Clinical findings and results of treatment in an outbreak of acute hemorrhagic conjunctivitis in southern Florida

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.

Dynamic modelling of strategies for the control of acute haemorrhagic conjunctivitis outbreaks in schools in Changsha, China (2004–2015)

Outbreaks of acute haemorrhagic conjunctivitis (AHC) – a rapidly progressing and highly contagious infection – often occur in schools during summer and autumn. We used dynamic modelling to evaluate the efficacy of interventions to control AHC outbreaks in schools. A susceptible-infected-recovered (SIR) model was built to simulate AHC outbreaks in Chinese schools, with isolation or school closure added into the model. We used outbreak data from the period 2004–2015 in our models to estimate the effective reproduction number and assess the efficacy of interventions. The median effective reproduction number (uncontrolled) of AHC outbreaks was 7·00 (range 1·77–25·87). The median effective reproduction number (controlled) of AHC outbreaks was 0·16 (range 0·00–2·28). Intervention efficacy is affected by the timing of isolation; earlier isolation is associated with a lower morbidity peak and smaller total attack rate (TAR). School closures were not effective; TARs were almost 100% and did not change even when different school closure durations were adopted. Isolation and school closure as a combined intervention strategy was used to simulate outbreak control, but the efficacy was the same as isolation alone. An isolation programme could be an effective primary intervention during AHC outbreaks in schools. However, school closure is not recommended.

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.

Subconjunctival hemorrhage: risk factors and potential indicators

Subconjunctival hemorrhage is a benign disorder that is a common cause of acute ocular redness. The major risk factors include trauma and contact lens usage in younger patients, whereas among the elderly, systemic vascular diseases such as hypertension, diabetes, and arteriosclerosis are more common. In patients in whom subconjunctival hemorrhage is recurrent or persistent, further evaluation, including workup for systemic hypertension, bleeding disorders, systemic and ocular malignancies, and drug side effects, is warranted.

Phylogenetic and molecular characterization of coxsackievirus A24 variant isolates from a 2010 acute hemorrhagic conjunctivitis outbreak in Guangdong, China

BACKGROUND

Acute hemorrhagic conjunctivitis is a common disease in China. As a notifiable disease, cases are registered by ophthalmologists on the AHC surveillance system. An AHC outbreak caused by CA24v was observed in Guangdong Province in 2007 by the National Disease Supervision Information Management System. Three years later, a larger outbreak occurred in Guangdong during the August-October period (2010). To characterize the outbreak and compare the genetic diversity of CA24v, which was determined to be the cause of the outbreak, the epidemiology and the molecular characterization of CA24v were analyzed in this study.

RESULTS

A total of 69,635 cases were reported in the outbreak. 73.5% of index cases originated from students, children in kindergarten and factory workers, with the ≦ 9 age group at the highest risk. The male to female ratio was 1.84:1 among 0-19 years. 56 conjunctival swabs were collected to identify the causative agent from five cities with the AHC outbreak. 30 virus strains were isolated, and two of the genomes had the highest identity values (95.8%) with CA24v genomes. Four CA24v genotypes were identified by phylogenetic analysis for the VP1 and 3C regions. CA24v which caused the outbreak belonged to genotype IV. Furthermore, full nucleotide sequences for four representative isolates in 2010 and 2007 were determined and compared. 20 aa mutations, two nt insertions and one nt deletion were observed in the open reading frame, with 5'- and 3'- UTR respectively between them.

CONCLUSIONS

CA24v was determined to be the pathogen causing the outbreak and belongs to genotype IV. VP1 is more informative than 3C(Pro) for describing molecular epidemiology and we hypothesize that accumulative mutations may have promoted the outbreak.

Caspase-3 and -7 mediate apoptosis of human Chang's conjunctival cells induced by enterovirus 70

Enterovirus 70 (EV70) is the major etiological agent of acute hemorrhagic conjunctivitis (AHC). EV70 m.o.i.- (multiplicity of infection) and time-dependently induced apoptosis in human Chang's conjunctival (HCC) cells. UV- or heat-inactivated EV70 did not induce apoptosis. EV70-induced apoptosis was inhibited by cycloheximide and methoxysuccinyl-Ala-Ala-Pro-Val-chloromethylketone (MPCMK), but not actinomycin D and guanidine.HCl (although guanidine.HCl inhibited the apoptosis induced by EV70 infection at 0.5 PFU/cell for 18 h). EV70 infection induced activation of caspase-3 and -7 and degradation of the constitutively activated caspase-6. EV70-induced apoptotic DNA ladders and activated caspase-3 and -7, correlated with virus release. Caspase inhibitor IX (Z-VD-FMK) inhibited EV70-induced apoptosis and virus release, but not intracellular viral production. The results suggest that infectious virus and the syntheses of viral proteins especially EV70 proteases, but not viral genome RNA, are required for caspase-3 and -7-mediated EV70-induced apoptosis, and that apoptosis through cell lysis promotes EV70 release from HCC cells.

Echovirus keratoconjunctivitis

PURPOSE

To investigate an outbreak of echovirus-related keratoconjunctivitis.

METHODS

We undertook a retrospective study of recent cases of echovirus infection with recall and further evaluation of conjunctivitis patients. All patients from whom an echovirus was isolated in Liverpool during 1995 were included. The natural course of ocular echovirus disease was studied, including the likelihood of echovirus keratoconjunctivitis being linked with meningitis and the risk of long-term carriage of the virus in the conjunctiva.

RESULTS

Of 10 unrelated patients with echovirus conjunctivitis, six also had a mild keratitis. None of these patients developed meningitis, and no cases of long-term carriage in the conjunctiva were encountered. There was no link between cases of echovirus meningitis and conjunctivitis. There was no corresponding increase in other ocular viral isolates.

CONCLUSIONS

Echovirus is a relatively unrecognized cause of keratoconjunctivitis. Echoviral keratoconjunctivitis appears to be an independent ocular event unassociated with systemic sequelae. Long-term carriage in the conjunctiva does not appear to occur.

Differentiating conjunctivitis of diverse origins

While symptoms can be very distressing, patients with conjunctivitis general maintain good vision and recover completely without permanent sequelae. The great majority of cases of conjunctivitis are infectious or allergic in origin. Seen with increasing frequency are external eye diseases related to contact lens wear or prolonged use of ophthalmic medications. The various forms of conjunctivitis are often not associated with pathognomonic features. A thorough history and ophthalmic examination often permit a presumptive diagnosis and initiation of empiric therapy. For example, a chronic bilateral conjunctivitis, characterized by itching and papillary hypertrophy, suggests an ocular allergy, most frequently the result of exposure to airborne allergens. However, a number of causes, including infections and hypersensitivity reactions, have the potential to threaten vision or produce marked conjunctival scarring which must be identified by the use of appropriate laboratory techniques, followed by specific therapy. Most bacterial and viral conjunctivitis are self-limited, but antimicrobial therapy for the former is advocated to shorten the course, improve patient comfort, prevent recurrence, avoid complications and limit spread to other individuals.

Spread of acute hemorrhagic conjunctivitis due to enterovirus-70: effect of air temperature and relative humidity on virus survival on fomites

Enterovirus 70 (EV-70) has caused at least two pandemics and several major epidemics of acute hemorrhagic conjunctivitis (AHC) in the past 18 years, with the largest number of cases occurring in the coastal areas of the tropics. The exact means of its spread are not known, but fomites and hands contaminated by them are the most likely vehicles. We, therefore, tested EV-70 survival under different environmental conditions using stainless steel disks (1 cm diameter). Each disk received 10 microliter of the virus in phosphate-buffered saline (PBS). The disks were held at various temperatures with the relative humidity (RH) at the low (20 +/- 5%), medium (50 +/- 5%), high (80 +/- 5%), or ultrahigh (95 +/- 5%) level. The virus was eluted from the disks with tryptose phosphate broth and the eluate assayed in LLC-MK2cells. Inactivation rates (Ki), expressed as hourly loss of virus plaque forming units (PFU) in log10, were then calculated. At 20 degrees C, virus survival was proportional to the RH level, with the highest virus survival at the ultrahigh RH; at this level nearly 5% of the input virus was detectable even after 24 hr. Virus inactivation rates were only slightly higher at the ultrahigh RH when the temperature was raised to 33 degrees C or 35 degrees C. However, at 80% RH, increasing the temperature from 20 degrees C to 33 degrees C resulted in a dramatic rise in virus inactivation. The finding that high levels of RH prolong EV-70 survival on fomites may help explain the epidemiology of AHC resulting from EV-70.

A recent epidemic of Coxsackie virus type A24 acute haemorrhagic conjunctivitis in Singapore

A recent epidemic of acute conjunctivitis in Singapore showed again the importance of Coxsackie virus type A24 variant as a causative agent of acute haemorrhagic conjunctivitis (AHC). Although the ocular manifestations appeared similar to those described for the 1970 and 1975 outbreaks, a markedly higher rate of respiratory involvements was noted. Not observed in previous epidemics were herpes-like vesicles in the conjunctiva and eyelids of one patient and vesicles in the buccal mucosa and lips of another from whom Coxsackie virus A24 was isolated. The most interesting finding in this study was the isolation of five wild (non-Sabin) poliovirus type 1 strains. Three strains were obtained from conjunctival and two from throat swabs of patients with mild to severe conjunctivitis. It is conceivable that the rare reports of polio-like paralysis or radiculomyelitis accompanying or following AHC in a few Asian countries could be attributed to concurrent infections with a poliovirus and either enterovirus type 70 or Coxsackie virus type A24.

Virus-specific, early appearing neutralizing activity and interferon in tears of patients with acute hemorrhagic conjunctivitis

Virus-specific, early appearing neutralizing activities (ENA) and interferon (IFN) were detected in tears collected from patients during epidemics of acute hemorrhagic conjunctivitis (AHC). In one study, ENA that neutralized enterovirus type 70 (EV70) was detected in tears collected from 114 of 130 AHC patients in Florida. In another study, ENA against coxsackievirus type A24 (CA24) was detected in tears collected from 39 of 57 patients in Singapore with AHC caused by CA24. No tear samples contained ENAs to both EV70 and CA24. Tear samples from uninfected eyes did not contain ENA to EV70 or CA24. ENA to EV70 was detected in 6 of 11 patients 1-6h before the onset of AHC. In addition, tears of 68% of patients seen on the day of onset produced tears that contained ENA to EV70. Thus, ENA to EV70 may be detected less than 24h after infection (based on 24h incubation period). IFN beta was detected in 30% of tear samples collected from patients on the day of onset of AHC caused by EV70. This finding suggested that ENA and IFN could act together to inhibit primary infections of AHC. It was found that the combination of ENA and IFN inhibited virus replication synergistically (greater than or equal to 300 fold reduction) in preinfected cells. Our findings suggest that ENA represents a previously unreported early defense mechanism of the eye, that endogenous ENA and endogenous IFN could inhibit viruses synergistically in vivo, and that ENA in tears could be useful in identifying the agent causing AHC.

Quantitation of enterovirus 70 antibody by microneutralization test and comparison with standard neutralization, hemagglutination inhibition, and complement fixation tests with different virus strains

We describe here a microneutralization procedure for conveniently testing large numbers of specimens for antibodies to enterovirus 70. The test utilized human rhabdomyosarcoma cells and was read by staining with crystal violet after 4 days of incubation. The test compares well with other serological assays, being more sensitive than the standard tube neutralization test and the complement fixation test, but less sensitive than the hemagglutination inhibition test. However, the hemagglutination inhibition test required concentrated, partially purified virus as antigen, as did the complement fixation test, and was difficult to read, so that its greater sensitivity may not be of practical significance. By all four test procedures, a recent isolate of enterovirus 70 was a more sensitive antigen than the prototype strain, as shown by greater geometric mean titers in sera of patients from various epidemics.