|Year : 1966 | Volume
| Issue : 5 | Page : 197-200
Trachoma eradication, a pilot study
LP Agarwal, SP Dhir, PA Lamba
Department of Ophthalmology, All India Institute of Medical Sciences, Delhi, India
|Date of Web Publication||17-Jan-2008|
L P Agarwal
Department of Ophthalmology, All India Institute of Medical Sciences, Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Agarwal L P, Dhir S P, Lamba P A. Trachoma eradication, a pilot study. Indian J Ophthalmol 1966;14:197-200
The incidence of trachoma varies in different parts of the country and so does the experience of the ophthalmologists from different zones of India. The incidence is very high in Punjab (97% are suffering or had suffered from the disease) as reported in our previous communications.
The objectives of this research scheme are
1. To evaluate the role of Trachoma vaccine as mass therapy, in the prevention and control of reinfection of trachoma.
2. To compare the trial of vaccine therapy with long acting sulphonamides.
3. To assess the role of long acting sulphonamides with and without trachoma vaccine.
4. To develop and assess other means of eradication of the disease.
To meet the above objectives a population of 12,000 people in the rural area of Ballabgarh Block was selected as the test site.
Out of this population there were 1,251 children under the age of 5 years available for ocular examination. The children were examined with the following objectives:
1. To find out the incidence of trachoma in the area under study.
2. To select normal children for a double blind study of the vaccine.
3. To select active cases of trachoma for therapy.
4. To study the natural history of the disease as existing at present.
5. To study the impact of our approach on the areas in comparison to the surrounding area at a later date.
The survey was conducted in the months of August, September and October, 1964 by two ophthalmoogists working as separate units, each unit consisting of one ophthalmologist, two lady health visitors and one laboratory assistant. The age and sex distribution of children examined are shown in [Table - 1]. (M=Males, F=Females, T=Total.)
The survey was conducted by house to house visiting. The lady health visitors used to visit the houses on a previous day and collected the demographic data. The optithalmologists examined the children on the subsequent day with a torch, binocular loupe and with the portable slit lamp. An attempt was made to examine all the available children under the age of 5 years.
The classification used in this study is that of Agarwal et al (1963). This classification aims at clearly demarcating two substantial groups. An active group of Trachoma which is classified as I and II and an inactive group which is classified as III & IV. The W.H.O. classification includes some of the active cases in group III which has not been considered as desirable because it is felt that active and inactive trachoma should be clearly demarcated. The modification has the advantage that it recognises healed trachoma with reinfection or reactivation as a definite entity in Trachoma II c, whereas under W.H.O. classification it should be classified as Trachoma III which gives a false impression of regression of the disease. We are of opinion that cases of trachoma diagnosed II c, should be actively treated and not neglected as may happen if they are relegated to Trachoma III (under W.H.O. classification) considering it as a regressive disease.
The diagnosis of the two Ophthalmologists were blindly cross checked and confirmed by laboratory methods wherever it was considered feasible and necessary. Inclusion bodies could be demonstrated in 60%, of the cases and we have been successful in isolating and culturing Indian strains of trachoma virus in yolk sacs of embryonated eggs.
[Table - 3] shows the Prevalence Data at a glance.
Population surveyed : 12,411.
Children under 5 years of age available for examination: 1,251.[Table - 3]
The 295 children (23.6%) under the age of 5 years which were diagnosed as normal were considered fit for vaccination against trachoma. Only 1 child showed signs of regression of the disease (Trachoma III), he was 4 years of age. No child under the age of 5 years showed sequelae of Trachoma (Trachoma IV).
In addition to trachoma, a large number of children had mucopurulent conjunctivitis.
| Conversion Rate|| |
To find out what has been the conversion rate from normal to trachoma in the past 5 years, cross-sectional data of the survey was used. It was presumed that no major change has occured in the area that would affect the conversion rate over various age groups or period of exposure. The results are shown in the graph I & II.
It is interesting to note that the maximum conversion to trachoma occurs in the age group of 3-6 months. By the age of 1 year 70% of the children contract the disease. By the age of 3 years 89% of the children suffer from trachoma. After the age of 3 years, there is very little increase in the conversion rate. Gupta and Preobragenski (1964) in their endemicity and epidemiological study convey a false impression of maximal conversion rate in the age group of 2-4 years. Whereas it is clearly evident that this is the period when the disease is actively manifested. The present study indicates a maximal conversion rate between 3-6 months of age.
| Duration of Exposure and Conversion to Trachoma|| |
By a 3 months exposure to the disease under the conditions prevalent in the area, 17%, of normal children will convert to trachoma. An exposure of 6 months will convert 30% to trachoma. After one year of exposure 45% of the normal children will contract the disease. In an exposure time of 2 years, 62% of the children will be having the disease. By the passage of 3 years, 70% of the normal children will convert to trachoma. A further increase in the duration of exposure by two years added only 6% to the conversion.
From the prevalence curves, it is evident that the highest incidence of Trachoma I is at 12 months of age whereas the incidence of Tr. II shows a peak at the age of 4 years, indicating that on an average it takes 3 years to convert from Trachoma I to Trachoma IL There were 8 cases (out of total 513) of Trachoma II diagnosed under the age of 3 months. In these cases the initial infection may have been heavy and the host reaction was probably severe.
The previous studies of Taylor (1962) Das et al (1961) and Agarwal et al (1963) have shown higher incidence and severer trachoma in females than in males. This study of children under the age of 5 years does not show [Table - 5] any statistically significant difference between the two sexes. It may be that the disease pattern is altered at a later age.
| References|| |
Agarwal, L. P.. S. R. K. Malik and Madan Mohan (1963) Orient. A. Onhthal. 100, 106.
Gupta, U. C. and Preobragenski V. V. (1964) J. All-India Ophthal. Soc. 12, 39.
Das, T., Niranakri, M. S. and Chadha, M. R. (1961). J. All India Ophthal. Soc. 12 (72-76).
Taylor, C. E., Gulati. P. V. and Harinarain (1962), Am. J. Trop. Med. & Hyg., 7 (42-50).
[Figure - 1], [Figure - 2]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]