Toxoplasma gondii - Clinical manifestation, Complications, Prognosis

Clinical manifestation of Toxoplasma gondii

Toxoplasmosis, caused by Toxoplasma gondii, may clinically manifest as acquired, congenital, ocular infections in immunocompetent hosts while in an immunocompromised host, the manifestations are more severe.

Congenital toxoplasmosis

• congenital toxoplasmosis occurs when a non-immune susceptible woman is infected during pregnancy

• Toxoplasma gondii is transmitted through the placenta to the fetus

• the disease is much more severe if the infection is acquired during the first trimester of pregnancy

  may lead to stillborn or miscarriage

  congenital toxoplasmosis occurs in 17% of cases

• if the infection occurs during the last trimester of pregnancy, the infant at the time of birth may show mild to no symptoms

  about 65% of cases occur during the last trimester of pregnancy

• cerebral calcifications, convulsions, and retinochoroiditis occur with congenital toxoplasmosis- retinochoroiditis being the most common (75%-80% of cases)

• other less frequent manifestations include microcephaly, hydrocephalus, mental retardation, anemia, jaundice, thrombocytopaenia, and organomegaly

• chronic infection does not lead to congenital toxoplasmosis i.e. if a mother had toxoplasmosis prior to the current pregnancy, the transplacental transmission does not occur

• around 80%-90% of pregnant women with toxoplasmosis are clinically asymptomatic while 10%-20% of pregnant women with toxoplasmosis show clinical symptoms- most commonly lymphadenopathy

Acquired toxoplasmosis

Although toxoplasmosis is a benign and self-limiting condition in an immunocompetent host, acquired toxoplasmosis is serious and life-threatening in immunocompromised individuals. They are classified into

• toxoplasmosis in immunocompetent individuals

• toxoplasmosis in the non-AIDS immunocompromised host

• toxoplasmosis in AIDS patients

Toxoplasmosis in immunocompetent individuals

• Benin and self-limiting Toxoplasma gondii infection

• acute toxoplasmosis is asymptomatic in 80% to 90% of cases while 10%to 20% are symptomatic

• the most common clinical symptom is lymphadenopathy in which deep cervical lymph nodes are affected

• uncommon sites infected by Toxoplasma gondii include supraclavicular, suboccipital, axillary, and inguinal lymph nodes

• the infected lymph nodes are characterized by discrete, non-tender, with varying firmness

• other symptoms include fever, sore throat, myalgias, night sweats, malaise, maculopapular skin rash (does not affect palms or soles), and retinochoroiditis (10% of cases)

• in rare cases, abdominal pain with retroperitoneal and mesenteric lymphadenopathy is seen

Toxoplasmosis in the non-AIDS immunocompromised host

• Toxoplasma gondii infection is seen in immunosuppressed individuals undergoing immunosuppressive therapy for malignancies (Hodgkin disease, leukemia) or patients who have under bone marrow transplant or solid organ transplantation

• the toxoplasmosis may be newly acquired or chronic (due to reactivation)

• the central nervous system is affected in 50% of cases

• common symptoms include hemiparesis, seizures, change in visual and mental status

• other severe clinical manifestations are encephalitis, meningoencephalitis, space-occupying lesions

• non-neurological symptoms include myocarditis and pneumonitis

Toxoplasmosis in AIDS patients

• Toxoplasma gondii infections in AIDS patients are the most severe and often fatal

• the brain is commonly infected in the majority of cases with the characteristic feature being Toxoplasmic encephalitis (TE) with or without focal CNS lesion

• common symptoms include seizures, meningismus, neuropsychiatric, altered mental state, sensory abnormalities cerebellar signs

• although the lung is not usually infected, pulmonary toxoplasmosis is now being increasingly recognized in patients with AIDS without proper therapeutic and clinical management

• pulmonary toxoplasmosis mostly occurs in AIDS patients whose CD4 count is less than 50 cells/mm³ and manifests as febrile illness, dyspnoea, and cough

• extra-pulmonary manifestation is seen in 50% of cases

• the less common syndrome is toxoplasmic chorioretinitis

Ocular toxoplasmosis

• the hallmark of ocular toxoplasmosis is focal necrotizing retinochoroiditis

• this manifestation accounts for about 35% of chorioretinitis in both children and adult

• ocular toxoplasmosis mainly occurs due to congenital infection

• in acquired infection chorioretinitis is unilateral while in bilateral infection, chorioretinitis is bilateral

• symptoms are blurred vision, photophobia, pain, and scotoma

Complications of Toxoplasma gondii

Congenital toxoplasmosis complications include symptoms such as seizures, deafness, and mental retardation.

The complication of ocular toxoplasmosis, caused by Toxoplasma gondii, is partial or complete blindness.

Central nervous system toxoplasmosis may become complicated with a seizure disorder or focal neurologic deficits

Prognosis of Toxoplasma gondii

The prognosis of Toxoplasma gondii is good in an immunocompetent host.

In immunocompromised individuals, the host prognosis is poor due to relapse if treatment is stopped.

In cases of HIV patients infected with Toxoplasma gondii, the mortality is high i.e. at 35%.