|Year : 1954 | Volume
| Issue : 4 | Page : 94-108
Statistical analysis of the incidence, relative and absolute, of trachoma in India and in Bombay State
Department of Ophthalmology, K. E. M. Hospital, Parel, Bombay 12, India
T N Ursekar
Department of Ophthalmology, K. E. M. Hospital, Parel, Bombay 12
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Ursekar T N. Statistical analysis of the incidence, relative and absolute, of trachoma in India and in Bombay State. Indian J Ophthalmol 1954;2:94-108
Trachoma is widely distributed all over the world. India falls in the category of large countries in which this eye disease is highly prevalent.
The present statistics are based on the data supplied by the Directors of Health Services of the different states of the Indian Union. They are necessarily incomplete, nevertheless they give a relative idea of the incidence of trachoma in various States of India, and allow some important conclusions to be drawn.
| Trachoma in India|| |
The statistical data was received from 14 out of 28 states in India to which a questionnaire was sent. The data from the remaining 15 states has not been received. In the case of Bhopal State, as no records have been kept with regard to this eye disease, the Director of Health Services of the State could not forward any information.
Out of the 14 states, only four have sent the statistical data with subclassification into males, females, children, adolescents and adults. Eight states sent only the figures for the total number of trachoma cases. The present analysis is, therefore, based only on the total number of trachoma cases in relation to the total population and to the overall incidence of eye diseases. Besides this statistical data regarding the incidence of trachoma the Directors of Health Services of the different states, were also requested to remark whether or not any particular community in their state is affected more with trachoma.
The Surgeon General with the Government of Bombay has sent the statistical data in regard to the incidence of trachoma from each of the districts in the State of Bombay except in the district of Dangs from where no such data is available. This data will be discussed subsequently.
Trachoma is rather unevenly distributed in the various States of the Indian Union [Table - 1] and (Map 1-[Figure - 1]). Rajasthan, Pepsu, Jammu and Kashmir and Madhya Pradesh j are the states where the incidence of trachoma is very high. As regards East Punjab, from where the official statistical data has not been received, one can gather from the article by Tulsi Das, Nirankari and Chaddah (1954), that the incidence of trachoma is very high. "Trachoma forms 60% of the preventible blindness in Punjab."
Because of unequal facilities for attending to eye diseases in different parts of India, we have prepared another table to show the incidence of trachoma in proportion to other eye diseases as reported from the different states. This shows the comparative fallacy of [Table - 1] and (Map I-[Figure - 1]). It will be noticed that in the States of Rajasthan and in lesser degree Uttar Pradesh, the incidence of trachoma per million population is relatively low, while the percentage of trachoma in relation to the overall eye diseases in these states is relatively high. This suggests that the total number of persons who obtain medical aid in these areas is proportionately lower than in other states and that at least among those who are able to obtain medical aid, the incidence of trachoma is high. From this point of view, [Table - 2] and (Map II-[Figure - 2]) are more accurate as they depict the incidence of trachoma in relation to the total number of eye diseases which have been reported.
From a study of [Table - 2] and (Map II-[Figure - 2]), it will be seen that there is a relatively high incidence of trachoma in the north-west part of India extending from Rajasthan (80.80%), East Punjab, Pepsu (70.60%) and Jammu and Kashmir (29.30% ). The other interesting part is that immediately to the south-east of this highly infected area is an area of comparatively very low incidence - Uttar Pradesh 19.40% and Madhya Bharat 2.59%. Thus a distinct line separates the two areas of high and low incidences of the disease. Even in Rajasthan, it has been ascertained that there is an area of high and low incidences separated by the Aravali Ranges as shown in (Map VI-[Figure - 4]). The Director of Medical and Health Services of Rajasthan, states, "A large area of Rajasthan particularly the western part of Rajasthan is a desert area; with very little rains and the winds blowing throughout the year. The north-eastern part of Rajasthan is more or less a plain, with agriculture going on in most of the places and the rest lying as a cultivable waste due to lack of water."
Another interesting fact is that no trachoma has been reported in the Cochin State. There is a relative low incidence of trachoma also in the three nearby state--, viz. Bombay (South), Mysore and Madras. It may be that people in the Cochin State are more resistant to trachoma infection or, as it seems more likely, the relative incidence of trachoma in the Cochin State is so low and mild that the cases although present may be easily missed.
On examining [Table - 2], it will be noticed that during the three years ( 1948-49-50), the percentage of trachomatous patients appears to be on the increase especially in the States of Bombay, Madras, Uttar Pradesh, Madhya Bharat, Rajasthan and Delhi. This most probably has been caused by the partition of India when a large influx of refugees into the different states of India took place especially in the above mentioned states. Most of these refugees came from Sindh and West Punjab where the incidence of trachoma was high. This incidence of trachoma has also been noted in refugees coming to Bombay City. In this connection, it is interesting to note the statement of Tulsi Das, Nirankari and Chaddah ( 1954) in their article that the lower incidence of trachoma in the South is due to lesser penetration of the Mohamedans to the South. These Mohamedans are supposed to have imported trachoma from the trachomatous middle-east. This suggests that one of the modes of the spread of trachoma to less infected districts is by every wave of mass migration of trachomatous populations, rather than a spread from individuals.
| Trachoma in Bombay State|| |
A separate study of this nature has been made for the State of Bombay where the details from most of the districts of the State itself have been provided by the Civil Surgeons through the Surgeon General with the Government of Bombay.
On viewing (Map IV-[Figure - 4]) and [Table - 4], it will be evident that the incidence of trachoma decreases as one travels from north to south in the Bombay State, similar to as demonstrated for the country as a whole and that the distribution of trachoma in the state is uneven. The percentage of trachoma in relation to the eye diseases is higher in the more northern districts especially Ahmedabad and Amreli, in the district of Kolaba and in the City of Bombay. The incidence of Trachoma per million population [Table - 3], (Map III[Figure - 3]) also roughly suggests the same distribution. In the case of the districts of Banas Kantha and Mehsana, there is a marked discrepancy in the incidence which is considered in the discussion.
The incidence also seems to decrease, though in a lesser measure as one goes from the Western Coast towards the East, the demarcation line being the mountain ranges of the Western Ghats, especially in the northern half.
| Communal Distribution of Trachoma|| |
It has been reported by the Directors of Medical Services of the states of Bombay, Uttar Pradesh, Madras and Mysore; that Muslims are affected more than the other communities in certain districts of their states. Bombay and Madras States further add that the Brahmin community stands second in the list of trachoma patients in their states. Statistical figures, however, have not been provided. Trachoma is seen more in the Punjabi and Sindhi refugees in the states of Uttar Pradesh (certain districts), Pepsu and Punjab according to the Directors of Health Services.
In the Bombay State, it is reported by the different Civil Surgeons in their respective districts that certain communities are much more affected with this eye disease than others. In the districts of Sabar Kantha, Baroda, Ahmedabad and Satara South, trachoma is noted to be more prevalent in the Muslims than the other communities in these districts. Most of the Civil Surgeons in the districts of Bombay State agree that the affection of trachoma is also seen more commonly in the "scheduled caste" people. Marwaris are the victims of trachoma in the districts of Ahmedabad, Ahmednagar, Poona, Ratnagiri and Bijapur. The Civil Surgeon of Poona says that the Jews in Poona are affected with this eye disease. He further adds that according to Dr. V. D. Sathe, 55 of the trachoma cases treated by him were from the Brahmin community and other high class communities who generally belonged to the Konkan area (Ratnagiri district) which is situated neat the Arabian Sea. A high incidence, of trachoma among the Brahmins is also noted by the Civil Surgeons of Baroda, Kolhapur and Bijapur. [Table - 5] shows the impressions of various Civil Surgeons, in the different communities of their districts.
Thus in the absence of proper statistical data and rather inconsistent impressions from the different health officers, it cannot be concluded that any one community is afflicted more than the other by this disease.
Looking at [Table - 5], however, one can see that the Marwari community is the most reported community to suffer from trachoma, followed closely by the Brahmins, the Mohamedans, the Punjabis and the Sindhis. As regards the Mohamedans they do not represent any particular province, and so may not be considered for the purposes of evaluating imported trachoma. On the other hand the Marwaris, the Brahmins, the Punjabis and the Sindhis are truly representative of definite parts of India. Thus the Marwari community emerging from Rajasthan, the Punjabis from Punjab and Pepsu, the Sindhis from Sind which are the three most highly infected states seem to carry their trachoma into the districts that they migrate to.
To a lesser extent the Brahmins from Ratnagiri (Bombay state) seem to carry their trachoma from the western coast across the Western Ghats to the tableland beyond in the east.
It appears thus, that the study of the distribution of trachoma in the communities does not convey an idea of a racial distribution but gives an indirect idea of the nuclei of infection from which the disease migrates.
| Influence of Hygiene|| |
It is well known that poor hygienic environment and unhygienic habits are responsible in some way for the spread of trachoma. We need only say here that these hygienic considerations only determine the severity of the disease as has been brought out by Tulsi Das (1954) in his paper on "Early diagnosis of trachoma."
The rather severe incidence in the better class Brahmins of Ratnagiri district appears to be an exception and needs investigating.
Overpopulation does not seem to be a contributing cause (Map VII C-[Figure - 7]), for some of the most overpopulated regions (Bengal) are comparatively free of trachoma whereas the least populated area (Rajasthan) is the most infected.
| Geological Considerations|| |
From the above considerations one feels that India is supremely placed for a determination of some of the contributing causes of trachoma. The remarkable feature is the high incidence of trachoma decreasing gradually from Rajasthan as one proceeds north-east towards the Pepsu, East Punjab, Jammu and Kashmir and a sudden drop beyond the east slopes of the Aravali Ranges (Map VI-[Figure - 6]). It is therefore worth while considering the geological factors involved in this curious limitation of the disease by the Aravali mountains and its neighbourhood. One must therefore consider (1) the rainfall, (2) the nature of the soil and (3) the prevailing winds in this part which may help in the explanation of this regional localization of the disease.
As regards the rainfall as seen from (Map V-[Figure - 5]), Rajasthan is a region of scanty rainfall, but the southern half of the country has also a poor rainfall inspite of which the incidence of trachoma is low.
The slopes of the Aravali Ranges (Map VI-[Figure - 6]) face roughly west and east. The country beyond the west of these mountains, is a vast desert called the Thar or the Great Indian desert below which lies the Cutch desert. The country to the east of these ranges according to the Director of Medical and Health Services of Rajasthan as already stated "is plain with agriculture going on in most of the places and the rest lying as a cultivable waste due to lack of water." Thus the soil on the two sides of these ranges is different -- sandy and uncultivable on the west and cultivable on the east.
Cultivation alone does not seem to be the cause of lower incidence of trachoma as can be seen by comparing (Map VII D-[Figure - 7]) with (Map II-[Figure - 2]).
If one looks at the map of the prevailing winds (Maps VI-[Figure - 6]and VII A and B-[Figure - 7]) during the summer and winter, one finds that the direction of the winds towards the beginning of monsoon (June) is from the south-west bifurcating at the junction of the Aravali and the Vindhya Ranges, one proceeding in a northerly direction across the desert towards the Pepsu, Punjab, Jammu and Kashmir and the other passing across the comparatively fertile coastal area on the west, directed eastwards by the Vindhya Ranges towards Madhya Bharat, Bengal and Assam. The prevailing winds in winter (December) proceed from Jammu and Kashmir in the Himalayas in a reverse direction across East Punjab and Rajasthan.
In the Bombay State it is known that the climate in the more northern and more trachomatous districts of Banas Kantha, Mehsana, Panchmahals and Ahmedabad is relatively hotter and the soil is sandier. Also in these areas one gets a number of sand storms. Again, it must be these climatic and soil conditions that account for a higher incidence of trachoma in the more northern districts of Bombay State.
In the southern half of the State of Bombay again we see a comparatively higher incidence in the coastal area and a lower incidence as we go eastwards, the demarcating line being the high mountains of the Western Ghats just as the latter form the demarcating line between areas of high and low rainfalls, (Map VI-[Figure - 6]) suggesting the influence of the monsoon winds.
It will be thus seen from these considerations that the explanation of the high incidence of trachoma in Rajasthan, waning gradually towards the north and limited abruptly by the western slopes of the Aravali Ranges should be sought in the prevailing winds towards the beginning of monsoon sweeping in the same direction. These areas are notorious for regular sand storms and in the months of June a peculiar dusky brown fog prevails which is due to suspension of fine particles of dust and not of moisture. Thus it appears to be a combination of a low rainfall area in a sandy desert swept over by strong winds from the southwest, raisin- sand storms that appears to be responsible at least in one way for the cause of this infection.
In the State of Bombay the comparative difference between the incidence on the west and east slopes of the Western Ghats can be similarly explained, only that the absence of sandy deserts makes the total incidence far lower than in Rajasthan, Punjab and Kashmir.
| Discussion|| |
Although these statistics have been gathered through the Civil Surgeons and the Directors of Medical & Health Services who are not all ophthalmologists, the high incidence of trachoma in our country equips them with enough experience to make an accurate clinical diagnosis of trachoma which is sufficient for a fair analysis of the distribution of trachoma in our country.
There are reasons to doubt the figures from Banas Kantha, Mehsana and Ratnagiri. Banas Kantha gives the highest figure per million population (10,000) and a very low figure (4.89) per cent. of eye diseases. Mehsana a district immediately adjoining supplies a very low figure per million population (370) and again a very low figure (4.9) per cent. of eye diseases. Both these districts are well-known trachomatous districts and such disparity in figures makes reliance on these figures dubious. These figures need checking.
By looking at [Table - 5] it will be noticed that the districts of Poona, Kolhapur and Bijapur report a high incidence in the Brahmin community which ordinarily comes from the Ratnagiri district. This is confirmed by Dr. V. D. Sathe's remark on page 100 about this community. We have also confirmed this from other practising ophthalmologists of Poona and Sholapur, one of whom remarked that whenever one sees a case of trachoma in a Brahmin in Poona, it is customary to inquire whether he comes from Ratnagiri district. This makes one feel that the figures supplied by Ratnagiri (210 per million and 5.33% of eye diseases) are perhaps too low and need checking.
Bombay city's high incidence in a neighbouring area of comparatively low incidence needs an explanation. We have already commented upon imported trachoma in a cosmopolitan city like Bombay which greatly exaggerates the usual incidence as ordinarily encountered in Bombay. Cooper (1949) in his report on the incidence of trachoma in the City of Bombay approached the problem in an indirect way by studying the incidence in a big industrial concern which covered all classes and communities ordinarily resident in Bombay and adopting these figures with certain modification to the population of Bombay City. In this way he has estimated the incidence at no more than 2.5%. He, however, found that the community of sweepers was much more affected than the other communities in the industrial concern. A similar study in other industrial concerns may give a more correct idea of the incidence of trachoma in the city. A study of the incidence of trachoma in various communities in the city will give an idea of the degree of importation of this disease.
Four main facts emerge from this study of the incidence of trachoma. (1) That the incidence gets less as one travels from north towards south in the whole country as well as in the State of Bombay, and in the latter State it also decreases from west to east. (2) The highest incidence is in Rajasthan which may be considered the Indian nucleus of trachoma infection from which infection seems to spread mostly towards Punjab and Kashmir along the prevailing winds in June. (3) The Aravali ranges in Rajasthan form the demarcating line between areas of very high and comparative low incidence of this disease. The Western Ghats form a similar demarcating line between areas of high and low incidence of trachoma in the Bombay State, to a lesser degree. (4) Migration of trachoma takes place with waves of mass shifting of the population.
From the deductions (1), (2) and (3) it may be gathered that the south-west winds beginning in monsoon (June) which sweep across the sandy desert areas seem to play an important part in the incidence of trachoma in India. One can only speculate as to what happens in the actual causation of trachoma. Is there something in the moist winds or in the sandy atmosphere of the desert or a combination of the two which is really responsible for the actual affliction by the disease? During monsoon it is a well known fact that many virus diseases are brought over to the shores of India e.g. herpes, epidemic encephalitis, superficial punctatee keratitis, epidemic kerato-conjunctivitis, Beale's conjunctivitis and even poliomyelitis-Gharpure (1954). If trachoma is brought along on the same winds, the west coast of India should be a hot bed for this disease. Moreover there should be seasonal incidence. As far as can be ascertained no such seasonal incidence is reported. We must confess that we have not. placed any enquiry about seasonal incidence in our questionnaire, which is worth investigating. However, the dark areas (Maps I-[Figure - 1] & II-[Figure - 2]) are so highly infected that a seasonal wave would not be appreciated unless a special study is made about it. Seasonal incidence is reported in Egyptian Trachoma, where it coincides with the "fly season". As far as can be ascertained the relation between this seasonal incidence and the prevailing winds in Egypt, Arabia and Persia have not been studied.
Thus it appears to be a combination of the monsoon winds over sandy deserts which is responsible for the incidence of trachoma. We can only speculate that either (1) the winds churn up the sandy atmosphere which may be loaded with the trachoma virus and is blown into conjunctival sacs of the population or (2) the sandy particles so irritate the human conjunctiva as to lower the natural resistance of the conjunctiva to the trachoma virus brought on the monsoon winds. It was with this view that we had undertaken the study of "conjunctival bed as a receptor for the trachoma virus".
Scarcity of rainfall and scarcity of water supply alone do not seem to be the factors responsible because the eastern slopes of the Aravali mountains which are water scarce areas as well as the southern part of the peninsula which is an area of scanty rainfall are comparatively trachoma free areas but for the imported trachoma.
A glance at the maps on density of population and cultivation also does not show any direct relation of these two factors to the relative incidence of trachoma in India. (Map VII, C and D).
| Summary|| |
- A study has been undertaken to investigate the possible factors in the causation and transmission of the trachoma infection.
- The fallacy of using the figures on trachoma per million population is rectified by using the figures of trachoma per cent. of eye diseases.
- Important geological factors have been investigated and incriminated in the import of the disease.
- Transmission of infection to unaffected areas and population appears to be brought about by waves of migration of infected communities.
- Unhygienic habits and environment only determine the severity of the affliction.
- Sufficient important conclusions have been drawn so as to merit a more statistically correct enquiry by ophthalmologists into the incidence and migration of trachoma in India.
| Acknowledgement|| |
I am greatly indebted to my teacher Dr. S. N. Cooper, who has directed me throughout this work. I am very thankful to the late Dr. R. G. Dhayagude, M.D., the then Dean of the Seth G. S. Medical College and the K. E. M. Hospital for helping me to gather the statistical data from the various states in the Indian Union.
Indeed I would have been misled in this statistical analysis but for the great help from Dr. Roger A. Lewis, M.D., Visiting Professor of Pharmocology through the WHO at the Seth G. S. Medical College to whom I am deeply grateful.
I take this opportunity to thank the Directors of all the Health Services of the States in the Indian Union who have kindly sent the required data.
My thanks are also due to the Deputy Director General of Observatories, Poona and to the Chief Botanist, Botanical Survey of India, Calcutta for sending me the map of Mean Annual Rainfall and the Atlas of Indian Agriculture respectively. My thanks are also due to John Bartholomew & Son Ltd. and the Oxford University Press to allow us to reproduce the maps from the Oxford School Atlas and to Mr. M. Nizampurkar for drawing maps I-IV.
Lastly, I thank Dr. S. N. Sutaria, M.B.B.S. for her help in the statistical calculations and Dr. Pandit, Secretary, Indian Council of Medical Research, New Delhi, for allowing me to publish this report.
| References|| |
Cooper, S. N. ( 1949) Trachoma dans l'Inde - Reported by Moutinho, H., Review Int. Trachome 26, 37.
Tulsi Das, Nirankari, M. S. and Chaddah, M. R. (1954) J. of All-India Ophth. Soc. 2, 1-14.
Gharpure (1954) Ind. J. of Child Health 3, 376.
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]