Albendazole for Treatment of Microsporidia Infection in Humans?
ABSTRACT & COMMENTARY
Synopsis: An HIV-infected Swiss man with microsporidiosis responded to albendazole with initial reduction in number and size of brain lesions, but he subsequently succumbed to infection.
Source: Weber R, et al. N Engl J Med 1997;336:474-478.
The authors present a case report of an hiv-infected Swiss man with multiple cerebral lesions and possible maxillary sinusitis due to infection with the rabbit strain of Encephalitozoon cuniculi. Multiple enhancing lesions with some surrounding edema were present in the hippocampal, mesencephalic, and intracortical areas. Using cultivation with human embryonic lung fibroblasts, the organism was isolated from cerebrospinal fluid, sputum, urine, and stool samples. Spores were detected within six weeks in CSF and within one week in urine and sputum specimens.
The patient received albendazole with an initial reduction in the number and size of the brain lesions and improvement in the sinusitis, but he subsequently succumbed to infection. Although he continued to shed spores three months after initiation of albendazole therapy, which suggests the presence of persistently active infection, the organism failed to propagate in cell culture.
COMMENT BY CAROL A. KEMPER, MD
Microsporidia are obligate, intracellular protozoa that can infect any animal group. At least five genera of microsporidia are known to infect humans, including Encephalitozoon, Enterocytozoon, Nosema, Pleistophora, and Septata. Most infections are believed to be zoonoses. Differentiation between species can be determined using immune-based and molecular techniques. Three different strains of E. cuniculi have been identified, with individual strains restricted to rabbits, canines, and in mice and blue foxes. The organism in this man proved to be similar to other rabbit strains isolated in Switzerland. Interestingly, he had a history of exposure to rabbits while living on a farm 6-9 years earlier, suggesting possible reactivation of latent infection.
The portal of infection is believed to be the gastrointestinal tract, from which the organism may rarely disseminate in immunosuppressed individuals. Inhalation has been suggested as another possible route of infection and may result in colonization of the respiratory tree. In either case, the relationship between the presence of organisms visualized within the intestinal and respiratory tracts and symptomatic disease is not always clear. For example, while microsporidia are not infrequently visualized in respiratory specimens in patients with AIDS, only two HIV-infected patients with symptomatic respiratory disease and histological evidence of bronchiolitis due to invasion of an organism have been reported.
Microsporidia have also been associated with keratoconjunctivitis, peritonitis, hepatitis, nephritis, and sinusitis. CNS disease is apparently rare, but several reports describe the occurrence of seizures in two children and in an HIV-infected man possibly due to infection with E. cuniculi. This report suggests that focal CNS lesions, resembling toxoplasmosis, can be due to microsporidial infection in patients with AIDS.
Data presented at the 1997 ICAAC conference are the first to demonstrate the possible efficacy of albendazole in the treatment of intentinal microsporidiosis in a randomized, placebo-controlled trial (see page 20 [Abstract I-148]).
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