Toxoplasmosis Symptoms and Manifestations

Toxoplasmosis

• More than 50% of toxoplasmosis patients show altered mental state, motor impairment, seizures, abnormal reflexes, and other neurologic sequelae.

Organ Involvement

• Lung is the next most common organ involved, often manifesting as interstitial pneumonitis.
• Gastrointestinal tract, liver, and heart may also be involved.
• Cutaneous toxoplasmosis presents as a prominent macular and papular rash on the palms and soles.

Disease Acquired in Immunocompetent Patients

• Disease severity depends on previous exposure to T.gondii by the donor and recipient, the type of organ transplanted, and the level of immunosuppression of the patient.
• Disease can be due to reactivation of a latent infection or an acute primary infection acquired directly from the transplanted organ.
• Stem cell transplant recipients are particularly susceptible to severe toxoplasmosis, primarily due to reactivation of a previously acquired latent infection.
• All potential transplant recipients should be tested for Toxoplasma-specific immunoglobulin G (IgG) antibodies to determine their antibody status.

AIDS Patients

• Fever and malaise usually precede the first neurologic symptoms; headache, confusion, seizures, or other focal signs strongly suggest the diagnosis of toxoplasmosis.
• Toxoplasma encephalitis (TE) is reported as a life-threatening infection among AIDS patients.
• This condition is fatal if untreated.
• Most AIDS patients with TE have detectable IgG antibodies to T.gondii; however, 5% may not have antibody in their serum.
• Psychiatric manifestations of toxoplasmosis may occur.
• Symptoms of congenital CNS involvement may not appear until several years later.
• Congenital transmission can occur even if the mother is immune, although this is rare; reinfection of the mother during pregnancy is possible.

Ocular Infections

• Ocular infections, also known as ocular toxoplasmosis, are seen in immunocompetent patients due to an earlier congenital infection.
• Patients may be asymptomatic until the second or third decade; at that point, cysts may rupture, with lesions then developing in the eye.
• Chorioretinitis is usually bilateral in patients with congenitally acquired infection and is generally unilateral in patients with recently acquired infection.

Diagnosis

• Sample: Tissue biopsy, spleen aspiration, bone marrow aspiration or lymph node aspiration, CSF, and blood.
• Acute Toxoplasma infections may be diagnosed by detection of parasites (tachyzoites) in blood, lymph node punctures, in fluid or in biopsies of tissues.
• Identification of tachyzoites in tissue sections is the definitive diagnosis method.
• Serologic tests: For the determination of the age of an infection.
• Molecular tests to detect T.gondii in deparaffinized ocular tissue sections, cerebrospinal fluid, blood, and bronchoalveolar fluid.

Pathogenesis

• In most cases, toxoplasmosis is mostly not noted, since the symptoms are unspecific and of low grade.
• T.gondii infections may become harmful, reaching the status of a severe disease.
• Pathogenesis involves four main categories: disease acquired or reactivated in immunosuppressed or immunodeficient patients, disease acquired in immunocompetent patients, congenital disease, and ocular disease.

Acquired Postnatal Infection

• Infection is acquired by ingestion of sporulated oocysts excreted by cats or by ingestion of undercooked raw meat of infected vertebrates.
• After an incubation period of about 2-3 weeks, the following symptoms can be observed:
  • Swellings of lymph nodes (adenitis)
  • Infections of the eyes (iridocyclitis, chorioretinitis)
  • Infections of the brain (meningoencephalitis)
  • Infection of visceral organs (e.g., leading to intestinal pneumonia, hepatitis, myocarditis, enterocolitis, myositis, oedema of the skin)