84 them warned that this would
happen and that the patadopted was unsatisfactory; a more cautious, experimental and piecemeal approach was felt to be desirable. Now we are faced with no development during 1976/77 and a possible reduction in expenditure of between 5 and 10% over 1977/79. Community medicine should bear its share of these cuts, but we must be quite certain that this share is a fair one in comparison with non-medical and non-nursing administrative staff whose numbers have increased by up to 30-40% in some cases. The risk of an excessive burden on community medicine follows from two important facts. Firstly, the total number of practitioners originally working in public health before 1974 was cut by a significant proportion during reorganisation, and is only now beginning slowly to recover as establishments expand. Secondly, the standstill in 1976/77 is based on staff in post in March, 1976, thereby excluding all vacant posts an important point in a specialty with approximately 20% of its estab-
than it has ever been, despite the widely spread responsibility for management in the more complex patterns of the new organisation.
lished posts vacant. All manpower forecasts must be integrated with economic objectives, particularly at the present time, and it would be unwise to attempt to expand community medicine at an unrealistic rate. However, the rate of increase must take full account of the numbers already partially trained and who wish to return to community medicine, in addition to a core of highly trained new recruits. The D.H.S.S. target of 30 new recruits per year to the registrar grade is equivalent to a rate of increase of 4% (taking Department of Health doctors into account), falling steadily to 3-5% per annum after 5 years and continuing to fall slightly thereafter. This rate of increase may be thought inadequate in view of the present number of vacancies, but it is unlikely that any higher rate could be sustained in view of lack of finance and of the recruitment possibilities. The morality of the action of Government in allowing administrative structures to build up and in recommending recruitment-rates comparable with those in clinical specialties, whilst being aware of the inevitable need eventually to make drastic cuts, must be questioned. But it may be appropriate under these circumstances, taking into account the nature of community medicine, to look carefully at the need for a permanent sub-specialist grade, possibly employed part-time. This would enable many people to contribute to the specialty who might not otherwise be in a position to do so. Many specialists have taken advantage of the opportunity to purchase "added years" and their early retirement could well make a considerable difference to the picture within the next few years. The importance of manpower planning in such a small specialty cannot be over-emphasised. There is, in addition, a need for counselling and advice at all stages in the careers of those who are in the training grades, which should be a specific responsibility of regional faculty advisers, but which cannot be ignored by any community physician. The people whom we should aim
CHOLERA TRANSMISSION NEAR A CHOLERA HOSPITAL
tern
have had an adequate training in the basic subjects of their specialty and the type of course offered must be no less rigorous or satisfying, in both content and presentation, than equivalent training programmes in clinical specialties. It is essential that the community physician of the future should be able to command the respect and confidence of all those with whom he or she will need to work; medical leadership in the provision of health care to populations is no less vital to attract must
We thank Dr R. A. Franklin and Dr A. G. Brown for advice and assistance in the preparation of this article. Requests for reprints should be addressed to P.J.H., Sheffield Area Health Authority (Teaching), Westbrook House, Sharrow Vale Road, Sheffield S 11 8EU. REFERENCES
1. 2.
Heath, P. J. Community Hlth, 1974, 5, 178. Report of the Royal Commission on Medical Education. H.M. Stationery Office, 1968. 3. Report of the Working Party on Transferred Medical Officers. British Medical Association, 1974. 4. Third Report of the Review Body on Doctors’ and Dentists’ Remuneration (First Supplement), H.M. Stationery Office, 1973.
Public Health
RICHARD J. LEVINE* STANISLAUS D’SOUZA
MOTIUR R. KHAN DAVID R. NALIN
Center for Disease Control, United States Public Health Service, Atlanta, Georgia, U.S.A., Epidemiology Division, Cholera Research Laboratory, Dacca, Bangladesh; Johns Hopkins University School of Hygiene, Department of Biostatistics, and Johns Hopkins University International Center for Medical Research, Dacca, Bangladesh, and Baltimore, Maryland 21205, U.S.A.
A review of the incidence of cholera from 1964 through 1974 in Matlab, Bangladesh, revealed that among the villages several had very high incidence-rates. Investigation indicated that high cholera-rates in two of these villages were probably related to water contamination from a nearby cholera hospital established in 1963. The data imply
Summary
heavy contamination can overcome resulting from repeated exposure.
that
any
immunity
INTRODUCTION
FIELD surveillance for cholera and collection of demographic data began in Matlab in late 1963 and a local cholera hospital, first on a canal-barge, then in a building, was established. Free ambulance boats were available day and night 1968-71 to bring patients to the hospital. area included 225 000 persons By 1968 the surveillance in 234 villages. 1-5 McCormack et al.’ reviewed data for 1964-1966 and found that most cases occurred during major winter and minor spring epidemics and were geographically widely scattered. He noted that the establishment of the vaccine trial area and hospital might alter natural cholera epidemiology. In the present study, the incidence of cholera over 11 years in Matlab was reviewed. While the overall pattern described earlier remained, several villages had consistently high incidence-rates. This report examines the hypothesis that high rates in two of the villages (8.6, 10-9 per 1000 annually) were related to contamination of canal water associated with the nearby cholera hospital. *Present address: Epidemiology Bureau, Center for Disease Control, Atlanta, Georgia 30333, U.S.A.
85
veyed from November, 1968, through February, 1971, the cholera hospitaC near the cholera hospital was 13-6 cases per 1000 persons per year compared with 3-9 for areas A, B, and D, and 2.0 for all 234 villages. The incidence-rate ratio of area C compared to areas A, B, and D was 4.0. Area C had the highest median hospital admission-rate of
lisation
rate
in
area
all village areas of similar size for the 5 epidemics surveyed. Equally striking was the high cholera reinfectionrate. Among reinfections from 56 villages between 1963 and 19699 the reinfection-rate for individuals from area C was more than 13 times as high as the rate for the other 54 villages (26.4 vs. 2.0 per 1000 person
Fig. 1-Map of study area.
METHODS
Cholera was diagnosed by rectal swab or faecal cultures6 from all patients who came to the hospital for treatment of diarrhaea (outpatients and cases admitted to hospital). The criterion for admission to the hospital was profuse diarrhoea leading to severe dehydration, usually with shock. During 1963-1969 inapparent infections and ambulatory cases were also detected by field surveys.’ Each family was visited at least twice weekly and rectal-swab stool cultures were obtained from persons with diarrhoea. During cholera vaccine trials daily rectal swabs were obtained for 4 days from’trial participants in families of persons with diarrhoea severe enough to limit normal activity. Demographic data were available from periodic censuses and from ongoing registration of vital events started in 1966. The two high-incidence villages were divided into four areas for the purpose of study (fig. 1): area A bordering a canal to the north; area B of similar size where homes did not adjoin a canal; area C demarcated from B by a road and situated along a canal whose currents flowed by the cholera hospital; and area D located on the same canal, but along a section where water did not pass the hospital. Records of diarrhoea! deaths for the two villages from 1944-1963 were examined to determine whether the high incidence of cholera antedated the establishment of the hospital. Although these records maintained by village headmen are undoubtedly incomplete, there is no reason to suspect bias in reporting vital events from different parts of the villages. In December, 1974, vibrio and coliform counts were performed on canal water from 17 sites, a sanitation survey was conducted, and water usage was determined by direct observation on 6 days and by questionary. RESULTS
High-incidence and average-incidence areas of the villages studied were almost the same distance from the hospital, and the ratio of mild to severely affected cases seeking medical attention was 1/3 in both areas. two
This suggests that admission-rates did not vary with distance from hospital. The high-incidence area (C; fig. 1) consisted of adjacent parts of the two villages. During 5 epidemics sur-
years). Comparison of annual mortality-rates 1944-1963 1963 population indicated
diarrhoea based on no excess
pre-hospital deaths in area C (see accompanying table), suggesting that the high rates developed after the hospital was established. Had severe cholera been as common before as after creation of the hospital, this should have been reflected in the rate of diarrhoea deaths for area C. During the period under study migrations into and out of the villages occurred with the net effect of Moslems replacing Hindus in some sections. Yet the population distribution among the four areas probably did not undergo major changes. In the first year of hospital operation cholera-rates in areas A, B, C, and D were similar and low. Afterwards area C’s rate increased in proportion to the overall number of cholera admissions; however, rates in areas A, B, and D, and in an adjacent village did not follow the graph of cholera admissions closely (fig. 2). Sanitation findings also suggested a relation between increased cholera and establishment of the hospital on the nearby canal (fig. 1). Patients brought by speedboat ambulance often defalcated near the landing, and faecally soiled boats were washed there. Patients’ relatives often infected themselves,10 used the canal bank for toilet, bathing, and washing contaminated clothes. The hospital sewage system was blocked; and leaking sewage drains and surface runways emptied untreated effluents from soakpits and sinks into the canal. The system was not sealed and could mix with monsoon flood waters. One of seventeen samples from seventeen canal sites yielded cholera vibrios. This site adjoined the hospital and had the highest coliform count (3000/ml; other sites 30 to 1000/ml). Most cholera patients from area C lived along the canal where water containing hospital effluents could reach (fig. 1). The area distant to the stagnant zone, DIARRHOEA DEATH-RATES (1944-1963) BEFORE ESTABLISHMENT OF THE HOSPITAL
86 The fact that cases of non-cholera diarrhoeas did not cluster around the canal suggests that water may not be important in their transmission. However, these noncholera diarrhoeas have multiple aetiologies, and patterns of spread may differ, so no firm conclusion can be drawn. This is the first report of cholera ascribed to contamination from a hospital. The benefit of the hospital to the community in terms of lives saved greatly outweighs the few extra cases in the hospital vicinity. Nevertheless, the data indicate the need for a simple inexpensive method of sterilising vast quantities of diarrhoea fluid in an area with a high water table and seasonal flooding.
Fig.
2-Annual
hospital cholera admissions
and rates of cholera.
where tidal currents from the 2 river inlets cancelled each other, was fed from a separate inlet and had a strikingly lower incidence-rate. During the 11 years, 1964-1974, cholera incidencerates in the village north of the canal were 13.6, 8.7, and 3-3/1000 per year, respectively, for families reporting use of canal water, reporting no use but living nearby (C, fig. 1), and reporting no use but living farther away (B, A, fig. 1). Differences between first and last were groups highly significant (p 1-tailed =0.0000001 with rate ratio 4-1and 90% confidence limits for rate ratio of 2-6 and 6-3). Hospital cases of non-cholera diarrhoea (3’3/10000/year, diverse actiologies) did not cluster near the canal. From 1964 through 1973, 6927 severely ill cholera patients were admitted to the hospital. According to previous mortality reports," approximately 60% would have died without treatment. Fluid and electrolyte replacement reduced mortality of hospital patients to only 0-6%. With a risk ratio 4-0 it can be estimated that during the same period an excess of 71 cholera cases from area C (or about 1% of the total) were admitted to
We thank the staff of the Cholera Research Laboratory for expert technical assistance and P. Brachman, R. Cash, A. Choudhury, W. Greenough, A. Langmuir, K. Monsur, and K. Rothman for valuable suggestions; and Dr Eugene Gangarosa for advice and encouragement in the preparation of the manuscript. This study was funded by N.I.H. research agreement R07AI10048-15 with the Johns Hopkins Center for Medical Research and by the Cholera Research Laboratory, an autonomous organisation supported by the Governments of the People’s Republic of Bangladesh, U.S.A., U.K., and Australia.
Requests for reprints should be addressed to R. J. L. REFERENCES 1.
W.
McCormack, W., Mosley, H., Fahimuddin, M., Benenson, A. S. Am. J. Epidem. 1969, 89, 393. 2. Oseasohn, R. O., Benenson, A. S., Fahimuddin, M. Lancet, 1965, i, 450. 3. Benenson, A. S., Mosley, W. H., Fahimuddin, M., Oseasohn, R. O. Bull. Wld Hlth Org. 1968, 38, 359. 4. Mosley, W. H., McCormack, W. M., Fahimuddin, M., Aziz, K. M. A., Rahman, A. S. M. M., Chowdhury, A. K. M. A., Martin, A. R., Feeley, J. C., Phillips, R. A. ibid. 1969, 40, 177. 5. Mosley, W. H., Woodward, W. E., Aziz, K. M. A., Rahman, A. S. M. M., Chowdhury, A. K. M. A., Ahmed, A., Feeley, J. C. J. infect. Dis. 1970, 121, suppl., 1. 6. Woodward, W. E., Mosley, W. H., McCormack, W. M. ibid. 1970, 121, suppl., 10. 7. District Commissioner’s Record Room, Comilla, Bangladesh. 8. Miettinen, O. S. J. Am. stat. Ass. 1974, 69, 380. 9. Woodward, W. E. J. infect. Dis. 1971, 123, 61. 10. Oseasohn, R. O., Ahmad, S., Islam, M. A., Rahman, A. S. M. M. Lancet, 1966, i, 340. 11. Pollitzer, R. Monograph Ser. W.H.O. 1959, no. 43. 12. Khan, M., Mosley, W. H. E. Pak. med. J. 1967, 11, 61.
hospital. DISCUSSION
The association of high incidence-rate with canalwater usage and the decline in rate with distance from the canal indicate that canal water was probably the vehicle of transmission of cholera. The combined data on incidence-rates, reinfection, mortality from diarrhoea and sanitation, and water flow suggest that hospital-related contamination of the canal accounts for the high cholera-rate in area C. The increased rate among those living near the canal but reporting no canal-water usage may be due to contamination of alternative water sources by infected persons using the canal or through monsoon connections to the canal. Although the canal is contaminated by boatmen,12 bazaar visitors, and others, the hospital is the most likely regular source of heavy vibrio contamination. Other canals within the surveillance area of 234 villages, including the canal bordering area A, are contaminated by boatman and bazaar visitors. But these have not resulted in unusual aggregations of cholera cases. The high reinfection-rate in area C indicates that heavy contamination of canal water can overcome any immunity resulting from repeated exposure.
FAILURE OF SANITARY WELLS TO PROTECT AGAINST CHOLERA AND OTHER DIARRHŒAS IN BANGLADESH
RICHARD J. LEVINE* STANISLAUS D’SOUZA
MOTIUR R. KHAN DAVID R. NALIN
Center for Disease Control, United States Public Health Service, Atlanta, Georgia, U.S.A., Epidemiology Division, Cholera Research Laboratory, Dacca, Bangladesh; Johns
Hopkins University School of Hygiene, Department of Biostatistics, and Johns Hopkins University International Center for Medical Research, Dacca, Bangladesh, and Baltimore, Maryland 21205, U.S.A. Within an area of Bangladesh in which the incidence of cholera was high, use of sanitary pipe wells did not protect against cholera or related non-cholera diarrhœas because well users also used contaminated water sources regularly enough to maintain high infection-rates. Protection was found to correlate with education and wealth.
Summary
*Present address: Epidemiology Bureau, Center for Disease Georgia 30333, U.S.A.
Control, Atlanta,
happen and that the patadopted was unsatisfactory; a more cautious, experimental and piecemeal approach was felt to be desirable. Now we are faced with no development during 1976/77 and a possible reduction in expenditure of between 5 and 10% over 1977/79. Community medicine should bear its share of these cuts, but we must be quite certain that this share is a fair one in comparison with non-medical and non-nursing administrative staff whose numbers have increased by up to 30-40% in some cases. The risk of an excessive burden on community medicine follows from two important facts. Firstly, the total number of practitioners originally working in public health before 1974 was cut by a significant proportion during reorganisation, and is only now beginning slowly to recover as establishments expand. Secondly, the standstill in 1976/77 is based on staff in post in March, 1976, thereby excluding all vacant posts an important point in a specialty with approximately 20% of its estab-
than it has ever been, despite the widely spread responsibility for management in the more complex patterns of the new organisation.
lished posts vacant. All manpower forecasts must be integrated with economic objectives, particularly at the present time, and it would be unwise to attempt to expand community medicine at an unrealistic rate. However, the rate of increase must take full account of the numbers already partially trained and who wish to return to community medicine, in addition to a core of highly trained new recruits. The D.H.S.S. target of 30 new recruits per year to the registrar grade is equivalent to a rate of increase of 4% (taking Department of Health doctors into account), falling steadily to 3-5% per annum after 5 years and continuing to fall slightly thereafter. This rate of increase may be thought inadequate in view of the present number of vacancies, but it is unlikely that any higher rate could be sustained in view of lack of finance and of the recruitment possibilities. The morality of the action of Government in allowing administrative structures to build up and in recommending recruitment-rates comparable with those in clinical specialties, whilst being aware of the inevitable need eventually to make drastic cuts, must be questioned. But it may be appropriate under these circumstances, taking into account the nature of community medicine, to look carefully at the need for a permanent sub-specialist grade, possibly employed part-time. This would enable many people to contribute to the specialty who might not otherwise be in a position to do so. Many specialists have taken advantage of the opportunity to purchase "added years" and their early retirement could well make a considerable difference to the picture within the next few years. The importance of manpower planning in such a small specialty cannot be over-emphasised. There is, in addition, a need for counselling and advice at all stages in the careers of those who are in the training grades, which should be a specific responsibility of regional faculty advisers, but which cannot be ignored by any community physician. The people whom we should aim
CHOLERA TRANSMISSION NEAR A CHOLERA HOSPITAL
tern
have had an adequate training in the basic subjects of their specialty and the type of course offered must be no less rigorous or satisfying, in both content and presentation, than equivalent training programmes in clinical specialties. It is essential that the community physician of the future should be able to command the respect and confidence of all those with whom he or she will need to work; medical leadership in the provision of health care to populations is no less vital to attract must
We thank Dr R. A. Franklin and Dr A. G. Brown for advice and assistance in the preparation of this article. Requests for reprints should be addressed to P.J.H., Sheffield Area Health Authority (Teaching), Westbrook House, Sharrow Vale Road, Sheffield S 11 8EU. REFERENCES
1. 2.
Heath, P. J. Community Hlth, 1974, 5, 178. Report of the Royal Commission on Medical Education. H.M. Stationery Office, 1968. 3. Report of the Working Party on Transferred Medical Officers. British Medical Association, 1974. 4. Third Report of the Review Body on Doctors’ and Dentists’ Remuneration (First Supplement), H.M. Stationery Office, 1973.
Public Health
RICHARD J. LEVINE* STANISLAUS D’SOUZA
MOTIUR R. KHAN DAVID R. NALIN
Center for Disease Control, United States Public Health Service, Atlanta, Georgia, U.S.A., Epidemiology Division, Cholera Research Laboratory, Dacca, Bangladesh; Johns Hopkins University School of Hygiene, Department of Biostatistics, and Johns Hopkins University International Center for Medical Research, Dacca, Bangladesh, and Baltimore, Maryland 21205, U.S.A.
A review of the incidence of cholera from 1964 through 1974 in Matlab, Bangladesh, revealed that among the villages several had very high incidence-rates. Investigation indicated that high cholera-rates in two of these villages were probably related to water contamination from a nearby cholera hospital established in 1963. The data imply
Summary
heavy contamination can overcome resulting from repeated exposure.
that
any
immunity
INTRODUCTION
FIELD surveillance for cholera and collection of demographic data began in Matlab in late 1963 and a local cholera hospital, first on a canal-barge, then in a building, was established. Free ambulance boats were available day and night 1968-71 to bring patients to the hospital. area included 225 000 persons By 1968 the surveillance in 234 villages. 1-5 McCormack et al.’ reviewed data for 1964-1966 and found that most cases occurred during major winter and minor spring epidemics and were geographically widely scattered. He noted that the establishment of the vaccine trial area and hospital might alter natural cholera epidemiology. In the present study, the incidence of cholera over 11 years in Matlab was reviewed. While the overall pattern described earlier remained, several villages had consistently high incidence-rates. This report examines the hypothesis that high rates in two of the villages (8.6, 10-9 per 1000 annually) were related to contamination of canal water associated with the nearby cholera hospital. *Present address: Epidemiology Bureau, Center for Disease Control, Atlanta, Georgia 30333, U.S.A.
85
veyed from November, 1968, through February, 1971, the cholera hospitaC near the cholera hospital was 13-6 cases per 1000 persons per year compared with 3-9 for areas A, B, and D, and 2.0 for all 234 villages. The incidence-rate ratio of area C compared to areas A, B, and D was 4.0. Area C had the highest median hospital admission-rate of
lisation
rate
in
area
all village areas of similar size for the 5 epidemics surveyed. Equally striking was the high cholera reinfectionrate. Among reinfections from 56 villages between 1963 and 19699 the reinfection-rate for individuals from area C was more than 13 times as high as the rate for the other 54 villages (26.4 vs. 2.0 per 1000 person
Fig. 1-Map of study area.
METHODS
Cholera was diagnosed by rectal swab or faecal cultures6 from all patients who came to the hospital for treatment of diarrhaea (outpatients and cases admitted to hospital). The criterion for admission to the hospital was profuse diarrhoea leading to severe dehydration, usually with shock. During 1963-1969 inapparent infections and ambulatory cases were also detected by field surveys.’ Each family was visited at least twice weekly and rectal-swab stool cultures were obtained from persons with diarrhoea. During cholera vaccine trials daily rectal swabs were obtained for 4 days from’trial participants in families of persons with diarrhoea severe enough to limit normal activity. Demographic data were available from periodic censuses and from ongoing registration of vital events started in 1966. The two high-incidence villages were divided into four areas for the purpose of study (fig. 1): area A bordering a canal to the north; area B of similar size where homes did not adjoin a canal; area C demarcated from B by a road and situated along a canal whose currents flowed by the cholera hospital; and area D located on the same canal, but along a section where water did not pass the hospital. Records of diarrhoea! deaths for the two villages from 1944-1963 were examined to determine whether the high incidence of cholera antedated the establishment of the hospital. Although these records maintained by village headmen are undoubtedly incomplete, there is no reason to suspect bias in reporting vital events from different parts of the villages. In December, 1974, vibrio and coliform counts were performed on canal water from 17 sites, a sanitation survey was conducted, and water usage was determined by direct observation on 6 days and by questionary. RESULTS
High-incidence and average-incidence areas of the villages studied were almost the same distance from the hospital, and the ratio of mild to severely affected cases seeking medical attention was 1/3 in both areas. two
This suggests that admission-rates did not vary with distance from hospital. The high-incidence area (C; fig. 1) consisted of adjacent parts of the two villages. During 5 epidemics sur-
years). Comparison of annual mortality-rates 1944-1963 1963 population indicated
diarrhoea based on no excess
pre-hospital deaths in area C (see accompanying table), suggesting that the high rates developed after the hospital was established. Had severe cholera been as common before as after creation of the hospital, this should have been reflected in the rate of diarrhoea deaths for area C. During the period under study migrations into and out of the villages occurred with the net effect of Moslems replacing Hindus in some sections. Yet the population distribution among the four areas probably did not undergo major changes. In the first year of hospital operation cholera-rates in areas A, B, C, and D were similar and low. Afterwards area C’s rate increased in proportion to the overall number of cholera admissions; however, rates in areas A, B, and D, and in an adjacent village did not follow the graph of cholera admissions closely (fig. 2). Sanitation findings also suggested a relation between increased cholera and establishment of the hospital on the nearby canal (fig. 1). Patients brought by speedboat ambulance often defalcated near the landing, and faecally soiled boats were washed there. Patients’ relatives often infected themselves,10 used the canal bank for toilet, bathing, and washing contaminated clothes. The hospital sewage system was blocked; and leaking sewage drains and surface runways emptied untreated effluents from soakpits and sinks into the canal. The system was not sealed and could mix with monsoon flood waters. One of seventeen samples from seventeen canal sites yielded cholera vibrios. This site adjoined the hospital and had the highest coliform count (3000/ml; other sites 30 to 1000/ml). Most cholera patients from area C lived along the canal where water containing hospital effluents could reach (fig. 1). The area distant to the stagnant zone, DIARRHOEA DEATH-RATES (1944-1963) BEFORE ESTABLISHMENT OF THE HOSPITAL
86 The fact that cases of non-cholera diarrhoeas did not cluster around the canal suggests that water may not be important in their transmission. However, these noncholera diarrhoeas have multiple aetiologies, and patterns of spread may differ, so no firm conclusion can be drawn. This is the first report of cholera ascribed to contamination from a hospital. The benefit of the hospital to the community in terms of lives saved greatly outweighs the few extra cases in the hospital vicinity. Nevertheless, the data indicate the need for a simple inexpensive method of sterilising vast quantities of diarrhoea fluid in an area with a high water table and seasonal flooding.
Fig.
2-Annual
hospital cholera admissions
and rates of cholera.
where tidal currents from the 2 river inlets cancelled each other, was fed from a separate inlet and had a strikingly lower incidence-rate. During the 11 years, 1964-1974, cholera incidencerates in the village north of the canal were 13.6, 8.7, and 3-3/1000 per year, respectively, for families reporting use of canal water, reporting no use but living nearby (C, fig. 1), and reporting no use but living farther away (B, A, fig. 1). Differences between first and last were groups highly significant (p 1-tailed =0.0000001 with rate ratio 4-1and 90% confidence limits for rate ratio of 2-6 and 6-3). Hospital cases of non-cholera diarrhoea (3’3/10000/year, diverse actiologies) did not cluster near the canal. From 1964 through 1973, 6927 severely ill cholera patients were admitted to the hospital. According to previous mortality reports," approximately 60% would have died without treatment. Fluid and electrolyte replacement reduced mortality of hospital patients to only 0-6%. With a risk ratio 4-0 it can be estimated that during the same period an excess of 71 cholera cases from area C (or about 1% of the total) were admitted to
We thank the staff of the Cholera Research Laboratory for expert technical assistance and P. Brachman, R. Cash, A. Choudhury, W. Greenough, A. Langmuir, K. Monsur, and K. Rothman for valuable suggestions; and Dr Eugene Gangarosa for advice and encouragement in the preparation of the manuscript. This study was funded by N.I.H. research agreement R07AI10048-15 with the Johns Hopkins Center for Medical Research and by the Cholera Research Laboratory, an autonomous organisation supported by the Governments of the People’s Republic of Bangladesh, U.S.A., U.K., and Australia.
Requests for reprints should be addressed to R. J. L. REFERENCES 1.
W.
McCormack, W., Mosley, H., Fahimuddin, M., Benenson, A. S. Am. J. Epidem. 1969, 89, 393. 2. Oseasohn, R. O., Benenson, A. S., Fahimuddin, M. Lancet, 1965, i, 450. 3. Benenson, A. S., Mosley, W. H., Fahimuddin, M., Oseasohn, R. O. Bull. Wld Hlth Org. 1968, 38, 359. 4. Mosley, W. H., McCormack, W. M., Fahimuddin, M., Aziz, K. M. A., Rahman, A. S. M. M., Chowdhury, A. K. M. A., Martin, A. R., Feeley, J. C., Phillips, R. A. ibid. 1969, 40, 177. 5. Mosley, W. H., Woodward, W. E., Aziz, K. M. A., Rahman, A. S. M. M., Chowdhury, A. K. M. A., Ahmed, A., Feeley, J. C. J. infect. Dis. 1970, 121, suppl., 1. 6. Woodward, W. E., Mosley, W. H., McCormack, W. M. ibid. 1970, 121, suppl., 10. 7. District Commissioner’s Record Room, Comilla, Bangladesh. 8. Miettinen, O. S. J. Am. stat. Ass. 1974, 69, 380. 9. Woodward, W. E. J. infect. Dis. 1971, 123, 61. 10. Oseasohn, R. O., Ahmad, S., Islam, M. A., Rahman, A. S. M. M. Lancet, 1966, i, 340. 11. Pollitzer, R. Monograph Ser. W.H.O. 1959, no. 43. 12. Khan, M., Mosley, W. H. E. Pak. med. J. 1967, 11, 61.
hospital. DISCUSSION
The association of high incidence-rate with canalwater usage and the decline in rate with distance from the canal indicate that canal water was probably the vehicle of transmission of cholera. The combined data on incidence-rates, reinfection, mortality from diarrhoea and sanitation, and water flow suggest that hospital-related contamination of the canal accounts for the high cholera-rate in area C. The increased rate among those living near the canal but reporting no canal-water usage may be due to contamination of alternative water sources by infected persons using the canal or through monsoon connections to the canal. Although the canal is contaminated by boatmen,12 bazaar visitors, and others, the hospital is the most likely regular source of heavy vibrio contamination. Other canals within the surveillance area of 234 villages, including the canal bordering area A, are contaminated by boatman and bazaar visitors. But these have not resulted in unusual aggregations of cholera cases. The high reinfection-rate in area C indicates that heavy contamination of canal water can overcome any immunity resulting from repeated exposure.
FAILURE OF SANITARY WELLS TO PROTECT AGAINST CHOLERA AND OTHER DIARRHŒAS IN BANGLADESH
RICHARD J. LEVINE* STANISLAUS D’SOUZA
MOTIUR R. KHAN DAVID R. NALIN
Center for Disease Control, United States Public Health Service, Atlanta, Georgia, U.S.A., Epidemiology Division, Cholera Research Laboratory, Dacca, Bangladesh; Johns
Hopkins University School of Hygiene, Department of Biostatistics, and Johns Hopkins University International Center for Medical Research, Dacca, Bangladesh, and Baltimore, Maryland 21205, U.S.A. Within an area of Bangladesh in which the incidence of cholera was high, use of sanitary pipe wells did not protect against cholera or related non-cholera diarrhœas because well users also used contaminated water sources regularly enough to maintain high infection-rates. Protection was found to correlate with education and wealth.
Summary
*Present address: Epidemiology Bureau, Center for Disease Georgia 30333, U.S.A.
Control, Atlanta,
