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Abstract
Purpose To describe the clinical presentations and results of laboratory analysis of waterborne ophthalmic granulomas of the anterior chamber (AC) in Egyptian patients.
Participants 110 patients with granulomatous anterior uveitis and distinctive AC nodules.
Design Prospective, non-comparative, case series.
Methods Demographic data including age, gender and place of residence were recorded. A full ophthalmic examination with emphasis on the inflammatory characteristics and systemic workup was performed. The nodules were surgically removed in selected cases and molecular and histopathological analyses were performed.
Results 102 boys and 8 girls were recruited (mean age 11.5 years). All children came from villages along the basin of the River Nile in Egypt and were engaged in swimming in the local fresh water repertoires just prior to the development of the ocular lesions. 99 patients (103 eyes) showed active granulomatous anterior uveitis with distinct pearl-like white nodules in the AC measuring between 2 and 7 mm in diameter. Inactive scarred lesions were noted in 11 patients (12 eyes). Structural complications including cataract, corectopia and phthisis were documented in 29 eyes. PCR detected digenic trematode DNA in 6 out of 14 excised nodules. Histopathological examination showed aggregates of eosinophils and epithelioid cell granulomas.
Conclusions In Egypt, a unique pattern of granulomatous anterior uveitis in rural children attributable to a waterborne helminthic infection is reported. The River Nile and its fresh water fauna are implicated in our series, and the need for an environmental investigation to further outline best management options in the given endemic areas is highlighted.
- helminths
- granulomatous uveitis
- pediatrics
- fresh water
- River Nile
- Egypt.
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Introduction
Several parasitic infestations and zoonotic illnesses have been reported over the past years to affect the human eye with involvement of the posterior segment, uveal tract, ocular coats and/or adnexa.1–5 Different agents, particularly with the advent of new molecular diagnostic techniques, are also being newly recognised as novel causes of human ocular infections.5–8 For many of those emerging infections, a greater threat exists for certain populations in certain geographic areas posing public health concerns.3 5 9 10 Unfortunately, further knowledge concerning these eye diseases, their geographical distribution and host specifications remains to be elucidated as data are limited to case reports from different countries and further studies if pursued, are invariably conducted on experimental animal models.11–13
We herein report from our locality a cohort of patients with a waterborne ocular parasitosis. The children in this study presented from different geographic locations along the basin of the River Nile in Egypt with granulomatous anterior uveitis and single or multiple white reactive nodules in the anterior chamber (AC) after swimming in the river waters during the day. The disease appears to be endemic in Egypt, and we attempt in this report to identify those paediatric patients with AC granulomas and further characterise the clinical presentations and culprits behind those waterborne infections that affect the human eye.
Subjects and methods
Patients with the distinctive AC granulomas and uveitis who visited our ophthalmology services in Egypt over the study period were identified. Demographic data including age, gender, place of residence and time of onset of eye symptoms were recorded with emphasis on precedent bathing in local river water if present. History of systemic disease, similar illness in other family members, trauma or previous ocular surgeries if any was noted in all patients. The study has followed the tenets of the Declaration of Helsinki and approval of the ethics committees in all study centres was obtained.
All clinical findings and ocular complications at presentation were noted on clinical assessment, which included best-corrected Snellen visual acuity (BCSVA), slit-lamp examination with grading of the intraocular inflammation (SUN working group scale), applanation tonometry, gonioscopy and fundus biomicroscopy.14 Ancillary ophthalmic imaging included B-scan ultrasonography for some selected cases. Other causes of granulomatous uveitis were excluded by review of systems, chest radiography, and serological testing as indicated by the screening physician in the study localities.
In an attempt to further characterise the disease presentations, patients who had single or multiple pearl-like nodules in the AC were classified as nodular disease type. Those with nodules that had eventually evolved into vascularised retrocorneal membranes were described as membranous, while patients who presented with both a membrane and a whitish granuloma at one edge were classified as mixed type. After obtaining written informed consent from the patients or their parents, selected patients with nodules larger than 3 mm in diameter at presentation, mixed disease pathology or incomplete resolution of inflammation after 4 weeks of steroid monotherapy underwent surgical removal of the lesions under general anaesthesia.5 Aqueous samples were aspirated and the AC nodules surgically removed through a paracentesis incision for further molecular testing and histopathological processing for paraffin serial sections with H&E staining.
DNA extraction and PCR amplification
DNA was extracted from aqueous and granuloma tissue samples using DNeasy blood and tissue kit (Qiagen) according to manufacturer’s instructions. A primer pair, CF (5-GATCGTAAATTTGGA/TACTGC-3) and CR (5-CCAACCATAAACATATGATG-3) targeting trematodal mitochondrial cytochrome c oxidase subunit 1 (CO1) gene was used in this study.15–17 PCR was made in 25 µL reaction containing 12.5 µL MyTaq HS red Master Mix (Bioline, England), 0.5 µM of each primer and 0.5 µL DNA extract. PCR conditions included initial denaturation at 95°C for 4 min followed by 35 cycles of denaturation at 95°C for 15 s, annealing at 54°C for 15 s and extension at 72°C for 30 s. PCR products were examined on 1.5% agarose gel stained with ethidium bromide to detect the expected 250 bp amplified product.
SPSS V.16.0 (SPSS, Chicago, Illinois, USA) was used for data analyses. A descriptive statistical analysis was performed, which included means for continuous variables and percentages for categorical ones.
Results
Patient demographic features and clinical findings
Over the period from March 2014 through April 2016, 110 patients were recruited for the study. One hundred two were boys and eight were girls. One hundred four patients were aged 16 years or younger (mean age of 11.5 years; range 5–20), whereas only six patients were older but had similar pathology to that noted in the paediatric patients group. None of the patients had known or newly detected systemic granulomatous disease or a history of previous ocular intervention or trauma.
One hundred three eyes of 99 patients showed distinct pearl-like white nodules in the AC measuring between 2 and 7 mm in diameter with active granulomatous anterior uveitis and/or a retrocorneal vascularised membrane. Fifty-six eyes had granulomas <3 mm in diameter, whereas 47 eyes had larger nodules. In four eyes, a concomitant subconjunctival nodule was also noted. Eleven patients (12 eyes) had been on daily topical steroid therapy prior to referral and had avascular retrocorneal membranes with scarred lesions and no active inflammation at the time of presentation. Figure 1 shows photos of varied types of clinical presentations of this disease entity, while table 1 summarises the main clinical characteristics of all patients at presentation.
(A) Slit-lamp photo of the left eye of a boy aged 11 years from the Nile Delta in Northern Egypt who presented with a distinct anterior chamber (AC) granuloma as well as a nasal subconjunctival nodule. (B) Photo showing multiple AC nodules in the right eye of a boy aged 6 years from Fayoum. (C) A boy aged 9 years from Fayoum presenting with mixed disease pattern; a vascularised retrocorneal membrane and a nodule extending into the pupillary region of the right eye. (D) Retrocorneal scar (membranous form) after resolution of disease activity in a boy aged 14 years from Souhag in the Upper Egypt.
Characteristics of patients with paediatric parasitic anterior chamber granulomas (n=110) at presentation
All these patients were brought in because they had developed ‘white tumours’ together with complaints of ocular redness after bathing during the day in the waters of the River Nile. Patients came from several rural locations along the river basin in Egypt starting from the river valley in Upper Egypt (Qena, Souhag, Aswan) down to Fayoum Governorate in the midlands then the Nile Delta (Abu Elmatamir and Abu Hommos in Beheira Governorate, Monufia and Qalyubia Governorates and Kafr El-Sheikh). None were locals of the coastal city of Alexandria where the Mediterranean Sea is the site for most recreational activities, fishing and swimming or Cairo where seldom are fresh water ponds used for such purpose.
Molecular and histopathological analysis
Twenty-five patients with large nodules were advised for surgical excision of the lesions and analysis of the AC extract, of which 14 consented. Histopathological examination of these samples revealed an inflammatory reaction formed of central suppuration surrounded by epithelioid cells and sheets of lymphocytes (figure 2A–C).
Results of molecular testing for 6 of the 14 granuloma samples using conventional PCR analysis (42.8%) were positive for trematode DNA (figure 2D). The samples underwent DNA extraction then amplification of mitochondrial CO1 gene fragments common in a number of digenetic trematode species.15–17
(A–C) Granulomatous lesion removed from the right eye of a boy aged 7 years from Fayoum showing an inflammatory reaction formed of sheets of lymphocytes, aggregates of eosinophils (thick arrow) and epithelioid granuloma (arrow head). (H&E x100). (D) Gel electrophoresis of samples from 1 to 12 using the proposed primers.
Discussion
The River Nile is the main source of water supply in Egypt with a resident agricultural society alongside its Delta and Valley.18 It is not unusual for children from rural areas, particularly boys, to head to the river waters during the day for bathing and recreation because of a typically hot dry climate, with temperatures reaching up to 113 °F in summer.
In a recent epidemiological study, a preponderance of cases of paediatric parasitic AC granulomas from Egypt was reported (34.8% of paediatric uveitis cases in the study population).19 The present work was conducted to provide characterisation of this unique pathology in Egypt and to further describe the clinical patterns of those waterborne infections that affect the human eye. The pathology is of no prior mention in studies from Africa or the Middle East nor other geographic locations. Meanwhile, similar cases from a unique report in South India have been attributed to incidental human infection with Procerovum varium, a trematode of fish-eating birds found in India and other countries of the Far East.20–22
The disease apparently has an affinity for paediatric eyes with a characteristic presentation of anterior uveitis with single or multiple pearly white AC nodules in one or both eyes that eventually evolve into vascularised retrocorneal membranes. Oftentimes, concomitant visually significant vitritis or subconjunctival nodules were noted. Complications at presentation in our study were not infrequent and can lead to total blindness due to extensive scarring within the AC and phthisis.
The disease appears to be endemic in Egypt with a widespread regional distribution along the river basin. Lesions were almost entirely noted in young boys; as girls in these localities are notably not allowed to publicly bathe or play in ponds for sociocultural considerations. All eight girls in our study had admitted being to the local pond for bathing during the day. Unlike the study form India, we noted no lid nodules in these particular referrals, but similar subconjunctival and AC nodules demonstrated to result from a local immune reaction to the presence of a larva in the human eye.5 22
Our DNA-molecular evidence although still tenuous, incriminates a digenetic trematode fluke, and Egypt is known to harbour many freshwater snails that transmit such infections to mammals and birds.23 Melanoides tuberculate, an established intermediate host of several digeneans and species of eye flukes is widely distributed within the Nile Valley and Delta.23 The digenic trematode Schistosoma is endemic throughout the waters of the Nile, and some species have been reported to cause ocular lesions involving the conjunctiva or lid chalazia in paediatric Egyptian patients.24 25 It is unclear whether the same or other unidentified helminths or snails are culprits and further identification of the species after further molecular analysis and sequencing is still required. It is also not known whether other countries of the mighty river basin suffer the same pathology, but our study together with the series from South India indicate that parasitic eye diseases pose a public health concern in some low-income and middle-income countries, and that trematode eye infections in particular may be common in areas where children are exposed to the local fresh water repertoires with their flora and fauna.
The present work also highlights the need for a local environmental investigation to identify the risk factors associated with this potentially blinding disease, as well as the best treatment options and possible preventive measures at community or regional levels.
References
Footnotes
Contributors RMA designed the study, collected data from Alexandria,analysed the data, and drafted the manuscript. She is guarantor. MBG andAMB refined the study protocol, actively participated in data acquisitionfrom Alexandria, and critically revised the paper. HFEG monitored datacollection from the study centers, analysed the data, drafted, and revised thefinal manuscript. AAN and AER collected the eye samples from Fayoumand Upper Egypt respectively, analysed the data, drafted, and revised the manuscript.WML designed data analysis tools, monitored sample collection for the study,and revised the draft paper. AHG conducted the molecular analysis,analysed the data, and revised the manuscript draft.
Competing interests None declared.
Ethics approval Board of Ethics Committee in the study referral centres.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice This paper has been amended since it was published Online First. Owing to a scripting error, some of the publisher names in the references were replaced with 'BMJ Publishing Group'. This only affected the full text version, not the PDF. We have since corrected these errors and the correct publishers have been inserted into the references.