Adenoviruses, one of the most common causes of conjunctivitis, are believed to cause 65% to 90% of cases of viral conjunctivitis and about 20% to 75% of all infectious conjunctivitis cases.1-3 This is a serious public health risk; typically, patients with confirmed cases are advised to remain home for anywhere from five days to two weeks.1 During the initial phase of the infection, when only a red eye may be present, eye care practitioners may actually aid the spread of the virus, infecting patients through personal contact or non-sterile equipment. Adenoviruses have been shown to survive chemical and hydrogen peroxide disinfection systems, so contact lens wearers should dispose of their lenses once the illness has resolved.4
Ocular adenoviral infections are classified into four distinct syndromes: epidemic keratoconjunctivitis (EKC), pharyngoconjunctival fever (PCF), chronic keratoconjunctivitis and acute nonspecific follicular conjunctivitis (NCF). EKC usually arises in the fall and winter and typically occurs unilaterally. Keratitis accompanied by discomfort, photophobia, tearing and mild blepharospasm occurs in approximately 80% of EKC patients around day five or six of the infection. The hallmark sign of EKC, subepithelial corneal infiltrates, develop on day 11. PCF mostly occurs in children and is characterized by a fever for about 10 days following an incubation period of about five to 12 days. Unlike EKC, PKC typically occurs bilaterally and is usually accompanied by a sore throat, slight burning, irritation and mild photophobia. Chronic keratoconjunctivitis, the rarest, is characterized by periods of tearing, redness and photophobia that can last up to 18 months. Patients will often have had a recent episode of acute conjunctivitis. NCF is typically mild, occurs with no corneal involvement and resolves within a week to 10 days.
Several signs distinguish adenoviral and bacterial conjunctivitis. An enlarged and painful preauricular lymph node and a follicular reaction of the conjunctiva are more common in adenoviral cases vs. bacterial ones, which usually present with a papillary reaction. Burning sensation, corneal involvement and a watery discharge are also more common in adenovirus cases, while bacterial cases are typically associated with a mucopurulent discharge. Finally, adenovirus infection is more common in adults, occurring less frequently in children under 12.1
When it comes to diagnosis, laboratory cell culture with confirmatory immunofluorescence assay (CC-IFA) is the gold standard of adenoviral detection. Because adenovirus is not part of the normal ocular flora, unlike many bacterial pathogens, the presence of adenovirus by CC-IFA is indicative of active infection. Polymerase chain reaction (PCR) also provides a better measure of the total quantity of virus present in a given sample. However, since PCR replicates not only live virus but also incomplete or dead viral material, a low amount suggests an inactive or resolved infection. Laboratory antigen tests, immunochromatography and enzyme immunoassays may also be used. Also, the Adeno Detector (Rapid Pathogen Screening), an in-office immunoassay diagnostic test, has shown 88% to 89% sensitivity and 91% to 94% specificity in detecting adenoviral conjunctivitis.5
Currently, there is no FDA-approved product for adenoviral conjunctivitis. But, an ophthalmic suspension of dexamethasone 0.1% with povidone-iodine (PVP-I) 0.4% (ForeSight Biotherapeutics) is currently in development. It may decrease the infectivity of the patient.6 Others in development include NVC-422 (Aganocide, NovaBay/Alcon), a drug comprised of analogs to the N-chlorinated molecules used by white blood cells to destroy viruses and bacteria, and EkcCide (Nanoviricides), a member of a new class of drugs designed to attack enveloped virus particles and dismantle them.
1. O’Brien TP, Jeng BH, McDonald M, Raizman MB. Acute conjunctivitis: truth and misconceptions. Curr Med Res Opin 2009;25(8):1953-61.
2. Gigliotti F, Williams WT, Hayden FG, et al. Etiology of acute conjunctivitis in children. J Pediatr 1981;98(4):531-6.
3. Woodland RM, Darougar S, Thaker U, et al. Causes of conjunctivitis and keratoconjunctivitis in Karachi, Pakistan. Trans R Soc Trop Med Hyg 1992;86(3):317-20.
4. Kowalski RP, Sundar-Raj CV, Romanowski EG, Gordon YJ. The disinfection of contact lenses contaminated with adenovirus. Am J Ophthalmol 2001;132(5):777-9.
5. Sambursky R, Tauber S, Schirra F, et al. The RPS adeno detector for diagnosing adenoviral conjunctivitis. Ophthalmology 2006;113(10):1758-64.
6. Pelletier JS, Stewart K, Trattler W, et al. A combination povidone-iodine 0.4%/dexamethasone 0.1% ophthalmic suspension in the treatment of adenoviral conjunctivitis. Adv Ther 2009;26(8):776-83.