Toxoplasmosis – Part 1 – Diagnosis and Treatment
- Toxoplasmosis is caused by the protozoan parasite called Toxoplasma gondii.
Sample
- Blood to prepare the serum.
- Store the blood at 2 °C to 6 °C if the test is delayed for more than 7 days.
- Serum should not be heat-inactivated, because this may give false-positive results.
Spread
- This is present worldwide in humans and domestic animals. This is also seen in wild animals.
- In human spread is by the half-cooked meats that contain the cyst,
- If there are infective oocyst from the contaminated cat feces.
- Spread through blood transfusion is also possible.
Presentation
- If there is an infection in utero in the early stage then there are possibilities of the death of the fetus, brain damage, hydrocephaly.
- The infected fetus will have fever, splenomegaly, jaundice, and convulsion at birth.
- Infection in late pregnancy can lead to mild disease.
- Immune-deficient patients may have Chorioretinitis, pneumonia, lymphadenopathy, myocarditis, and possible death.
Laboratory Diagnosis
- Cultures can be done and it needs long incubation.
- In body fluids, tissue, and blood the presence of Tachyzoites are confirmatory.
- Immunoperoxidase or Fluorescent techniques can be done.
- Antibody dependants tests are diagnostic for toxoplasmosis. IgM antibody appears roughly after 5 days of the infection. This is suggestive of intrauterine infection.
- IgM titer lasts up to one year.
- IgM antibody can be found in the cord blood.
- Polymerase chain reaction (PCR) is highly specific and sensitive.
Source 2
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- Serology of Toxoplasmosis
- IgG antibody titer represents present or past infection.
- IgM antibody is needed to confirm the present infection.
- Antibody IgM titer <1:16 = shows no exposure to virus.
- Antibody IgM titer >1:4 to 1:256 = acquired infection in last 18 months.
- Antibody IgM >1: 1024 = Acquired infection in last 4 months
- Serology of Toxoplasmosis
Toxoplasma antibody interpretation:
IgG antibody | IgM antibody | Interpretation |
Negative | local evidence of toxoplasmosis infection | |
Negative | Positive | Positive for early infection or false positive so repeat the test |
Positive | Negative | Past infection 6 months or more |
Positive | Positive | Positive recent infection within the last 12 months |
Treatment
- Sulfadiazine, Pyrimethamine, and folic acid are given.