- Email: [email protected]
Prevalence and causes of vision loss in Southern Sudan
.Soc.‘Sci. Med. Vol. 17, No. Printed in Great Bntain
22. pp. 1785-1788,
PREVALENCE
1983
0277-YSM183 53.00 + 0.0(1 Perfamon Pres\ Lkl
AND CAUSES OF VISION SOUTHERN SUDAN
LOSS IN
TEFERA TIZAZIJ’ and F. M. MBURU’ ‘Malawi Rural Blindness Prevention Project, International Eye Foundation. P.O. Box 2273, Blantyre, Malawi and *Department of Community Health, Faculty of Medicine, University of Nairobi. P.O. Box 30588, Nairobi, Kenya Abstract-Blindness in Southern Sudan is thought to be highly prevalent due to the high prevalence 01 onchocerciasis and trachoma. In addition, socioeconomic development in the area has been low and growth slow. Communities in the South have not changed much having been unaffected by modern institutions more prevalent in the North. Traditional methods of Farming. tishing and pastor&m still persist. However. even these may be hampered by the large scale presence of blackfly and trdchoma. This paper describes one approach to define the prevalence and causes of vision loss in Southern Sudan.
INTRODUCTION A multiplicity of factors, singly or interacting, cause vision loss. Such factors may include living habits, socioeconomic status, ecological conditions’ and occupational activities. Varied degrees of vision loss,
including total blindness, are prevalent in Southern Sudan where modern aspects of development, including basic health infrastructures, are few and far apart. Many communities still live in much the same way as their ancestors, unaffected by modern farming, fishing, industrialization and urbanization, all of which are more prevalent in the northern part of the country. Perhaps owing to the high prevalence of onchocerciasis in some provinces of Southern Sudan, other common causes of vision loss have received little or no attention. Recently a number of national and international agencies have shown interest in the control of avoidable blindness, especially at an early age. This paper briefly describes the general health status and the distribution of impaired vision and also blindness in the Equatoria Provinces. Some of the socioeconomic and sociocultural factors involved in the prevention and control of blindness are discussed. An analysis of these factors is a necessary condition for the prevention of blindness. Most pertinently, resources for preventive and curative activities should be related to the magnitude and ramifications of the problem to be removed. The present survey is therefore a contribution toward the prevention of vision loss in these provinces. RATIONALE OF THE SURVEY The survey was conducted
Equatoria
in the West and East Provinces. The aims were:
(i) to identify the prevalence and distribution of eye diseases: (ii) to determine the major causes of blindness in the two provinces; and (iii) to recommend to the Ministry of Health and Social Welfare. appropriate action to be taken to deal with the common eye problems identified. The results will assist in the mounting of a biindness prevention training programme in the area.
Among the resources to be taken into account is health education for the prevention of blindness. It is well known that most blindness found in Africa is avoidable-it can be and should be prevented. But neither the government nor any international agency can effectively undertake the task without knowing what the problem is, its distribution and. the critical factor, namely the population at risk. METHODS AND RESOURCES
The Equatoria Provinces were selected because eye disease, impaired vision and blindness are said to be highly prevalent. Travellers through villages in the South have reported an unusually high prevalence of poverty, unhygienic living standards. shortage of water and swarms of flies. Adequate demographic data of the distribution of population in Southern Sudan is not available. It was therefore not possible to obtain a satisfactory sampling frame even for a cross-sectional study of this type especially due to the difficulties of establishing the number, size and location of villages [I]. These difficulties notwithstanding, broad areas west and east of the Nile were selected. Six villages in the West Equatoria and six in East’were selected with the assistance of the local administration. As wide an area as possible was covered to provide a crosssection of the population. The sample in each ‘cluster’ was obtained with the assistance of the village subchief. Households are in fenced clusters, some of which are close together while in other cases two clusters may be miles apart. Once the clusters were selected. all members of the household were registered. vision checked, and the patient examihed by an ophthalmologist. This-took place early in the morning before people left the village. In some villages. as the results show, some age-groups were under-represented partly because men. especially those between 30 and 45 were out with grazing hvestock for days and sometimes weeks. and partly as a result of the seventeen-year war that ended in 1972. leaving a population with a reduced number of young adult males. Examination for visual acuity followed the WHO
1786
TEFERA TIZAZU and F. M. MBURU Table I. Location and population Province
of villages sampled. West and East Equatoria
Village
West
Tribe Jnt Jnr/Dinka Zande Zande, Balanda Movukodo Zandei Balanda Achali/ Lotuko Achali/ Lotuko Didinga Toposa Lotuko Lokoro
Domeri Mvolo Moruco Mbiri
Equatoria
Woko Nadjangere East Eqnatoria
Kalisoni Lerwa Lam0 Mogos Lendo Lafon
recommendation, those having 6/18 or less being examined more thoroughly to assess the cause of visual impairment or blindness [l]. Except for treatment where necessary no inducements were provided. RESULTS It is widely documented that onchocerciasis (OV) occurs mainly to the west of the Nile. This survey confirmed that only villages to the west of the river are infected with OV. The WHO recommended criterion of blindness (vision less than 3/60) was not used in this study. It was felt that the criterion was too limiting for a disease like OV and for ‘a population which is pastoral and needs good vision for livelihood. In this survey vision worse than 6/60 in the better eye constituted ‘blindness’.
WEST EQUATORIA
The contribution of OV to blindness was found to be 4.3% in the total sample of the area. Of the total .sample of 5 18 in West Equatoria, 17.6% were found to be infected with OV. Other major causes of blindness in the region were found to be cataract and trauma. The prevalence of OV, vision loss and blindness varied from one village to another; they were higher where simulium breeding sites were common and where relevant ways of life strengthened the risk of infection. It is known that onchocerciasis is more Table
Domeri Mvolo Moruco Mbirl
IO1
Nadjangera
100
*In the better eye.
Village population
133 57 87
225 700 I25 300
IO1 100
300 300
225
300
IO0
700
106 145 91 200
500 500 250 24.000
50
’
severe where there is more frequent biting by the blackfly. Fishermen who live by the riverside are likely to be bitten more than farmers who live away from the rivers. One would therefore expect to find more OV blindness along river banks and less as the distance from a river increased. For reasons which are hard to explain the data produced some unexpected results. For instance, Mvolo is a village on a river and would be expected to be among the highest prevalence rate of OV and blindness. But of the total sample (133 out of 700) 2.4% were found to have a vision of 6160 and 8% had 6/16 or less. Domeri village, which is away from the river, had 16% of the sample with a vision of 6/18 or less. Whereas 28% of the Domeri population showed the presence of OV, 50% of the Mvolo population was found to be infected. It would therefore follow that many more people in Mvolo would be blind or have impaired vision than the results show. A possible explanation for this discrepancy may have been the small sample sizes (see Table 2). Although a significant proportion of the population in West Equatoria is infected with OV, blindness due to OV was generally found among those aged 50 or above. Even then, males who were infected and who had impaired vision outnumbered females by 2: 1 or more. This finding was supported by the data from other OV areas. Among other West Equatoria villages, low vision
2. Visual acuity and causes of viston loss in selected villages m Western Equatoria. Southern Sudan Causes of wsion loss Visual acuity* Onchocerea Cataract Cornea1 6/1X or volvulus opactty either 6/i!%6160 6161 or less Total better eye (‘:;) (OV) (“/‘,) (“,) sample (NJ (X>J vn) (%) 8 0 0 50 (1, (16) & (;I I IO I25 II2 ,792, (342, (234, (89.6) (0.8) (8) 2 45 57 (533, (3.5) (1598, (79.9) 85 0 (761, 3 5 2 (5.9) (2.4) (3.5)
Woko
Total
Sample
518
(&, 90 (90.0) 465 (89.8)
(2’0, (660) 40 (3.9)
(Z’O, 4 (4.0) 33 (6.4)
0
0
0
0
II (2.1)
22 (4.3)
(26, (110,
Prevalence and causes of vision loss in Southern
17x7
Sudan
Table 3. Visual acuity and causes of vision loss in selected villages in Eastern Equatoria, Visual acuity
Kalisoni Lerwa
Total sample (N)
6118 or better
6/I g-6160
6161 or less
Cataract either
(X)
(%)
(%)
eye (%)
(%)
(OV (“A
224
217 (99. I) 94 (96.9)
I (1.5) 0
0
(I”*, 0
j (1.4)
(SC,
(If,,
:*& 84 (92.3) 157 (81.3) (749 (90.7)
(463,
97
Laura
106
Mogos
120
Loudo
86
Lafon
193
Total
Southern Sudan (‘;:,) CUM3 of wsion loss Cornea1 Onchocerea volvulus opacity
826
(A, (\17) 24 12.9)
EAST EQUATORIA
In East Equatoria the prevalence of low vision (6/l S-6/60) was 2.9x, but it was much higher in some villages, especially Lafon and Mogos where it was 5.7 and 4.3% respectively. Lerwa and Loudo had a significantly low prevalence of visual acuity, less than 6/60. These low rates may have been due to the small sample sizes in these two villages. In Kalisoni and Lauro visual acuity of less than 6/60 accounted for about 2.0%. The prevalence of blindness, using WHO criteria, less than 3160, was found to be 6.4%. Again there were variations from village to village, with Lafon leading with 13.0x, Mogos, 10.7x, Lauro, 6.6% and the lowest rate in Loudo 1.1% (Table 3). Trachoma and cataract were the major causes of blindness. The percentage of active trachoma has been certainly reduced since dispensaries were established, providof avoidable
(3:*, (3:6,.
(:02)
(111,
(zf,,
(III) 9 (4.7) 28 (3.41
(3!I,
was found to be significantly prevalent in Moruco where 15.8’% of the population had a vision between 6118 and 6/60, and 5.3% had a visual acuity of 6/61 or less. Mbiri village had 7.1% of the population blind (6/61 or less), though only 2.4% of the population had OV. Trauma and cataract were more prevalent where OV was not a leading cause of visual loss. The villages of Woko and Nodjangere showed no OV, vitamin A deficiency and trauma-induced vision loss. Perhaps the absence of these conditions explain the low prevalence of visual impairment in these two villages (see Table 2).
Table 4. Distribution
(6:6, 14 (10.7)
3 (1.4) 2 (2.1) 3 (2.8)
(CO, 53 (6.4)
(497, 21 (2.5)
Lerwa Laura Mogos Luodo
DISCUSSION
AND CONCLUSIONS
The importance of socioeconomic minants of impaired vision
Lafon
and ecological deter -
In most African societies where eye problems have been reported, for instance in Eastern and Central African countries, a number of factors have been
causes of vision
loss by village
in Eastern Equitaoria,
No. W 6161 or less
No. with active trachoma
No. with other multiple causes
2 village with avoidable ca”?&S
7 (3.1) 3 (3.1) 9 (8.5) (,?7,
0
5
2.2
I
2
3.1
4
13
16.0
10
34
25.8
0
8
8.1
20
38
29.5
2 (2.3) 36
20 (10.4) 35 (4.2)
ing treatment for the last five to seven years in areas like Loudo, Mogos and Lauro. Tables 4 and 5 illustrate the magnitude of the various preventable causes in Equatoria Region. Comparing the two areas of the survey, it would appear that where OV occurred larger populations have impaired vision (Tables 3 and 4). It may be emphasized that while trachoma and trauma are easily prevented, cataract can as effectively be cured. This is not the case with OV. The control of OV requires massive economic outlays and perhaps a radical resettlement of the populations away from the affected areas. The achievement of such an ambitious goal would be slow. OV is more prevalent among males than among females while the prevalence and seriousness of the disease increases with age. Indeed age is related to the occurrence and seriousness of both trachoma and onchocerciasis. It should be pointed out that previous data from Southern Sudan indicated that blindness affected about 1.0% of the rural population in the trachoma area and 5.1% in the onchocerciasis areas [2,3]. Our survey showed much higher prevalence rates (6.4%) in both areas, although the criteria for ‘blindness’ differed.
Southern Sudan
Kalisom
I (1.0) 4 (3.8) IO (7.2) 0
1788
TEFERA TIZAZU Table 5. Distributton
Mvolo Moruco Mbtri Woko Nadjangere
F. M.
MBURU
of avotdable causes of vtsual loss by village in Western Equatoria. Southern Sudan No. wtth 6.61 or less (““J
Domen
and
8 (16.0) 13 (26.0) I2 (21.1) ,?“I, (440) IO (10.0)
No. wth ov
No. with other multiple cattses
‘a village with avoidable causes
14
3
34.0
63
8
56.8
9
6
26.3
2
8
11.8
0
2
2.0
0
I
1.0
found to relate to the occurrence of impaired vision. Most significant among these are climatic conditions that bring about either dry dusty conditions, or warm and damp environments. Water availability and pattern of use largely determine the status of personal hygiene. However, availability by itself is not a sufficient condition for improved personal hygiene. Cleanliness is culturally defined and developed. There are societies in Africa where washing of any part of the body is rare and when it occurs, it may not be adequate to keep the body or part of it. the eyes, for example, free from dirt and flies. The Turkana. the Pokot and the Masai of Kenya are examples where children are rarely encouraged to bathe. In Southern Sudan the Topoza, the Didinga, Lokoro, among others, may be cited for similar behaviour. Ecological factors determine the mode of living in many parts of Africa where people are unable to modify the environment. People have molded their pattern of living habits to suit the existing physical handicaps or advantages. Potentially, sociocultural and socioeconomic patterns may compromise health standards that are already low. Cattle herding is the dominant cultural and economic activity in the grasslands of sub-Saharan Africa. People move with rain and animal grazing patterns. Life is a constant struggle in search of grass for cattle, green bushes for sheep and goats. The success of the family can be judged largely by the size of the herd or the flock. Just as the domestic animals follow their feed, flies follow the animals. The greater the resources of one family, the more the animals and the more the flies. One does not have flies in the kraal or the manyatta unless there are animals. And so to have no flies-and almost inevitably trachoma-is to be poor and consequently to have relatively low social status in the community. Nomadic communities invariably appear to have low standards of domestic hygiene. The reasons are not always clear but it would appear that nomadism is inextricably related to some perceived temporary nature of the homestead and perhaps of life itself. Whether that is the case or not, personal hygiene and cleanliness do not appear to be priorities in some African societies. Admittedly, cleanliness is a subjective and culturally defined condition. But in this paper the term is used to include such aspects as washing of the hands, face and body and to keep
oneself or the family in a manner that does not encourage breeding of pests like lice, flies and fleas. Among the Lokoro tribe (Lafon Village, Torit District, Eastern Equatoria), there are no latrines, and bushes serve the purpose. For the Lokoro it is culturally unbecoming to defecate in the same place twice, but the space available to the clusters of villages with a population of nearly 25,000 people is severely limited. The Lokoro tribe lives on the slopes of sharp hills, and the villages are densely populated. Consequently, the surrounding environment is heavily contaminated with faeces washed down the valleys by the occasional rain. Water is obtained from bore holes, 60-7004 of which are out of use at any one time. Personal hygiene is extremely poor and exacerbated by poverty, flies and dirty environment. Trachoma is therefore highly prevalent, leading to unnecessary blindness. Broadly, disorders of the eye, like many other disorders, are due to a combination of ecological, biological and social factors and personal habits. Factors commonly known to be causes of blindness or loss of vision are the end results of a spectrum of enabling or underlying determinants. In an onchocerciasis area, for example, the breeding sites, distance from the river, and the number of bites by the flies all combine to determine the epidemiology of the disease. Like trachoma, onchocerciasis in Western Equatoria occurs only in some selected areas. Control measures, then, must ultimately touch on the factors that cause disease. Short of that, any action taken will largely be palliative and bound to have only a limited impact. Acknow/edRemenrs-Funding for data collection was provided by the Norwegian Council for the Prevention of Blindness. The kind assistance of MS Madle Brekke, R.N., is gratefully acknowledged. REFERENCES
I World Health Organization.
Methods of assessment of avoidable blindness. Draft Paper, Report of Task Force, San Francisco, PBL/AG/80.5, 1979. 2. Wld Hlth Org. Chron. 33, 275, 1979. 3. See also: Wilson Sir J. Prevention of blindness in Africa. Paper read at the International Agency for the Prevention of Blindness Meeting, 1980.
22. pp. 1785-1788,
PREVALENCE
1983
0277-YSM183 53.00 + 0.0(1 Perfamon Pres\ Lkl
AND CAUSES OF VISION SOUTHERN SUDAN
LOSS IN
TEFERA TIZAZIJ’ and F. M. MBURU’ ‘Malawi Rural Blindness Prevention Project, International Eye Foundation. P.O. Box 2273, Blantyre, Malawi and *Department of Community Health, Faculty of Medicine, University of Nairobi. P.O. Box 30588, Nairobi, Kenya Abstract-Blindness in Southern Sudan is thought to be highly prevalent due to the high prevalence 01 onchocerciasis and trachoma. In addition, socioeconomic development in the area has been low and growth slow. Communities in the South have not changed much having been unaffected by modern institutions more prevalent in the North. Traditional methods of Farming. tishing and pastor&m still persist. However. even these may be hampered by the large scale presence of blackfly and trdchoma. This paper describes one approach to define the prevalence and causes of vision loss in Southern Sudan.
INTRODUCTION A multiplicity of factors, singly or interacting, cause vision loss. Such factors may include living habits, socioeconomic status, ecological conditions’ and occupational activities. Varied degrees of vision loss,
including total blindness, are prevalent in Southern Sudan where modern aspects of development, including basic health infrastructures, are few and far apart. Many communities still live in much the same way as their ancestors, unaffected by modern farming, fishing, industrialization and urbanization, all of which are more prevalent in the northern part of the country. Perhaps owing to the high prevalence of onchocerciasis in some provinces of Southern Sudan, other common causes of vision loss have received little or no attention. Recently a number of national and international agencies have shown interest in the control of avoidable blindness, especially at an early age. This paper briefly describes the general health status and the distribution of impaired vision and also blindness in the Equatoria Provinces. Some of the socioeconomic and sociocultural factors involved in the prevention and control of blindness are discussed. An analysis of these factors is a necessary condition for the prevention of blindness. Most pertinently, resources for preventive and curative activities should be related to the magnitude and ramifications of the problem to be removed. The present survey is therefore a contribution toward the prevention of vision loss in these provinces. RATIONALE OF THE SURVEY The survey was conducted
Equatoria
in the West and East Provinces. The aims were:
(i) to identify the prevalence and distribution of eye diseases: (ii) to determine the major causes of blindness in the two provinces; and (iii) to recommend to the Ministry of Health and Social Welfare. appropriate action to be taken to deal with the common eye problems identified. The results will assist in the mounting of a biindness prevention training programme in the area.
Among the resources to be taken into account is health education for the prevention of blindness. It is well known that most blindness found in Africa is avoidable-it can be and should be prevented. But neither the government nor any international agency can effectively undertake the task without knowing what the problem is, its distribution and. the critical factor, namely the population at risk. METHODS AND RESOURCES
The Equatoria Provinces were selected because eye disease, impaired vision and blindness are said to be highly prevalent. Travellers through villages in the South have reported an unusually high prevalence of poverty, unhygienic living standards. shortage of water and swarms of flies. Adequate demographic data of the distribution of population in Southern Sudan is not available. It was therefore not possible to obtain a satisfactory sampling frame even for a cross-sectional study of this type especially due to the difficulties of establishing the number, size and location of villages [I]. These difficulties notwithstanding, broad areas west and east of the Nile were selected. Six villages in the West Equatoria and six in East’were selected with the assistance of the local administration. As wide an area as possible was covered to provide a crosssection of the population. The sample in each ‘cluster’ was obtained with the assistance of the village subchief. Households are in fenced clusters, some of which are close together while in other cases two clusters may be miles apart. Once the clusters were selected. all members of the household were registered. vision checked, and the patient examihed by an ophthalmologist. This-took place early in the morning before people left the village. In some villages. as the results show, some age-groups were under-represented partly because men. especially those between 30 and 45 were out with grazing hvestock for days and sometimes weeks. and partly as a result of the seventeen-year war that ended in 1972. leaving a population with a reduced number of young adult males. Examination for visual acuity followed the WHO
1786
TEFERA TIZAZU and F. M. MBURU Table I. Location and population Province
of villages sampled. West and East Equatoria
Village
West
Tribe Jnt Jnr/Dinka Zande Zande, Balanda Movukodo Zandei Balanda Achali/ Lotuko Achali/ Lotuko Didinga Toposa Lotuko Lokoro
Domeri Mvolo Moruco Mbiri
Equatoria
Woko Nadjangere East Eqnatoria
Kalisoni Lerwa Lam0 Mogos Lendo Lafon
recommendation, those having 6/18 or less being examined more thoroughly to assess the cause of visual impairment or blindness [l]. Except for treatment where necessary no inducements were provided. RESULTS It is widely documented that onchocerciasis (OV) occurs mainly to the west of the Nile. This survey confirmed that only villages to the west of the river are infected with OV. The WHO recommended criterion of blindness (vision less than 3/60) was not used in this study. It was felt that the criterion was too limiting for a disease like OV and for ‘a population which is pastoral and needs good vision for livelihood. In this survey vision worse than 6/60 in the better eye constituted ‘blindness’.
WEST EQUATORIA
The contribution of OV to blindness was found to be 4.3% in the total sample of the area. Of the total .sample of 5 18 in West Equatoria, 17.6% were found to be infected with OV. Other major causes of blindness in the region were found to be cataract and trauma. The prevalence of OV, vision loss and blindness varied from one village to another; they were higher where simulium breeding sites were common and where relevant ways of life strengthened the risk of infection. It is known that onchocerciasis is more Table
Domeri Mvolo Moruco Mbirl
IO1
Nadjangera
100
*In the better eye.
Village population
133 57 87
225 700 I25 300
IO1 100
300 300
225
300
IO0
700
106 145 91 200
500 500 250 24.000
50
’
severe where there is more frequent biting by the blackfly. Fishermen who live by the riverside are likely to be bitten more than farmers who live away from the rivers. One would therefore expect to find more OV blindness along river banks and less as the distance from a river increased. For reasons which are hard to explain the data produced some unexpected results. For instance, Mvolo is a village on a river and would be expected to be among the highest prevalence rate of OV and blindness. But of the total sample (133 out of 700) 2.4% were found to have a vision of 6160 and 8% had 6/16 or less. Domeri village, which is away from the river, had 16% of the sample with a vision of 6/18 or less. Whereas 28% of the Domeri population showed the presence of OV, 50% of the Mvolo population was found to be infected. It would therefore follow that many more people in Mvolo would be blind or have impaired vision than the results show. A possible explanation for this discrepancy may have been the small sample sizes (see Table 2). Although a significant proportion of the population in West Equatoria is infected with OV, blindness due to OV was generally found among those aged 50 or above. Even then, males who were infected and who had impaired vision outnumbered females by 2: 1 or more. This finding was supported by the data from other OV areas. Among other West Equatoria villages, low vision
2. Visual acuity and causes of viston loss in selected villages m Western Equatoria. Southern Sudan Causes of wsion loss Visual acuity* Onchocerea Cataract Cornea1 6/1X or volvulus opactty either 6/i!%6160 6161 or less Total better eye (‘:;) (OV) (“/‘,) (“,) sample (NJ (X>J vn) (%) 8 0 0 50 (1, (16) & (;I I IO I25 II2 ,792, (342, (234, (89.6) (0.8) (8) 2 45 57 (533, (3.5) (1598, (79.9) 85 0 (761, 3 5 2 (5.9) (2.4) (3.5)
Woko
Total
Sample
518
(&, 90 (90.0) 465 (89.8)
(2’0, (660) 40 (3.9)
(Z’O, 4 (4.0) 33 (6.4)
0
0
0
0
II (2.1)
22 (4.3)
(26, (110,
Prevalence and causes of vision loss in Southern
17x7
Sudan
Table 3. Visual acuity and causes of vision loss in selected villages in Eastern Equatoria, Visual acuity
Kalisoni Lerwa
Total sample (N)
6118 or better
6/I g-6160
6161 or less
Cataract either
(X)
(%)
(%)
eye (%)
(%)
(OV (“A
224
217 (99. I) 94 (96.9)
I (1.5) 0
0
(I”*, 0
j (1.4)
(SC,
(If,,
:*& 84 (92.3) 157 (81.3) (749 (90.7)
(463,
97
Laura
106
Mogos
120
Loudo
86
Lafon
193
Total
Southern Sudan (‘;:,) CUM3 of wsion loss Cornea1 Onchocerea volvulus opacity
826
(A, (\17) 24 12.9)
EAST EQUATORIA
In East Equatoria the prevalence of low vision (6/l S-6/60) was 2.9x, but it was much higher in some villages, especially Lafon and Mogos where it was 5.7 and 4.3% respectively. Lerwa and Loudo had a significantly low prevalence of visual acuity, less than 6/60. These low rates may have been due to the small sample sizes in these two villages. In Kalisoni and Lauro visual acuity of less than 6/60 accounted for about 2.0%. The prevalence of blindness, using WHO criteria, less than 3160, was found to be 6.4%. Again there were variations from village to village, with Lafon leading with 13.0x, Mogos, 10.7x, Lauro, 6.6% and the lowest rate in Loudo 1.1% (Table 3). Trachoma and cataract were the major causes of blindness. The percentage of active trachoma has been certainly reduced since dispensaries were established, providof avoidable
(3:*, (3:6,.
(:02)
(111,
(zf,,
(III) 9 (4.7) 28 (3.41
(3!I,
was found to be significantly prevalent in Moruco where 15.8’% of the population had a vision between 6118 and 6/60, and 5.3% had a visual acuity of 6/61 or less. Mbiri village had 7.1% of the population blind (6/61 or less), though only 2.4% of the population had OV. Trauma and cataract were more prevalent where OV was not a leading cause of visual loss. The villages of Woko and Nodjangere showed no OV, vitamin A deficiency and trauma-induced vision loss. Perhaps the absence of these conditions explain the low prevalence of visual impairment in these two villages (see Table 2).
Table 4. Distribution
(6:6, 14 (10.7)
3 (1.4) 2 (2.1) 3 (2.8)
(CO, 53 (6.4)
(497, 21 (2.5)
Lerwa Laura Mogos Luodo
DISCUSSION
AND CONCLUSIONS
The importance of socioeconomic minants of impaired vision
Lafon
and ecological deter -
In most African societies where eye problems have been reported, for instance in Eastern and Central African countries, a number of factors have been
causes of vision
loss by village
in Eastern Equitaoria,
No. W 6161 or less
No. with active trachoma
No. with other multiple causes
2 village with avoidable ca”?&S
7 (3.1) 3 (3.1) 9 (8.5) (,?7,
0
5
2.2
I
2
3.1
4
13
16.0
10
34
25.8
0
8
8.1
20
38
29.5
2 (2.3) 36
20 (10.4) 35 (4.2)
ing treatment for the last five to seven years in areas like Loudo, Mogos and Lauro. Tables 4 and 5 illustrate the magnitude of the various preventable causes in Equatoria Region. Comparing the two areas of the survey, it would appear that where OV occurred larger populations have impaired vision (Tables 3 and 4). It may be emphasized that while trachoma and trauma are easily prevented, cataract can as effectively be cured. This is not the case with OV. The control of OV requires massive economic outlays and perhaps a radical resettlement of the populations away from the affected areas. The achievement of such an ambitious goal would be slow. OV is more prevalent among males than among females while the prevalence and seriousness of the disease increases with age. Indeed age is related to the occurrence and seriousness of both trachoma and onchocerciasis. It should be pointed out that previous data from Southern Sudan indicated that blindness affected about 1.0% of the rural population in the trachoma area and 5.1% in the onchocerciasis areas [2,3]. Our survey showed much higher prevalence rates (6.4%) in both areas, although the criteria for ‘blindness’ differed.
Southern Sudan
Kalisom
I (1.0) 4 (3.8) IO (7.2) 0
1788
TEFERA TIZAZU Table 5. Distributton
Mvolo Moruco Mbtri Woko Nadjangere
F. M.
MBURU
of avotdable causes of vtsual loss by village in Western Equatoria. Southern Sudan No. wtth 6.61 or less (““J
Domen
and
8 (16.0) 13 (26.0) I2 (21.1) ,?“I, (440) IO (10.0)
No. wth ov
No. with other multiple cattses
‘a village with avoidable causes
14
3
34.0
63
8
56.8
9
6
26.3
2
8
11.8
0
2
2.0
0
I
1.0
found to relate to the occurrence of impaired vision. Most significant among these are climatic conditions that bring about either dry dusty conditions, or warm and damp environments. Water availability and pattern of use largely determine the status of personal hygiene. However, availability by itself is not a sufficient condition for improved personal hygiene. Cleanliness is culturally defined and developed. There are societies in Africa where washing of any part of the body is rare and when it occurs, it may not be adequate to keep the body or part of it. the eyes, for example, free from dirt and flies. The Turkana. the Pokot and the Masai of Kenya are examples where children are rarely encouraged to bathe. In Southern Sudan the Topoza, the Didinga, Lokoro, among others, may be cited for similar behaviour. Ecological factors determine the mode of living in many parts of Africa where people are unable to modify the environment. People have molded their pattern of living habits to suit the existing physical handicaps or advantages. Potentially, sociocultural and socioeconomic patterns may compromise health standards that are already low. Cattle herding is the dominant cultural and economic activity in the grasslands of sub-Saharan Africa. People move with rain and animal grazing patterns. Life is a constant struggle in search of grass for cattle, green bushes for sheep and goats. The success of the family can be judged largely by the size of the herd or the flock. Just as the domestic animals follow their feed, flies follow the animals. The greater the resources of one family, the more the animals and the more the flies. One does not have flies in the kraal or the manyatta unless there are animals. And so to have no flies-and almost inevitably trachoma-is to be poor and consequently to have relatively low social status in the community. Nomadic communities invariably appear to have low standards of domestic hygiene. The reasons are not always clear but it would appear that nomadism is inextricably related to some perceived temporary nature of the homestead and perhaps of life itself. Whether that is the case or not, personal hygiene and cleanliness do not appear to be priorities in some African societies. Admittedly, cleanliness is a subjective and culturally defined condition. But in this paper the term is used to include such aspects as washing of the hands, face and body and to keep
oneself or the family in a manner that does not encourage breeding of pests like lice, flies and fleas. Among the Lokoro tribe (Lafon Village, Torit District, Eastern Equatoria), there are no latrines, and bushes serve the purpose. For the Lokoro it is culturally unbecoming to defecate in the same place twice, but the space available to the clusters of villages with a population of nearly 25,000 people is severely limited. The Lokoro tribe lives on the slopes of sharp hills, and the villages are densely populated. Consequently, the surrounding environment is heavily contaminated with faeces washed down the valleys by the occasional rain. Water is obtained from bore holes, 60-7004 of which are out of use at any one time. Personal hygiene is extremely poor and exacerbated by poverty, flies and dirty environment. Trachoma is therefore highly prevalent, leading to unnecessary blindness. Broadly, disorders of the eye, like many other disorders, are due to a combination of ecological, biological and social factors and personal habits. Factors commonly known to be causes of blindness or loss of vision are the end results of a spectrum of enabling or underlying determinants. In an onchocerciasis area, for example, the breeding sites, distance from the river, and the number of bites by the flies all combine to determine the epidemiology of the disease. Like trachoma, onchocerciasis in Western Equatoria occurs only in some selected areas. Control measures, then, must ultimately touch on the factors that cause disease. Short of that, any action taken will largely be palliative and bound to have only a limited impact. Acknow/edRemenrs-Funding for data collection was provided by the Norwegian Council for the Prevention of Blindness. The kind assistance of MS Madle Brekke, R.N., is gratefully acknowledged. REFERENCES
I World Health Organization.
Methods of assessment of avoidable blindness. Draft Paper, Report of Task Force, San Francisco, PBL/AG/80.5, 1979. 2. Wld Hlth Org. Chron. 33, 275, 1979. 3. See also: Wilson Sir J. Prevention of blindness in Africa. Paper read at the International Agency for the Prevention of Blindness Meeting, 1980.