Ocular complications of smallpox vaccination

Mpox Keratitis: A Case Report and Review

PURPOSE

Mpox is a rare infectious disease. Lack of knowledge among eye care professionals regarding mpox keratitis greatly reduces the likelihood of diagnosis and effective management. This report and review seek to increase the knowledge of mpox keratitis among eye care professionals.

METHODS

We report a patient with mpox keratitis who underwent successful penetrating keratoplasty, with 20 years of follow-up. A systematic literature search and review of cases of mpox keratitis from 1970 to 2024 was performed.

RESULTS

A total of 24 articles and 2 abstracts reporting 35 cases of mpox keratitis were identified. A frequency of 0.5% to 1.0% may be the lower range of mpox keratitis among symptomatic patients with a confirmed mpox diagnosis. Mpox keratitis occurred with and without systemic mpox. Initial misdiagnoses were common (40%). Polymerase chain reaction results aided clinical diagnosis. Corneal disease ranged from mild epitheliopathy to fulminant ulcerative keratitis. Outcomes ranged from 20/20 acuity to no light perception. In the absence of fulminant systemic disease, tecovirimat was associated with clinical improvement of mpox keratitis in almost all cases. Our case is the only known report of successful penetrating keratoplasty for mpox keratitis and the only case whereby monkeypox virus was cultured from the corneal surface.

CONCLUSIONS

Mpox keratitis is rare but can result in severe vision loss and blindness. Systemic tecovirimat seems to be effective in treating mpox keratitis, although the low frequency of keratitis precludes clinical trials. Topical steroids may extend virus survival in the cornea. Polymerase chain reaction may help confirm mpox corneal involvement.

Update on Mpox: What the Primary Care Clinician Should Know

Mpox is a viral infection, which primarily caused sporadic outbreaks in West and Central Africa until causing a global epidemic in 2022. The disease has disproportionately affected people with human immunodeficiency virus and men who have sex with men. Transmission is through close physical contact, including sexual contact. Infection presents with a characteristic rash, with frequent anogenital involvement-polymerase chain reaction of skin lesions is diagnostic. Vaccination is available for primary prevention and postexposure prophylaxis. Treatment consists of supportive care, with antiviral medications available via clinical trials and/or for patients with severe disease.

Mpox and HIV-Collision of Two Diseases

PURPOSE OF REVIEW

The global outbreak of mpox has brought renewed attention to a previously neglected disease which is particularly severe in people with underlying untreated HIV co-infection. For this population, the disease is progressive, severe, and often lethal. In this review, we examine the pathogenesis of mpox disease and its collision with co-existent HIV infection and discuss key considerations for management as well as emerging clinical dilemmas and areas for future research.

RECENT FINDINGS

Co-existent untreated HIV infection characterized by severe immunocompromise potentiates the nefarious effects of monkeypox virus infection leading to severe manifestations of mpox. Treating mpox in the context of HIV requires mpox-directed therapies, supportive care, and HIV-specific treatment to restore immune function. Preventative measures for PWH are like those in healthy individuals, but the effectiveness and durability of protection conferred by existing vaccines in PWH remain to be fully characterized. Mpox is an important opportunistic infection in PWH. Clinicians should be aware of the unique features of the disease in this population and approaches to care and management of mpox in PWH.

Human MPox (Monkeypox) Virus Membranous Keratoconjunctivitis With Transient Corneal Hypoesthesia and Late Symblepharon Formation: A Novel Case and Clinical Implications

PURPOSE

The aim of this study was to describe a case of corneal involvement as an early manifestation of ocular disease in the 2022 human mpox (monkeypox) virus outbreak.

METHODS

This is a single case report with longitudinal care.

RESULTS

A 47-year-old immunocompetent man presented with viral conjunctivitis before development of skin lesions or systemic symptoms. Subsequently, he developed membranous keratoconjunctivitis and a corneal epithelial defect. Orthopoxvirus-positive polymerase chain reaction test from his ocular surface was positive. The epithelial defect did not heal with conservative treatment but was successfully treated with amniotic membrane transplantation over 8 days. Reduced corneal sensation was noted after epithelial healing, and polymerase chain reaction from the ocular surface remained positive at 17 days from symptom onset, with slowly recovering conjunctivitis at 21 days. Continued membrane formation required repeated removal but significantly improved with topical corticosteroid treatment after epithelial healing by 29 days of symptom onset. Corneal sensation normalized by 87 days from symptom onset at which time symblepharon were noted but PCR testing from the ocular surface was negative.

CONCLUSIONS

Early corneal involvement of human monkeypox virus is possible. Transient corneal hypoesthesia may be due to acute inflammation. Chronic inflammatory changes can result in symblepharon. These findings have potential implications in patient care and corneal donation.

Monkeypox-Associated Disciform Keratitis

PURPOSE

The purpose of this study was to describe a case of monkeypox (MPX)-associated disciform keratitis.

METHODS

This is a case report.

RESULTS

A 36-year-old male patient presented to the infectious diseases clinic with a 1-week history of disseminated pustular skin lesions, a 4-day history of constitutional symptoms, and redness in the left eye. Testing of blood, 2 skin lesions, and a conjunctival swab confirmed the presence of MPX virus by polymerase chain reaction. On ophthalmologic examination on the 17th day of illness, there was a corneal epithelial ridge that stained with fluorescein with disciform corneal edema and underlying keratic precipitates. The patient was treated with oral tecovirimat 600 mg twice a day for 14 days and topical prednisolone acetate 1% 4 times daily, starting 2 days later. On completion of oral treatment, his corneal findings had resolved except for a small subepithelial scar at which time topical steroids were tapered.

CONCLUSIONS

MPX may cause disciform keratitis and scarring that closely resembles other ocular viral infections. Clinical trials are urgently needed to define the optimal management of human MPX infections and reduce vision loss.

Interim Clinical Treatment Considerations for Severe Manifestations of Mpox - United States, February 2023

Monkeypox (mpox) is a disease caused by infection with Monkeypox virus (MPXV), an Orthopoxvirus (OPXV) in the same genus as Variola virus, which causes smallpox. During 2022, a global outbreak involving mpox clade IIb was recognized, primarily among gay, bisexual, and other men who have sex with men.* Most affected patients have been immunocompetent and experienced ≤10 rash lesions (1). CDC has recommended supportive care including pain control.^† However, some patients have experienced severe mpox manifestations, including ocular lesions, neurologic complications, myopericarditis, complications associated with mucosal (oral, rectal, genital, and urethral) lesions, and uncontrolled viral spread due to moderate or severe immunocompromise, particularly advanced HIV infection (2). Therapeutic medical countermeasures (MCMs) are Food and Drug Administration (FDA)-regulated drugs and biologics that are predominantly stockpiled by the U.S. government; MCMs developed for smallpox preparedness or shown to be effective against other OPXVs (i.e., tecovirimat, brincidofovir, cidofovir, trifluridine ophthalmic solution, and vaccinia immune globulin intravenous [VIGIV]) have been used to treat severe mpox. During May 2022-January 2023, CDC provided more than 250 U.S. mpox consultations. This report synthesizes data from animal models, MCM use for human cases of related OPXV, unpublished data, input from clinician experts, and experience during consultations (including follow-up) to provide interim clinical treatment considerations. Randomized controlled trials and other carefully controlled research studies are needed to evaluate the effectiveness of MCMs for treating human mpox. Until data gaps are filled, the information presented in this report represents the best available information concerning the effective use of MCMs and should be used to guide decisions about MCM use for mpox patients.

Ophthalmic Features and Implications of Poxviruses: Lessons from Clinical and Basic Research

Amidst the ongoing monkeypox outbreak, global awareness has been directed towards the prevention of viral transmission and case management, with the World Health Organization declaring the outbreak a public health emergency of international concern. Monkeypox virus is one of several species in the Orthopoxvirus genus, with other species of the genus including the variola, cowpox, mousepox, camelpox, raccoonpox, skunkpox, and volepox viruses. Although the nomenclature of these species is based on the animal host from which they were originally isolated, transmission from animals to humans has been reported with several species. The progression of disease, following an incubation period, typically consists of a prodromal phase with systemic flu-like symptoms. Various organ systems may be affected in addition to the formation of pathognomonic skin lesions. As monkeypox poses a continued public health concern, the ophthalmic sequelae of monkeypox virus, especially those leading to vision loss, warrant consideration as well. This review provides a comprehensive summary of the ophthalmic implications of poxviruses in clinical and laboratory settings reported in the literature, as well as areas of unmet need and future research.

Bilateral Immune-Mediated Keratolysis After Immunization With SARS-CoV-2 Recombinant Viral Vector Vaccine

PURPOSE

The purpose of this study was to report an unusual case of bilateral immune-mediated corneal melting and necrosis after ChAdOx1 nCoV-19 (Covishield) vaccination.

METHODS

This is a case report and literature review.

RESULTS

A 48-year-old man presented to the ophthalmic emergency department with progressive bilateral corneal melting 5 weeks after receiving the first dose of ChAdOx1 nCoV-19 (Covishield) vaccine. Systemic complaints of fever, diarrhea, and vomiting were noted in the first 2 weeks, which subsided before the onset of ocular symptoms at day 21 of vaccine administration. The patient could only perceive light bilaterally and demonstrated features of bilateral keratolysis with choroidal detachment on ultrasonography. The microbiological scraping specimen did not reveal growth of any microorganism. Tectonic penetrating keratoplasty was performed, and the host corneal tissue was sent for histopathology, bacterial culture, fungal culture, polymerase chain reaction for herpes simplex virus, varicella zoster virus, cytomegalovirus, adenovirus, and SARS-CoV-2. Microbial culture was sterile, and viral polymerase chain reaction reports were negative. Histopathological examination revealed dense inflammatory cell infiltration. Detailed systemic workup revealed no underlying systemic or autoimmune pathology.

CONCLUSIONS

Immune-mediated keratolysis after ChAdOx1 nCoV-19 (Covishield) vaccination is a rare entity, and we believe that this is the first report of a temporal association between a serious ocular adverse event after a single dose of any SARS-CoV-19 vaccine. It may be included as a possible adverse event associated with this vaccine.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

Ocular adverse events following vaccination: overview and update

The Food and Drug Administration has licensed, approved, and expanded guidelines for dozens of vaccines since 2010. Although advancements in biotechnology have made vaccines more effective and safer, none are completely free from adverse effects. Many vaccines have been implicated in causing ocular adverse events based on the temporal association of exposure and putative complication. Determination of causality is difficult. We provide an overview of vaccine side effects and also examine the English literature and the Vaccine Adverse Events Reporting System (VAERS) from 2010 through 2020 for vaccine-implicated ocular adverse events. While reactions of eyelids and conjunctiva are commonly reported, the most frequently implicated serious adverse events are optic neuritis and various patterns of intraocular inflammation. Live attenuated vaccines have the potential to cause ocular infection from vaccine-strain organisms, particularly in those immunosuppressed. While postmarketing registries for suspect vaccination adverse events, such as VAERS, are unable to determine causal associations, they are a mainstay in signaling suspected trends that require investigation. The majority of probable and possible serious ocular adverse effects are distinctly uncommon.

The Spectrum of Microbial Keratitis: An Updated Review

Background:

In microbial keratitis, infection of the cornea can threaten vision through permanent corneal scarring and even perforation resulting in the loss of the eye. A literature review was conducted by Karsten, Watson and Foster (2012) to determine the spectrum of microbial keratitis. Since this publication, there have been over 2600 articles published investigating the causative pathogens of microbial keratitis.

Objective:

To determine the current spectrum of possible pathogens implicated in microbial keratitis relative to the 2012 study.

Methods:

An exhaustive literature review was conducted of all the peer-reviewed articles reporting on microbial pathogens implicated in keratitis. Databases including MEDLINE, EMBASE, Scopus and Web of Science were searched utilising their entire year limits (1950-2019).

Results:

Six-hundred and eighty-eight species representing 271 genera from 145 families were implicated in microbial keratitis. Fungal pathogens, though less frequent than bacteria, demonstrated the greatest diversity with 393 species from 169 genera that were found to cause microbial keratitis. There were 254 species of bacteria from 82 genera, 27 species of amoeba from 11 genera, and 14 species of virus from 9 genera, which were also identified as pathogens of microbial keratitis.

Conclusion:

The spectrum of pathogens implicated in microbial keratitis is extremely diverse. Bacteria were most commonly encountered and in comparison, to the review published in 2012, further 456 pathogens have been identified as causative pathogens of microbial keratitis. Therefore, the current review provides an important update on the potential spectrum of microbes, to assist clinicians in the diagnosis and treatment of microbial keratitis.

A Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology

The critical nature of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician/advanced practice provider and the microbiologists who provide enormous value to the healthcare team. This document, developed by experts in laboratory and adult and pediatric clinical medicine, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. This document presents a system-based approach rather than specimen-based approach, and includes bloodstream and cardiovascular system infections, central nervous system infections, ocular infections, soft tissue infections of the head and neck, upper and lower respiratory infections, infections of the gastrointestinal tract, intra-abdominal infections, bone and joint infections, urinary tract infections, genital infections, and other skin and soft tissue infections; or into etiologic agent groups, including arthropod-borne infections, viral syndromes, and blood and tissue parasite infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. In addition, the pediatric needs of specimen management are also emphasized. There is intentional redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a guidance for physicians in choosing tests that will aid them to quickly and accurately diagnose infectious diseases in their patients.

Ribosome Profiling Reveals Translational Upregulation of Cellular Oxidative Phosphorylation mRNAs during Vaccinia Virus-Induced Host Shutoff

Vaccinia virus infection causes a host shutoff that is marked by global inhibition of host protein synthesis. Though the host shutoff may facilitate reallocation of cellular resources for viral replication and evasion of host antiviral immune responses, it poses a challenge for continuous synthesis of cellular proteins that are important for viral replication. It is, however, unclear whether and how certain cellular proteins may be selectively synthesized during the vaccinia virus-induced host shutoff. Using simultaneous RNA sequencing and ribosome profiling, two techniques quantifying genome-wide levels of mRNA and active protein translation, respectively, we analyzed the responses of host cells to vaccinia virus infection at both the transcriptional and translational levels. The analyses showed that cellular mRNA depletion played a dominant role in the shutoff of host protein synthesis. Though the cellular mRNAs were significantly reduced, the relative translation efficiency of a subset of cellular mRNAs increased, particularly those involved in oxidative phosphorylation that are responsible for cellular energy production. Further experiments demonstrated that the protein levels and activities of oxidative phosphorylation increased during vaccinia virus infection, while inhibition of the cellular oxidative phosphorylation function significantly suppressed vaccinia virus replication. Moreover, the short 5' untranslated region of the oxidative phosphorylation mRNAs contributed to the translational upregulation. These results provide evidence of a mechanism that couples translational control and energy metabolism, two processes that all viruses depend on host cells to provide, to support vaccinia virus replication during a host shutoff.IMPORTANCE Many viral infections cause global host protein synthesis shutoff. While host protein synthesis shutoff benefits the virus by relocating cellular resources to viral replication, it also poses a challenge to the maintenance of cellular functions necessary for viral replication if continuous protein synthesis is required. Here we measured the host mRNA translation rate during a vaccinia virus-induced host shutoff by analyzing total and actively translating mRNAs in a genome-wide manner. This study revealed that oxidative phosphorylation mRNAs were translationally upregulated during vaccinia virus-induced host protein synthesis shutoff. Oxidative phosphorylation is the major cellular energy-producing pathway, and we further showed that maintenance of its function is important for vaccinia virus replication. This study highlights the fact that vaccinia virus infection can enhance cellular energy production through translational upregulation in the context of an overall host protein synthesis shutoff to meet energy expenditure.

Genomic identification of human vaccinia virus keratoconjunctivitis and its importance as a laboratory-acquired infection

Context:

Vaccinia virus (VACV) is a member of orthopoxvirus genus of the family Poxviridae. VACVs are enveloped, double-stranded DNA viruses. Several species of this family, for example, molluscum contagiosum, smallpox, deerpox, horsepox, rabbitpox, and VACVs may cause conjunctivitis.

Aims:

Given the high incidence of keratoconjunctivitis in Iran (approximately 3.6%–53.9%) and insufficient clinical diagnostic measures, laboratory tests for detection of its causes and determination of accurate keratoconjunctivitis/conjunctivitis prevalence due to different pathogens are essential.

Settings and Design:

In this research, conjunctival samples collected from 100 patients with keratoconjunctivitis signs were referred to an eye hospital of Iran.

Subjects and Methods:

After DNA extraction, polymerase chain reaction (PCR) was carried out for detection of VACV. PCR-positive products were further subjected to DNA sequencing.

Statistical Analysis Used:

The results were analyzed using Chi-square test.

Results:

In this study, 28% of the samples were positive and a statistically significant relationship obtained between working in medical or research laboratories and VACV prevalence (P < 0.05).

Conclusions:

This study showed a high rate of VACV keratoconjunctivitis, and therefore, further studies for its prevention and control are necessary.

Both CD8+ and CD4+ T Cells Contribute to Corneal Clouding and Viral Clearance following Vaccinia Virus Infection in C57BL/6 Mice

Vaccinia virus (VACV) keratitis is a serious complication following smallpox vaccination and can lead to blindness. The pathological mechanisms involved in ocular VACV infection are poorly understood. Previous studies have used rabbits, but the lack of immune reagents and transgenic or knockout animals makes them less suitable for mechanistic studies. We report that infection of C57BL/6 mice with 1 × 10(7) PFU of vaccinia virus strain WR results in blepharitis, corneal neovascularization, and stromal keratitis. The DryVax strain of VACV was completely attenuated. Infection required corneal scarification and replication-competent virus, and the severity of ocular disease was similar in 4- to 6-week-old and 1-year-old mice. Viral titers peaked at approximately 1 × 10(6) PFU on day 5 postinfection, and virus had not cleared by day 13 postinfection. Neutrophils were found in the peripheral cornea on day 1 after infection and then declined, followed by infiltration of both CD4(+) and CD8(+) T cells, which remained peripheral throughout the infection. Blood vessel growth extended 2 to 5 mm into the cornea from the limbus. Infection of CD4(-/-), CD8(-/-), or antibody-depleted mice resulted in similar disease severity and corneal clouding, indicating that both T-cell subsets were involved in the immunopathological response. Depletion of both CD4(+) and CD8(+) T cells resulted in significantly more severe disease and failure to clear the virus. On the basis of our results, the pathology of VACV keratitis is significantly different from that of herpes simplex virus keratitis. Further studies are likely to reveal novel information regarding virulence and immune responses to viral ocular infection.

IMPORTANCE

Potentially blinding eye infections can occur after vaccination for smallpox. Very little is known about the pathological mechanisms that are involved, and the information that is available was generated using rabbit models. The lack of immunological reagents for rabbits makes such studies difficult. We characterized a mouse model of vaccinia virus ocular disease using C57BL/6 mice and strain WR and show that both CD4(+) and CD8(+) T-cell subsets play a role in the blinding eye disease and in controlling virus replication. On the basis of these results, vaccinia virus keratitis is significantly different from herpes simplex virus keratitis, and further studies using this model should generate novel insights into immunopathological responses to viral ocular infection.

Defending against smallpox: a focus on vaccines

Smallpox has shaped human history, from the earliest human civilizations well into the 20th century. With high mortality rates, rapid transmission, and serious long-term effects on survivors, smallpox was a much-feared disease. The eradication of smallpox represents an unprecedented medical victory for the lasting benefit of human health and prosperity. Concerns remain, however, about the development and use of the smallpox virus as a biological weapon, which necessitates the need for continued vaccine development. Smallpox vaccine development is thus a much-reviewed topic of high interest. This review focuses on the current state of smallpox vaccines and their context in biodefense efforts.

Peptide therapeutics for treating ocular surface infections

Microbial pathogens-bacteria, viruses, fungi, and parasites-are significant causes of blindness, particularly in developing countries. For bacterial and some viral infections a number of antimicrobial drugs are available for therapy but there are fewer available for use in treating fungal and parasitic keratitis. There are also problems with current antimicrobials, such as limited efficacy and the presence of drug-resistant microbes. Thus, there is a need to develop additional drugs. Nature has given us an example of 1 potential source of new antimicrobials: antimicrobial peptides and proteins that are either present in bodily fluids and tissues constitutively or are induced upon infection. Given the nature of peptides, topical applications are the most likely use to be successful and this is ideal for treating keratitis. Such peptides would also be active against drug-resistant pathogens and might act synergistically if used in combination therapy. Hundreds of peptides with antimicrobial properties have been isolated or synthesized but only a handful have been tested against ocular pathogens and even fewer have been tested in animal models. This review summarizes the currently available information on the use of peptides to treat keratitis, outlines some of the problems that have been identified, and discusses future studies that will be needed. Most of the peptides that have been tested have shown activity at concentrations that do not warrant further development, but 1 or 2 have promising activity raising the possibility that peptides can be developed to treat keratitis.

A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2013 recommendations by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM)(a)

The critical role of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician and the microbiologists who provide enormous value to the health care team. This document, developed by both laboratory and clinical experts, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. Sections are divided into anatomic systems, including Bloodstream Infections and Infections of the Cardiovascular System, Central Nervous System Infections, Ocular Infections, Soft Tissue Infections of the Head and Neck, Upper Respiratory Infections, Lower Respiratory Tract infections, Infections of the Gastrointestinal Tract, Intraabdominal Infections, Bone and Joint Infections, Urinary Tract Infections, Genital Infections, and Skin and Soft Tissue Infections; or into etiologic agent groups, including Tickborne Infections, Viral Syndromes, and Blood and Tissue Parasite Infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. There is redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a reference to guide physicians in choosing tests that will aid them to diagnose infectious diseases in their patients.

Diversity of microbial species implicated in keratitis: a review

Background:

Microbial keratitis is an infectious disease of the cornea characterised by inflammation and is considered an ophthalmic emergency requiring immediate attention. While a variety of pathogenic microbes associated with microbial keratitis have been identified, a comprehensive review identifying the diversity of species has not been completed.

Methods:

A search of peer-reviewed publications including case reports and research articles reporting microorganims implicated in keratitis was conducted. Search engines including PubMed, Scopus and Web of Science with years ranging from 1950-2012 were used.

Results:

232 different species from 142 genera, representing 80 families were found to be implicated in microbial keratitis. Fungi exhibited the largest diversity with 144 species from 92 genera. In comparison, 77 species of bacteria from 42 genera, 12 species of protozoa from 4 genera and 4 types of virus were identified as the infectious agents. A comparison of their aetiologies shows reports of similarities between genera.

Conclusions:

The diversity of microbial species implicated in keratitis has not previously been reported and is considerably greater than suggested by incidence studies. Effective treatment is heavily reliant upon correct identification of the responsible microorganisms. Species identification, the risk factors associated with, and pathogenesis of microbial keratitis will allow the development of improved therapies. This review provides a resource for clinicians and researchers to assist in identification and readily source treatment information.

Evaluation of therapeutic interventions for vaccinia virus keratitis

BACKGROUND

Vaccinia virus keratitis (VACVK) is a complication of smallpox vaccination that can result in blindness. There are no Food and Drug Administration-approved treatments for VACVK, and vaccinia immunoglobulin (VIG) is contraindicated in isolated VACVK. We used a rabbit model of infection to compare several therapeutic options for VACVK.

METHODS

Rabbit eyes were infected with 10(5) plaque-forming units of the Dryvax strain of vaccinia virus and scored daily for 28 days using a modified MacDonald-Shadduck scoring system. Animals were treated for 10 days after the onset of keratitis with albumin, VIG, prednisolone acetate, trifluridine, or combinations thereof. Ocular viral titers and vaccinia-specific antibody titers were determined by plaque assay and enzyme-linked immunosorbent assay, respectively.

RESULTS

Treatment with intravenous VIG neither exacerbated nor ameliorated VACVK. Topical prednisolone acetate interfered with viral clearance, and ocular disease rebounded in prednisolone-treated groups. The most effective treatment was topical trifluridine alone.

CONCLUSIONS

We conclude that (1) VIG did not negatively affect the treatment of isolated keratitis, (2) topical corticosteroids should not be used for treating VACVK, and (3) treatment with topical trifluridine, with or without intravenous VIG, is the preferred therapeutic regimen for treating VACVK.

A quantitative rabbit model of vaccinia keratitis

PURPOSE

The goal of this study was to use multiple quantitative disease measures to evaluate the effect of various viral inocula on the development of vaccinia keratitis in rabbits.

METHODS

Trephined eyes of female rabbits were infected with 10(4), 10(5), 10(6), or 10(7) plaque-forming units (pfu) of the Dryvax strain of the vaccinia virus and scored daily for disease for 14 days according to a modification of the MacDonald-Shadduck scoring system. Ocular viral titers and vaccinia-specific antibody titers were determined by plaque assay and ELISA, respectively.

RESULTS

The amount of virus used for infection affected the severity of disease, with 10(4) pfu eliciting milder keratitis after delayed onset compared with higher amounts of virus. At inocula above 10(5) pfu the course and severity of corneal disease was not significantly different. The time to reach peak titers was delayed in the 10(4) group but peak titers were similar in all groups. Severe conjunctival chemosis interfered with scoring in animals infected with 10(6) or 10(7) pfu. Virus-specific antibody titers were similar in all groups at day 14. Body weights decreased less than 10% in all groups.

CONCLUSIONS

The course of vaccinia keratitis in rabbits paralleled that in humans. A viral inoculum of 10(5) pfu/eye was determined to be optimal for use in further studies of vaccinia keratitis.

Kinetics of immune cell infiltration in vaccinia virus keratitis

PURPOSE

Vaccinia virus keratitis leading to blindness is a severe complication of smallpox vaccination. The clinical manifestations of vaccinia virus keratitis are similar to those of herpes simplex virus keratitis, a well-studied immunopathologic disease. Vaccinia virus keratitis is likely to involve an immunopathologic component, but little is known about the pathogenesis of the disease. The goal of this study was to determine type and kinetics of immune cell infiltration in the cornea during vaccinia virus keratitis.

METHODS

Rabbit eyes were trephined and inoculated with 1x10(5) pfu of the Dryvax strain of the vaccinia virus. On days 2, 4, 7, 10, 14, and 28 after infection, the animals were scored for clinical disease and eye sections were stained for B cells, CD4+ cells, CD8+ cells, and neutrophils. The eyelid, ciliary body, cornea, iris, iridocorneal angle, and choroid were examined.

RESULTS

Corneal vaccinia virus challenge resulted in the infiltration of B cells, CD4+ cells, CD8+ cells, and neutrophils into the cornea and eyelids. Neutrophils were the predominant cell type on days 2 and 3 after infection, whereas CD4+ cells were the predominant cell type detected in corneas on days 4 through 10. CD8+ cells and B cells peaked on day 10, but at lower levels than CD4+ cells and neutrophils.

CONCLUSIONS

These results suggest that sequential migration of neutrophils, then CD4+ cells, plays an important role in vaccinia virus keratitis.

Smallpox in the 21st century

The viral disease, smallpox, was well known through the end of the 20th Century. Because it has been eradicated from natural populations, the present clinical experience with managing the disease is limited. Similarly, research in the pathophysiology, treatment, and prevention of the disease has recently become a priority. Concerns regarding smallpox as a weapon of bioterrorism have led to the implementation of a new prophylactic vaccine program, a renewal in variola vaccine research, and treatment regimens against variola infection.

Ocular vaccinia following exposure to a smallpox vaccinee

PURPOSE

To describe the presentation and management of the first identified case of ocular vaccinia infection associated with the current smallpox vaccination program.

DESIGN

Case report.

METHODS

Vaccinia virus was isolated by cell culture of a conjunctival swab. Direct staining with fluorescein isothiocyanate-labeled vaccinia antibody and polymerase chain reaction testing confirmed the diagnosis.

RESULTS

In February 2003, a 26-year-old woman developed right preseptal cellulitis and blepharoconjunctivitis following contact with a vaccinated member of the military. The preseptal cellulitis resolved with antibacterial therapy, and the conjunctival infection was treated successfully with a 14-day course of topical trifluridine and a single dose of intravenous vaccinia immune globulin.

CONCLUSIONS

To facilitate rapid diagnosis and appropriate treatment, clinicians must maintain a high index of suspicion for ocular smallpox vaccine-associated adverse reactions in vaccine recipients and their close contacts.