Toxoplasma antibodies (IgG & IgM)

The Toxoplasma antibodies (IgG & IgM) blood test measures IgG and IgM antibodies produced in response to Toxoplasma gondii, a microscopic parasite capable of infecting humans and many animals.

The test assesses 1 combined specialist serology marker: Toxoplasma Antibodies (IgG+IgM).

Toxoplasma gondii infection is known as toxoplasmosis.

People can acquire the parasite through several routes, including eating undercooked contaminated meat, exposure to contaminated soil or food and contact with material contaminated by infected cat faeces.

Most healthy people who acquire Toxoplasma develop either mild symptoms or no symptoms at all.

After infection, the parasite can remain dormant within tissues for many years.

The antibody pattern can provide important information about whether exposure has occurred and whether infection may be recent or historical.

Toxoplasma IgM antibodies usually develop relatively early after infection.

However, IgM can persist for many months and sometimes longer.

A positive IgM result therefore does not automatically prove that infection is very recent.

IgG antibodies develop after infection and generally remain detectable long term.

A positive IgG with negative IgM is commonly consistent with previous exposure.

Interpretation becomes particularly important in pregnancy because a primary maternal infection acquired during pregnancy can potentially be transmitted to the developing fetus.

Where recent infection is possible, additional specialist testing such as IgG avidity, repeat serology or Toxoplasma PCR may be required.

Toxoplasmosis can also be clinically important in severely immunocompromised people because latent infection can reactivate.

For these reasons, one antibody result should always be interpreted alongside symptoms, immune status, pregnancy status and previous results.

The current live London Blood Tests page lists a turnaround of approximately 8–10 days after laboratory receipt for Toxoplasma antibodies (IgG & IgM).

The sample undergoes specialist serological analysis, quality-control procedures and result authorisation.

Turnaround begins when the specimen reaches the laboratory rather than necessarily from the exact time of collection.

Where IgM is reactive or the timing of infection remains uncertain, additional avidity or confirmatory testing can extend the overall investigation.

The combination of IgG and IgM provides more information than either antibody alone.

An IgG-negative and IgM-negative pattern generally indicates that no serological evidence of previous infection has been detected.

An IgG-positive and IgM-negative pattern is commonly consistent with previous exposure and established antibodies.

An IgM-positive result requires more caution.

IgM can be present during recent infection, but it can persist for months or longer and can occasionally produce non-specific reactivity.

An IgG-positive and IgM-positive result therefore does not reliably establish exactly when infection occurred.

Where recent infection is clinically important, particularly during pregnancy, IgG avidity or repeat testing may help estimate timing.

A high-avidity IgG result can provide evidence against a very recent primary infection in appropriate circumstances.

The laboratory's own interpretation and specialist clinical assessment should take priority.

London Blood Tests provides private Toxoplasma IgG and IgM testing for people requiring assessment of previous or possible recent Toxoplasma gondii exposure.

The test costs £218 and assesses 1 combined specialist biomarker.

Results are expected approximately 8–10 days after laboratory receipt.

Where pregnancy or a reactive IgM result is involved, further specialist testing may be required before the timing of infection can be established.