Epidemic outbreak of acute haemorrhagic conjunctivitis caused by coxsackievirus A24 in Thailand, 2014

Identification of coxsackievirus A-24 GIV C5 strain as the cause of acute hemorrhagic conjunctivitis outbreak in Hyderabad, India in 2022

Viral infection is frequently the cause for acute hemorrhagic conjunctivitis (AHC) epidemics. AHC can result from adenoviruses, with enterovirus 70 and coxsackievirus A24 being the primary agents. AHC was initially identified in Ghana in 1969, caused by enterovirus 70 and leading to a global pandemic. Since 2000, outbreaks of AHC linked to coxsackievirus A24 variant have been documented in Spain, Pakistan, Singapore, India, Korea, and China. A sudden surge of conjunctivitis cases reported in October 2022 in and out of the Hyderabad region. This infection presented with usual symptoms of redness of the eyes, discharge, pain in the eyes and crusting. Occular swab samples from 110 patients were collected in order to identify and characterize the virus that was causing the epidemic. We examined adenovirus, enterovirus, COVID-19 and Herpes Simplex Virus by using commercially kits available at the hospital. Conserved regions in the enteroviral 5'-UTR and VP2 gene were analyzed further for characterization of serotype at the National apex laboratory. None of them was found positive except Enterovirus in 16.36 % (18/110) of the patients. From enterovirus-positive samples, the coxsackievirus A24 was observed in all 18 positive samples. These clinical isolates constitute a new lineage cluster associated with genotype IV-C5, according to additional sequencing of the full-length VP2 genes and subsequent phylogenetic analysis. In conclusion, the current outbreak of acute haemorrhagic conjunctivitis in Hyderabad, India was traced to the coxsackievirus A24 strain GIV C5.

An outbreak of acute hemorrhagic conjunctivitis due to Coxsackievirus A24 in a residential school, Naharlagun, Arunachal Pradesh: July 2023

PURPOSE

An acute conjunctivitis outbreak was investigated at a residential school in Naharlagun, Arunachal Pradesh, Northeast India, in July 2023. We aimed to identify the etiological agent and assess any complications in follow-up cases.

METHODS

We used a structured questionnaire to record clinical findings and followed up with cases one-month post-conjunctivitis. Sixty-one cases were examined and eight conjunctival and oropharyngeal swab samples were collected after obtaining informed consent from guardians/school authorities. We screened for 33 viral and bacterial pathogens using an IVD-approved Real-time PCR assay. Further, the samples were subjected to nucleic acid sequencing.

RESULTS

Among 465 screened students and staff, 80 individuals (approximately 17.2%) showed acute hemorrhagic conjunctivitis symptoms among which 61 cases were available for clinical examination. We identified the Enterovirus responsible by targeted sequencing using next-generation sequencing. The etiological agent was found to be Coxsackievirus A24, a member of Enterovirus C, in seven out of eight samples subjected to sequencing. Common symptoms included conjunctival hyperemia and foreign body sensation (100%), bilateral eye involvement (73.8%), eye pain (70%), watery discharge (49.2%), and eyelid swelling (38%). Only 6.5% had purulent discharge. Most cases resolved within 5-6 days, with only 9.8% reporting abdominal symptoms post-conjunctivitis. No serious complications occurred within one month. Throat swabs aided in diagnosing enterovirus infections alongside eye swabs.

CONCLUSIONS

The outbreak of acute conjunctivitis was caused by Coxsackievirus A24, a member of Enterovirus C. Cases resolved spontaneously within 6-7 days, with no severe complications. Collecting oropharyngeal swabs alongside conjunctival swabs could improve enteroviral conjunctivitis diagnosis.

Non-Polio Enterovirus C Replicate in Both Airway and Intestine Organotypic Cultures

Non-polio enteroviruses (EV) belonging to species C, which are highly prevalent in Africa, mainly among children, are poorly characterized, and their pathogenesis is mostly unknown as they are difficult to culture. In this study, human airway and intestinal organotypic models were used to investigate tissue and cellular tropism of three EV-C genotypes, EV-C99, CVA-13, and CVA-20. Clinical isolates were obtained within the two passages of culture on Caco2 cells, and all three viruses were replicated in both the human airway and intestinal organotypic cultures. We did not observe differences in viral replication between fetal and adult tissue that could potentially explain the preferential infection of infants by EV-C genotypes. Infection of the airway and the intestinal cultures indicates that they both can serve as entry sites for non-polio EV-C. Ciliated airway cells and enterocytes are the target of infection for all three viruses, as well as enteroendocrine cells for EV-C99.

First detection and characterization of EV-A71 and a new genogroup of CVA-24 causing neurological disease in Tunisia

Aim: Molecular characterization of enterovirus A71 (EV-A71) and coxsackievirus A24 (CVA-24) strains isolated during neurological diseases surveillance activities in Tunisian patients. Materials & methods: Specimens were obtained from two Tunisian children and analyzed for enterovirus with quantitative reverse transcription PCR (RT-qPCR). We sequenced the whole genome of strains detected. Results: The EV-A71 sequence reported was assigned to subgenogroup C2 with a high nucleotide sequence identity to other EV-A71 C2 detected in other countries, which suggests virus migration. Interestingly, in the VP1 coding region, the Tunisian CV-A24 strain displayed high sequence divergence from other CV-A24, which confirms that it represents a new genogroup. Conclusion: This is the first report of EV-A71 in Tunisia and the first report of a CV-A24 strain causing aseptic meningitis.

Epidemiological trends and sociodemographic factors associated with acute hemorrhagic conjunctivitis in mainland China from 2004 to 2018

Background

Acute hemorrhagic conjunctivitis (AHC) is classified as a class C notifiable infectious disease in China and poses a great threat to public health. This study aimed to investigate the epidemiological trends and hotspots of AHC in mainland China. Sociodemographic factors that could contribute to early warning of AHC were further explored.

Methods

Yearly and monthly incidences of acute hemorrhagic conjunctivitis by date and region from 2004 to 2018 were extracted from the Data Center of China Public Health Science. Joinpoint regression and spatial autocorrelation analysis were performed to explore the epidemiological trends and hotspots of AHC. A generalized linear model was then applied to explore the relationship between sociodemographic factors and AHC incidence.

Results

The average annual AHC incidence was 3.58/100,000 in mainland China. The first-level spatial and temporal aggregation areas were distributed in Guangxi, Hainan, Guangdong, Guizhou, Hunan, Jiangxi, Fujian, Chongqing, Hubei, Anhui, and Zhejiang, with gathering times from 2010/1/1 to 2010/12/31 (RR = 20.13, LLR = 474,522.89, P < 0.01). After 2010, the AHC incidence was stable (APC = − 8.37, 95% CI: − 23.02–9.06). However, it was significantly increased in low- and middle-income provinces (AAPC = 10.65, 95% CI: 0.62–21.68, AAPC = 11.94, 95% CI: 0.62–24.53). The peak of AHC occurred during the August to October period. Children who age 0–3 years are identified as high-risk group with AHC incidence significantly increased (APC = 31.54, 95% CI: 0.27–72.56). Birth rate, population ages 0–14 (% of total population), passenger traffic, and urban population (% of total population) were positively associated with the AHC incidence, while per capita gross domestic product was negatively associated with the AHC incidence.

Conclusion

Overall, the AHC incidence was stable after 2010 in China, but it was significantly increased in low- and middle-income provinces. Regions with a high birth rate, population ages 0–14 (% of the total population), passenger traffic, urban population (% of the total population) and low per capita gross domestic product are at high risk of incidences of AHC. In the future, public health policy and resource priority for AHC in regions with these characteristics are necessary.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01758-6.

Long-term effects of weather condition and air pollution on acute hemorrhagic conjunctivitis in China: A nationalwide surveillance study in China

BACKGROUND

Global climate change could have potential impact on enterovirus (EV)-induced infectious diseases. However, the environmental factors promoting acute hemorrhagic conjunctivitis (AHC) circulation remain inconclusive. This study aimed to quantify the relationship between the environment and AHC.

METHODS

We retrieved the monthly counts and incidence of AHC, meteorological variables and air quality in mainland China between 2013 and 2018. Exposure risks were evaluated by multivariate distributed lag nonlinear models.

RESULTS

A total of 219,599 AHC cases were reported in 31 provinces of China, predominantly in southern and central China, seasonally increased in summer. AHC incidence increased by 7% between 2013 and 2018, from 2.6873 to 2.7570 per 100,000 people. A moderate positive correlation was seen between AHC and monthly mean temperature, relative humidity (RH) and precipitation. Each unit increment was associated with a relative risk for AHC of 1.058 at 17°-32 °C at lag 0 months, 1.017 at 65-71% RH at lag 1.4 months, and 1.039 at 400-569 mm at lag 2.4 months. By contrast, a negative correlation was seen between monthly ambient NO₂ and AHC.

CONCLUSION

Long-term exposure to higher mean temperature, RH and precipitation were associated with an increased risk of AHC. The general public, especially susceptible populations, should pay close attention to weather changes and take protective measures in advance to any AHC outbreak as the above situations occur.

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.

Molecular evolution of coxsackievirus A24v in Cuba over 23-years, 1986-2009

Coxsackievirus A24 variant (CVA24v) is a major causative agent of acute hemorrhagic conjunctivitis outbreaks worldwide, yet the evolutionary and transmission dynamics of the virus remain unclear. To address this, we analyzed and compared the 3C and partial VP1 gene regions of CVA24v isolates obtained from five outbreaks in Cuba between 1986 and 2009 and strains isolated worldwide. Here we show that Cuban strains were homologous to those isolated in Africa, the Americas and Asia during the same time period. Two genotypes of CVA24v (GIII and GIV) were repeatedly introduced into Cuba and they arose about two years before the epidemic was detected. The two genotypes co-evolved with a population size that is stable over time. However, nucleotide substitution rates peaked during pandemics with 4.39 × 10-3 and 5.80 × 10-3 substitutions per site per year for the 3C and VP1 region, respectively. The phylogeographic analysis identified 25 and 19 viral transmission routes based on 3C and VP1 regions, respectively. Pandemic viruses usually originated in Asia, and both China and Brazil were the major hub for the global dispersal of the virus. Together, these data provide novel insight into the epidemiological dynamics of this virus and possibly other pandemic viruses.

Epidemiological Characteristics and Spatiotemporal Analysis of Acute Hemorrhagic Conjunctivitis from 2004 to 2018 in Chongqing, China

Chongqing is one of the five provinces in China that has the highest incidence of acute hemorrhagic conjunctivitis (AHC). Data of AHC cases from 2004 to 2018 were obtained from National Notifiable Diseases Reporting Information System (NNDRIS). Descriptive statistical methods were used to analyze the epidemiological characteristics; incidence maps were used to reflect incidence trends in each district; spatial autocorrelation was used to identify hotspot regions and spatiotemporal patterns of AHC outbreaks; spatiotemporal scan were conducted to identify AHC clusters. A total of 30,686 cases were reported with an annual incidence of 7.04 per 100,000. The incidence rates were high in 2007 and 2014, and large epidemics were observed in 2010 with the seasonal peak in September. Individuals aged 10–19 years, males, students and farmers were the prime high-risk groups. Except for 2012 and 2013, the spatial distribution of AHC did not exhibit significant global spatial autocorrelation. Local indicators of spatial association showed that the high-risk regions are Chengkou and Wuxi. The spatiotemporal scan indicated that all clusters occurred in September 2010, and the high-incidence clusters were mainly distributed in the northeast of Chongqing. The results could assist public health agencies to consider effective preventive measures based on epidemiological factors and spatiotemporal clusters in different regions.

Forecast of the trend in incidence of acute hemorrhagic conjunctivitis in China from 2011-2019 using the Seasonal Autoregressive Integrated Moving Average (SARIMA) and Exponential Smoothing (ETS) models

BACKGROUND

This study aimed to explore the demographic and distributive features of acute hemorrhagic conjunctivitis (AHC). We constructed seasonal autoregressive integrated moving average (SARIMA) and exponential smoothing (ETS) models to predict its trend in incidence in mainland China and provided evidence for the government to formulate policies regarding AHC prevention.

METHODS

Data regarding the distribution and demographic characteristics of AHC in China from 2011-2016 were retrieved from the Public Health Scientific Data website. Monthly AHC data from January 2011 to June 2019 were used to establish and evaluate the SARIMA and ETS models.

RESULTS

During 2011-2016, a total of 213,325 cases were reported; 46.01% were farmers, patients aged ≤9 years had the highest risk, and the male:female ratio was 1.31:1. Guangxi and Guangdong had the highest number of reported AHC cases. The SARIMA (0, 0, 1) (2, 0, 0) ₁₂ model with the minimum root mean squared error and mean absolute percentage error were finally selected for in-sample simulation.

CONCLUSIONS

AHC remains a serious public health problem in Southern and Eastern China that mainly affects farmers and children younger than 9 years. It is recommended that the health administration strengthen the publicity and education regarding AHC prevention among farmers and accelerate the development of related vaccines and treatment measures.

Seasonal and Temporal Trends in Childhood Conjunctivitis in Burkina Faso

Acute conjunctivitis follows a seasonal pattern. Although its clinical course is typically self-limited, conjunctivitis epidemics incur a substantial economic burden because of missed school and work days. This study investigated seasonal and temporal trends of childhood conjunctivitis in the entire country of Burkina Faso from 2013 to 2016, using routine monthly surveillance from 2,444 government health facilities. A total of 783,314 cases were reported over the 4-year period. Conjunctivitis followed a seasonal pattern throughout the country, with a peak in April. A nationwide conjunctivitis outbreak with a peak in September 2016 was noted (P < 0.001), with an excess number of cases first detected in June 2016. Nationwide passive surveillance was able to detect an epidemic 3 months before its peak, which may aide in allocation of resources for containment and mitigation of transmission in future outbreaks.

Molecular epidemiology of acute hemorrhagic conjunctivitis caused by coxsackie A type 24 variant in China, 2004-2014

To understand control interventions, the molecular epidemiology of acute hemorrhagic conjunctivitis (AHC) was investigated from 2004 to 2014.A total of 613,485 AHC cases (annualized cases 55,771) with two deaths were included. Our findings showed that AHC was reported in all provinces, predominantly in Southern and Eastern China. The incidence rates were highest in 2007 (5.65/100,000) and 2010 (21.78/100,000) respectively. A clear seasonal pattern was identified with a peak from August to October. AHC cases occurred in all age groups; however, five to 14 years was the predominant group [23.06%, 133, 510/578,909]. The median age was 24 years (one month~97 years). The median duration from onset to diagnosis was 1.5 days, and there was no difference between the <15, 15~60 and >60-year-old patients [p = 0.0653]. The phylogenetic analysis of 100 nonstructural proteins (3C) and 84 structural proteins (VP1) revealed that AHC outbreaks were caused by Coxsackievirus A24 variant. Genotypes G4-c5a, G4-c5b, and G4-c3 co-circulated with both temporal and geographical overlaps. In conclusion, despite the overall steady decline in the number of AHC cases since the peak in 2010, it still remains a serious public health problem in Southern and Eastern China that targets on the school aged children under 15 years old.

Laboratory Surveillance of Polio and Other Enteroviruses in High-Risk Populations and Environmental Samples

In the context of poliomyelitis eradication, a reinforced supplementary laboratory surveillance of enteroviruses was implemented in Greece. Between 2008 and 2014, the Hellenic Polioviruses/Enteroviruses Reference Laboratory performed detailed supplementary surveillance of circulating enteroviruses among healthy individuals in high-risk population groups, among immigrants from countries in which poliovirus is endemic, and in environmental samples. In total, 722 stool samples and 179 sewage water samples were included in the study. No wild-type polioviruses were isolated during these 7 years of surveillance, although two imported vaccine polioviruses were detected. Enterovirus presence was recorded in 25.3 and 25.1% of stool and sewage water samples, respectively. Nonpolio enteroviruses isolated from stool samples belonged to species A, B, or C; coxsackievirus A24 was the most frequently identified serotype. Only enteroviruses of species B were identified in sewage water samples, including four serotypes of echoviruses and four serotypes of coxsackie B viruses. Phylogenetic analysis revealed close genetic relationships among virus isolates from sewage water samples and stool samples, which in most cases fell into the same cluster. To the best of our knowledge, this is the first study to compare enterovirus serotypes circulating in fecal specimens of healthy individuals and environmental samples, emphasizing the burden of enterovirus circulation in asymptomatic individuals at high risk. Given that Greece continues to receive a large number of short-term arrivals, students, migrants, and refugees from countries in which poliovirus is endemic, it is important to guarantee high-quality surveillance in order to maintain its polio-free status until global eradication is achieved.IMPORTANCE This article summarizes the results of supplementary poliovirus surveillance in Greece and the subsequent characterization of enteroviral circulation in human feces and the environment. The examination of stool samples from healthy refugees and other individuals in "high-risk" groups for poliovirus enables the identification of enterovirus cases and forms the basis for further investigation of the community-level risk of viral transmission. In addition, the examination of composite human fecal samples through environmental surveillance links poliovirus and nonpoliovirus isolates from unknown individuals to populations served by the sewage or wastewater system. Supplementary surveillance is necessary to comply with the prerequisites imposed by the World Health Organization for monitoring the emergence of vaccine-derived polioviruses, reemergence of wild polioviruses, or disappearance of all vaccine-related strains in order for countries such as Greece to maintain their polio-free status and contribute to global poliovirus eradication.

Circulation of multiple serotypes of highly divergent enterovirus C in the Xinjiang Uighur Autonomous Region of China

Poliomyelitis associated with circulating vaccine-derived polioviruses (cVDPVs) is a serious public health issue in the post-eradication era, and the occurrence of recombinant cVDPVs emphasizes the need to elucidate enterovirus C (EV-C) epidemiology. Stool samples were collected from 826 healthy children in Southern Xinjiang in 2011 to investigate EV-C circulation and epidemiology. Thirty-six EV-Cs were isolated and assigned to eight EV-C serotypes by molecular serotyping, suggesting the circulation of diverse EV-Cs in Xinjiang. Phylogenetic analysis showed that the Xinjiang EV-C strains had larger variation compared to the prototype and other modern strains. Additionally, the results showed unique characteristics of Xinjiang EV-Cs, such as the cytopathicity of CV-A1 strains to RD cells; the high divergence in CV-A11, CV-A13, CV-A17, and CV-A20 strains; the divergence of Xinjiang CV-A24 from AHC-related CV-A24 variant stains distributed worldwide; and the circulation of two novel EV-C serotypes (EV-C96 and EV-C99). Evaluations of this dense and diverse EV-C ecosystem will help elucidate the processes shaping enteroviral biodiversity. This study will improve our understanding of the evolution of enteroviruses and the recombination potential between polioviruses and other EV-Cs.

Phylodynamic Characterization of an Ocular-Tropism Coxsackievirus A24 Variant

Recent phylodynamic studies have focused on using tree topology patterns to elucidate interactions among the epidemiological, evolutionary, and demographic characteristics of infectious agents. However, because studies of viral phylodynamics tend to focus on epidemic outbreaks, tree topology signatures of tissue-tropism pathogens might not be clearly identified. Therefore, this study used a novel Bayesian evolutionary approach to analyze the A24 variant of coxsackievirus (CV-A24v), an ocular-tropism agent of acute hemorrhagic conjunctivitis. Analyses of the 915-nucleotide VP1 and 690-nt 3Dpol regions of 21 strains isolated in Taiwan and worldwide during 1985-2010 revealed a clear chronological trend in both the VP1 and 3Dpol phylogenetic trees: the emergence of a single dominant cluster in each outbreak. The VP1 sequences included three genotypes: GI (prototype), GIII (isolated 1985-1999), and GIV (isolated after 2000); no VP1 sequences from GII strains have been deposited in GenBank. Another five genotypes identified in the 3Dpol region had support values >0.9. Geographic and demographic transitions among CV-A24v clusters were clearly identified by Bayes algorithm. The transmission route was mapped from India to China and then to Taiwan, and each prevalent viral population declined before new clusters emerged. Notably, the VP1 and 3Dpol genes had high nucleotide sequence similarities (94.1% and 95.2%, respectively). The lack of co-circulating lineages and narrow tissue tropism affected the CV-A24v gene pool.

Effects of carvedilol reduce conjunctivitis through changes in inflammation, NGF and VEGF levels in a rat model

Carvedilol is a novel third generation β-blocker that acts as an antagonist of β and α adrenergic receptors, and is able to regulate various cell factors. In addition, it possesses antioxidant activity, is capable of reversing cardiac remodeling effects and has anti-arrhythmic effects. The present study aimed to investigate whether the effects of carvedilol were able to reduce conjunctivitis clinical scores. Initially, 24 Sprague Dawley (SD) rats were randomly divided into three equal groups as follows: Control group, model group and carvedilol group. The model and carvedilol group adult SD rats were injected with lipopolysaccharide (LPS) to induce conjunctivitis. In the carvedilol group, the eight SD rats with LPS-induced conjunctivitis also received 50 mg/kg/day of carvedilol for 4 weeks. Next, the effects carvedilol were assessed utilizing a system of clinical sign scores, and an enzyme-linked immunosorbent assay was used to determine the expression levels of interleukin-1β (IL-1β), IL-6, IL-8 and tumor necrosis factor-α (TNF-α). Finally, nuclear factor-κB (NF-κB), nerve growth factor (NGF) and vascular endothelial growth factor (VEGF) were analyzed by western blotting. Carvedilol was observed to significantly reduce clinical sign scores in a dose-dependent manner (P<0.01), and reduce IL-1β, IL-6, IL-8 and TNF-α expression levels (P<0.01) in the LPS-induced rat model of conjunctivitis. Carvedilol was also able to significantly reduce the protein expression levels of NF-κB, and induce the protein expression levels of NGF and VEGF in the LPS-induced rat model of conjunctivitis (P<0.01). In conclusion, the effects of carvedilol may reduce conjunctivitis clinical scores through inflammation, NGF and VEGF in LPS-induced rat models.

The epidemiology of non-polio enteroviruses: recent advances and outstanding questions

PURPOSE OF REVIEW

There are over 100 serotypes of human enteroviruses, which cause a spectrum of illnesses, including meningitis, encephalitis, paralysis, myocarditis and rash. Increasing incidence of hand-foot-and-mouth disease in the Asia-Pacific region and recent outbreaks of enterovirus-associated disease, such as severe respiratory illness in the United States in 2014, highlight the threat of these viruses to human health.

RECENT FINDINGS

We describe recent outbreaks of human enteroviruses and summarize knowledge gaps regarding their burden, spectrum of diseases and epidemiology.

SUMMARY

Reported outbreaks of respiratory, neurological, skin and eye diseases associated with human enteroviruses have increased in frequency and size in recent years. Improved molecular diagnostics and genetic sequence analysis are beginning to reveal the complex dynamics of individual serotypes and genotypes, and their contribution to these outbreaks. However, the biological mechanisms underlying their emergence and transmission dynamics remain elusive. They are likely to involve changes in the virus, such as fitness, antigenicity, virulence or tropism, and in the human population, such as levels of sanitation and of homotypic and heterotypic immunity. Improvements in surveillance, serological surveys and detailed genetic and antigenic characterization of viral populations would help to elucidate these mechanisms. This will be important for the design of outbreak control and vaccine development strategies.

Acute hemorrhagic conjunctivitis: anti-coxsackievirus A24 variant secretory immunoglobulin A in acute and convalescent tear

Purpose

The purpose of this paper is to present the clinical course of a laboratory-acquired case of acute hemorrhagic conjunctivitis (AHC) caused by coxsackievirus A24 variant (CA24v). Also, the anti-CA24v neutralizing activity and anti-CA24v immunoglobulin (Ig) G and secretory IgA (sIgA) in acute and convalescent tears and/or sera are presented.

Case

A 60-year-old male presented with acute-onset left eyelid edema, tearing, conjunctival erythema, pain, foreign body sensation, and subconjunctival hemorrhage 24 hours after suspected laboratory exposure. Bilateral conjunctivitis presented 24 hours later and resolved in 10 days.

Methods

Tear and blood samples were collected for virus isolation and neutralizing assays. CA24v-reactive IgG and sIgA in tear and/or serum samples were detected by immunofluorescent antibody analysis of ethanol-fixed virus-infected cells.

Results

Peak tear neutralization titers (1,000–1,500 U/mL) against the isolated virus occurred 1 day post-onset (po) of AHC. Tear neutralization titers became undetectable by the sixth day as serum neutralization titers became detectable on the ninth day po (60 U/mL), peaked by 21 days (3,000 U/mL), declined by 1 year to 200 U/mL, and remained at 30 U/mL 5 years po. Antibody to human IgG, IgA, and secretory component (sIgA) reacted with CA24v-infected cells treated with pooled acute tears collected 1–4 days po. Predominantly, sIgA was detected in CA24v-infected cells treated with tears collected 4 years and 5 years post-AHC, while convalescent serum contained predominantly anti-CA24v IgG.

Conclusion

AHC was confirmed by CA24v isolation, tear anti-CA24v neutralizing activity, and seroconversion. The detection of CA24v-reactive IgG, sIgA, and neutralizing activity in tears collected 1–4 days po of AHC supports plasma extravasation of IgG and suggests a defensive role for tear anti-CA24v sIgA. The results suggest that immunofluorescent antibody analysis of tears for persistent anti-CA24v sIgA may be useful in epidemiological monitoring of AHC.