|Year : 1964 | Volume
| Issue : 2 | Page : 39-49
Trachoma in India - Endemicity and epidemiological study
UC Gupta, VV Preobragenski
|Date of Web Publication||14-Feb-2008|
U C Gupta
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Gupta U C, Preobragenski V V. Trachoma in India - Endemicity and epidemiological study. Indian J Ophthalmol 1964;12:39-49
In the world today with its population of about 3,000 million nearly 10 million persons have been estimated to be blind, although some research workers consider this figure to be an under-estimate.
In 1944, Government of India Central Advisory Board of Health & Education reporting on blindness in this country stated that 250 per 100,000 represented the probable ratio of the totally blind, with an exactly similar ratio of partially blind needing welfare services, giving the total figure of 500 per 100,000 population. The proportion applied to the then approximate population of 400 million gave a figure of 2 million blind in the country, a figure which is one-fifth of the blind population of the world.
The latest survey conducted by Trachoma Control Pilot Project-India (Indian Council of Medical Research), have estimated that amongst a rural population of 355 million in the 15 states of the country, 19.9 million have impairment of vision of various degrees, out of which 3.5 million are economically blind.
It has been recognized world over that trachoma is one of major causes of blindness specially in those countries which are still under-developed. In India alone trachoma and associated infections account for 3.9 million with impaired vision including 0.57 million economically blind.
Trachoma and associated infections are preventable problems. It becomes painful when we realize that this has been allowed to disseminate, unchecked and unattended making millions blind, rendering them helpless, social out-casts and economic burdens not only on the particular society but also on the community and the nation as a whole.
| Problem|| |
Although it is a preventable condition, the task of eradication of trachoma in India which is still a developing country with low standards of living of the masses, is faced with problems peculiar to itself. Environmental sanitation, personal hygiene, educational standards are yet to be raised. Age-old beliefs, superstitions and taboos, quacks and charlatans have still their place among the people.
| Historical|| |
Trachoma - also known as "Rohe", "Kukre", "Khil" or "Dane" in various parts of India, in local dialects, is a disease as old as the ancient scriptures and is mentioned in the various treatises of Charak and Susruta. It cannot definitely be said when the infection actually came to India. It appears reasonable to believe, that the disease spread mainly through north and north-west passages to the country through the migrating populace from Moneolia.
| Epidemiological Considerations|| |
Epidemiological studies were conducted by Trachoma Control Pilot Project-India (Indian Council of Medical Research) during 1956-63. The investigations included the survey on geographical distribution of the disease in the rural areas of 15 states of the country, studies of influence of the socio-economic and cultural practices of the people on the prevalence rates of trachoma, bacteriological studies with variations throughout the year, the change of pattern of trachoma with seasonal variations and influence of fly population on the incidence and course of trachoma and associated infections during different months.
The preliminary studies were conducted in the district of Aligarh, a north-west district of Uttar Pradesh, while for the geographical distribution of the disease a random sample survey was conducted involving 2494 villages from 302 districts of the fifteen states. The number of total persons examined during survey belonging to all age-groups and of both sexes was 1,77,864.
Size of the Country and Population Density
India covers an area of about 3,280,000 sq. kms. with a population of about 439 million people. This gives a density of about 134 per sq. km. which is 5 times more than that of U.S.A., and next to that of Japan. India has one of the most over-crowded rural areas in the whole world.
Prevalence Endemicity and Geographical Distribution
The climate of India varies from region to region. There are parts in this country which have the world record rainfall while certain parts suffer from draught. The temperatures vary from -5.0° to +50°c. Some areas are fertile plains, some unproductive wastelands and some regular deserts. There are plateaus, hills and mountains. These variations lead to differences in the epidemiological conditions from state to state and sometimes even in different parts of the same state.
The geographical distribution of trachoma in India is not even. The analysis of the random survey conducted in rural areas of the fifteen states, revealed a high difference in the prevalence of trachoma in various states as well as in different districts of the same state. The variation in total trachoma in different states has been found to be from 0.5% (West Bengal) to 79.10A (Punjab). From the map opposite, it can be visualised that from a peak infection in Punjab and Rajasthan, the incidence drops progressively towards the north, east and south. Basing on the data collected during the survey, it has been possible to classify the endemicity of the whole of India into three categories: (i) high, (ii) moderate and (iii) low, as shown in Map 1.
Distribution pattern of the disease obtained during the survey may be summarised as follows:
(1) High Endemic Region: -
This group includes the states of Gujarat (56.0%), Rajasthan (74.2%), Punjab (79.9%) and Uttar Pradesh (72.7%). Most of these areas are dust laden and even 90% prevalence was observed in some villages of this group.
Complications due to trachoma were found also to be high in this region.
(2) Moderate Endemic Region
This group consists of the States of Madhya Pradesh (43.3%), Bihar 35.1%, Assam 25.2% and Mysore (22.6%). Although these are the moderate endemic regions, there are some pockets in the states which are highly endemic.
(3) Low Endemic Region:
Most of these are maritime states situated in the Southern and Eastern parts of the country, i.e., the States of West Bengal (0.5%), Orissa (2.72%), Maharashtra (11.3%), Madras (4.6%), Andhra Pradesh (5.3%) and Kerala (8.7%) with only exception of Jammu & Kashmir (16.8%) which is in the extreme north where, in the plains a much higher prevalence was noted than in the mountainous regions.
Variations in the geo-physical conditions of the land and its climate influence the epidemiology of any endemic disease including trachoma.
Geological and certain climatological factors of different regions, which particularly favour the formation and dissemination of irritant dust, are important epidemiological factors responsible for high prevalence of infection in Rajasthan, Gujarat, Punjab and Uttar Pradesh. The dust particles with silica here and other irritant substances give rise to micro-traumatism of the conjunctival epithelium which in turn becomes a suitable host for trachoma or other secondary bacterial infections.
Altitude: Although Parsons states that trachoma is commoner in low lying damp districts and Daralone remarked that as trachoma heals spontaneously at a certain altitude the disease does not exist above the altitude of 3,000 feet, our survey has not confirmed these views. Trachoma has been found at altitudes much higher than 3,000 ft., e.g., Almora hills of U.P., Kashmir in Jammu & Kashmir, Mysore in the south. Probably altitude does not play a very important role in the epidemiology of trachoma. Darjeeling (West Bengal) has no trachoma while Kashmir valley at nearly the same height has recorded the average figures of 32.5%.
Rainfall and Temperature: Trachoma has been seen in areas with heavy rainfalls like Assam and also in areas where the rainfall is a bare minimum as in Rajasthan and North Gujarat. Similarly the fact that in Kashmir where the temperature goes down below freezing point in winter and in the Punjab, U.P. and Rajasthan where it shoots up 50°c or even more during summer, clearly indicates that heat also does not play any direct role in trachoma epidemiology.
Racial Susceptibility and Immunity
This question is often raised. In India we have large number of different races with varied socio-economic and cultural practices. Aborigines had migrated to South on arrival of Aryans who settled in North and North-West region. Both inhabit the country even today, but we do not come across any racial susceptibility or immunity in this country.
Some differences in severity and clinical signs have been noted in communities following different religions. The differences appear to be more on account of different socio-cultural habits which are in practice in accordance with the dictates of various religions followed by different communities.
Evolutive Stages of Trachoma
(a) AGE: The epidemiological studies have shown that the increase of the general prevalence rate of the region leads to the onset of the disease at earlier age among the population. In regions where the prevalence is high, children of less than 1 year of age have been found suffering with the disease. In regions of U.P., Punjab, Rajasthan and Gujarat where the prevalence of total trachoma is more than 50%, children between 2-4 years were found to have maximum infection of active trachoma (Tr. I-II), next to it was the group of 0-2 years and then 4 to 9 years. In areas of 20-50% prevalence the earliest cases of Tr. I have been noted within the first year of life but number of such cases is less in comparison to high prevalence regions. In low prevalence regions, persons with Tr. I infection are generally over 2 years of age. During the preliminary epidemiological studies also, it was revealed that children in the age-group 2-4 years had the highest prevalence of active Trachoma (Tr. I-II) (Graph I).
To sum up, the active stages of trachoma were generally observed among children under ten mainly in the states with high prevalence of the disease and among children under 14 years in the States with moderate prevalence of trachoma.
(b) SEX : There was no difference in the prevalence amongst the two sexes upto the age of 6 years. But beyond this age, it was observed that females suffered more than males and had a more severe and protracted form of the disease. The explanation for it may be that women remain more exposed to irritating factors such as smoke and dust and are more neglectful about curative or preventive measures. Besides they remain more in contact with children who have a high degree of infection as seen above.
Secondary Bacterial Conjunctivitis
It is recognised that conjunctivitis modifies the course and pattern of trachoma infection. Trachoma, free from secondary associated infections, often passes on to spontaneous cure with minimal of scarring, but when it is associated with the bacterial infection, the course is more prolonged and healing takes place by thick scarring which often leads on to trichiasis, entropion, corneal ulcer and at times to ultimate blindness.
In northern India, there are two peaks of seasonal epidemic conjunctivitis, March-May and August-October, the months of onset of monsoon and its withdrawal. These regions having such two peaks, have extremes of temperature during summer and winter. The cytological studies revealed that B. Koch-weeks is responsible in majority of conjunctivitis cases during March-May peak while the weather is more favourable for B. Morax Axenfield during August-October. Other bacteria found were pneumococcus, diphtheroids, staphylococcus aureaus etc. (Graph II).
Seasonal Variations : The repeated monthly survey conducted in some villages of district Aligarh revealed that unlike conjunctivitis the incidence of trachoma does not fluctuate during the different months of the year. But it was noted that during the two peak periods of secondary bacterial conjunctivitis, there were comparatively more new cases of trachoma and mild cases passed on to florid forms (Graph III).
It has been stated that trachoma is a disease of poverty. Conditions in a poor and illiterate population with cattle and family crowded under the same roof, play their contributory roles in maintaining the endemicity of this contagious disease.
Cooking without a vent fills such huts with irritant smoke. The abundance of dust in the villages, which settles on the eyes and face is not washed away for lack of water and complete absence of soap in most hutments. Thus smoke and dust together supply the required non-specific trauma for boosting the trachomatous infection.
Lack of washing and cleaning facilities, unsatisfactory drainage, careless disposal of refuse encourage also the breeding of flies and consequent spread of the disease. The common practice of having a common 'salai' (metal or glass rod) for applying eye cosmetics like 'kajal' or 'surma' and the necessity of using one's clothes for wiping the face and eyes, because the villager cannot afford the luxury of a clean towel, contribute further to the contagiousness.
Modes of Transmission of Infection
It has been established that an important role is played by the common house fly. Studies undertaken on flies during the preliminary epidemiological surveys have shown that the fly index rises before the onset of the two peaks of seasonal epidemic conjunctivitis. It has also been noted that the age-group of children 2-4 years which is most exposed to flies as they are not much carried in their mother's arms and at the same time have not sufficient sense and capability to keep the flies off their faces, gets the maximum infection. (Graph IV)
In the next age-group after the above, ignorant mothers, elder sisters and brothers play a part in disseminating infection. In this age-group, there is greater contact between them and the child as the latter is being carried about in their arms.
Children while playing certain games, unknowingly transmit infection to healthy eyes by their own fingers, if any one of the playmates happens to be suffering from trachoma and associated infections.
Regional Clinical Evaluation
Regarding clinical picture of trachoma in various states the differences observed were well recognizable, and depended upon the classification under which the State has been categorized as one of high, medium or low incidence (Map 1)-[Figure - 5]. The higher the incidence, the more fully developed and vivid are the manifestations, with distressing sequelae and complications. On the other hand in States with relatively low incidence, the infection can be so mild that the only criterion for early diagnosis would be the presence of tarsal conjunctival follices.
The differences observed may be due in part to variations of virulence of the causative agent, but are certainly related to the severity and the frequency of associated conjunctivitis. In some cases it was observed that there were signs of limbal involvement but the palpebral conjunctival signs were practically absent and in other cases the signs were reversed. In such cases it may be possible that the causative agent had predilection for limbal or palpebral conjunctival tissues. There is also the possibility that the causative virus in different parts of the country may be of different strains, with different selectivity for ocular tissues.
The incidence of spontaneous cures was more at places with milder infection, higher age of initial infection, and where the associated bacterial infection was low and unimportant.
The Relative Gravity: It could be said that in the three groups of low, moderate and high prevalence of trachoma, in persons afflicted with trachomatous and/or associated infections, disability was more in the last group. The proportion of disabling sequelae was marked in the age-group beyond 40 years. This actually does not give a true picture of gravity of the disease as it is prevalent today, as the people of that generation were infected about 4-5 decades ago and have been subjected to repeated attacks of conjunctivitis during the years following.
| Summary|| |
The epidemiological study of trachoma by the Trachoma Pilot Project of India is briefly presented under the following heads
a) Relative incidence and geographical distribution with classification under high, moderate and low endemic areas.
b) Geo-physical considerations.
c) Racial susceptibility.
d) Considerations of age and sex.
e) Secondary bacterial infections and seasonal variations.
f) Socio-economic considerations.
g) Modes of transmission.
h) Regional clinical evaluation.
i) Relative Gravity.
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]