Outbreak of seasonal hyperacute panuveitis disease in Nepal
Authors: Mitesh Karn, Jamuna Gurung
Journal: The Lancet Global Health (2021)

Seasonal hyperacute panuveitis is a mysterious and rapidly progressive seasonal, sight-threatening intraocular inflammatory disease with confirmed reports of cases coming solely from Nepal. It was initially described in 1975 in Pokhara in the Kaski District of Nepal as a severe inflammatory eye disease, which presented typically as a “white pupil in a red eye” with rapid loss of vision.1Upadhyay MP Shrestha BR SHAPU: forty years on mystery persists.Nepal J Ophthalmol. 2017; 9: 13-16Google Scholar Since then, it has occurred epidemically in odd calendar years right after the monsoon season (August to September) until the peak of winter (December to January).2Upadhyay M Sitaula RK Shrestha B et al.Seasonal hyperacute panuveitis in Nepal: a review over 40 years of surveillance.Ocul Immunol Inflamm. 2019; 27: 709-717Google Scholar The disease has such a rapid and severe course that more than two-thirds of patients present with blindness, while for the remaining third, most rapidly lose vision despite aggressive management within hours or days. Usually developing from unilateral painless red eye, profound visual loss quickly progresses to a soft eye with a shallow anterior chamber (malignant hypotony), the intraocular reactions proceeding from the anterior to posterior segment of the eye. The pathology eventually involves the entire uveal tract causing cosmetic disfigurement due to phthisis bulbi. Because of its cyclic and seasonal occurrence, rapid progression, and involvement of both anterior and posterior segments of the eye, the disease has rightfully been termed as seasonal hyperacute panuveitis. Seasonal hyperacute panuveitis predominantly affects children, but it can affect people of any age, with evidence suggesting its occurrence in infants as young as 38 days.3Kharel Sitaula R Karki P Joshi SN Sharma AK Upadhyay MP Youngest reported seasonal hyperacute panuveitis case.Am J Ophthalmol Case Rep. 2019; 15100523Google Scholar It is the commonest reported cause of panuveitis among people of all ages (15·2%) and the commonest cause of both uveitis and panuveitis (27·7%) among Nepalese children.4Manandhar A Patterns of uveitis and scleritis in Nepal: a tertiary referral center study.Ocul Immunol Inflamm. 2017; 25: S54-S62Google Scholar Despite the first description of this disease almost 50 years ago, many aspects of the condition remain a mystery, including the exact cause and pathophysiology. Two major pathogenic mechanisms have been suggested—one being infective and the other immunological. Various organisms, including bacteria (Staphylococcus aureus, Streptococcus pneumoniae, and Acinetobacter) and viruses (human anelloviridae and varicella zoster virus) have been isolated from ocular fluids of cases, suggesting an infectious cause. Others consider it an immunological response to an antigen that causes inflammation of the uvea.1Upadhyay MP Shrestha BR SHAPU: forty years on mystery persists.Nepal J Ophthalmol. 2017; 9: 13-16Google Scholar Moths of the Gazalina genus have been implicated in disease occurrence. In a nationwide study conducted during the 2017 outbreak, only direct physical contact with moths was associated with a significantly increased odds of developing the condition.5Upadhyay MP Sitaula RK Manandhar A et al.The risk factors of seasonal hyperacute panuveitis.Ophthalmic Epidemiol. 2020; 28: 250-257Google Scholar This finding was further supported by the identification of moth hairs in the ocular structures of patients with the condition. It is assumed that these moths, either through their toxins or as vectors for microbes, cause seasonal hyperacute panuveitis. Because the exact cause is not yet outlined, treatment is also difficult. Prevention remains pivotal and revolves around avoiding contact with the moths. In early stages of the disease, various treatment modalities such as antibiotics; steroids via topical, subconjunctival, or intravitreal injection; and early vitrectomy have been found useful.6Manandhar A Seasonal hyperacute panuveitis: an update.Curr Opin Ophthalmol. 2011; 22: 496-501Google Scholar However, prognosis remains poor and in many cases, irreversible visual loss occurs. Seasonal hyperacute panuveitis has caused irreversible loss of vision in many Nepalese individuals, especially children, resulting in substantial physical, psychological, and financial loss. Thousands of people have been affected by the condition. During the last outbreak, more than 1500 people were affected, mostly children in the Gandaki Province.7Sharma LP Khadka G Tiwari A Treatable eye disease is causing blindness among children in Gandaki districts.https://kathmandupost.com/gandaki-province/2021/09/18/treatable-eye-disease-is-causing-blindness-among-children-in-gandaki-districtsDate accessed: October 20, 2021Google Scholar The 2021 outbreak is ongoing and more than 100 cases have already been reported, with this number expected to rise. Because of the rapidity, irreversibility, and magnitude of visual loss associated with seasonal hyperacute panuveitis, it is considered an ocular emergency and a clinically significant public health problem. Climate change has affected many disease patterns, which seems to be the case for this disease as well.8Karn M Sharma M Climate change, natural calamities and the triple burden of disease.Nat Clim Chang. 2021; 11: 796-797Google Scholar Although the condition was initially seen to follow a continuous cyclic pattern and occur in specific areas in the subtropical, temperate, and subalpine regions of eastern, central, and western Nepal in odd years only, it is now being observed in even years and in varying geographical regions.2Upadhyay M Sitaula RK Shrestha B et al.Seasonal hyperacute panuveitis in Nepal: a review over 40 years of surveillance.Ocul Immunol Inflamm. 2019; 27: 709-717Google Scholar Notably, two suspected cases of seasonal hyperacute panuveitis were also reported from Bhutan in 2020, the first possible instances of the condition to have occurred outside Nepal.9Rai BB Morley MG Bernstein PS Maddess T Pattern of vitreo-retinal diseases at the national referral hospital in Bhutan: a retrospective, hospital-based study.BMC Ophthalmol. 2020; 20: 1-11Google Scholar Seasonal hyperacute panuveitis is not well known to ophthalmologists globally, and because of its close resemblance to endophthalmitis, it is highly probable that many seasonal hyperacute panuveitis cases outside of Nepal are being incorrectly diagnosed as endophthalmitis. It is time that this disease is assigned a unique code in the International Classification of Diseases and clinicians in the ophthalmic community are made aware of this condition to prevent mass morbidity. Through this Correspondence, we would also like to call for global support in managing this poorly understood condition and initiating further clinical, epidemiological, and entomological research. We declare no competing interests.