H1N1-associated acute retinitis

Response of Human Retinal Microvascular Endothelial Cells to Influenza A (H1N1) Infection and the Underlying Molecular Mechanism

Purpose

Whether H1N1 infection-associated ocular manifestations result from direct viral infections or systemic complications remains unclear. This study aimed to comprehensively elucidate the underlying causes and mechanism.

Method

TCID50 assays was performed at 24, 48, and 72 hours to verify the infection of H1N1 in human retinal microvascular endothelial cells (HRMECs). The changes in gene expression profiles of HRMECs at 24, 48, and 72 hours were characterized using RNA sequencing technology. Differentially expressed genes (DEGs) were validated using real-time quantitative polymerase chain reaction and Western blotting. CCK-8 assay and scratch assay were performed to evaluate whether there was a potential improvement of proliferation and migration in H1N1-infected cells after oseltamivir intervention.

Results

H1N1 can infect and replicate within HRMECs, leading to cell rounding and detachment. After H1N1 infection of HRMECs, 2562 DEGs were identified, including 1748 upregulated ones and 814 downregulated ones. These DEGs primarily involved in processes such as inflammation and immune response, cytokine-cytokine receptor interaction, signal transduction regulation, and cell adhesion. The elevated expression levels of CXCL10, CXCL11, CCL5, TLR3, C3, IFNB1, IFNG, STAT1, HLA, and TNFSF10 after H1N1 infection were reduced by oseltamivir intervention, reaching levels comparable to those in the uninfected group. The impaired cell proliferation and migration after H1N1 infection was improved by oseltamivir intervention.

Conclusions

This study confirmed that H1N1 can infect HRMECs, leading to the upregulation of chemokines, which may cause inflammation and destruction of the blood-retina barrier. Moreover, early oseltamivir administration may reduce retinal inflammation and hemorrhage in patients infected with H1N1.

Risk Factors and Treatment Strategy for Retinal Vascular Occlusive Diseases

Retinal occlusive diseases are common diseases that can lead to visual impairment. Retinal artery occlusion and retinal vein occlusion are included in the clinical entity, but they have quite different pathophysiologies. Retinal artery occlusion is an emergent eye disorder. Retinal artery occlusion is mainly caused by thromboembolism, which frequently occurs in conjunction with life-threatening stroke and cardiovascular diseases. Therefore, prompt examinations and interventions for systemic vascular diseases are often necessary for these patients. Retinal vein occlusion is characterized by retinal hemorrhage and ischemia, which may impair visual function via several complications such as macular edema, macular ischemia, vitreous hemorrhage, and neovascular glaucoma. Even though anti-vascular endothelial growth factor therapy is the current established first-line of treatment for retinal vein occlusion, several clinical studies have been performed to identify better treatment protocols and new therapeutic options. In this review, we summarize the current findings and advances in knowledge regarding retinal occlusive diseases, particularly focusing on recent studies, in order to provide an update for a better understanding of its pathogenesis.

Ocular manifestations of emerging viral diseases

Emerging infectious diseases (EIDs) are an increasing threat to public health on a global scale. In recent times, the most prominent outbreaks have constituted RNA viruses, spreading via droplets (COVID-19 and Influenza A H1N1), directly between humans (Ebola and Marburg), via arthropod vectors (Dengue, Zika, West Nile, Chikungunya, Crimean Congo) and zoonotically (Lassa fever, Nipah, Rift Valley fever, Hantaviruses). However, specific approved antiviral therapies and vaccine availability are scarce, and public health measures remain critical. Patients can present with a spectrum of ocular manifestations. Emerging infectious diseases should therefore be considered in the differential diagnosis of ocular inflammatory conditions in patients inhabiting or returning from endemic territories, and more general vigilance is advisable in the context of a global pandemic. Eye specialists are in a position to facilitate swift diagnosis, improve clinical outcomes, and contribute to wider public health efforts during outbreaks. This article reviews those emerging viral diseases associated with reports of ocular manifestations and summarizes details pertinent to practicing eye specialists.

Bilateral optic neuritis with spine demyelination associated with influenza A H1N1 infection

Purpose

To report a rare case of optic neuritis with spine demyelination following H1N1 virus infection.

Observation

A 66-year-old female presented with decreased vision in both eyes (left > right) following a recent episode of fever and flu. She was diagnosed as H1N1 infection confirmed by viral antigen analysis of throat swab. On examination, she had a profound vision drop in the left eye with optic disc edema. MRI brain and orbit revealed bilateral optic nerve and frontal dural thickening with a ring-enhancing lesion in the right frontal lobe. MRI spine showed long cord signals at T1-T7 suggestive of demyelination. The patient had a complete recovery of vision and visual fields after intravenous and oral steroids.

Conclusion/Importance

Influenza A virus can manifest with a wide range of symptoms including flu-like illness to neurological complications. This case highlights optic neuritis as a presenting feature of H1N1 infection.

Fungal retinitis following influenza virus type A (H1N1) infection

A 43-year-old male presented with left eye foveal retinits causing an acute visual loss following influenza virus type A infection (H1N1 infection or Swine flu). Considering viral (influenza) etiology, a prompt treatment with oral corticosteroids was started. But an initial poor response prompted an immediate diagnostic vitrectomy, which revealed Candida albicans. The retinitis healed with scar formation following anti-fungal therapy. This case highlights that even in the setting of an acute retinitis in an immunocompetent patient with recent history of viral systemic illness, a high index of suspicion of a fungal (rather than viral) infection should be kept in mind.

Pediatric viral orbital cellulites secondary to H1N1 infection: A case report

A 10-year-old boy admitted for high-grade fever and pneumonia developed left preseptal and early orbital cellulitis, unresponsive to higher intravenous antibiotics. He received oseltamivir, on testing positive for H1N1 virus on the nasopharyngeal and throat swabs. There was dramatic improvement with resolution of orbital cellulitis within 24 h of starting oseltamivir. We report a very rare presentation of pediatric orbital cellulitis secondary to systemic H1N1 infection. Prompt investigations and timely treatment with oseltamivir aided in complete resolution, avoiding vision and life-threatening complications.

The hidden burden of influenza: A review of the extra-pulmonary complications of influenza infection

Severe influenza infection represents a leading cause of global morbidity and mortality. Although influenza is primarily considered a viral infection that results in pathology limited to the respiratory system, clinical reports suggest that influenza infection is frequently associated with a number of clinical syndromes that involve organ systems outside the respiratory tract. A comprehensive MEDLINE literature review of articles pertaining to extra‐pulmonary complications of influenza infection, using organ‐specific search terms, yielded 218 articles including case reports, epidemiologic investigations, and autopsy studies that were reviewed to determine the clinical involvement of other organs. The most frequently described clinical entities were viral myocarditis and viral encephalitis. Recognition of these extra‐pulmonary complications is critical to determining the true burden of influenza infection and initiating organ‐specific supportive care.

Ocular Complications in Influenza Virus Infection

Purpose: To describe a case series of ocular complications associated with upper respiratory tract infections. Methods: Four patients aged 21-61 years (three females, one male) had confirmed ocular complications connected with a general upper respiratory tract infection with myalgia and fever. Ophthalmological examination, including a visual acuity test, a slit-lamp exam, intraocular pressure measurements, fluorescein and indocyanine green angiography, optical coherence tomography (OCT), and diagnostic tests for influenza were performed in the patients (RT-PCR, HAI). Results: Acute posterior multifocal placoid pigment epitheliopathy (APMPPE) was diagnosed in three patients and serous macular detachment (SME) in one. Influenza virus infection was confirmed by molecular biological methods (RT-PCR) or the hemagglutination inhibition test (HAI) in two patients. All patients were treated with systemic prednisone. Conclusion: A coincidence between APMPPE and SME epitheliopathy and influenza virus infection was observed in different months of a given epidemic season.

Viral posterior uveitis

The causes of posterior uveitis can be divided into infectious, autoimmune, or masquerade syndromes. Viral infections, a significant cause of sight-threatening ocular diseases in the posterior segment, include human herpesviruses, measles, rubella, and arboviruses such as dengue, West Nile, and chikungunya virus. Viral posterior uveitis may occur as an isolated ocular disease in congenital or acquired infections or as part of a systemic viral illness. Many viruses remain latent in the infected host with a risk of reactivation that depends on various factors, including virulence and host immunity, age, and comorbidities. Although some viral illnesses are self-limiting and have a good visual prognosis, others, such as cytomegalovirus retinitis or acute retinal necrosis, may result in serious complications and profound vision loss. Since some of these infections may respond well to antiviral therapy, it is important to work up all cases of posterior uveitis to rule out an infectious etiology. We review the clinical features, diagnostic tools, treatment regimens, and long-term outcomes for each of these viral posterior uveitides.

Bilateral vaso-occlusive retinal vasculitis with h1n1 influenza a infection

PURPOSE

The purpose of this study is to report a unique case of vaso-occlusive retinal vasculitis in the setting of H1N1 influenza A.

METHODS

This study includes ophthalmologic examination, fluorescein angiogram, optical coherence tomography, neuroimaging, cerebral spinal fluid analysis, serologies, chart review, and review of the relevant literature.

RESULTS

A 13-year-old Caucasian female presented with bilateral vision loss accompanied by mental status changes and flu symptoms. Fundus examination revealed bilateral disk edema, peripapillary and macular flame hemorrhages, macular edema, and cherry-red spots. Fluorescein angiogram revealed vaso-occlusive vasculitis resulting in poor perfusion of the maculae. There was also staining of the optic nerves bilaterally. Optical coherence tomography revealed bilateral macular edema with intraretinal and subretinal fluid.

CONCLUSION

This is a unique case of H1N1 influenza A presenting with vaso-occlusive retinal vasculitis, encephalitis, and flu symptoms. The poor vision is not entirely accounted for by the macular disease. Given the accompanying disk edema, there is likely a similar vaso-occlusive process of the central nervous system that contributed to the bilateral light perception vision.

Neurological events related to influenza A (H1N1) pdm09

OBJECTIVES

To review neurological complications after the influenza A (H1N1) pdm09, highlighting the clinical differences between patients with post-vaccine or viral infection.

DESIGN

A search on Medline, Ovid, EMBASE, and PubMed databases using the keywords “neurological complications of Influenza AH1N1” or “post-vaccine Influenza AH1N1.”

SETTING

Only papers written in English, Spanish, German, French, Portuguese, and Italian published from March 2009 to December 2012 were included.

SAMPLE

We included 104 articles presenting a total of 1636 patient cases. In addition, two cases of influenza vaccine-related neurological events from our neurological care center, arising during the period of study, were also included.

MAIN OUTCOME MEASURES

Demographic data and clinical diagnosis of neurological complications and outcomes: death, neurological sequelae or recovery after influenza A (H1N1) pdm09 vaccine or infection.

RESULTS

The retrieved cases were divided into two groups: the postvaccination group, with 287 patients, and the viral infection group, with 1349 patients. Most patients in the first group were adults. The main neurological complications were Guillain-Barre syndrome (GBS) or polyneuropathy (125), and seizures (23). All patients survived. Pediatric patients were predominant in the viral infection group. In this group, 60 patients (4.7%) died and 52 (30.1%) developed permanent sequelae. A wide spectrum of neurological complications was observed.

CONCLUSIONS

Fatal cases and severe, permanent, neurological sequelae were observed in the infection group only. Clinical outcome was more favorable in the post-vaccination group. In this context, the relevance of an accurate neurological evaluation is demonstrated for all suspicious cases, as well as the need of an appropriate long-term clinical and imaging follow-up of infection and post-vaccination events related to influenza A (H1N1) pdm09, to clearly estimate the magnitude of neurological complications leading to permanent disability.

Ocular Pathology: Role of Emerging Viruses in the Asia-Pacific Region-A Review

The role of viral infections in ocular pathology varies greatly, involving all the components of the eye. Some viruses like herpes simplex, herpes zoster, adenovirus, enterovirus 70, influenza virus, human immunodeficiency virus, and cytomegalovirus are well-known for their role in ocular pathology. In recent years, emerging and resurging viral infections represent an important public health problem. The Asia-Pacific region has witnessed a number of pandemic and epidemic outbreaks caused by these viruses during the last 2 decades. The number of ocular complications being reported in patients of these viral infections has also increased significantly during this period. Ophthalmologists and physicians should be aware of ocular manifestations of newly emerging or resurging viral diseases. We conducted a review of the literature published during the last 20 years with the objectives of finding out outbreaks of emerging and reemerging viruses in the Asia-Pacific region and finding out any ocular involvement in these viral infections. An iterative search of the MEDLINE and the Google databases was made using the search terms emerging virus, ocular manifestations, ocular complications, Chikungunya, Dengue, Japanese encephalitis, West Nile fever, Kyasanur forest disease, Rift valley fever, Hantavirus, Henipavirus, Influenza virus, Enterovirus 71, and Asia-Pacific region, separately and with reported ocular involvement in combination. This review article discusses the epidemiology and the systemic and ocular manifestations of all emerging viral infections with reported ocular involvement in the Asia-Pacific region.

Ocular manifestations of emerging infectious diseases

PURPOSE OF REVIEW

Emergent and resurgent infectious diseases are major causes of systemic morbidity and death that are expanding worldwide mainly because of climate changes and globalization. Among them, specific diseases have been recently associated with ocular involvement. This review presents the ocular manifestations of selected emerging infectious diseases relevant to the ophthalmologist.

RECENT FINDINGS

An array of ocular manifestations, involving mainly the posterior segment, have been recently described in association with specific arthropod vector-borne diseases including rickettsioses, West Nile virus, Rift Valley fever, Dengue fever, and Chikungunya. Influenza A (H1N1) virus has also been recently associated with ocular involvement. On the contrary, with advances in laboratory testing applied to ocular fluids, new infectious agents, mainly viruses, are increasingly being found to be associated with uveitis.

SUMMARY

Emerging infectious diseases should be considered in the differential diagnosis of retinitis, chorioretinitis, retinal vasculitis, optic neuropathy, or any other ocular inflammatory condition in a patient living in or traveling back from a specific endemic area. On the contrary, ocular fluid sampling and analysis for specific new pathogens can be recommended in selected patients with uveitis of unexplained cause.

Swine flu is back again: a review

Flu viruses have mainly affected humans, birds and pigs worldwide. During the past 10 years these viruses are in limelight at a global level due to pandemic threats of Avian/Bird Flu and Swine Flu and their public health impacts, with added pandemic of swine flu virus recently. The current ongoing episodes of bird flu and swine flu are beyond the control, when and where or which country they start with nobody can predict. The continuous evolution and emergence of new strains indicate that the flu viruses are becoming more and more dangerous and this situation has posed a challenge to researchers to discover effective vaccines and therapeutics. Moreover, the role of pig as 'mixing bowl' for the virus to get reassorted has added to the complicated epidemiological scenario. The swine flu H1N1 reassorted subtype caused the first global pandemic in last 40 years, resulting in substantial illness, hospitalizations of millions of peoples and thousands of deaths throughout the world. A pace is there within these novel and emerging flu viruses and the scientific community, where the scientific community has to win the race so as to save the mankind. In this review, a brief overview on swine flu is presented highlighting the characteristics of the causative virus, the disease and its public health consequences, advances made in its diagnosis, vaccine and control, precautionary measures to be adapted in the wake of an outbreak.

New infectious etiologies for posterior uveitis

Emergent and resurgent arthropod vector-borne diseases are major causes of systemic morbidity and death and expanding worldwide. Among them, viral and bacterial agents including West Nile virus, Dengue fever, Chikungunya, Rift Valley fever, and rickettsioses have been recently associated with an array of ocular manifestations. These include anterior uveitis, retinitis, chorioretinitis, retinal vasculitis and optic nerve involvement. Proper clinical diagnosis of any of these infectious diseases is based on epidemiological data, history, systemic symptoms and signs, and the pattern of ocular involvement. The diagnosis is usually confirmed by the detection of a specific antibody in serum. Ocular involvement associated with emergent infections usually has a self-limited course, but it can result in persistent visual impairment. There is currently no proven specific treatment for arboviral diseases, and therapy is mostly supportive. Vaccination for humans against these viruses is still in the research phase. Doxycycline is the treatment of choice for rickettsial diseases. Prevention, including public measures to reduce the number of mosquitoes and personal protection, remains the mainstay for arthropod vector disease control. Influenza A (H1N1) virus was responsible for a pandemic human influenza in 2009, and was recently associated with various posterior segment changes.