B60.11 Meningoencephalitis due to Acanthamoeba (culbertsoni)

Name of the Condition

• Meningoencephalitis due to Acanthamoeba (culbertsoni)

Summary

Meningoencephalitis due to Acanthamoeba (culbertsoni) is a rare but severe infection of the brain and its surrounding membranes caused by the free-living amoeba Acanthamoeba culbertsoni. This condition primarily affects the central nervous system, leading to inflammation and neurological impairment. Diagnosis requires specialized testing to identify the specific amoebic species, and treatment involves targeted antimicrobial therapy.

Causes

The infection is caused by Acanthamoeba culbertsoni, a species of amoeba found in environmental sources such as soil, freshwater, and contaminated water systems. Transmission typically occurs through direct contact with contaminated water (e.g., swimming in untreated lakes or using contaminated tap water for nasal irrigation) or via inhalation of cysts. The amoeba can enter the body through the nasal passages or skin wounds, eventually reaching the central nervous system.

Risk Factors

• Exposure to contaminated freshwater or soil, particularly in immunocompromised individuals.
• Use of tap water for nasal irrigation or contact lens cleaning.
• Skin trauma or wounds that come into contact with contaminated environments.
• Weakened immune system, including conditions like HIV/AIDS or immunosuppressive therapy.

Symptoms

• Severe headache, fever, and neck stiffness.
• Altered mental status, confusion, or seizures.
• Nausea, vomiting, or photophobia.
• Focal neurological deficits, such as weakness or sensory changes.

Diagnosis

Diagnosis involves a combination of clinical evaluation, imaging studies (e.g., MRI or CT scans showing characteristic brain lesions), and laboratory testing. Cerebrospinal fluid (CSF) analysis may reveal elevated white blood cells, protein, and low glucose. Definitive diagnosis requires identifying Acanthamoeba cysts or trophozoites in CSF or tissue samples, often via microscopy or PCR testing.

Treatment Options

Treatment typically includes a combination of antimicrobial agents, such as miltefosine, pentamidine, and azithromycin, administered intravenously or intrathecally. Supportive care, including management of increased intracranial pressure and seizures, is critical. The duration of therapy is prolonged, often lasting months, and may require adjustments based on clinical response.

Prognosis and Follow-Up

Prognosis is generally poor, with high mortality rates, especially in untreated or delayed cases. Survivors may experience long-term neurological sequelae, such as cognitive impairment or motor deficits. Follow-up includes regular neurological assessments, imaging to monitor for recurrence, and ongoing antimicrobial therapy until clinical and radiological improvement is confirmed.

Complications

• Permanent neurological damage, including cognitive or motor deficits.
• Increased intracranial pressure leading to herniation.
• Secondary infections due to immunosuppression.
• Death in severe or untreated cases.

Lifestyle & Prevention

• Avoid swimming in untreated freshwater or using contaminated water for nasal irrigation.
• Practice good hygiene when handling contact lenses or cleaning wounds.
• Immunocompromised individuals should minimize exposure to soil or stagnant water.
• Promptly clean and cover skin wounds to reduce infection risk.

When to Seek Professional Help

Seek immediate medical attention if experiencing severe headache, fever, neck stiffness, or neurological symptoms (e.g., confusion, seizures). Early intervention is critical to improve outcomes, especially in high-risk individuals.

Tips for Medical Coders

• Use code B60.11 for confirmed cases of meningoencephalitis due to Acanthamoeba (culbertsoni).
• Ensure documentation supports the specific causative organism (e.g., lab confirmation of Acanthamoeba culbertsoni).
• Differentiate from other protozoal infections or non-infectious causes of meningoencephalitis.
• Include details on clinical presentation and diagnostic findings to support code assignment.