Definition

Cerebral toxoplasmosis, also known as neurotoxoplasmosis, is a brain infection caused by the parasite Toxoplasma gondii. This infection is acquired through consuming undercooked meat, exposure to cat feces containing the parasite, and transmission from mother to child during pregnancy. Toxoplasmosis usually causes only mild symptoms in individuals with strong immunity. However, in vulnerable populations, such as those with HIV/AIDS or undergoing chemotherapy, the infection can result in cerebral toxoplasmosis.

The incidence of toxoplasmosis in Indonesia between 1982 and 1994 was 36.7%, with 8.4% of cases occurring in people with HIV/AIDS in Jakarta. In 2011, data from Cipto Mangunkusumo Hospital (RSCM) in Jakarta showed that toxoplasma infection accounted for 48.5% of opportunistic infections in people with HIV/AIDS.

Causes

Cerebral toxoplasmosis is caused by the parasite Toxoplasma gondii. T. gondii can infect various animals, but its primary host is cats. The parasite enters the human body in the form of cysts that transform and reside in nerves and muscles. These cysts trigger an inflammatory response in the body, causing symptoms.

This infection is not transmitted from human to human but from animal to human. Exposure to cat feces is the main route of transmission. Cats, both wild and domestic, are the only animals that can excrete these parasite cysts in their feces. Conditions that can lead to toxoplasma infection include:

• Consuming undercooked meat. Other animals can be infected with toxoplasma, with the parasite's cysts residing in their muscles or meat. Eating undercooked meat from these animals poses a risk of toxoplasma infection.
• Exposure to cat feces containing the parasite when cleaning cat litter or touching anything contaminated with cat feces.
• Consuming food or water contaminated with the parasite. Unpasteurized milk can contain the parasite. Fruits and vegetables not properly washed can also harbor the parasite, making it important to peel fruits before consumption.
• Mother-to-child transmission.
• Exposure from organ transplants or blood transfusions. 

If exposed to T. gondii, the parasite's cysts can settle throughout the body, including the brain and heart. A healthy immune system can control the parasite, keeping it inactive. However, if immunity decreases or immunosuppressive drugs are taken, the infection can reactivate, leading to severe complications.

Risk factor

Anyone can develop toxoplasmosis. However, cerebral toxoplasmosis is more common in the following populations:

• People with HIV/AIDS with CD4 <200 cells/uL. They are more susceptible to both new and reactivated toxoplasmosis infections, especially if not previously on prophylactic antibiotics.
• Those undergoing chemotherapy. Chemotherapy can weaken the immune system, making it difficult for the body to fight infections.
• Those taking steroids or other immunosuppressive drugs.

Symptoms

Symptoms of cerebral toxoplasmosis can include:

• Headache
• Visual disturbances
• Cranial nerve paralysis
• Stiff neck
• Seizures
• Projectile vomiting
• Decreased consciousness

Diagnosis

Doctors will inquire about the patient's disease history, past medical conditions, and current medications. The definitive diagnosis of cerebral toxoplasmosis involves identifying cysts in a brain biopsy, though this is rarely done. Common supportive tests include:

• Serology. Antibody titers against toxoplasma can serve as a quick screening. However, negative serology results do not necessarily rule out toxoplasma, particularly in Indonesia where toxoplasma incidence is high.
• CT scan or MRI with contrast. These imaging tests provide a radiological view of the head and brain. MRI is a low-risk, non-invasive procedure, although time-consuming. Doctors may find ring-enhancing lesions in the brain of toxoplasmosis patients.
• PCR of cerebrospinal fluid.

Management

Treatment of cerebral toxoplasmosis aims to limit parasite replication during active infection. This therapy is primarily administered to individuals with weakened immune systems and chronic infections. Treatment can be divided into two phases: primary therapy and secondary therapy. In both phases, doctors will prescribe a combination of three different antibiotics. Primary therapy lasts for at least six weeks, while secondary therapy continues for six consecutive months thereafter. Folic acid may also be given to prevent folic acid deficiency.

Complications

Severe toxoplasmosis can be fatal. However, with prompt and proper treatment, clinical improvement in cerebral toxoplasmosis can be seen within 10-14 days of antibiotic therapy. Relapses are common. Continuing antiretroviral therapy (ART) and antibiotic use is crucial to prevent recurrence.

One complication of cerebral toxoplasmosis in HIV/AIDS patients is the potential development of Immune Reconstruction Inflammatory Syndrome (IRIS) with concurrent use of ART and antibiotics.

Prevention

Preventive measures for cerebral toxoplasmosis include:

• Wearing gloves while gardening or handling soil.
• Avoiding consumption of undercooked meat.
• Thoroughly cleaning kitchen utensils, especially after handling raw meat. Use warm water and soap to prevent contamination of other foods. Wash hands after preparing food.
• Washing all fruits and vegetables before consumption. Peel fruits after washing if possible.
• Avoiding unpasteurized milk.
• Maintaining the health of pet cats. Avoid feeding them raw meat and provide canned or dry food. Regularly check their health.
• Avoiding the adoption of stray cats. If adopting, test for T. gondii first. Cats typically do not show signs of infection, so testing is necessary.
• Undergoing a complete health check before pregnancy. Preventive measures for HIV/AIDS patients include taking prophylactic antibiotics if CD4 <200 cells/uL until ART is achieved and CD4 remains >200 cells/uL for three consecutive months. Consult with a doctor.

When to see a doctor?

If you have HIV/AIDS, are taking immunosuppressive drugs, or are pregnant or planning to become pregnant, visit a healthcare facility to check for toxoplasma infection. A negative result may indicate no exposure to toxoplasma or an acute infection. Consult your doctor for further treatment.

Early symptoms of cerebral toxoplasmosis, such as severe headache, visual disturbances, seizures, and loss of consciousness, are warning signs that require immediate medical attention.

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