Journal of Infection (1992) 25, 133-137
Neonatal tetanus estimates of mortality derived from a c l u s t e r s u r v e y in N o r t h e r n N i g e r i a Charles Osayande Eregie
Department of Paediatrics, Specialist Hospital Yola, Adamawa State, Nigeria Accepted for publication 27 November I 9 9 I Summary A two-stage cluster survey of deaths from neonatal tetanus (NNT) was carried out in Kano metropolis, Northern Nigeria in order to estimate the mortality from the disease. Estimates of mortality were obtained by three different methods which were compared. According to clinical diagnosis, mortality was 2o'6/lOOO live-births while reports of 4-14 day deaths gave a figure of 11"4/1OOOlive-births. From information volunteered by informants, it appeared to be only 4"6/lOOO live-births. N N T accounted for 68 % neonatal deaths. The sex-specific mortality rates were 23"4 and 17'9 per IOOO live-births for males and females respectively. There was, however, no significant association between sex and death from neonatal tetanus. The mortality for the first 6 months of recall period was I5"2/IOOO live-births and 24"2/iooo live-births for the last 6 months. There was also no significant association between recall period and death. In view of the markedly different estimates by the various methods of diagnosis, retrospective clinical diagnosis is suggested for community-based surveys of mortality related to neonatal tetanus.
Introduction M o r t a l i t y related to neonatal tetanus remains alarmingly high in m o s t developing countries. 14 T h e disease has a case-fatality rate ranging from 4 o - 9 o %.~-7 It has virtually been eliminated from developed countries which have i m p l e m e n t e d prevention strategies for the disease. 8 A n i m p o r t a n t c o m p o n e n t of these strategies is the determination of mortality in a defined c o m m u n i t y t h r o u g h c o m m u n i t y - b a s e d surveys. 9 Estimates o f mortality from hospital-based data and routine reporting systems have s h o w n that neonatal tetanus is largely u n d e r - r e p o r t e d . 3,4,1° M o s t series 1'11-17 from Nigeria are hospital-based with only one report from a cluster survey. Since the mortality varies f r o m c o u n t r y to c o u n t r y and from region to region within the same countryfl this survey was u n d e r t a k e n in K a n o metropolis, N o r t h e r n Nigeria, in order to estimate the mortality of neonatal tetanus as a c o n t r i b u t o r y step towards preventing the disease and as a baseline for future assessments of prevention strategies.
Materials and methods T h e s t u d y was c o n d u c t e d in July I99O in K a n o metropolis, N o r t h e r n Nigeria, after initial orientation and training for personnel. T h e survey lasted 2 weeks with 15 teams of interviewers participating. A supervisor was attached to two teams and a Medical Officer to three. o163-4453/92/o5o133 +05 $08.00/0
© I992 The British Society for the Study of Infection
134
c . o . EREGIE
Table I Estimates of the mortality of neonatal tetanus by three different methods of ascertainment among 79 neonatal deaths Method (i) (ii) (iii)
No. Clinical features 4-14 day death Cause of death according to informant
54* 3or I2~
Mortality per IO00 live-births 20"6 I I'4 4"6
* Of the 54 deaths; 22 were diagnosed by (ii), seven were diagnosed by (iii), only five were diagnosed by (i), (ii) and (iii). -~ Of the 30 deaths; 22 were diagnosed by (i), seven were diagnosed by (iii), only five were diagnosed by (i), (ii) and (iii). :~ Of the I2 deaths; seven were diagnosed by (i), seven were diagnosed by (ii), only five were diagnosed by (i), (ii) and (iii). For 54 deaths due to neonatal tetanus, proportion of neonatal mortality -- 68"4 %.
A two-stage cluster sampling m e t h o d for evaluating vaccination coverage in the W H O Expanded P r o g r a m m e on Immunisation. TM was employed. T h i r t y clusters were randomly selected with a sampling frame and population size c o m p u t e d as previously described. 18 T h e population evaluated included all mothers in the selected 3o clusters who were delivered of live babies in the last I - I 3 m o n t h s preceding the start of the survey (i.e. 9 June I989 to 8 June I99o). At least 87 live-births were recorded per cluster with a projected sample size of 26Io. T h e mothers (or nearest relatives) in each household were interviewed and relevant data recorded on proformae for identifying live-births. For each neonatal death recorded, a more detailed evaluation was undertaken by a Medical Officer using a different proforma so as to establish deaths which might have been due to neonatal tetanus. T h r e e different estimates of mortality were obtained and compared by means of three different methods of ascertaining deaths. T h e methods were (i) death recorded as taking place at 4 - I 4 days of life/(ii) cause of death volunteered by an informant and (iii) ascertained clinical features including sucking and crying normally during first 2 days of life with onset of illness between the 3rd and 28th days; inability to suck at onset followed by stiffness a n d / o r spasms and death. Estimates of mortality by sex and period of recall were also evaluated. Results
A total of 2623 live-births was recorded in 3o clusters over the 12-month period. T h e y included Iz83 males and x34o females. T h e r e were 79 neonatal deaths with a neonatal mortality rate of 3 o ' I / I o o o live-births. Table I shows the different estimates by the three methods of ascertainment. T h e mortality was z o . 6 / I o o o live-births for clinical diagnosis. According to 4-14 day deaths, the mortality was I I - 4 / I o o o live births and 4"6/Iooo livebirths when cause of death volunteered by an informat was used. T h e estimate by Clinical diagnosis was used for further analysis. T h u s , neonatal tetanus accounted for 68"4 % neonatal mortality.
Neonatal tetanus in Nigeria
135
Table II Distribution of 79 neonatal deaths by sex and cause of death D e a t h s due to neonatal tetanus
D e a t h s n o t due to neonatal tetanus
Total
Male Female
30 24
12 13
42 37
Total
54
25
79
Sex
X2, o"391 ; d f I ; P > 0"05.
Table I I I D~tributionof79 neonatal deathsbyperiodofrecaH and cause ofdeath P e r i o d o f recall (months)
D e a t h s d u e to neonatal tetanus
D e a t h s n o t due to neonatal tetanus
Total
1-7 8-13
38 16
21 4
59 20
Total
54
25
79
X2, 1"681; d f I ; P > 0"05 . T o t a l live-births by recall p e r i o d : 1-7 m o n t h s = 1573, 8-13 m o n t h s = lO5O.
Table II shows distribution ofneonatal deaths by sex and cause of death. T h e sex-specific mortality rates were 23"4 and z7"9 per zooo live-births for males and females respectively. T h e r e was no significant association between sex and death (P > o'o5). Table I I I illustrates the distribution of neonatal deaths by period of recall and cause of death. T h e mortality rate for the first 6 months of the recall period was I5-2/zooo live-births and 24"2/zooo live-births for the last 6 months. T h e association between recall period and death from neonatal tetanus was not significant. Discussion
T h e estimates of mortality by the three methods of ascertainment were strikingly different. T h e very low estimate according to cause of death volunteered by an informant may be a reflection of the low level of awareness of the existence and recognition of the disease in the population. This implies a need for health education of the populace. On the other hand, willingness to recall, accuracy and reliability of recall of dates of death probably accounted for the relatively low estimate of I I'4/IOOO live-births when 4 - I 4 day deaths were used. While there is an association between deaths from neonatal tetanus and total 4-14 day deaths, 4 this method of ascertainment is likely to yield falsely low estimates in community-based surveys. We therefore, suggest that reliable estimates of mortality from cluster surveys be based on widely accepted clinical features for retrospective diagnosis of possible death from neonatal tetanus.
136
c . o . EREGIE
T h e mortality o f 20-6/I000 live-births reported f r o m this survey in K a n o metropolis is very high. T h i s m a y be due to lack o f use o f health services in the population. T h e survey in Ilorin, Nigeria, reported a rate of I I.9/IOOO livebirths. 17 T h e s e regions differ m a r k e d l y in their location, climate, cultural and agricultural activities. I n d e e d , such a difference in mortality within the same c o u n t r y is well recognised, s H i g h mortality has also been reported f r o m other developing countries. 1-4 According to this study, deaths f r o m neonatal tetanus accounted for 68 % total neonatal deaths. T h i s agrees with most surveys which report a range of 2 o - 7 2 % . 2-4'9 Well-designed strategies to control neonatal tetanus will, therefore, significantly reduce total neonatal mortality in most developing countries. A l t h o u g h the sex-specific mortality rate for neonatal tetanus was higher for males, there was no significant association between sex and death f r o m neonatal tetanus. T h e r e is no agreement on the sex p r e p o n d e r a n c e reported from m o s t studies ~s-23 and these were largely n o t analysed for significance. M o r t a l i t y o f neonatal tetanus was m u c h higher for the last 6 m o n t h s of the recall period. T h i s t r e n d was also observed for total neonatal mortality and mortality f r o m diseases other than neonatal tetanus and was, therefore, n o t significant. T h i s m a y be a f u n c t i o n o f more accurate and reliable recall of recent events. T h e observation o f increased mortality f r o m neonatal tetanus with decreasing recall period and with the latter 6 m o n t h s has been r e p o r t e d previously f r o m a survey. 24 T h i s report illustrates the m a g n i t u d e o f the mortality of neonatal tetanus in a Nigerian population. Clinical features for ascertaining deaths f r o m neonatal tetanus should be e m p l o y e d for cluster surveys of mortality f r o m this disease. N o significant association between the mortality rate and sex and the period of recall was recorded in this study. (This report is part of a study wholly supported by a Nigeria CCCD Operational Research Grant. I thank Dr Gabriel Ofovwe for his assistance. The efforts of the personnel who participated in the field work are much appreciated. The secretarial assistance of Mr Dimas Daniel is acknowledged with thanks.)
References
I. Tompkins AB. Neonatal tetanus in Nigeria. B Med J I958; I: r382-I385. 2. Berggren WL, Berggren GM. Changing incidence of fatal tetanus of the newborn: a retrospective study in a defined rural Haitian population. Am J Trop Med Hyg I97I ; 2o: 491-494. 3. Basu RN, Sokhey J. Special combined survey for poliomyelitis and neonatal tetanus as supplement to routine surveillance system in India. ff Comp Dis I984; x6: I48-I53. 4- Melgaard B, Mutie DM, Kimani G. A cluster survey of mortality due to neonatal tetanus in Kenya. I n t J Epidemiol I988; I7: I74-I77. 5. Bytchenko B. Geographical distribution of tetanus in the World, x95 r - 60: a review of the problem. Bull WHO I966; 34: 7I-ro4. 6. Blankson JM. Problems of neonatal tetanus as seen in Ghana. Afr ff Med Sci 1977; 6: I-6. 7. Gupta A, Chopra K, Khalil A. Tetanus neonatorum. Ind Pediatr J I977; x4: 2II-213. 8. Hinman AR, Foster SO, Wasailak SGF. Neonatal tetanus: potential for elimination in the world. Pediatr Infect Dis ff I987; 6: 813-816.
Neonatal tetanus in Nigeria
I37
9. World Health Organisation. Prevention of neonatal tetanus. Wkly Epidem Rec I982; 57: 137-144. IO. Stanfield JP, Galazka A. Neonatal t e t a n u s - an under-reported scourge. World Health Forum I985; 6:127-129. I I . Ogbeide M I . Problems of neonatal tetanus in Lagos. J Trop Pediatr I966; xz: 71-79. I2. Daramola T. Tetanus in Lagos. IV Aft MedJ 1968; 17: r36-I38. r3. Idoko A. Neonatal tetanus in Benue Plateau State of Nigeria. Nig J Paediatr 1975; 2: 47-50. 14. Effiong CE. Neonatal morbidity and mortality in Ibadan: a review of cases seen in the outpatient clinics. J Trop Pediatr 1976; zz: 265-267. I5. Elenwune VO. Childhood tetanus with particular reference to Nigeria. Ann Trop Pediatr
I982; 2: I89-I93. I6. Osuhor PC. Neonatal tetanus in Zaria, Northern Nigeria. Ind.7 Public Health I983; z7: 32-37. 17. Babaniyi OA, Parakoyi BD. Mortality from neonatal tetanus in Ilorin: results of a community-based survey. J Trop Pediatr 1989; 35: r37-r38. 18. Henderson RH, Sundareson T. Cluster sampling to assess immunization coverage: a review of experience with a simplified sampling method. Bull WHO I982; 6o: 253-26o. 19. Standfield JP, Galazka A. Neonatal tetanus in the world today. Bull WHO I984; 6z: 647-669. 2o. Galazka A. Control of neonatal tetanus. Ind ff Pediatr 1985; 5z: 329-341. 2I. Maternal and Child Health (MCH). Control of neonatal tetanus, China. Ivkly Epidem Rec
I985~ 61): 5--6. 22. Expanded Programme on Immunisation. Neonatal tetanus mortality survey, Ivory Coast. Ivkly Epidem Rec I983; 58: 71-72. 23. Expanded Porgramme on Immunisation. Neonatal tetanus mortality surveys, Kenya. IVkly Epidem Rec I986; 6 I : II7--II8. 24. Expanded Programme on Immunisation. Neonatal tetanus mortality survey, Malawi. IVkly Epidem Rec I983; 58: 326-327.
Neonatal tetanus estimates of mortality derived from a c l u s t e r s u r v e y in N o r t h e r n N i g e r i a Charles Osayande Eregie
Department of Paediatrics, Specialist Hospital Yola, Adamawa State, Nigeria Accepted for publication 27 November I 9 9 I Summary A two-stage cluster survey of deaths from neonatal tetanus (NNT) was carried out in Kano metropolis, Northern Nigeria in order to estimate the mortality from the disease. Estimates of mortality were obtained by three different methods which were compared. According to clinical diagnosis, mortality was 2o'6/lOOO live-births while reports of 4-14 day deaths gave a figure of 11"4/1OOOlive-births. From information volunteered by informants, it appeared to be only 4"6/lOOO live-births. N N T accounted for 68 % neonatal deaths. The sex-specific mortality rates were 23"4 and 17'9 per IOOO live-births for males and females respectively. There was, however, no significant association between sex and death from neonatal tetanus. The mortality for the first 6 months of recall period was I5"2/IOOO live-births and 24"2/iooo live-births for the last 6 months. There was also no significant association between recall period and death. In view of the markedly different estimates by the various methods of diagnosis, retrospective clinical diagnosis is suggested for community-based surveys of mortality related to neonatal tetanus.
Introduction M o r t a l i t y related to neonatal tetanus remains alarmingly high in m o s t developing countries. 14 T h e disease has a case-fatality rate ranging from 4 o - 9 o %.~-7 It has virtually been eliminated from developed countries which have i m p l e m e n t e d prevention strategies for the disease. 8 A n i m p o r t a n t c o m p o n e n t of these strategies is the determination of mortality in a defined c o m m u n i t y t h r o u g h c o m m u n i t y - b a s e d surveys. 9 Estimates o f mortality from hospital-based data and routine reporting systems have s h o w n that neonatal tetanus is largely u n d e r - r e p o r t e d . 3,4,1° M o s t series 1'11-17 from Nigeria are hospital-based with only one report from a cluster survey. Since the mortality varies f r o m c o u n t r y to c o u n t r y and from region to region within the same countryfl this survey was u n d e r t a k e n in K a n o metropolis, N o r t h e r n Nigeria, in order to estimate the mortality of neonatal tetanus as a c o n t r i b u t o r y step towards preventing the disease and as a baseline for future assessments of prevention strategies.
Materials and methods T h e s t u d y was c o n d u c t e d in July I99O in K a n o metropolis, N o r t h e r n Nigeria, after initial orientation and training for personnel. T h e survey lasted 2 weeks with 15 teams of interviewers participating. A supervisor was attached to two teams and a Medical Officer to three. o163-4453/92/o5o133 +05 $08.00/0
© I992 The British Society for the Study of Infection
134
c . o . EREGIE
Table I Estimates of the mortality of neonatal tetanus by three different methods of ascertainment among 79 neonatal deaths Method (i) (ii) (iii)
No. Clinical features 4-14 day death Cause of death according to informant
54* 3or I2~
Mortality per IO00 live-births 20"6 I I'4 4"6
* Of the 54 deaths; 22 were diagnosed by (ii), seven were diagnosed by (iii), only five were diagnosed by (i), (ii) and (iii). -~ Of the 30 deaths; 22 were diagnosed by (i), seven were diagnosed by (iii), only five were diagnosed by (i), (ii) and (iii). :~ Of the I2 deaths; seven were diagnosed by (i), seven were diagnosed by (ii), only five were diagnosed by (i), (ii) and (iii). For 54 deaths due to neonatal tetanus, proportion of neonatal mortality -- 68"4 %.
A two-stage cluster sampling m e t h o d for evaluating vaccination coverage in the W H O Expanded P r o g r a m m e on Immunisation. TM was employed. T h i r t y clusters were randomly selected with a sampling frame and population size c o m p u t e d as previously described. 18 T h e population evaluated included all mothers in the selected 3o clusters who were delivered of live babies in the last I - I 3 m o n t h s preceding the start of the survey (i.e. 9 June I989 to 8 June I99o). At least 87 live-births were recorded per cluster with a projected sample size of 26Io. T h e mothers (or nearest relatives) in each household were interviewed and relevant data recorded on proformae for identifying live-births. For each neonatal death recorded, a more detailed evaluation was undertaken by a Medical Officer using a different proforma so as to establish deaths which might have been due to neonatal tetanus. T h r e e different estimates of mortality were obtained and compared by means of three different methods of ascertaining deaths. T h e methods were (i) death recorded as taking place at 4 - I 4 days of life/(ii) cause of death volunteered by an informant and (iii) ascertained clinical features including sucking and crying normally during first 2 days of life with onset of illness between the 3rd and 28th days; inability to suck at onset followed by stiffness a n d / o r spasms and death. Estimates of mortality by sex and period of recall were also evaluated. Results
A total of 2623 live-births was recorded in 3o clusters over the 12-month period. T h e y included Iz83 males and x34o females. T h e r e were 79 neonatal deaths with a neonatal mortality rate of 3 o ' I / I o o o live-births. Table I shows the different estimates by the three methods of ascertainment. T h e mortality was z o . 6 / I o o o live-births for clinical diagnosis. According to 4-14 day deaths, the mortality was I I - 4 / I o o o live births and 4"6/Iooo livebirths when cause of death volunteered by an informat was used. T h e estimate by Clinical diagnosis was used for further analysis. T h u s , neonatal tetanus accounted for 68"4 % neonatal mortality.
Neonatal tetanus in Nigeria
135
Table II Distribution of 79 neonatal deaths by sex and cause of death D e a t h s due to neonatal tetanus
D e a t h s n o t due to neonatal tetanus
Total
Male Female
30 24
12 13
42 37
Total
54
25
79
Sex
X2, o"391 ; d f I ; P > 0"05.
Table I I I D~tributionof79 neonatal deathsbyperiodofrecaH and cause ofdeath P e r i o d o f recall (months)
D e a t h s d u e to neonatal tetanus
D e a t h s n o t due to neonatal tetanus
Total
1-7 8-13
38 16
21 4
59 20
Total
54
25
79
X2, 1"681; d f I ; P > 0"05 . T o t a l live-births by recall p e r i o d : 1-7 m o n t h s = 1573, 8-13 m o n t h s = lO5O.
Table II shows distribution ofneonatal deaths by sex and cause of death. T h e sex-specific mortality rates were 23"4 and z7"9 per zooo live-births for males and females respectively. T h e r e was no significant association between sex and death (P > o'o5). Table I I I illustrates the distribution of neonatal deaths by period of recall and cause of death. T h e mortality rate for the first 6 months of the recall period was I5-2/zooo live-births and 24"2/zooo live-births for the last 6 months. T h e association between recall period and death from neonatal tetanus was not significant. Discussion
T h e estimates of mortality by the three methods of ascertainment were strikingly different. T h e very low estimate according to cause of death volunteered by an informant may be a reflection of the low level of awareness of the existence and recognition of the disease in the population. This implies a need for health education of the populace. On the other hand, willingness to recall, accuracy and reliability of recall of dates of death probably accounted for the relatively low estimate of I I'4/IOOO live-births when 4 - I 4 day deaths were used. While there is an association between deaths from neonatal tetanus and total 4-14 day deaths, 4 this method of ascertainment is likely to yield falsely low estimates in community-based surveys. We therefore, suggest that reliable estimates of mortality from cluster surveys be based on widely accepted clinical features for retrospective diagnosis of possible death from neonatal tetanus.
136
c . o . EREGIE
T h e mortality o f 20-6/I000 live-births reported f r o m this survey in K a n o metropolis is very high. T h i s m a y be due to lack o f use o f health services in the population. T h e survey in Ilorin, Nigeria, reported a rate of I I.9/IOOO livebirths. 17 T h e s e regions differ m a r k e d l y in their location, climate, cultural and agricultural activities. I n d e e d , such a difference in mortality within the same c o u n t r y is well recognised, s H i g h mortality has also been reported f r o m other developing countries. 1-4 According to this study, deaths f r o m neonatal tetanus accounted for 68 % total neonatal deaths. T h i s agrees with most surveys which report a range of 2 o - 7 2 % . 2-4'9 Well-designed strategies to control neonatal tetanus will, therefore, significantly reduce total neonatal mortality in most developing countries. A l t h o u g h the sex-specific mortality rate for neonatal tetanus was higher for males, there was no significant association between sex and death f r o m neonatal tetanus. T h e r e is no agreement on the sex p r e p o n d e r a n c e reported from m o s t studies ~s-23 and these were largely n o t analysed for significance. M o r t a l i t y o f neonatal tetanus was m u c h higher for the last 6 m o n t h s of the recall period. T h i s t r e n d was also observed for total neonatal mortality and mortality f r o m diseases other than neonatal tetanus and was, therefore, n o t significant. T h i s m a y be a f u n c t i o n o f more accurate and reliable recall of recent events. T h e observation o f increased mortality f r o m neonatal tetanus with decreasing recall period and with the latter 6 m o n t h s has been r e p o r t e d previously f r o m a survey. 24 T h i s report illustrates the m a g n i t u d e o f the mortality of neonatal tetanus in a Nigerian population. Clinical features for ascertaining deaths f r o m neonatal tetanus should be e m p l o y e d for cluster surveys of mortality f r o m this disease. N o significant association between the mortality rate and sex and the period of recall was recorded in this study. (This report is part of a study wholly supported by a Nigeria CCCD Operational Research Grant. I thank Dr Gabriel Ofovwe for his assistance. The efforts of the personnel who participated in the field work are much appreciated. The secretarial assistance of Mr Dimas Daniel is acknowledged with thanks.)
References
I. Tompkins AB. Neonatal tetanus in Nigeria. B Med J I958; I: r382-I385. 2. Berggren WL, Berggren GM. Changing incidence of fatal tetanus of the newborn: a retrospective study in a defined rural Haitian population. Am J Trop Med Hyg I97I ; 2o: 491-494. 3. Basu RN, Sokhey J. Special combined survey for poliomyelitis and neonatal tetanus as supplement to routine surveillance system in India. ff Comp Dis I984; x6: I48-I53. 4- Melgaard B, Mutie DM, Kimani G. A cluster survey of mortality due to neonatal tetanus in Kenya. I n t J Epidemiol I988; I7: I74-I77. 5. Bytchenko B. Geographical distribution of tetanus in the World, x95 r - 60: a review of the problem. Bull WHO I966; 34: 7I-ro4. 6. Blankson JM. Problems of neonatal tetanus as seen in Ghana. Afr ff Med Sci 1977; 6: I-6. 7. Gupta A, Chopra K, Khalil A. Tetanus neonatorum. Ind Pediatr J I977; x4: 2II-213. 8. Hinman AR, Foster SO, Wasailak SGF. Neonatal tetanus: potential for elimination in the world. Pediatr Infect Dis ff I987; 6: 813-816.
Neonatal tetanus in Nigeria
I37
9. World Health Organisation. Prevention of neonatal tetanus. Wkly Epidem Rec I982; 57: 137-144. IO. Stanfield JP, Galazka A. Neonatal t e t a n u s - an under-reported scourge. World Health Forum I985; 6:127-129. I I . Ogbeide M I . Problems of neonatal tetanus in Lagos. J Trop Pediatr I966; xz: 71-79. I2. Daramola T. Tetanus in Lagos. IV Aft MedJ 1968; 17: r36-I38. r3. Idoko A. Neonatal tetanus in Benue Plateau State of Nigeria. Nig J Paediatr 1975; 2: 47-50. 14. Effiong CE. Neonatal morbidity and mortality in Ibadan: a review of cases seen in the outpatient clinics. J Trop Pediatr 1976; zz: 265-267. I5. Elenwune VO. Childhood tetanus with particular reference to Nigeria. Ann Trop Pediatr
I982; 2: I89-I93. I6. Osuhor PC. Neonatal tetanus in Zaria, Northern Nigeria. Ind.7 Public Health I983; z7: 32-37. 17. Babaniyi OA, Parakoyi BD. Mortality from neonatal tetanus in Ilorin: results of a community-based survey. J Trop Pediatr 1989; 35: r37-r38. 18. Henderson RH, Sundareson T. Cluster sampling to assess immunization coverage: a review of experience with a simplified sampling method. Bull WHO I982; 6o: 253-26o. 19. Standfield JP, Galazka A. Neonatal tetanus in the world today. Bull WHO I984; 6z: 647-669. 2o. Galazka A. Control of neonatal tetanus. Ind ff Pediatr 1985; 5z: 329-341. 2I. Maternal and Child Health (MCH). Control of neonatal tetanus, China. Ivkly Epidem Rec
I985~ 61): 5--6. 22. Expanded Programme on Immunisation. Neonatal tetanus mortality survey, Ivory Coast. Ivkly Epidem Rec I983; 58: 71-72. 23. Expanded Porgramme on Immunisation. Neonatal tetanus mortality surveys, Kenya. IVkly Epidem Rec I986; 6 I : II7--II8. 24. Expanded Programme on Immunisation. Neonatal tetanus mortality survey, Malawi. IVkly Epidem Rec I983; 58: 326-327.
