The Design of Computer Forms for Tropical Medical Research

The design of forms for recording medical research data in the field is discussed in the light of the computer hardware and software to be used for their subsequent analysis. In particular, the principles of relational database management systems are extrapolated to the structure of forms. Specific issues of subject identification, layout of forms, different types of data and coding methods are developed. Finally, the special problems of applying these principles in the tropics, and experiences of so doing, are considered.

On-line Tropical Epidemiology -A Case-Study from The Gambia

This paper reports on a computerised approach to the management of an epidemiological field trial, which aimed at determining the effects of insecticide-impregnated bed nets on the incidence of malaria in children. The development of a data system satisfying the requirements of the project and its implementation using a database management system are discussed. The advantages of this method of management in terms of rapid processing of and access to data from the study are described, together with the completion rates and error rates observed in data collection.

Tropical Epidemiology: A System for Continuous Demographic Monitoring of a Study Population

Epidemiologists in many developing countries, where official demographic services are unavailable, have to include some demographic functions in their work. The usual method of documenting a study population for epidemiological research in a developing country consists of three stages: mapping, enumeration and vital registration. This paper considers the last element of this process, detailing the development of a suitable data system and explaining how its implementation using microcomputers and a database management system can help in the creation of an on-line continuous vital registration system for a study population as an epidemiological tool. The issues covered are data collection, entry and analysis, and the advantages of such a system for use in epidemiological research in developing countries are also discussed.

The development of a localised HIV epidemic and the associated excess mortality burden in a rural area of South Africa

The human immunodeficiency virus (HIV) epidemic in South Africa rapidly developed into a major pandemic. Here we analyse the development of the epidemic in a rural area of the country. The data used were collected between 1992 and 2013 in a longitudinal population survey, the Agincourt Health and Demographic Surveillance Study, in the northeast of the country. Throughout the period of study mortality rates were similar in all villages, suggesting that there were multiple index cases evenly spread geographically. These were likely to have been returning migrant workers. For those aged below 39 years the HIV mortality rate was higher for women, above this age it was higher for men. This indicates the protective effect of greater access to HIV testing and treatment among older women. The recent convergence of mortality rates for Mozambicans and South Africans indicates that the former refugee population are being assimilated into the host community. More than 60% of the deaths occurring in this community between 1992 and 2013 could be attributed directly or indirectly to HIV. Recently there has been an increasing level of non-HIV mortality which has important implications for local healthcare provision. This study demonstrates how evidence from longitudinal analyses can support healthcare planning.

Non-specific sex-differential effect of DTP vaccination may partially explain the excess girl child mortality in Ballabgarh, India

OBJECTIVE

To test the hypothesis that a gender differential exists in the effect on child mortality of BCG, DTP, measles vaccine as administered under programme conditions in Ballabgarh HDSS area.

METHODS

All live births in 28 villages of Ballabgarh block in North India from 2006 to 2011 were followed until 31 December 2011 or 36 months of age whichever was earlier. The period of analysis was divided into four time periods based on eligibility for vaccines under the national immunisation schedule (BCG for tuberculosis, primary and booster doses of diphtheria-tetanus-pertussis and measles). Cox proportional hazards regression was used to assess the association between sex and risk of mortality by vaccination status using age as the timescale in survival analysis and adjusting for wealth index, access to health care, the presence of a health facility in the village, parental education, type of family, birth order of the child and year of birth.

RESULTS

702 deaths (332 boys and 370 girls) occurred among 12,142 children in the cohort in the 3 years of follow-up giving a cumulative mortality rate of 57.5 per 1000 live births with 35% excess girl child mortality. Age at vaccination for the four vaccines did not differ by sex. There was significant excess mortality among girls after immunisation with DTP, for both primary (HR 1.65; 95% CI:1.17-2.32) and DTPb (2.21; 1.24-3.93) vaccinations. No significant excess morality among girls was noted after exposure to BCG 1.06 (0.67-1.67) or measles 1.34 (0.85-2.12) vaccine.

CONCLUSION

This study supports the contention that DTP vaccination is partially responsible for higher mortality among girls in this study population.

Motherhood, migration and mortality in Dikgale: modelling life events among women in a rural South African community

OBJECTIVES

Although particular types of life events in populations are often studied separately, this study investigated the joint effects of three major event types in South African women's lives: motherhood, migration and mortality.

STUDY DESIGN

Data were taken from a health and demographic surveillance site (HDSS) over an 11-year period, reflecting the entire population of a defined geographic area as an open cohort, in which individuals participated in regular longitudinal surveillance for health and demographic events. This HDSS is a member of the Indepth Network.

METHODS

Multivariate Poisson regression models were built for each of the three life event types, in which individual person-time observed out of the total possible 11-year period was used as a rate multiplier. These models were used to calculate adjusted incidence rate ratios for each factor.

RESULTS

In the 21,587 person-years observed for women aged 15-49 years, from 1996 to 2006, adjusted rate ratios for mortality and migration increased substantially over time, while motherhood remained fairly constant. Women who migrated were less likely to bear children; temporary migrants were at greater risk of dying, while permanent in-migrants had higher survival rates. Women who subsequently died were much less likely to bear children or migrate.

CONCLUSIONS

The associations between motherhood, migration and mortality among these rural South African women were complex and dynamic. Extremely rapid increases in mortality over the period studied are presumed to reflect the effects of the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic. Understanding these complex interactions between various life events at population level is crucial for effective public health planning and service delivery.

Prevalence, awareness, treatment and control of hypertension in Vietnam-results from a national survey

The objective of this study was to estimate mean blood pressure (BP), prevalence of hypertension (defined as BP ≥140/90 mm Hg) and its awareness, treatment and control in the Vietnamese adult population. This cross-sectional survey took place in eight Vietnamese provinces and cities. Multi-stage stratified sampling was used to select 9832 participants from the general population aged 25 years and over. Trained observers obtained two or three BP measurements from each person, using an automatic sphygmomanometer. Information on socio-geographical factors and anti-hypertensive medications was obtained using a standard questionnaire. The overall prevalence of hypertension was 25.1%, 28.3% in men and 23.1% in women. Among hypertensives, 48.4% were aware of their elevated BP, 29.6% had treatment and 10.7% achieved targeted BP control (<140/90 mm Hg). Among hypertensive aware, 61.1% had treatment, and among hypertensive treated, 36.3% had well control. Hypertension increased with age in both men and women. The hypertension was significantly higher in urban than in rural areas (32.7 vs 17.3%, P<0.001). Hypertension is a major and increasing public health problem in Vietnam. Prevalence among adults is high, whereas the proportions of hypertensives aware, treated and controlled were unacceptably low. These results imply an urgent need to develop national strategies to improve prevention and control of hypertension in Vietnam.

Ageing of a rural Ethiopian population: who are the survivors?

OBJECTIVES

This study assessed trends in survival to old age and identified the factors associated with longevity among the elderly (age > or = 65 years).

STUDY DESIGN

Cohort analysis of demographic surveillance data.

METHODS

The study was conducted in the Butajira Rural Health Programme Demographic Surveillance Site in Ethiopia. Using data collected between 1987 and 2004, the probability of survival to 65 years and remaining life expectancy for women and men aged 65 years were computed. Cox regression analysis was used to assess survival by different factors.

RESULTS

Although the elderly represented 3% of the population, their person-time contribution increased by 48% over the 18-year period. Less than half reached 65 years of age, with remaining life expectancy at 65 years ranging from 15 years in rural men to 19 years in urban women. Rural residence, illiteracy and widowhood were associated with lower survival adjusted for other factors, whereas gender did not show a significant difference. However, the effect of these factors differed between men and women, as demonstrated by survival curves and Cox regression. Widowhood [hazard ratio (HR) 2.02, 95% confidence interval (CI) 1.59-2.57] and illiteracy (HR 2.26, 95% CI 1.86-2.73) affected males to a greater extent than females, and rural residence was associated with poorer female survival (HR 1.68, 95% CI 1.55-1.83).

CONCLUSIONS

The number of elderly people is increasing in Ethiopia, with the chance of survival into older age being similar between men and women and approaching that in developed countries. However, rural women and illiterate women and men, particularly widowers, are disadvantaged in terms of survival.

Identifying humanitarian crises in population surveillance field sites: simple procedures and ethical imperatives

OBJECTIVES

Effective early warning systems of humanitarian crises may help to avert substantial increases in mortality and morbidity, and prevent major population movements. The Butajira Rural Health Programme (BRHP) in Ethiopia has maintained a programme of epidemiological surveillance since 1987. Inspection of the BRHP data revealed large peaks of mortality in 1998 and 1999, well in excess of the normally observed year-to-year variation. Further investigation and enquiry revealed that these peaks related to a measles epidemic, and a serious episode of drought and consequent food insecurity that went undetected by the BRHP. This paper applies international humanitarian crisis threshold definitions to the BRHP data in an attempt to identify suitable mortality thresholds that may be used for the prospective detection of humanitarian crises in population surveillance sites in developing countries.

STUDY DESIGN

Empirical investigation using secondary analysis of longitudinal population-based cohort data.

METHODS

The daily, weekly and monthly thresholds for crises in Butajira were applied to mortality data for the 5-year period incorporating the crisis periods of 1998-1999. Days, weeks and months in which mortality exceeded each threshold level were identified. Each threshold level was assessed in terms of prospectively identifying the true crisis periods in a timely manner whilst avoiding false alarms.

RESULTS

The daily threshold definition is too sensitive to accurately detect impending or real crises in the population surveillance setting of the BRHP. However, the weekly threshold level is useful in identifying important increases in mortality in a timely manner without the excessive sensitivity of the daily threshold. The weekly threshold level detects the crisis periods approximately 2 weeks before the monthly threshold level.

CONCLUSION

Mortality measures are highly specific indicators of the health status of populations, and simple procedures can be used to apply international crisis threshold definitions in population surveillance settings for the prospective detection of important changes in mortality rate. Standards for the timely use of surveillance data and ethical responsibilities of those responsible for the data should be made explicit to improve the public health functioning of current sentinel surveillance methodologies.

Association between body mass index and blood pressure across three populations in Africa and Asia

Despite a growing burden of obesity and hypertension in developing countries, there is limited information on the contribution of body mass index (BMI) to blood pressure (BP) in these populations. This study examines the association between BMI and BP in three populations across Africa and Asia. Data on BMI, BP and other background characteristics of study participants were generated using the World Health Organization STEPwise approach to surveillance (STEPS), at three demographic surveillance sites in Ethiopia, Vietnam and Indonesia. BMI and BP increased along the socioeconomic gradient across the three countries. Mean (s.d.) BMI in men varied between 19.41 (2.28) in Ethiopia to 21.17 (2.86) in Indonesia. A high prevalence of overweight/obesity was noted among Indonesian women (25%) and men (10%), whereas low BMI was widely prevalent in Ethiopia and Vietnam, ranging from 33 to 43%. Mean (s.d.) systolic BP (SBP) among men varied between 117.15 (15.35) in Ethiopia to 127.33 (17.80) in Indonesia. The prevalence of hypertension was highest among women (25%) and men (24%) in Indonesia. Mean BP levels increased with increasing BMI. The risk of hypertension was higher among population groups with overweight and obesity (BMI>/=25 kg/m(2)); odds ratio (95% confidence interval); 2.47 (1.42, 4.29) in Ethiopia, 2.67 (1.75, 4.08) in Vietnam and 7.64 (3.88, 15.0) in Indonesia. BMI was significantly and positively correlated with both SBP and DBP in all the three populations, correlation coefficient (r) ranging between 0.23 and 0.27, P<0.01. High BP exists in a background of undernutrition in populations at early stages of the epidemiologic transition.

Gender differences in prevalence and socioeconomic determinants of hypertension: findings from the WHO STEPs survey in a rural community of Vietnam

In Vietnam, hypertension was estimated to cause a large number of deaths in hospitals. However, population-based knowledge about the magnitude of hypertension in Vietnam and its relationship with socioeconomic status, especially in the rural communities, still remains scarce. This paper, taking advantage of a study on noncommunicable disease (NCD) risk factors in Bavi district, Vietnam, using the WHO STEPs approach, estimates the prevalence of hypertension in the setting and examines its association with some socioeconomic factors. A representative sample comprising 2000 adults aged 25-64 years were selected randomly and surveyed in 2002. The JNC VII criteria for hypertension were used. Socioeconomic status of the study subjects was estimated by assessing their education, occupation and economic conditions. Descriptive techniques and multivariate logistic regression were used. The prevalence of hypertension was 14.1%. Of hypertensives, only 17.4% were aware of their hypertensive status. Men were hypertensive more often than women and age was positively associated with hypertension. The association between hypertension and socioeconomic status was complex and differed between men and women. Among men, those with lower educational and occupational status but who were richer were more likely to be hypertensive. More women with lower occupational and economic status were hypertensive.

Unintentional injuries over a 1-year period in a rural Vietnamese community: describing an iceberg

OBJECTIVES

To document unintentional injuries in a rural community over a 1-year period as a basis for prioritizing preventive activities.

STUDY DESIGN

Quarterly home visits over 1 year to elicit experience of injury among household members in the preceding 3 months.

METHODS

In total, 24,776 people living in rural communities in the Bavi District, Northern Vietnam, were surveyed in home visits during 2000. In the home visits, injuries that needed care or disrupted normal activities were recorded, together with their circumstances.

RESULTS

Overall, 2079 new non-fatal injuries were recorded over 23,338 person-years, a rate of 89/1000 person-years-at-risk. Males had a significantly higher injury rate than females for all age groups except for those aged 35-59 years and the elderly (P<0.05). The elderly were at highest risk of injury (P<0.05), particularly females. Home injuries occurred at the highest overall rate, particularly among the elderly. Road traffic injuries were most common among children. Most injuries involved contact with another object. Less than one-quarter of injury victims sought care at a health facility.

CONCLUSIONS

Community-based household surveys revealed the hidden part of the injury iceberg, as well as showing high incidence rates, indicating that injury is an important public health problem which should be a priority for intervention in rural Vietnam, and probably elsewhere. This comprehensive study is intended to contribute evidence and methods to the Ministry of Health's national programme for injury prevention, and to a wider audience.

Empirical modelling of population sampling: lessons for designing sentinel surveillance

BACKGROUND

In order to consider the practical viability of 1% sentinel area surveillance for health information in resource-poor settings where complete registration is unrealistic, the effects of different sampling procedures on the representativeness of 1% population samples have been investigated.

METHODS

Using the 1991 census of England as a basis for modelling, 20 1% samples, each incorporating seven key parameters, were drawn at random from the overall dataset by each of eight different sampling procedures. Each sample was compared with the 'gold standard' of the overall census results, enabling comparisons between the different sampling procedures.

RESULTS

Representativeness of the 1% samples varied considerably between parameters and sampling procedures. At one extreme, the proportion of males in the population was distributed such that different sampling methods had little effect. On the other hand, samples of a heterogeneous parameter such as the proportion of non-whites in the population depended greatly on the procedure used. Sampling smaller administrative units tended to be more accurate. However, sampling units using probability proportional to size generally gave less representative samples. Stratifying urban and rural populations in the samples had little effect. Multistage sampling, emulating typical demographic surveillance sites, also generally gave less representative samples.

CONCLUSIONS

It is possible to achieve representative data by taking 1% of a national population in a sentinel surveillance approach, but sampling design can have an important influence on the outcome. This modelling supports the concept of 1% sentinel surveillance for health information in poorer settings, where complete data are unavailable.

Schistosome transmission, water-resource development and altitude in northern Ethiopia

Schistosomiasis continues to be a major public-health problem, not least in association with water-resource developments. The impact of microdam construction in the northern Ethiopian highlands, in relation to possible increased risks of Schistosoma mansoni infection, has now been assessed. The results of incidence studies, carried out on 473 individuals sampled across eight microdam sites at altitudes of 1800-2225 m above sea level, indicated an overall annual incidence of 0.20 infections/person at risk. A multivariate Poisson regression model showed altitude and sex to be significant risk factors for infection, whereas proximity to a microdam was not significant, except possibly at very high altitudes. It was concluded that altitude was the major factor in this environment and that therefore, at least in terms of public-health planning, microdams should be sited as high as local geography permits.

The role of demographic surveillance systems (DSS) in assessing the health of communities: an example from rural Ethiopia

Longitudinal demographic surveillance systems (DSSs) in selected populations can provide important information in situations where routine health information is incomplete or absent, particularly in developing countries. The Butajira Rural Health Project is one such example, initiated in rural Ethiopia in 1987. DSSs rely on regular community-based surveillance as a means of vital event registration, among a sufficient population base to draw meaningful conclusions about rates and trends in relatively rare events such as maternal death. Enquiries into specific health problems can also then use this framework to quantify particular issues or evaluate interventions. Demographic characteristics and trends for a rural Ethiopian population over a 10-y period are presented as an illustration of the DSS approach, based on 336 000 person-years observed. Overall life expectancy at birth was 50 y. Demographic parameters generally showed modest trends towards improvement over the 10-y period. The DSS approach is useful in characterising populations at the community level over a period of time, providing important information for health planning and intervention. Methodological issues underlying this approach need further exploration and development.

Aims, options and outcomes in measuring maternal mortality in developing societies

BACKGROUND

Effective methods for measuring maternal mortality in developing countries are important, particularly in assessing interventions aiming for safer motherhood. Here the performance of different approaches is compared in the same setting.

METHODS

Estimates of maternal mortality in a rural Ethiopian community are reported, made by direct observation, a case-control approach, and the sisterhood method.

RESULTS

Adjusted estimates of MMR using these methods ranged between 440 and 665 per 100,000 live births.

CONCLUSIONS

The advantages and disadvantages of the different approaches are compared, both for operational feasibility and outcome.

The ALERT MDT Field Evaluation Study (AMFES): a descriptive study of leprosy in Ethiopia. Patients, methods and baseline characteristics

The ALERT MDT Field Evaluation Study (AMFES) is a long-term prospective study of 650 patients (594 new cases and 56 relapses after dapsone monotherapy), treated with fixed-duration multiple-drug therapy (MDT), as recommended by WHO. Follow-up has continued for up to 11 years from the start of treatment. This paper presents the methodology of the study and the baseline characteristics of the cohort, while accompanying papers examine the incidence of, and possible risk factors for, the various complications of leprosy, including relapse, reactions and nerve function impairment. The methods of diagnosis, classification and treatment with MDT are described; nerve function was assessed at every visit to the clinic using a standardized methodology, so that reactions and new impairment could be detected early and treated. Eighty-four per cent of new case had at least one thickened nerve, with the ulnar nerve most commonly involved. Seventy-seven per cent of cases completed treatment and only one adverse reaction to the MDT drugs was noted. Twenty-eight per cent of all patients were given steroids at one time or another, almost always for new nerve function impairment, and 3% of these developed significant complications of steroid treatment. Twenty-nine patients (5%) received hospital care, including 14 patients who underwent major surgery. Sixty-one per cent of the women over 19 years of age had at least one pregnancy, but pregnancies were much less common after leprosy was diagnosed.

ENL reactions in the multibacillary cases of the AMFES cohort in central Ethiopia: incidence and risk factors

Erythema nodosum leprosum (ENL), or type 2 leprosy reactions are an important complication of multibacillary leprosy. The AMFES cohort includes 300 new multibacillary cases that have been followed for up to 10 years from the start of treatment, in central Ethiopia. Sixteen (5.3%) patients had ENL reactions. The incidence of ENL was maximal in the second and third years after the start of treatment, reaching 6.9 episodes per 100 person years at risk. Factors associated with being lepromatous [LL classification and a high bacillary index (BI)] gave an increased risk of developing ENL; in the univariate analysis, LL classification gave a relative risk of 3.6 (95% CI 1.3-10) and a BI of 6 gave a relative risk of 8.6 (95% CI 2.3-32) for the development of ENL. HIV co-infection was found to be a risk factor in this cohort, but as the numbers involved are small (only two HIV positive patients had ENL), this finding must be confirmed in larger studies. Ten of the 16 cases had recurrent episodes and five had at least five episodes occurring over a period of more than 2 years. The management and prognosis of ENL reactions are discussed.

Reversal reactions in the skin lesions of AMFES patients: incidence and risk factors

Reversal reactions affect the skin and/or nerves of leprosy patients. This paper looks at reversal reactions involving the skin in 594 new patients in central Ethiopia, followed for between 6 and 11 years after the start of treatment. The incidence of reversal reaction declines steadily after the start of treatment, but the first episode may occur as long as 5 years after diagnosis in both paucibacillary (PB) and multibacillary (MB) patients. Recurrent episodes occurred up to 6 years after diagnosis. PB patients were at greatest risk for reversal reaction in the first year after diagnosis and MB patients in the first 4 years. The highest incidence rate was 18 episodes per 100 person years in MB patients during the first year after diagnosis. The ratio of the incidence rates for the first 3 years in MB versus PB patients is 2.4 (95% CI 1.6-3.8). This study confirms that starting effective treatment and borderline classification are risk factors for reversal reactions. Pregnancy/delivery in the 6 months prior to diagnosis was a significant risk factor for presenting with a reversal reaction [relative risk (RR) 5.9 (95% CI 2.1-16.5)], but later pregnancies were not associated with an increased risk. Being female was a significant risk factor for the late appearance of the first episode of reversal reaction. Having a reversal reaction in the first year after diagnosis was a highly significant risk factor for the development of later reactions [RR in PB cases 11.9 (95% CI 3.4-41.7); in MB cases 6.4 (95% CI 3.8-10.6)]. Being HIV positive was a risk factor for developing recurrent reversal reactions, although only three out of 29 recurrent cases were HIV positive [RR 2.7 (95% CI 1.4-5.1)].

Relapses after fixed duration multiple drug therapy: the AMFES cohort

Relapse rates after multiple-drug therapy (MDT) have been low, although there remains a concern about the possibility of late relapse in those with an initially high bacterial load. In all, 502 patients in the AMFES cohort completed fixed-duration MDT and are included in this report. There have been no confirmed relapses in the AMFES cohort, in a follow-up period of up to 8 years after completion of treatment, even in the 57 cases with an initial average bacillary index of > or = 4.0, 20 of whom have been followed for more than 5 years after ceasing MDT. Methods of diagnosing a relapse are discussed.

The pattern of decline in bacillary index after 2 years of WHO recommended multiple drug therapy: the AMFES cohort

With effective antibiotic treatment, the bacillary index (BI) in multibacillary leprosy patients declines over a number of years. This can be quantified as a rate of decline in log-units per year or as the time until smear negativity is reached. In the AMFES cohort 220 cases had data on the changes in their BI over time, while 170 cases are documented until smear negativity. The average BI at the start was 3.3 (SD 1.5; range 0.3-5.5) and the mean rate of decline was 0.85 units per year (median 0.7 units per year); in the first 2 years after diagnosis, the mean rate of decline was 1.15 units per year. The rate of decline was not related to any clinical features of the disease except delay in diagnosis: patients presenting for treatment early had a significantly faster rate of clearing the bacilli (adjusted relative risk 2.3; 95% CI 1.0-5.1). Fifty-eight percent of cases took longer than 3 years to reach smear negativity, but this time interval is largely determined by the initial BI and classification, making it a less useful indicator of bacterial clearance. More severe impairment at the start of treatment was associated with a faster return to smear negativity, for which no obvious explanation can be given. Reversal reactions, which occurred in 25% of the cases reviewed, are not associated with a more rapid clearance of bacilli.

The pattern of leprosy-related neuropathy in the AMFES patients in Ethiopia: definitions, incidence, risk factors and outcome

The ALERT MDT Field Evaluation Study (AMFES) began in 1988 and followed patients prospectively for up to 10 years after release from treatment (RFT). This paper presents the findings from this cohort with regard to neuropathy and nerve damage. Five hundred and ninety-four new cases of leprosy are included in the study, 300 multibacillary (MB) and 294 paucibacillary (PB) cases. Fifty-five percent of patients had some degree of impairment at diagnosis and a further 73 (12%) developed new nerve function impairment (NFI) after starting multiple drug therapy (MDT). The overall incidence rate for neuropathy was 39 episodes per 100 PYAR in the first year after diagnosis, gradually declining to 12 episodes per 100 PYAR in the sixth year. In those patients without impairment at diagnosis, the incidence rate of neuropathy was 25 episodes per 100 PYAR for MB cases and 11 per 100 PYAR for PB cases in the first year; in 33% of MB cases whose first episode of neuropathy occurred after diagnosis, that first episode took place after the first year, or after the normal period of treatment with MDT. Seventy-three patients with neuropathy developing after diagnosis are reported more fully: 34 (47%) had only one nerve involved and of these 25 (73%) had a single, acute episode of neuropathy. Nine (27%) had further episodes. Thirty-nine (53%) had more than one nerve involved and of these 16 (41%) had a single, acute episode, while 23 (59%) had further episodes. The terms 'chronic' and 'recurrent' neuropathy are defined and used to describe the pattern of neuropathy in those with repeated attacks. In patients with no impairment at the start of the study, treatment with steroids resulted in full recovery in 88% of nerves with acute neuropathy but only 51% of those with chronic or recurrent neuropathy. The median time to full recovery from acute neuropathy was approximately 6 months, but in a few cases recovery occurred gradually over 2-3 years. Severe neuropathy was less likely to be followed by a complete recovery than mild or moderate neuropathy. Forty-two percent of nerves with acute neuropathy that were not treated with steroids also fully recovered. In the group of patients who were thought to have old, permanent impairments at diagnosis, full recovery of nerve function occurred in 87/374 (23%) of the nerves involved. The overall outcome is illustrated by examining the average EHF score for groups of patients. Patients with no new neuropathy after diagnosis show a gradual improvement in their EHF score, while those with any episodes of neuropathy after diagnosis show a gradual deterioration after completion of MDT. Possible explanations for these findings are discussed. Risk factors for neuropathy, for chronic and recurrent neuropathy, and for a poor outcome 5 years after release from treatment, are examined. Impairment at diagnosis was the main risk factor for a poor outcome, accompanied by the occurrence of chronic/recurrent neuropathy or a reversal reaction.

The effect of HIV status on the clinical picture of leprosy: a prospective study in Ethiopia

No major interaction between HIV infection and leprosy has been documented. The ALERT MDT Field Evaluation Study (AMFES) has allowed the examination of possible interactions in a prospective manner, although the total number of HIV-positive individuals was not high at 22 (3.8%) of 581 patients tested. There was an excess number of deaths in the HIV-positive group: 27% compared with 5.7% in the HIV-negative group, although the causes of death were not recorded (relative risk 4.8; 95% CI 2.2-10.2). HIV-positive individuals had a higher risk of ENL reactions (relative risk 5.2; 95% CI 1.7-15.9). Reversal reactions and neuritis (both acute and chronic) were not significantly influenced by HIV status, although there was a possible increase in recurrent reversal reactions in HIV-positive cases (relative risk 2.2; 95% CI 0.98-4.7). There was no evidence to suggest an increased risk of developing leprosy or of developing multibacillary rather than paucibacillary disease. There was no association between HIV positivity and the development of impairment.

Prior BCG vaccination improves survival of Gambian patients treated for pulmonary tuberculosis

The protection provided by BCG against pulmonary tuberculosis ranges from nil to over 90%. While BCG protects against the more serious forms of tuberculosis, it is not known whether or not it protects patients with pulmonary tuberculosis from death. In a study designed to look at the effects of immunotherapy with M. vaccae as an adjunct to chemotherapy in 285 adult Gambian patients treated for proven pulmonary tuberculosis, we examined the association between the presence or absence of a BCG scar and mortality. The data showed that subjects who had a BCG scar were significantly younger than those who did not, and were less likely to have nutritional oedema. During the course of treatment, none of the 85 patients who had a BCG scar died compared to 35 of 200 patients (17.5%) who did not (P < 0.001). In these Gambian patients with pulmonary tuberculosis, prior vaccination with BCG may have provided substantial protection against death. However, there is the possibility that this finding is the result of confounding by other factors or has arisen from bias. Researchers with similar data need to investigate this question as this association, if true, could have major implications for BCG vaccination.

Household risk factors for malaria among children in the Ethiopian highlands

Malaria transmission varies from village to village and even from family to family in the same village. The current study was conducted in northern Ethiopia to identify risk factors responsible for such variations in a hypoendemic highland malaria setting: 2114 children aged < 10 years living in 6 villages situated close to small dams at altitudes from 1775 to 2175 m were monitored. Monthly malaria incidence was determined 4 times over a 1-year period during 1997. Incidence results were then analysed by 14 individual and household factors using Poisson multivariate regression. Among 14 factors analysed, use of irrigated land (rate ratio[RR] = 2.68, 95% CI 1.64-4.38), earth roof (RR = 2.15, 95% CI 1.31-3.52), animals sleeping in the house (RR = 1.92, 95% CI 1.29-2.85), windows (RR = 1.84, 95% CI 1.30-2.63), open eaves (RR = 1.85, 95% CI 1.19-2.88), no separate kitchen (RR = 1.57, 95% CI 1.10-2.23), and 1 sleeping room (RR = 1.52, 95% CI 1.05-2.20), were significantly associated with malaria. The proportion of infection among children exposed to one or no risk factor was 2.1%, increasing with the number of risk factors and reaching 29.4% with 5 or more. Further studies are needed to confirm the importance of particular risk factors, possibly leading to simple health education and control measures that could become part of routine control programmes, implemented with inter-sectoral collaboration.

Incidence of malaria among children living near dams in northern Ethiopia: community based incidence survey

OBJECTIVE

To assess the impact of construction of microdams on the incidence of malaria in nearby communities in terms of possibly increasing peak incidence and prolonging transmission.

DESIGN

Four quarterly cycles of malaria incidence surveys, each taking 30 days, undertaken in eight at risk communities close to dams paired with eight control villages at similar altitudes but beyond flight range of mosquitoes.

SETTING

Tigray region in northern Ethiopia at altitudes of 1800 to 2225 m.

SUBJECTS

About 7000 children under 10 years living in villages within 3 km of microdams and in control villages 8-10 km distant.

MAIN OUTCOME MEASURES

Incidence of malaria in both communities.

RESULTS

Overall incidence of malaria for the villages close to dams was 14.0 episodes/1000 child months at risk compared with 1.9 in the control villages-a sevenfold ratio. Incidence was significantly higher in both communities at altitudes below 1900 m.

CONCLUSIONS

There is a need for attention to be given to health issues in the implementation of ecological and environmental development programmes, specifically for appropriate malaria control measures to counteract the increased risks near these dams.

Guidelines for anal cytology--to make cytological diagnosis and follow up much more reliable

Anal intraepithelial neoplasia is a difficult diagnostic and management problem, particularly when it occurs in women with synchronous or metachronous genital intraepithelial neoplasia. Diagnosis and follow up by colposcopy is too specialized for widespread use, and although anal cytology has been used before it has been thought of as too inconsistent for practical application. This study standardized collection of specimens and investigated interobserver variation. The aim of the study was to determine whether observers could reliably distinguish high grade anal intraepithelial neoplasia from other conditions. Standardized collection of anal preparations was achieved in the host centre. A meeting of experienced cytopathologists was convened to agree guidelines for anal cytology. These guidelines were sent to the panel of six observers who were subsequently circulated with 30 cytopathological preparations in random order and asked to report them all. The results were collected and processed centrally. Four individuals were in complete agreement about those preparations which were inadequate for reporting, but two others had a lower threshold for rejecting preparations as inadequate. There was agreement between the observers in over 95% of cases in distinguishing high grade intraepithelial neoplasia from other cytological conditions. Kappa values range from 0.66 to 1.00. This study demonstrates that the provision of guidelines for the interpretation of anal cytopathological preparations can result in a high degree of interobserver agreement about the clinically important distinction between high grade anal intraepithelial neoplasia and other conditions. Anal cytology is a more useful technique for diagnosis and follow up of 'at risk' individuals than has previously been suggested, and should be utilized more widely in this group of patients.

A one-year community study of under-fives in rural Ethiopia: health and behavioural determinants of morbidity

Based on a one-year weekly home surveillance study, morbidity patterns of 1,304 children under five years of age in a rural Ethiopian community were measured, together with nutritional and health behavioural determinants. Using Poisson regression models, the study showed that nutritional and health care factors make a significant impact on under-five morbidity. Gastroenteritis was particularly associated with child care factors, while acute respiratory infections were particularly associated with nutritional factors. Lack of immunization, low birthweight and pre-term delivery (more than one month early) were not found to have any independent effect on morbidity. Breast feeding was universal, but the introduction of supplementary foods was found to protect from excess morbidity. The study concludes by discussing possible applications of the results in intervention programmes.

Mortality and morbidity from malaria after stopping malaria chemoprophylaxis

Gambian children who had received malaria chemoprophylaxis for a variable period of time during their first 5 years of life were followed to determine whether they experienced a rebound in mortality or in morbidity from malaria during the period after chemoprophylaxis was stopped. The risk of dying between the ages of 5 years, when chemoprophylaxis was stopped, and 10 years was no higher among children who had received chemoprophylaxis with Maloprim (pyrimethamine plus dapsone) for some period during their first 5 years of life than among children who had received placebo (21 vs. 24 deaths) and the beneficial effect of chemoprophylaxis on mortality observed during the first 5 years of life was sustained. The incidence of clinical attacks of malaria during the year after medication was stopped was significantly higher among children who had previously received Maloprim for several years than among children who had previously received placebo. However, at the end of this year, there was no significant difference in spleen rate, parasite rate or packed cell volume between the 2 groups of children. Thus, stopping chemoprophylaxis after a period of several years increased the risk of clinical malaria but did not result in a rebound in mortality in Gambian children. However, the number of deaths recorded was small, so a modest effect on mortality cannot be excluded.

Assessment and possible control of endemic measles in urban Nigeria

BACKGROUND

Measles remains as a serious problem of infancy and childhood in the developing world, despite the availability of a vaccine. Increasing urbanization is changing patterns of endemicity.

METHODS

A survey of measles in an urban area of Nigeria, using a rapid assessment approach, was carried out to characterize measles in this community.

RESULTS

An annual incidence rate of 11.8% among under-fives was found, associated with an acute case fatality rate of 3.3%. This level of endemicity was two orders of magnitude greater than that suggested by official case reports. An endemic, rather than epidemic, pattern was found over the six-month period of the study. Vaccine efficacy was estimated at 26%. Risk factor analyses showed the major risks for measles to be clinic attendance in the month preceding disease, households with more than one mother, and having under-five siblings. Measles itself was the principal risk factor for malnutrition and against survival.

CONCLUSIONS

Improved understanding of measles epidemiology and risk factors are prerequisites for effective control. Possible strategies should include vertical vaccination efforts in addition to routine programmes.

A one-year community study of under-fives in rural Ethiopia: patterns of morbidity and public health risk factors

A prospective weekly home surveillance study was undertaken to determine morbidity patterns within the Butajira Rural Health project in central Ethiopia. Overall prevalence of illness was 5.8% in 1216 person-years observed among rural Ethiopian children aged under 5 years. Acute respiratory infections (ARI) (prevalence 2.8%) and acute diarrhoea (2.4%) were the commonest conditions. Episodes of illness were distributed unequally among children, with a mean of 2.34 episodes per child. These included an average of 1.13 episodes of ARI (of which 0.16 had lower respiratory symptoms [ALRI]) and 1.17 episodes of acute diarrhoea. Sanitation factors were the principal risks for gastroenteritis, while living in rural areas predisposed children to ARI. Parental factors such as illiteracy were also linked to morbidity.

Field evaluation of WHO-MDT of fixed duration, at ALERT, Ethiopia: the AMFES project--II. Reaction and neuritis during and after MDT in PB and MB leprosy patients

For a cohort of 286 leprosy patients the incidence rates and clinical manifestations of leprosy reactions during treatment and surveillance are described. Currently, individual patients had been observed for up to 4 years. It is intended that surveillance within this project should continue for up to 5 years after treatment. Of 128 PB patients, observed for 267 person-years (mean 2.1) 27 had 35 episodes of reaction, corresponding to an overall incidence rate of 131 events per 1000 person-years-at-risk (pyar). Of 158 MB patients observed for 402 person years (mean 2.5), 64 had 114 reactions, with an overall incidence of 284 events per 1000 pyar. For both PB and MB patients, incidence rates during treatment and post-MDT surveillance were similar. For PB patients, pre-existing physical impairment at the start of MDT was a significant risk factor for the occurrence of subsequent events, but this was not found in MB patients.

Field evaluation of WHO-MDT of fixed duration at ALERT, Ethiopia: the AMFES project--I. MDT course completion, case-holding and another score for disability grading

We report on 286 new leprosy patients (128 PB, 158 MB) enrolled in the AMFES project, a field study in which patients are monitored during WHO-MDT and during 5 years thereafter, by active surveillance. This first paper describes the purposes, organization and methods of the study, patient enrollment and preliminary results of MDT completion and case-holding. Of 128 PB patients 102 (79.7%) completed MDT and of 91 on surveillance for more than 1 year, coverage with reviews had been good or very good for 31, fair or poor for 36 and very poor or nil for 21 PB patients. Of 158 MB patients 64 had completed MDT, and 26/128 (20.3%) PB and 18/158 (11.4%) MB patients were lost to follow-up during treatment, with 76 MB patients still on treatment. At first diagnosis, 159/286 (55.6%) had nerve function impairment, with no significant differences in disability grade by gender or between PB and MB patients. The proportion of disability grade 0 amongst new cases decreased very significantly with age, from 28/41 (68.3%) for age 0-14 years to 13/57 (22.8%) for 50 years and above. In view of the limitations of patient disability grades, a score per patient of the sum of disability grades for the four extremities, named 'HF-impairment score', is shown to be more informative. Incidence of leprosy reactions and neuritis in these patients, during treatment and during surveillance, is reported upon in Part II (on pp. 320-332 of this issue).

Field comparison of 10-g and 1-g filaments for the sensory testing of hands in Ethiopian leprosy patients

In ALERT's leprosy control programme sensory testing of hands and feet is done with a nylon filament giving a 10-g stimulus, but doubts arose that early partial sensory loss in hands would not thus be discovered. In order to evaluate the relative performance of 1-g and 10-g filaments for sensory testing on the palms of hands, both filaments were used separately in a series of 1,021 examinations on several consecutive occasions in 159 leprosy patients and 97 nonleprosy controls. The 1-g filament was always felt on normal hands and does not lead to false positive findings of nerve dysfunction. If the 1-g filament were used routinely, almost twice as many instances of 'neuritis' would be discovered and treated, if the criterion for diagnosis and treatment of new nerve dysfunction remained as it is for nerves tested with the 10-g filament. It appears desirable to distinguish between testing for early sensory loss and for loss of protective sensation. The two tests may each need their own instrument and separate recording of the results.

Daily morbidity records: recall and reliability

Methodological issues concerning the collection and analysis of daily morbidity data in community studies in developing countries are discussed. The effects of recall period and inter-observer variation on symptom prevalence are considered in the context of a longitudinal study in The Gambia, in which prevalence fell by about half over 1-week's recall. In the same study, many infant-days were recorded separately on two occasions, allowing an assessment of reliability in this type of morbidity diary data. The implications of these findings both in terms of data quality and cost-effectiveness are discussed, with the conclusion that weekly interviews examining the previous week's morbidity on a day-by-day basis are operationally optimal.

The immunogenicity and safety of Haemophilus influenzae type b-tetanus toxoid conjugate vaccine in Gambian infants

In developing countries, Haemophilus influenzae type b is a major cause of meningitis and pneumonia in the 1st year of life. The safety and immunogenicity of a Haemophilus influenzae type b polysaccharide-tetanus toxoid conjugate vaccine (PRP-T) were evaluated in two studies of Gambian infants. In the first study, 131 infants were recruited and randomized into three groups to receive PRP-T at 1 and 3 months (group A), PRP-T at 2 and 4 months (group B) or no PRP-T (group C). The liquid form of PRP-T was used. The geometric mean titre (GMT) of anti-PRP antibody 1 month after the second dose was 0.26 microgram/ml in group A and 0.41 microgram/ml in group B. In the second study, 66 infants were given PRP-T in the lyophilized form at 2, 3 and 4 months of age. The GMT 1 month after the first dose was 0.09 microgram/ml, after the second 0.74 microgram/ml and after the third 2.32 micrograms/ml. After the third dose, 72% of children had antibody levels greater than 1.0 microgram/ml and 93% greater than 0.15 microgram/ml. No serious side-effects were observed and the rate of adverse reactions was consistent with the concurrent administration of diphtheria-tetanus-pertussis (DPT) vaccine.