Year : 1998 | Volume
: 46 | Issue : 4 | Page : 217--220
Current trends in trachoma in a previously Hyperendemic area
The Trachoma Study Group
The Trachoma Study Group
In response to reports of an excessive number of cases of trachoma at the end of 1995 from the western parts of the North Indian state of Uttar Pradesh, 837 children in the age-group 1-10 years were examined in three villages from where the maximum number of cases hailed. Clinically, the prevalence of trachoma was found to be 8.5% (71). The prevalence was significantly higher in males as compared to females (p < 0.05); and was observed to increase with age. 85.9% (61) of the clinically diagnosed children were active infective cases. 54.9% (39) of the clinically diagnosed cases showed the presence of antigen in the upper tarsal conjunctival scraping from the affected eye, using the Chlamydia trachomatis direct specimen kit (Syva MicroTrak, UK). It was concluded that ophthalmologists must be reoriented to the clinical diagnosis of trachoma to prevent overdiagnosis.
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Study Group T. Current trends in trachoma in a previously Hyperendemic area.Indian J Ophthalmol 1998;46:217-220
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Study Group T. Current trends in trachoma in a previously Hyperendemic area. Indian J Ophthalmol [serial online] 1998 [cited 2013 Jun 19 ];46:217-220
Available from: http://www.ijo.in/text.asp?1998/46/4/217/24168
It is estimated that at least 100-150 million children suffer from active trachoma worldwide., Nearly 15 percent of global blindness is still attributable to trachoma. Northern India which is the drier part of the country has been a major endemic focus in the past., Though there has been a major reduction in trachoma-related blindness in India, as seen from the trend observed between 1971-74 and 1986-89,  hospital records still reflect a substantial number of diagnoses of trachoma. In Uttar Pradesh, one of the hyperendemic states in the 1960s, cases are still reported from almost all the districts. The Management Information Systems (MIS) formats introduced in the State in 1995 showed that at the end of that year, nearly 60,000 cases of trachoma were reported by the districts. A majority of these cases were reported from the three districts of Dehradun, Bulandshahr and Ghaziabad in Western Uttar Pradesh. This sudden upsurge in reporting warranted immediate public health action, as it was necessary to document whether there was any real increase in trachoma or whether this was due to overdiagnosis or overreporting. Hence, a rapid epidemiological investigation was carried out in selected areas from where a large number of cases were reported.
Materials and Methods
Three districts of Western Uttar Pradesh where a large number of cases of trachoma were reported in 1995 were selected for the present study. The district ophthalmic surgeons and the District Blindness Control Societies were then asked to identify pockets from which they were getting reports of trachoma. The outpatient data of the district hospitals were also examined to provide leads on the areas from where a large number of cases were reported. Based on a consensus, three villages were then identified for further examination. Villages were selected such that at least 200 children below the age of 10 years were available for examination. This methodology adopted in the study is accepted for rapid epidemiological assessment for trachoma, wherein at least 50 children aged 1-10 years need to be examined. Since active transmission of infection was the focus of interest, older populations were not included.
Two days prior to the scheduled examination date, the villages were visited by one of the investigators (PB) and the local Primary Health Centre staff. The site for examination was decided on this visit and wide publicity was given for 48 hours. The local panchayat was also involved in this exercise. All children below 10 years of age were listed and the time and place of examination was intimated. A total of 919 children were listed out through the census.
On the day of the investigation, a team comprising two ophthalmologists, two microbiologists, two public health physicians and support staff reached the selected villages at the designated time. Clinical examinations were conducted by the two ophthalmologists independently for validation, and after consensus, the final diagnosis was established. The standard WHO system for assessment of trachoma in the field was utilised for this purpose. The WHO grading system for field assessment of trachoma is as follows:
TF (Follicular Trachoma): Presence of 5 or more follicles ≥0.5 mm diameter in the upper tarsal conjunctiva.
TI (Intense Trachomatous Inflammation): 2/3 or more of the upper tarsal conjunctiva is inflamed and normal blood vessels in this region are obliterated.
TS (Trachomatous Scarring): Scars are easily visible as white lines, bands or sheets in the tarsal conjunctiva.
TT (Trachoma Trichiasis): At least one eyelash rubs against the eyeball. Evidence of recent removal of inturned eyelashes is also graded as Trichiasis.
CO (Corneal Opacity): A visible whitish opacity covering the pupillary margin which thus appears blurred.
From each clinically diagnosed case, the following specimen was collected for supportive diagnosis:
Upper tarsal conjunctival scraping from the affected eye was smeared on clean teflon-coated glass slides. The slides were then air-dried and fixed in cold acetone for 10 minutes after which they were transferred to a cold carrier to maintain the cold chain until they reached the laboratory. At the laboratory, all specimens were stored at -70°C till examination.
Chlamydia trachomatis direct specimen kit (Syva MicroTrak, UK) was used because of its proven reliability and the test was performed as per the manufacturer's instructions. The smears of the conjunctival specimens were covered with 30 ml of Fluorescein Iso-thiocyanate (FITC) conjugated murine monoclonal antibodies for 30 minutes at room temperature. The slides were washed in distilled water, air-dried, mounted and observed under xl00 objective of a fluorescent microscope (Nikon, Japan). A positive and negative control slide was set up for each specimen slide.
A total of 837 (91.08% of those identified ) children aged 1-10 years were examined clinically. 58.9% (493) were males and 41.1% (344) were females. 30% (251) of the children were below 5 years and the remaining 70% (586) were aged 5-10 years. 8.5% (71) children were diagnosed to be clinically suffering from different grades of trachoma. Males were observed to be suffering more from trachoma (10.1 %) compared to females (6.1%) [Table:1]. This difference was found to be statistically significant (p<0.05). Among the clinically diagnosed cases of trachoma, 85.9 % were active infective cases (61) denoting the transmission potential of trachoma.
The prevalence of trachoma (all stages) was observed to increase with increasing age [Table:2]. Children below 3 years had a much lower prevalence of scarring manifestations compared to older children.
Laboratory diagnosis was utilised to document the presence of antigen which would indicate active transmission of disease and to confirm the diagnosis of trachoma. It was observed that more than half the cases (54.9 %) which were clinically diagnosed as trachoma also showed the presence of the antigen [Table:3]. Antigen positivity was much higher in the active stages of the disease where more than half the cases had chlamydia antigens.
India is one of the endemic zones of trachoma. Uttar Pradesh was a hyperendemic state in the early 1960s and there have been continued reports of trachoma from the state. In the ICMR Survey (1959-63), a prevalence of 45.1% was recorded in Uttar Pradesh for active trachoma. A study conducted in Uttar Pradesh in 1978 reported a prevalence rate of 33.7% among primary school-going children. The changing trend in trachoma and related blindness is also borne out by the reduction in trachoma as a cause of blindness between 1974 and 1989., Thus, most published reports have documented a definite reduction in trachoma load in the community. The present study showed that the prevalence of trachoma is low and it is likely that a large number of cases reported from out-patient departments as trachoma were actually not due to chlamydia. Other causes of follicular/chronic conjunctivitis are possibly being categorised as trachoma.
There have been no studies on the reasons for the reduction in the prevalence of trachoma in India. The transmission of trachoma is related to many environmental factors and changes in these factors may be attributed to the reduced prevalence of trachoma. The lack of hygiene, inadequate water supplies, low socioeconomic status, crowding, density of contact, the presence of flies and behavioural parameters are all important in the epidemiology of trachoma. Thus, a reduction of trachoma over the years could be because of changes in some of these parameters. One of the factors most studied is water availability. This included the quality and quantity of water available, and hygiene practices related to water. Over the past two decades, the quality and quantity of water available for household purposes has increased significantly all over the country and this could be an important reason for the reduction of the prevalence of trachoma. It has been documented that improving the water supply can change the epidemiological pattern of trachoma from a severe blinding endemic disease to a relatively mild non-blinding infection. Closely related to water availability is water-use behaviour. When more water is available in the household, it tends to be used for personal hygiene practices like face washing and bathing. This behavioural change is also closely associated with reduced prevalence of trachoma as has been seen in many countries around the world.
Another major factor that can change the epidemiology of trachoma relates to the availability of antibiotics in the endemic pockets. Chlamydia trachomatis is sensitive to many commonly used antibiotics, including tetracycline, erythromycin, sulphonamides, and rifampicin. Tetracycline eye ointment as well as other topical preparations like sulfacetamide have been available and have been used indiscriminately in most rural areas in India. Similarly, rifampicin has been widely used in tuberculosis and leprosy control programmes in the country. It is likely that this factor, along with improved water supply and environmental sanitation may also have played a role in reducing the transmission of the disease.
Corroboratory evidence of the low transmission potential in the study area is the age and sex distribution of the affected cases. In hyperendemic communities, all children have trachoma before the age of 2 years, and nearly half are afflicted below the age of 1 year. In the present study, this was not the case and there was a steady increase in the prevalence of trachoma with increasing age till 10 years of age. It has been suggested that when 15% or more of children under 10 years in a community have severe or moderate grades of conjunctival inflammation, there will be a continuing involvement of new cohorts in the potentially blinding process. The prevalence of active trachoma has been much lower in the present study. It has also been seen that the classical situation of more females being afflicted is true of the major endemic pockets, but in communities where trachoma is not blinding, the susceptibility differences between the sexes have not been very significant. All this evidence points to a low level of transmission in the study area.
Antigen detection assay using a monoclonal antibody-based immunofluorescence assay for the detection of Chlamydia trachomatis antigen, was used to provide laboratory support for the field study. The test used has been repeatedly shown to have a very high sensitivity (96-97 %) and also high specificity (99%)., In more than half of the clinically diagnosed cases, the presence of the organism could be demonstrated by antigen detection assay. In previous studies conducted in various parts of the world, among clinically diagnosed cases, Chlamydia trachomatis has been reported to be present, either by culture or antigen detection to the extent of 8.4-19.9% in different studies, compared to 54.9% by antigen detection in the present study. The likelihood of antigen detection is much more in the active stages of trachoma (TF/TI) rather than during the late and healed stages (pannus/TS/CO). This was clearly evident in the current study where antigen detection was twice as much in the TF/TI stages compared to the later stage.
What are the implications of the present study in terms of the control strategies for trachoma in the state? It can be safely stated that because of a low prevalence of inflammatory stages of trachoma in the study area, a concerted public health action is not required. Cases of trachoma will continue to occur, albeit at a low frequency, and these individual cases will require prompt treatment. This means that the primary eye-care facilities should have adequate supplies of tetracycline eye ointment to treat cases presenting at the outpatient clinics of Primary Health Centres. Eye-health education efforts should be continued to consolidate personal and facial hygiene practices. School educational programmes, child-to-child and child-to-family approach can also be used to impart health education in communities and families. Continued attention to environmental sanitation will help to reduce the fly population and thus the transmission potential of the disease even further. There is a need to reorient ophthalmologists to the clinical diagnosis of trachoma so that an overdiagnosis can be avoided. The tendency to categorise all cases of chronic folliculosis as trachoma in a previously endemic area needs to be addressed. At the same time, it is important to keep a watch on the situation by carrying out epidemiological investigations at periodic intervals to indicate any change in the disease trend.
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