Balamuthia mandrillaris is a free-living ameba (a single-celled living organism) naturally found in the environment. Balamuthia can cause a very rare but serious infection of the brain and spinal cord called Granulomatous Amebic Encephalitis (GAE).

Epidemiology & Risk Factors

Balamuthia infection is very rare but often causes fatal disease. Since Balamuthia was first discovered in 1986, about 200 cases of infection have been reported worldwide. This number includes at least 70 confirmed cases in the United States. Because disease caused by Balamuthia is so uncommon, it is possible that there have been additional cases that were misdiagnosed.
Balamuthia amebas (single-celled living organisms) are thought to enter the body when soil containing Balamuthia comes in contact with skin wounds and cuts, or when dust containing Balamuthia is breathed in or gets in the mouth. Once inside the body, the amebas can then travel to the brain and cause Granulomatous Amebic Encephalitis (GAE). GAE is a severe disease of the brain that is fatal in over 95% of cases. It can take weeks to months to develop the first symptoms of Balamuthia GAE after initial exposure to the amebas.
Balamuthia amebas live freely in soil around the world. Gardening, playing with dirt, or breathing in soil carried by the wind might increase the risk for infection. Balamuthia might also be present in fresh water. There have been reports of Balamuthia GAE infection in dogs that swam in ponds. However, there have been no reported human cases where the only potential exposure was swimming.
The Balamuthia ameba is able to infect anyone, including healthy people. Those at increased risk for infection include:

• People with HIV/AIDS, cancer, liver disease, or diabetes mellitus
• People taking immune system inhibiting drugs
• Alcoholics
• Young children or the elderly
• Pregnant women

In the United States, Balamuthia infection might be more common among Hispanic Americans. However, the cause of this trend is unknown and might be due to differences in exposure, biology, data collection, or other reasons. More research is needed to understand what factors might be associated with increased reporting among persons of Hispanic ethnicity.
There have been no reports of a Balamuthia infection spreading from one person to another except through organ donation/transplantation.

Balamuthia infection is very rare. The Balamuthia amebas can infect the skin, sinuses, brain and other organs of the body. Therefore, Balamuthia infection can cause a wide range of symptoms. Disease can begin with a skin wound on the face, trunk, or limbs and can then progress to the brain where it cause a disease called Granulomatous Amebic Encephalitis (GAE). Diagnosis of Balamuthia GAE can be difficult, but some early symptoms may include:

• Headaches
• Stiff neck or head and neck pain with neck movement
• Sensitivity to light
• Nausea
• Vomiting
• Lethargy (tiredness)
• Low-grade fever

Other signs of Balamuthia GAE may include:

• Behavioral changes
• Seizures
• Weight loss
• Partial paralysis
• Speech difficulties
• Difficulty walking

Balamuthia can also cause a widespread infection involving multiple body parts.
The disease might appear mild at first but can become more severe over weeks to several months. Often the disease is fatal, with a death rate of more than 95%. Overall, the outlook for people who get this disease is poor, although early diagnosis and treatment may increase the chances for survival.

Balamuthia Granulomatous Amebic Encephalitis (GAE) is a serious infection of the brain and spinal cord caused by Balamuthia. GAE is often diagnosed only after death. However, it can be diagnosed by examining blood, cerebrospinal fluid, and tissue samples from a living patient as well. Diagnosis of GAE in a living patient is less common because the amebas are difficult to identify under the microscope, even with commonly used stains.
However, there are three types of tests that can help confirm the diagnosis of GAE. The indirect immunofluorescence assay (IFA) is a test used to detect antibodies attached to Balamuthia amebas in body tissues. In contrast, immunohistochemistry (IHC) uses specific antibodies against Balamuthia to detect the amebas. Finally, a polymerase chain reaction (PCR) molecular assay can detect Balamuthia DNA.

Although there have been more than 200 cases of Balamuthia infection worldwide, few patients are known to have survived as a result of successful drug treatment. Early diagnosis and treatment might increase the chances for survival.
Drugs used in treating Granulomatous Amebic Encephalitis (GAE) caused by Balamuthia have included a combination of flucytosine, pentamidine, fluconazole, sulfadiazine and either azithromycin or clarithromycin. Recently, miltefosine in combination with some of these other drugs has shown some promise. Much more information is needed in treating patients with GAE due to Balamuthia.

Currently, there are no known ways to prevent infection with Balamuthia since it is unclear how and why some people become infected while others do not.
There have been no reports of a Balamuthia infection spreading from one person to another except through organ donation/transplantation.