Quantitative Investigation of Viral Load in Acute to Subacute Human Adenovirus Type 54 Conjunctivitis

To understand the clinical course of human adenoviral (HAdV) conjunctivitis and establish a better treatment regimen, 38 eyes of 19 patients with HAdV-54 conjunctivitis for less than one week from onset were evaluated for clinical signs and symptoms and DNA copy numbers. A viral load of 10⁴-10⁵ is required to develop symptoms of HAdV conjunctivitis, as symptoms were present in eyes with viral loads of ≥10⁴ at least once during the course. Next, it was observed that asymptomatic infections in the contralateral eyes are common, as the virus was detected in most eyes that did not develop conjunctivitis. Furthermore, there was no rapid decrease in the viral load in healed eyes; on the contrary, the viral load in the healed eyes on day 15 was significantly higher than that in the unhealed eyes. This was likely due to corticosteroid instillation, which rapidly alleviated symptoms but prolonged the duration of viral shedding. Recently, combination treatment with iodine and corticosteroids has been recommended for HAdV conjunctivitis. Assessing changes in the viral load and clinical symptoms would be helpful to better understand the clinical course of this disease.