, most infected pregnant women receive treatment in time to greatly reduce these risks.

What are the first signs? And why is it so hard to notice

Here is the great challenge of toxoplasmosis in pregnancy: most of the time, the infected pregnant woman feels nothing different. When there are symptoms, they are the same ones already described (fatigue, swollen glands, low fever), easy to confuse with any common viral infection during pregnancy.

This is exactly why toxoplasmosis is not a disease you "notice," but rather a disease you screen for. The routine prenatal blood test (toxoplasmosis serology) is what allows you to discover the infection before it gives any visible sign, and this is why it is usually repeated throughout pregnancy in women who have not yet had contact with the parasite.

How to prevent it

The good news is that prevention is simple and is within reach of any pregnant woman, or anyone, in their daily life:

  • Cook meat well, avoiding any raw or undercooked parts.
  • Wash fruits, vegetables, and legumes thoroughly before consuming, and peel when possible.
  • Wear gloves when working in the garden or vegetable garden soil, and wash your hands afterward.
  • Avoid cleaning the cat's litter box during pregnancy. If you don't have someone to do it for you, wear gloves and a mask, and clean the box every day (the parasite takes at least 24 hours to become infectious after it is eliminated in the feces).
  • Keep the cat indoors and feed it dry food, preventing it from hunting and eating raw animals.
  • Wash your hands and kitchen utensils thoroughly after handling raw meat.
  • Avoid unpasteurized milk and its derivatives.

Diagnosis and treatment

Diagnosis is made by blood test, which shows whether the person has already had contact with the parasite before (which is usually reassuring) or whether the infection is recent (which requires greater attention). When the infection is identified during pregnancy, there is specific medication treatment, which changes depending on the stage of pregnancy, and which aims to reduce the chance of transmission to the baby and, if it has already occurred, to decrease the severity of the effects. This is why regular prenatal follow-up is the most important tool in this whole story.

If you are pregnant or planning to become pregnant, talk to your doctor about toxoplasmosis screening and about the precautions that make sense for your routine.

This content is educational and informative in nature and does not replace individualized medical consultation, diagnosis, or treatment. Always seek a healthcare professional to evaluate your case.

Dr. Rebeca Soares Andrade CRM - GO 39335