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Praveen Kumar Balne, Savitri Sharma, Sujata Das, Srikant K Sahu; Epidemic Keratoconjunctivitis in India: Is it adenoviral or microsporidial?. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2837.
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To investigate the presence of microsporidia and/or adenovirus in ocular sample from patients with epidemic keratoconjunctivitis (EKC).
The study was approved by the institutional review board of L V Prasad Eye Institute, Bhubaneswar, India. About 304 non-consecutive patients with the clinical features of keratoconjunctivitis (test group), 102 patients with microbial keratitis other than microsporidia (disease controls) and 28 healthy controls were included in the study. Water samples were also collected from three villages. After the complete ocular examination, multiple samples were taken from the cornea (scraping using surgical blade no. 15) or conjunctiva (rayon swab) by an ophthalmologist under topical anaesthesia. Microscopy, culture and PCR for microsporidial and adenoviral DNA were done for samples from EKC patients and disease controls, where as only PCR was done for healthy controls and water samples. Microsporidial species and adenoviral serotypes were identified by DNA sequencing.
Smear was positive for microsporidial spores in 210/243 (86.4%) samples from EKC patients, where as all the disease control samples were negative. Out of 304 samples from EKC patients 253 (83.2%) were positive for microsporidial DNA and 30 (9.86%) were positive for adenoviral DNA and 23 (7.56%) were positive for both by PCR. Bacteria was grown in 25/216 (11.6%) samples from EKC patients, which were also positive for microsporidia by microscopy and/or PCR. Two disease control samples were positive for microsporidial DNA and 1 sample for adenoviral DNA and none of the healthy controls was positive by PCR. Water samples from 2 villages were positive for microsporidial DNA and all three village samples were negative for adenoviral DNA. Based on DNA sequencing, Vittaforma corneae was identified in 213 samples and Human adenovirus (HAdV) serotype 8 in 4 samples and HAdV serotype 35 (which were also shown similar homology with HAdV serotype 11) in 10 samples.
The association of microsporidia with EKC was significantly higher than adenovirus (p value < 0.0001), however, this study has brought out for the first time that these two highly diverse organisms can co-exist in the cornea and conjunctiva during the clinical manifestation of EKC. Detection of microsporidial DNA in water samples suggests that, exposure to contaminated water could be one of the risk factors for EKC.
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