Bala-what? Balamuthia madrillari!
Admittedly, this amoeba rarely shows up as a cause of infection even for infectious disease specialists like myself. Infections by Balamuthia mandrillari are of the sort that feature only on esoteric board examinations. I have never seen it.
This amoeba was first identified in the 1990s and to date has probable caused a couple hundred known human infections worldwide. This is a scary microbe in my books and I’ll tell you why.
This week’s CDC MMWR highlights a recent tragic case. A 4-year-old boy died in Mississippi last year of encephalitis presumably secondary to influenza. His kidneys, heart, and liver were donated to people who needed them. The two adults who received the kidneys came down with neurological symptoms weeks after transplantation – one died, and the other is left with severe deficits. Workup revealed ring-shaped lesions in their brains. They re-examined the boy who died, the organ donor. I imagine there was tissue available in the lab. Turns out he did not die of influenza. Ooops! No, he had encephalitis secondary to B.mandrillari. The two toddlers who received the heart and liver were located and treated for B.mandrillari though they have not yet developed neurological signs and hopefully won’t.
If that is not a nightmare I don’t know what is. Nightmare for the 4-year-old that died. Nightmare for his parents and healthcare providers. What if they too are at risk? Nightmare for the organ recipients who thought they were getting a chance to avoid dialysis (kidney transplantation is rarely urgent) and now are dead or disabled. Nightmare for the organ recipients who thought they were getting a second chance at life only to have this infection now hang over their heads like a Damascus sword.
B.mandrillari infections are difficult to treat. In fact encephalitis (brain infection) secondary to this is uniformly fatal.
I know what you are thinking now. Why transplant organs from a patient with the flu in the first place? Well, the four-year old boy had been diagnosed with influenza and he was treated for it. The seizures he had afterwards that led to his death were thought to be secondary to a post-flu syndrome. When he died, he was checked for viral, bacterial, and fungal infections. All turned up negative. Of course, what the CDC found when they went back to check his tissues was not a bacteria, nor a virus, nor a fungus but rather an amoeba. Even if this was known when he first presented with “flu” it’s unlikely that his life could have been saved. I doubt his organs would have been transplanted…although organs from infected patients can be transplanted…that is as long as both the donor and the recipient receive the proper antibiotics…that is as long as we are talking about simple infections.
What is so strange about Balamuthia mandrillari is that it is all around us in the soil and dust worldwide. What makes one person then get an infection and another not? We don’t know. So far, most of the cases described have been detected at the time of autopsy…or earlier at the time of brain biopsy…when it’s already too late.
That brings me to the second revelation. The MMWR report intended to describe the first case of B.mandrillari transmission through organ transplantation. Lo and behold, a second cluster of organ transplantation occurred in Arizona last month. This time the donor was a 27-year-old landscaper, presumably healthy, who died of a stroke! His liver went to a man who died within a month and his kidney-pancreas went to another man who died shortly afterwards. Again, an investigation led to the identification of B.mandrillari in the donor and the recipients who died. Subsequently, the amoeba was identified in the recipients of his heart and other kidney who had not yet begun to show signs of infection.
Isn’t this scary? That you could be out there breathing in the fine fresh air of nature and these little particles of dust/soil carry deadly amoeba that lodge themselves in your brain and cause you to die in a matter of weeks? Maybe I’m just scared because I have been known to ingest sand in my youth. Hey don’t judge! In fact, that’s probably why many of the 200 human cases of infection described have been in children. They ingest anything!
The one thing I will say though is maybe it’s time we stop accepting organs (or rather offering organs) from patients who have died from encephalitis (known or unknown) and other neurological conditions. I have actually had a similar case that illustrates why this may not be such a wise practice.
In my first year of infectious disease fellowship I was consulted for fevers in a man just admitted with fever, seizure and mental status change. He was middle-aged (40-50s), semi-homeless, enjoyed alcohol, and didn’t have much of a past medical history. We recommended the usual. Treat empirically for bacterial and viral meningitis/encephalitis while pending studies. I must have changed services within a few days because I don’t remember his course beyond that. He was unremarkable really from an infectious disease standpoint because his presentation could have been due to alcohol abuse.
A couple of months later I find out that he had died of a cardiac arrest, that his organs had been transplanted, and that both recipients of his kidneys had developed multi-organ failure. Turns out my patient had lymphocytic choriomeningitis virus (LCMV), a rodent-borne virus found worldwide. My patient presumably got infected by exposure to rodent excrement what with him being semi-homeless and all. Lymphocytic choriomeningitis is also a rare infection and now two more patients had it because of transmission through organ donation.
I remember this very well because at the time I was battling a mouse infestation in my apartment complex. See, we poor medical residents and fellows kinda have to share our space with vermin especially when we live and train in large academic centers in big expensive cities. Can I say I hate mice? To this day I see phantom mice scuttling around in the periphery of my vision. *shudder* I have recurring nightmares of throwing out sticky traps with mice attached, either dead or still wiggling. Oh heavens! Remove such thoughts from my memory! I remember sweeping up their excrement, tiny chocolate sprinkle lookalikes, and thinking oh goodness I’m going to get lymphocytic choriomeningitis. See, doctors can be hypochondriacs too! To think that as a child in primary school I took care of little white mice which I thought were cute as a member of the Pet Club.
Anyway, my point is my patient with neurologic symptoms (encephalitis, seizures) transmitted LCMV to recipients of his organs and they died. That in both MMWR clusters, B.mandrillari infection was transmitted from donors with neurological symptoms (encephalitis, stroke) to recipients who also died. And that Clinical Infectious Diseases journal reported a case of a 26-year-old woman who died after presenting with mental status change ie. encephalitis-like, had the usual workup for encephalitis which turned up negative, and her organs went to SIX people (cornea, liver, kidney, kidney/pancreas, lung). Three ended up having similar symptoms to what she had (encephalitis-like) and workup revealed RABIES. Needless to say, they died…and the donor was found to have undiagnosed RABIES as well. Apparently, she had sustained a dog bite while travelling in India, a history element that was not obtained until it was too late.
Which really begs the question, shouldn’t there be a ban on transplanting organs from donors with undiagnosed (or presumably diagnosed) encephalitides especially when the recipient is not in a life-threatening status, eg. cornea transplants?! I understand that organs are scarce and all, but even if I were to need immediate life saving transplant of a heart for example, I think I as the recipient (or rather my family if I can’t speak for myself) should understand that I’m getting the heart from someone who died from an unclear neurologic cause and that I risk development of some rare or not so rare infection especially since I will be placed on immunosuppressive medications to prevent my body from rejecting the foreign organ.
Scary! Scary! Scary!
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