38th Annual Meeting of the Society for Invertebrate Pathology

The Genus Brachiola was established and placed within the family Nosematidae, to accommodate organisms that share the features of that family but also possess some unique features including several variations of the plasmalemma, adaptation to higher host body temperatures, and specifically, with the features of the type species, vesicularum, the ability to extend its protoplasm into long branches named protoplasmic extensions (often longer than the parasite cell itself) while maintaining the plasmalemmal variations demonstrated on the main body of the parasite cells. This parasite, B. vesicularum, was described from human skeletal muscle infection in an individual who was immune compromised. Some of the features of this parasite are shared with the parasite formerly known as Nosema algerae, however, after much ultrastructural examination of it, we concluded that they were closely related but morphologically differing in the presence or absence of the protoplasmic extensions, which have not been demonstrated on any other microsporidium. An evaluation of the extensive literature on N. algerae, revealed the consensus that molecularly it was considered an “out group” and should probably be in another genus. Thus, the genus Brachiola was established to accommodate the new parasite, B. vesicularum,, and the organism, N. algerae, was transferred into it, becoming B. algerae. In other studies, we and others presented the ability of B. algerae to tolerate higher temperatures than previously reported and in 2004, it was demonstrated as the causative agent in a case of severe myositis of a woman with rheumatoid arthritis who was being treated with immunosuppressive drugs for the treatment of that disease. After extensive electron microscopic examination, it was concluded that in an environmental situation virtually identical to that in which B. vesicularum had formed the protoplasmic extensions, B. algerae did not develop them, thus demonstrating a significant morphological difference between the two species. This infection was molecularly proven to be B. algerae with a greater than 99% match using the B. algerae primers and sequence data from genbank. Thus, this mosquito-infecting microsporidium did cause myositis and ultimately lead to the death of a 57- year-old woman.