Epidemio-Clinical, Therapeutic and Evolving Aspects of Tropical Endemic Limboconjunctivitis in Children in the Ophthalmology Department of the Bouake University Hospital Center

Tropical Endemic Limboconjunctivitis (TELC) vernal keratoconjunctivitis in temperate countries is a sub-acute or chronic inflammation of the limbs and conjunctiva secondary to exposure of the eye to an allergenic or irritant agent [1]. 

It is a common condition in children between 4 and 7 years of age in tropical and inter-tropical areas because it accounts for 0.1 to 0.5% of eye problems in children [2]. It is classified into 4 evolutionary stages according to Diallo and presents 3 clinical forms, namely the palpebral, bulbar and mixed form [3]. It is usually mild but can sometimes be complicated by severe corneal damage due to scratching lesions that may progress to blindness [4]. The management of this condition is long and restrictive, so the success of the treatment depends on close collaboration between the doctor and the family or the patient, the only guarantee of good therapeutic compliance. The aim of this study was to contribute to a better knowledge of TELC in order to improve its management.

This descriptive retrospective cross-sectional study was carried out in the ophthalmology department of the university hospital center of Bouaké from January 01, 2020 to December 31, 2020 (1 year). 

It enabled us to identify 201 patients aged 0 to 15 years with signs of Tropical endemic limboconjunctivitis who had or have not received treatment. 

A case of TELC was defined by the simultaneous existence of the following three criteria from Diallo’s work [3] in one patient. 

Criterion 1: associates conjunctival hyperemia and superficial punctate keratitis.

Criterion 2: associates at least one of the following three signs, a limbit and / or grains of trantas and or follicles or papillae in cobblestones.

Criterion3: ocular itch. 

Any child, who consulted during the study period for signs of eye allergy, but in whom these criteria could not be found simultaneously, was excluded from the study. 

The analyzed parameters were epidemiological (disease frequency, gender, age), Clinical (reason for consultation, clinical signs, time elapsed before the first consultation, number of seizures during the year, family history, visual acuity, slit lamp examination, stage according to Diallo’s classification), therapeutic ( specific treatment and adjuvant treatment) progressive (without treatment and under treatment). 

After reviewing the files, the figures were produced in Excel 2007, the tables and data entry in World 2007 and the data analysis were carried out using the EPI info software version 7.0.

Epidemiology 

Out of a total of 588 files of children aged 0 to 15 years analyzed, 201 had Tropical endemic limboconjunctivitis corresponding to a relative frequency of 34.18% (Table 1). The mean age of the patients was 6.14 years with extremes of 6 months and 15 years. The majority of our patients with TELC, i.e. 59.70% (120/201), were male with a sex ratio of 1.40 (Table 2). 

Table 1: Frequencies of eye pathologies in children in our department. 

Table 2: Distribution of patients with TELC by age and gender. 

Clinical 

Eye itching was the main reason for consultation with 88.06% (262/297 patients) (Figure 1). The majority of our patients had consulted before 1 month after the onset of the first symptoms, i.e. 74.63% (150/201). The patients who presented 2 seizures during the year were the most numerous with 48.94% (99/201 patients). Familial atopy was at the forefront of the family history with 40.5% (81/201 patients). Our patients in whom visual acuity could be measured had visual acuity > 3/10 in the majority of cases, i.e. 72.72% (96/132 eyes) in the right eye and 63.63% (83/130 eyes) in the left eye (Table 3). Limbit represented the most frequent adnexal involvement with 65% (70/201 patients).Superficial punctate keratitis was the most observed anterior segment lesion with 80% (46/58 patients) (Figure 2). Most of our patients had been received at stage II of Diallo’s classification with 66.53% (134/201 patients) (Figure 3). 

 Figure 1: Repartition of patients according to the reason for consultation. 

Table 3: Repartition of patients according to visual acuity. 
 

Figure 2: Repartition of patients according to lesions observed in the anterior segment. 

 Figure 3: Repartition of patients according to DIALLO’s classification.  

Treatment 

The antihistamine was the most prescribed specific medical treatment with 56.15 % (177/315 patients) followed by anti-biocorticoids 42.46% (134/315). 

The post-treatment course was favorable in the majority of our patients with 82%. Fibro vascular veil was the most common complication in our patients who consulted late with 44.82% (Table 4) (Figure 4). 

Table 4: reparation of patients who consulted late according to complications. 

Figure 4: A 6-year-old girl with bilateral TELC seen during our consultation at the ophthalmology department of the UNIVERSITY HOOSPITAL CENTER in Bouake on 02-20-2020.

Tropical Endemic Limboconjunctivitis (TELC) or vernal kerato-conjunctivitis accounts for 0.1 to 0.5% of eye problems in children between 0 and 15 years [2]. The relative frequency of TELC in our study was 34.18% indicating its resurgence in recent years due to the heavy pollution of urban areas. 

Throughout the literature, the frequencies of TELC vary according to the regions concerned. However, our results are superimposable of those of Chenge [5] in Cameroon (32.9%) and Koki [6] in Congo (31.55%) but by far differ from those of Resnikoff [7] in Chad and Bremond [8] in France found respective prevalence of TELC of 5% and 0.032% in their patients. Although, allergic kerato-conjunctivitis is a cosmopolitan affection it is particularly prevalent in sub-Saharan Africa, Asia, the Mediterranean region and Latin America due to their hot climate and moist favorable to the expansion of allergens [9]. All these areas are characterized by more sunlight; increased ultraviolet rays and the permanent presence of dusty air are all factors in the occurrence of conjunctivitis allergic and particularly in that of TELC [7]. The average age of our patients was 6.14 years with extremes of 6 months and 15 years. Our results are in accordance with those of some authors who in their respective works noted similar averages of age; these are the cases of Banla [10] in Togo (6.5 years) and Lazreg [11] in Algeria (6, 5 years ± 3.4). The immaturity of the immune system of children from 0 to 15 years old described by Bloch-Michel [12] would be at the origin of the early onset of immediate hypersensitivity to dust and photosensitivity in the latter, thus promoting the occurrence of TELC.

Male subjects were in the majority (59.71%) with a sex ratio of 1.40. This male predominance of limbo-conjunctivitis was also observed in the work of Al-Akily [13] in Yemen and Banla [10] in Togo with respective sex ratios of 3 and 1.6. This clear male predominance of TELC could be linked to the greater freedom granted to little boys resulting in their more frequent contact with dust and pollen grains during play compared to the young girl. 

Ocular pruritus was the most frequent reason for consultation with (88.06%). 

The presence of ocular pruritus as the most common functional sign in our patients. Koki [6] and Saboo [14] in their respective work carried out in Cameroon and India on allergic kerato-conjunctivitis, they noted the constant presence of ocular pruritus in their patients at frequencies of 60.90% and 88%. The presence of ocular pruritus as the main clinical manifestation of allergic conditions has its source in the pathogenesis of this disease. 

Non-specific conjunctival causing intense pruritus [15]. Our patients had made their first consultation in the majority of cases before 1 month after the onset of the first symptoms (74.63%). 

The parents' rapid reaction to TELC is due on the one hand to the embarrassing manifestations of this condition with sometimes a change in the color of the eyes and on the other hand their concern for the visual functional prognosis of their offspring. 

The period from December to February recorded the highest number of consultations in the year at respective frequencies of 15%, 17.50% with a peak in December (32.34%). The resurgence of TELC during the dry season is found in many works in Africa. Thus Resnikoff [7] and Nidain [16] noted respectively in Chad and Togo peaks of occurrence of TELC March (47.6%) and in April (95.08%) corresponding to dry seasons in these different areas. The frequent occurrence of this condition during the dry seasons of the year would be consistent with the pathogenesis of TELC involving various factors such as more intense solar radiation, very dusty air and especially the expansion of pollen grains. In our series, patients who presented 2 annual seizures came to the fore with 48.94%. The same observation was made by BANLA [10] who noted recurrence in 77.8% of cases, when allergological management was late. These recurrences are believed to be due in part to difficulties in isolating the causative allergen, so symptoms reappear as soon as the patient comes into contact with it again. The recurrent nature of TELC is at the origin of the chronicity of this condition which generates corneal complications due to scratching lesions. This permanent corneal damage could put into stake the visual functional prognosis making all the seriousness of this affection. 

Familial atopy was the most common family medical history in 40.5% of cases, followed by asthma (27%) and allergic rhinitis (25%). LAZREG [11] in its study carried out in Algeria on the treatment of perennial allergic conjunctivitis noted the predominance of allergic rhinitis (37%) and asthmatic disease (16%). 

The association of other extra ocular allergic manifestations is thought to be due both to the involvement of immunoglobulin dependent of mechanisms and to genetic factors involved in the genesis of vernal kerato-conjunctivitis or Tropical endemic lymboconjunctivitis [17]. Most of our patients had better visual acuity > 3/10 with 72.72% in the right eye and 63.63% in the left eye. 

Our results are close to those of Chenge [5] in Cameroun and Saboo [14] in India who found good visual acuity in their patients in the respective proportions of 81% and 100%. 

This reflects the early management of a large number of patients before the onset of complications, but it also highlights the benign nature of this condition. However, blindness was observed in 9.09% in the right eye and 14.54% in the left eye of our patients whose management was late. Chenge [5] made the same observation in these patients who presented blindness in 10.53% of cases. The functional loss of the eye during this condition is thought to be due to the occurrence of corneal complications linked to late consultations due to lack of financial means as well as to the scarcity of specialized structures. 

The limbus was the most affected adnexal structure with 65%. Our results can be compared to those of Saboo [14] in India and Al-Akily [13] in Yemen, who found 73% and 50% limbic involvement, respectively, in their studies on vernal kerato-conjunctivitis. Chenge [5] in Cameroon and Ukponmwa [18] in Nigeria also noted damage to the corneal limbus in all of their patients with TELC. These data would testify to the importance of this sign in the TELC giving it its name in Africa. This manifestation is also sometimes a source of complications related to a corneal invasion of reactive neovessels causing blindness by the loss of corneal transparency Superficial punctate keratitis was the lesion of the anterior segment the most found with 80%. Corneal involvement in endemic limbo-conjunctivitis in the tropics or vernal kerato-conjunctivitis in temperate zones was also found in studies by Bremond [8] in Europe and Khan [19] in Pakistan, which found respectively 31, 7%, and 49% of corneal lesions cases. The corneal lesions observed during this affection are the resultant of late consultations in developing countries, frequent recurrence of the disease and its evolution towards chronicity. Patients admitted to stage II of Diallo’s classification were in the majority with 66.53%. Some African authors would confirm that stage II of TELC constitutes the diagnostic stage of the disease in the tropics, thus N'diaye [20] in Senegal, Banla [10] in Togo respectively noted frequencies of 51.7% and 50% of patients seen in stage II. 

All these results are linked by the expressive nature of the symptoms at this stage of the disease, thus constituting a real visual discomfort, forcing patients to consult a doctor. However, Koki [6] in Cameroon and Ayena [21] in Togo noted a clear predominance of patients consulting with stage I of the disease in proportions of 55.25% and 64.8%. This variability of the stage at which the patient is admitted for consultation would be related to the susceptibility of the patients and also the atopic history sometimes worsening the clinical table [17]. Antihistamines were the most specific treatment prescribed in our daily practices with 56, 62% followed by antibiotic -corticosteroids (42.46%). This fact has been reported in various works. 

In the studies carried out in Algeria by Lazreg [11], and in Senegal by N’doye [20], we noted the massive use of antihistamine. Although the antihistamine is the treatment of choice, the antibiotic corticosteroid also plays an important role in the treatment of TELC because it makes it possible to fight effectively against inflammation and prevent or treat super infection. The post-treatment course was favorable in 82.08% of our patients with improvement of symptoms. The same observation has been made by several authors, such as Al-Akily [13] in Iran and N’doye [20] in Senegal, who respectively found 84.3% and 87.60% recovery after well-conducted medical treatment. The favorable outcome of limbo-conjunctivitis under drug treatment could be explained on the one hand by the benign nature of this condition and on the other hand by the effectiveness of the combination of antihistamines and antibiotic corticosteroids in the management of endemic limbo-conjunctivitis in the tropics. However, 6.96% of patients presented complications, the most frequent of which was represented by the fibro vascular veil with 35.71%. Corneal involvement has been found as a major complication of keratoconjunctivitis in the world literature. For example, Khan [18] in Pakistan and Tabbara [4] in Saudi Arabia found corneal complications in patients with vernal keratoconjunctivitis at frequencies of 49% and 17.3%, respectively. These complications would result from late consultations linked to the scarcity of specialty services, the insufficiency of specialists, lack of financial means and above all, treatment non-compliance.

Tropical endemic limboconjunctivitis is a chronic relapsing allergic disease seen in the majority of cases in children. It is a generally benign condition characterized by the maintenance of visual acuity and the main manifestation of which remains ocular pruritus. Its evolution is most often favorable but can sometimes be complicated by corneal lesions when the medical treatment is late or poorly conducted. This corneal damage is the whole issue of this condition because it can affect the visual functional prognosis. Hence the value of early diagnosis and rapid medical care of children is the only guarantee of good progress.

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