Peter Byass

Mortality and morbidity from malaria among children in a rural area of The Gambia, West Africa

Mortality and morbidity from malaria were measured among 3000 children under the age of 7 years in a rural area of The Gambia, West Africa. Using a post-mortem questionnaire technique, malaria was identified as the probable cause of 4% of infant deaths and of 25% of deaths in children aged 1 to 4 years. The malaria mortality rate was 6.3 per 1000 per year in infants and 10.7 per 1000 per year in children aged 1 to 4 years. Morbidity surveys suggested that children under the age of 7 years experienced about one clinical episode of malaria per year. Calculation of attributable fractions showed that malaria may be responsible for about 40% of episodes of fever in children. Although the overall level of parasitaemia showed little seasonal variation, the clinical impact of malaria was highly seasonal; all malaria deaths and a high proportion of febrile episodes were recorded during a limited period at the end of the rainy season.

Health and climate change: policy responses to protect public health

The 2015 Lancet Commission on Health and Climate Change has been formed to map out the impacts of climate change, and the necessary policy responses, in order to ensure the highest attainable stand ...

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

Abstract 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. Key messages Environmental development may have important effects on the epidemiology of vector borne diseases such as malaria This may be particularly important where disease transmission is unstable—for example, in highland areas Children in villages near recently constructed microdams in northern Ethiopia had a significantly increased risk of malaria It seems that this irrigation development programme is leading to increased malaria transmission across a range of altitudes and seasons Intersectoral collaboration is necessary in development projects that may affect communities both positively and negatively

TRIAL OF AN ATTENUATED BOVINE ROTAVIRUS VACCINE (RIT 4237) IN GAMBIAN INFANTS

A randomised, controlled trial of bovine rotavirus vaccine was undertaken in Gambian infants. Three doses were administered, from the age of ten weeks, concurrently with oral or killed polio vaccine. Prevaccination rotavirus neutralising antibody levels were high. 84/185 infants (45%) showed an increase in neutralising antibody titre after receiving rotavirus vaccine, compared with 20/91 (22%) unvaccinated infants. Clinical rotavirus infection was detected in 24/78 (31%) children in the rotavirus/oral polio group, 34/83 (41%) children in the placebo/oral polio group, and 23/92 (25%) children in the rotavirus/killed polio group, giving an overall vaccine efficacy of 33% (95% CI 4-53%). RIT 4237 did not appear to reduce the severity of clinical infections. Most cases (92%) were caused by rotaviruses with short RNA electropherotypes. Serological responses to rotavirus vaccination appeared unaffected by the concurrent administration of oral polio vaccine. Lower types 1 and 3 polio antibody levels were found in children who received oral polio and rotavirus vaccines but the differences were not statistically significant.

The INDEPTH Network: filling vital gaps in global epidemiology

INDEPTH Network, PO Box KD213, Kanda, Accra, Ghana, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa, Umeå Centre for Global Health Research, Department of Public Health and Clinical Medicine, Umeå University, Umeå 90187, Sweden and MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

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.

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/m2); 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.

The effects of malaria chemoprophylaxis given by traditional birth attendants on the course and outcome of pregnancy

A trial of malaria chemoprophylaxis given by traditional birth attendants was undertaken in a rural area of The Gambia where access to antenatal clinics is difficult. Women received one or more doses of Maloprim or placebo from a traditional birth attendant during 1049 of 1208 pregnancies (87%) recorded in 16 villages over a 3-year period. Primigravidae who received Maloprim had a lower parasite rate and a significantly higher mean packed cell volume than primigravidae who received placebo, and their babies were significantly heavier (6% low birth weight vs 22%). In multigravidae chemoprophylaxis reduced malaria parasitaemia but it had no beneficial effect on haemoglobin level and much less effect on birth weight than was observed in primigravidae. However, the mean birth weight of babies born to grandemultigravidae who received chemoprophylaxis was significantly higher than that of babies born to grandemultigravidae who did not.

Strengthening standardised interpretation of verbal autopsy data: the new InterVA-4 tool.

Background : Verbal autopsy (VA) is the only available approach for determining the cause of many deaths, where routine certification is not in place. Therefore, it is important to use standards and methods for VA that maximise efficiency, consistency and comparability. The World Health Organization (WHO) has led the development of the 2012 WHO VA instrument as a new standard, intended both as a research tool and for routine registration of deaths. Objective : A new public-domain probabilistic model for interpreting VA data, InterVA-4, is described, which builds on previous versions and is aligned with the 2012 WHO VA instrument. Design : The new model has been designed to use the VA input indicators defined in the 2012 WHO VA instrument and to deliver causes of death compatible with the International Classification of Diseases version 10 (ICD-10) categorised into 62 groups as defined in the 2012 WHO VA instrument. In addition, known shortcomings of previous InterVA models have been addressed in this revision, as well as integrating other work on maternal and perinatal deaths. Results : The InterVA-4 model is presented here to facilitate its widespread use and to enable further field evaluation to take place. Results from a demonstration dataset from Agincourt, South Africa, show continuity of interpretation between InterVA-3 and InterVA-4, as well as differences reflecting specific issues addressed in the design and development of InterVA-4. Conclusions : InterVA-4 is made freely available as a new standard model for interpreting VA data into causes of death. It can be used for determining cause of death both in research settings and for routine registration. Further validation opportunities will be explored. These developments in cause of death registration are likely to substantially increase the global coverage of cause-specific mortality data. To access the supplementary material to this article ‘The InterVA-4 User Guide’ please see Supplementary files under Article Tools online.

Setting international standards for verbal autopsy

In many countries most deaths occur at home. Such countries often have civil registration systems that are limited or non-existent and therefore most deaths go unrecorded. Countries that cannot record the number of people who die or why they die cannot realize the full potential of their health systems. Health systems need reliable numbers and causes of death to function properly. But in these circumstances – in the absence of a complete picture of the population’s health – there are tools and techniques that can be used to obtain a fairly accurate representation of mortality trends. It takes a long time for countries to achieve a fully functioning civil registration system with medical certification of cause of death. In the meantime, more and more countries are using verbal autopsies (VA) to meet the information needs of their health systems.1 Verbal autopsy is a method of ascertaining probable causes of a death based on an interview with primary caregivers about the signs, symptoms and circumstances preceding that death. Different institutions have been researching and developing all aspects of the verbal autopsy process over the past two decades. We have also been working on this process, particularly to improve the questionnaire and the methods of analysing the resulting information. However, this has been a largely uncoordinated effort and one that has not reached consensus on what to cover in the interview and how to analyse the results, despite previous attempts to promote standard tools.2–4 The main consequence of this failure to agree on a standard approach is that now we cannot compare results from different countries. Currently, 36 Demographic Surveillance Sites (DSS) in 20 countries, the Sample Registration System (SRS) sites in India, and the Disease Surveillance Points (DSP) in China regularly use VA on a large scale, primarily to assess the causes-of-death structure of a defined population.1 Despite such a widespread use of verbal autopsy, we are unable to assess how consistent and reliable the data are. We are also unable to replicate procedures used to assign cause of death. Because verbal autopsy data sets are not widely shared, it is impossible to independently assess the quality of the assignment. Really useful validation studies are rare and verbal autopsy research is often done on small and non-representative samples of the population. The Millennium Development Goals (MDG) have put pressure on countries to track their progress in terms of population health. But to track that progress, countries need reliable numbers. In other words, they need a strong empirical basis for cause-specific mortality data. This is essential for evaluating the impact of disease control programmes and major global health initiatives. One way of dealing with incomplete information is to use models of mortality patterns. But cause-of-death information predicted by such models is not suitable for monitoring progress on what works and what does not.5 That leaves verbal autopsy as the only practical option in these countries and one that will play a key role in tracking progress towards the MDGs. Agreement on a core set of verbal autopsy tools (including technical standards and guidelines for their use) and their widespread adoption is needed now. To tackle this challenge, WHO led an expert group of researchers, data users, and other stakeholders, with sponsorship from the Health Metrics Network (HMN), in developing the necessary standards. The expert group systematically reviewed, debated, and condensed the accumulated experience and evidence from the most widely-used and validated procedures. This synthesis was done to achieve a high degree of consistency and comparability across verbal autopsy data sets. WHO has now published the results of this collaboration as: Verbal autopsy standards: ascertaining and attributing cause of death. The new standards include: Verbal autopsy questionnaires for three age groups (under four weeks; four weeks to 14 years; and 15 years and above); Cause-of-death certification and coding resources consistent with the International Classification of Diseases and Related health Problems, tenth revision (ICD-10); and A cause-of-death list for verbal autopsy prepared according to the ICD-10. The content is freely available on the WHO web site (www.who.int) and will be distributed in print; and incorporated into HMN’s resource kit. This is an important publication, but it is not the last word on verbal autopsy methods. Research is needed to validate these standard core procedures in several countries with different patterns of mortality. Other areas of research include further development of items included in questionnaires, and automated methods for assigning causes of death from verbal autopsy that remove human bias, while producing replicable and valid results.6 Operational issues need addressing: sampling methods and size when using verbal autopsy tools in research demographic surveillance sites; sample or sentinel registration; censuses; and household surveys. Research is also required when adapting these questionnaires to specific situations in different countries, taking into account relevant cultural, epidemiological and administrative considerations. WHO is working with partners to do this research and develop guidelines on these issues. With time, this guidance and experience will better inform the users of verbal autopsy, and improve the comparability and consistency of its results. For the present, we urge that these new international consensus standards become the foundation of verbal autopsy practices wherever possible. ■