Trachipleistophora hominis: molecular characterization of a rare pathogen causing microsporidial stromal keratitis.

The authors report the clinical and microbiological findings of a unique case of stromal keratitis caused by a rare microsporidium, Trachipleistophora hominis. This case of stromal keratitis was in a 49-year-old male with a history of COVID-19 infection and diabetes mellitus. Corneal scraping specimens revealed numerous microsporidia spores upon microscopic examination. PCR of the corneal button revealed the presence of T. hominis infection, which could be controlled by penetrating keratoplasty surgery. The graft was clear with no recurrence of infection until the last follow-up 6 weeks postsurgery. This is the first case of human stromal keratitis caused by this organism in a post-COVID infection, confirmed by molecular diagnosis.

Clinical profile of keratitis treated within 3 months of acute COVID-19 illness at a tertiary care eye centre.

PURPOSE: To report the spectrum of keratitis treated within 3 months of acute COVID-19 infection. METHODS: Retrospective, descriptive case series study of 19 eyes of 16 patients who presented at tertiary eye care centre in Southern India. RESULTS: Median age of the patients was 43(IQR 35-55.5) years. Majority (15/16, 93.75%) were males. Unilateral affliction was predominant (13/16, 81.25% patients). Nine had a history of hospitalization, five had received oxygen supplementation and five had been treated with steroids during COVID-19 illness. The median duration between COVID-19 diagnosis and the ocular symptoms in the eye was 29 (IQR 22-57) days. Microbiological diagnosis consisted of microsporidia in nine eyes of seven patients, fungus in six patients, Pythium in one patient, and herpes zoster ophthalmicus in one patient. One patient had neurotrophic keratitis. Therapeutic penetrating keratoplasty was performed in five patients, glue application in two patients and three were managed with tarsorrhaphy with/without amniotic membrane grafting or tenonplasty. There was medical and surgical cure in all patients. CONCLUSIONS: Microsporidia was the commonest cause of keratitis, followed by fungal infection. Majority of the microsporidia infections were keratoconjunctivitis. The fungal isolates identified were Aspergillus and Mucor species. All patients responded to conventional management guidelines with favourable outcomes.

Microsporidia, a Highly Adaptive Organism and Its Host Expansion to Humans.

Emerging infectious disease has become the center of attention since the outbreak of COVID-19. For the coronavirus, bats are suspected to be the origin of the pandemic. Consequently, the spotlight has fallen on zoonotic diseases, and the focus now expands to organisms other than viruses. Microsporidia is a single-cell organism that can infect a wide range of hosts such as insects, mammals, and humans. Its pathogenicity differs among species, and host immunological status plays an important role in infectivity and disease severity. Disseminated disease from microsporidiosis can be fatal, especially among patients with a defective immune system. Recently, there were two Trachipleistophora hominis, a microsporidia species which can survive in insects, case reports in Thailand, one patient had disseminated microsporidiosis. This review gathered data of disseminated microsporidiosis and T. hominis infections in humans covering the biological and clinical aspects. There was a total of 22 cases of disseminated microsporidiosis reports worldwide. Ten microsporidia species were identified. Maximum likelihood tree results showed some possible correlations with zoonotic transmissions. For T. hominis, there are currently eight case reports in humans, seven of which had Human Immunodeficiency Virus (HIV) infection. It is observed that risks are higher for the immunocompromised to acquire such infections, however, future studies should look into the entire life cycle, to identify the route of transmission and establish preventive measures, especially among the high-risk groups.

Sparse Evidence for Giardia intestinalis, Cryptosporidium spp. and Microsporidia Infections in Humans, Domesticated Animals and Wild Nonhuman Primates Sharing a Farm-Forest Mosaic Landscape in Western Uganda.

Zoonotic pathogen transmission is considered a leading threat to the survival of non-human primates and public health in shared landscapes. Giardia spp., Cryptosporidium spp. and Microsporidia are unicellular parasites spread by the fecal-oral route by environmentally resistant stages and can infect humans, livestock, and wildlife including non-human primates. Using immunoassay diagnostic kits and amplification/sequencing of the region of the triosephosphate isomerase, small ribosomal subunit rRNA and the internal transcribed spacer genes, we investigated Giardia, Cryptosporidium, and microsporidia infections, respectively, among humans, domesticated animals (livestock, poultry, and dogs), and wild nonhuman primates (eastern chimpanzees and black and white colobus monkeys) in Bulindi, Uganda, an area of remarkably high human-animal contact and spatial overlap. We analyzed 137 fecal samples and revealed the presence of G. intestinalis assemblage B in two human isolates, G. intestinalis assemblage E in one cow isolate, and Encephalitozoon cuniculi genotype II in two humans and one goat isolate. None of the chimpanzee and colobus monkey samples were positive for any of the screened parasites. Regular distribution of antiparasitic treatment in both humans and domestic animals in Bulindi could have reduced the occurrence of the screened parasites and decreased potential circulation of these pathogens among host species.