Editorial commentary
The discovery of biofilm-forming protozoa in human blood

In this issue’s paper Fry and colleagues have described protozoal microorganisms that they found in peripheral blood drawn from several patients suffering from chronic illnesses, such as: lupus erythematosus, chronic fatigue syndrome, fibromyalgia, multiple sclerosis, amyotrophic lateral sclerosis and arteriosclerosis [1]. Of note, these protozoa – although genetically related to already known organisms, primarily of aquatic origin – probably represented new species that have never been previously described. Moreover, they seemed to form biofilm communities in the bloodstream. Of course, this intriguing finding should be confirmed by independent researches, and protozoa described in this paper should be revealed in more patients (actually, in this preliminary report only a single case of each disease has been portrayed). Still, there are several potential breakthroughs in our understanding chronic incurable human diseases, providing that other scientists would also demonstrate such biofilm-forming protozoa in the patients’ blood.
Firstly, bacterial and fungal biofilms are recognized important players in human pathology. In cases where the bacteria or fungi succeed in forming a biofilm, the infection often becomes difficult to treat and will develop into a chronic state. On the contrary, much less is known about protozoal biofilms. Some of them can form a biofilm in vitro [2], yet protozoal biofilm have not yet been described in the human blood.
Secondly, although protozoa described by Fry and colleagues can be of minor clinical relevance for their human hosts, a pathological role of these microorganisms cannot be ruled out. The strongest body of evidence supporting a hypothetical protozoal infection as a cause of the disease comes from the research on multiple sclerosis. Actually, the very idea that multiple sclerosis could be triggered by an infectious microorganism is not new and there are important data supporting the role for such a factor involved [3-6]. But – of as yet – not a single microorganism meeting the criteria of a causative factor has been identified. Until now, the researchers have primarily examined viruses. Others suggested a role for several bacterial species (e.g. Chlamydia pneumoniae) – similarly, with inconclusive results. What is new and promising in the Fry’s and colleagues strategy is the focus at a different class of microorganisms, namely the protozoa. Potential pathological role of not yet identified...


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