Malaria mortality in Africa and Asia: evidence from INDEPTH health and demographic surveillance system sites

Adult malaria mortality during 2019 at Bo Government Hospital, Sierra Leone

It is uncertain whether malaria is an important cause of death among adults in endemic areas. We performed a chart review of adults admitted to Bo Government Hospital during 2019. Of 893 admissions, 149 (59% female, mean age 58.5 years) had a laboratory diagnosis of malaria and 22 (14.8%) died. Mortality was significantly higher among patients with severe malaria compared with those who had non-severe malaria (6/20 [30%] versus 16/129 [12.4%], p=0.031).  Our results suggest that malaria is a common cause of death in hospitalized Sierra Leonian adults.

Service availability and readiness of malaria surveillance information systems implementation at primary health centers in Indonesia

One of the most important indicators in malaria eradication is the malaria surveillance information system (SISMAL) for recording and reporting medical cases. This paper aims to describe the availability and readiness of SISMALs at primary health centers (PHCs) in Indonesia. A cross-sectional survey was implemented in seven provinces for this study. The data was analyzed using bivariate, multivariate, and linear regression. The availability of the information system was measured by assessing the presence of the electronic malaria surveillance information system (E-SISMAL) at the studied PHCs. The readiness was measured by averaging each component of the assessment. From 400 PHC samples, only 58.5% had available SISMALs, and their level of readiness was only 50.2%. Three components had very low levels of readiness: (1) the availability of personnel (40.9%), (2) SISMAL integration and storage (50.2%), and (3) the availability of data sources and indicators (56.8%). Remote and border (DTPK) areas had a 4% better readiness score than non-DTPK areas. Endemic areas were 1.4% better than elimination areas, while regions with low financial capacity were 3.78% better than regions with high financial capacity, with moderate capacity (2.91%). The availability rate of the SISMAL at PHCs is only 58.5%. Many PHCs still do not have SISMALs. The readiness of the SISMAL at these PHCs is significantly related to DTPK/remote area, high endemicity status, and low financial capacity. This study found that the implementation of SISMAL is more accessible to malaria surveillance for the remote area and regions with low financial capacity. Therefore, this effort will well-fit to address barrier to malaria surveillance in developing countries.

Adult malaria mortality during 2019 at Bo Government Hospital, Sierra Leone

It is uncertain whether malaria is an important cause of death among adults in endemic areas. We performed a chart review of adults admitted to Bo Government Hospital during 2019. Of 893 admissions, 149 (59% female, mean age 58.5 years) had a laboratory diagnosis of malaria and 22 (14.8%) died. Mortality was significantly higher among patients with severe malaria compared with those who had non-severe malaria (6/20 [30%] versus 16/129 [12.4%], p=0.031).  Our results suggest that malaria is a common cause of death in hospitalized Sierra Leonian adults.

Harnessing the Potential of miRNAs in Malaria Diagnostic and Prevention

Despite encouraging progress over the past decade, malaria remains a major global health challenge. Its severe form accounts for the majority of malaria-related deaths, and early diagnosis is key for a positive outcome. However, this is hindered by the non-specific symptoms caused by malaria, which often overlap with those of other viral, bacterial and parasitic infections. In addition, current tools are unable to detect the nature and degree of vital organ dysfunction associated with severe malaria, as complications develop silently until the effective treatment window is closed. It is therefore crucial to identify cheap and reliable early biomarkers of this wide-spectrum disease. microRNAs (miRNAs), a class of small non-coding RNAs, are rapidly released into the blood circulation upon physiological changes, including infection and organ damage. The present review details our current knowledge of miRNAs as biomarkers of specific organ dysfunction in patients with malaria, and both promising candidates identified by pre-clinical models and important knowledge gaps are highlighted for future evaluation in humans. miRNAs associated with infected vectors are also described, with a view to expandind this rapidly growing field of research to malaria transmission and surveillance.

Surveillance strategies using routine microbiology for antimicrobial resistance in low- and middle-income countries

BACKGROUND

Routine microbiology results are a valuable source of antimicrobial resistance (AMR) surveillance data in low- and middle-income countries (LMICs) as well as in high-income countries. Different approaches and strategies are used to generate AMR surveillance data.

OBJECTIVES

We aimed to review strategies for AMR surveillance using routine microbiology results in LMICs and to highlight areas that need support to generate high-quality AMR data.

SOURCES

We searched PubMed for papers that used routine microbiology to describe the epidemiology of AMR and drug-resistant infections in LMICs. We also included papers that, from our perspective, were critical in highlighting the biases and challenges or employed specific strategies to overcome these in reporting AMR surveillance in LMICs.

CONTENT

Topics covered included strategies of identifying AMR cases (including case-finding based on isolates from routine diagnostic specimens and case-based surveillance of clinical syndromes), of collecting data (including cohort, point-prevalence survey, and case-control), of sampling AMR cases (including lot quality assurance surveys), and of processing and analysing data for AMR surveillance in LMICs.

IMPLICATIONS

The various AMR surveillance strategies warrant a thorough understanding of their limitations and potential biases to ensure maximum utilization and interpretation of local routine microbiology data across time and space. For instance, surveillance using case-finding based on results from clinical diagnostic specimens is relatively easy to implement and sustain in LMIC settings, but the estimates of incidence and proportion of AMR is at risk of biases due to underuse of microbiology. Case-based surveillance of clinical syndromes generates informative statistics that can be translated to clinical practices but needs financial and technical support as well as locally tailored trainings to sustain. Innovative AMR surveillance strategies that can easily be implemented and sustained with minimal costs will be useful for improving AMR data availability and quality in LMICs.

Malaria infection and severe disease risks in Africa

The relationship between community prevalence of Plasmodium falciparum and the burden of severe, life-threatening disease remains poorly defined. To examine the three most common severe malaria phenotypes from catchment populations across East Africa, we assembled a dataset of 6506 hospital admissions for malaria in children aged 3 months to 9 years from 2006 to 2020. Admissions were paired with data from community parasite infection surveys. A Bayesian procedure was used to calibrate uncertainties in exposure (parasite prevalence) and outcomes (severe malaria phenotypes). Each 25% increase in prevalence conferred a doubling of severe malaria admission rates. Severe malaria remains a burden predominantly among young children (3 to 59 months) across a wide range of community prevalence typical of East Africa. This study offers a quantitative framework for linking malaria parasite prevalence and severe disease outcomes in children.

Dendritic cell responses to Plasmodium falciparum in a malaria-endemic setting

Background

Plasmodium falciparum causes the majority of malaria cases worldwide and children in sub-Saharan Africa are the most vulnerable group affected. Non-sterile clinical immunity that protects from symptoms develops slowly and is relatively short-lived. Moreover, current malaria vaccine candidates fail to induce durable high-level protection in endemic settings, possibly due to the immunomodulatory effects of the malaria parasite itself. Because dendritic cells play a crucial role in initiating immune responses, the aim of this study was to better understand the impact of cumulative malaria exposure as well as concurrent P. falciparum infection on dendritic cell phenotype and function.

Methods

In this cross-sectional study, the phenotype and function of dendritic cells freshly isolated from peripheral blood samples of Malian adults with a lifelong history of malaria exposure who were either uninfected (n = 27) or asymptomatically infected with P. falciparum (n = 8) was assessed. Additionally, plasma cytokine and chemokine levels were measured in these adults and in Malian children (n = 19) with acute symptomatic malaria.

Results

With the exception of lower plasmacytoid dendritic cell frequencies in asymptomatically infected Malian adults, peripheral blood dendritic cell subset frequencies and HLA-DR surface expression did not differ by infection status. Peripheral blood myeloid dendritic cells of uninfected Malian adults responded to in vitro stimulation with P. falciparum blood-stage parasites by up-regulating the costimulatory molecules HLA-DR, CD80, CD86 and CD40 and secreting IL-10, CXCL9 and CXCL10. In contrast, myeloid dendritic cells of asymptomatically infected Malian adults exhibited no significant responses above the uninfected red blood cell control. IL-10 and CXCL9 plasma levels were elevated in both asymptomatic adults and children with acute malaria.

Conclusions

The findings of this study indicate that myeloid dendritic cells of uninfected adults with a lifelong history of malaria exposure are able to up-regulate co-stimulatory molecules and produce cytokines. Whether mDCs of malaria-exposed individuals are efficient antigen-presenting cells capable of mounting an appropriate immune response remains to be determined. The data also highlights IL-10 and CXCL9 as important factors in both asymptomatic and acute malaria and add to the understanding of asymptomatic P. falciparum infections in malaria-endemic areas.

Case Report: Sudden Splenic Rupture in a Plasmodium falciparum-Infected Patient

Spontaneous splenic rupture is a rare and life-threatening complication of severe malaria. It demands particular attention since delayed or missed diagnosis can be potentially fatal. The exact incidence is unknown largely due to underreporting. Acute malarial infection accounts for most of the spontaneous splenic rupture. Plasmodium vivax has been associated with the majority of them; however, on rare occasion, other Plasmodium infections have also resulted in splenic rupture. We report the case of a 74-year-old male who was diagnosed with severe malaria caused by Plasmodium falciparum (P. falciparum) infection and developed an acute abdomen while on treatment due to spontaneous splenic rupture which necessitated emergency splenectomy.

Malaria infection, disease and mortality among children and adults on the coast of Kenya

BACKGROUND

Malaria transmission has recently fallen in many parts of Africa, but systematic descriptions of infection and disease across all age groups are rare. Here, an epidemiological investigation of parasite prevalence, the incidence of fevers associated with infection, severe hospitalized disease and mortality among children older than 6 months and adults on the Kenyan coast is presented.

METHODS

A prospective fever surveillance was undertaken at 6 out-patients (OPD) health-facilities between March 2018 and February 2019. Four community-based, cross sectional surveys of fever history and infection prevalence were completed among randomly selected homestead members from the same communities. Paediatric and adult malaria at Kilifi county hospital was obtained for the 12 months period. Rapid Diagnostic Tests (CareStart™ RDT) to detect HRP2-specific to Plasmodium falciparum was used in the community and the OPD, and microscopy in the hospital. Crude and age-specific incidence rates were computed using Poisson regression.

RESULTS

Parasite prevalence gradually increased from childhood, reaching 12% by 9 years of age then declining through adolescence into adulthood. The incidence rate of RDT positivity in the OPD followed a similar trend to that of infection prevalence in the community. The incidence of hospitalized malaria from the same community was concentrated among children aged 6 months to 4 years (i.e. 64% and 70% of all hospitalized and severe malaria during the 12 months of surveillance, respectively). Only 3.7% (12/316) of deaths were directly attributable to malaria. Malaria mortality was highest among children aged 6 months-4 years at 0.57 per 1000 person-years (95% CI 0.2, 1.2). Severe malaria and death from malaria was negligible above 15 years of age.

CONCLUSION

Under conditions of low transmission intensity, immunity to disease and the fatal consequences of infection appear to continue to be acquired in childhood and faster than anti-parasitic immunity. There was no evidence of an emerging significant burden of severe malaria or malaria mortality among adults. This is contrary to current modelled approaches to disease burden estimation in Africa and has important implications for the targeting of infection prevention strategies based on chemoprevention or vector control.

Is Malaria an Important Cause of Death among Adults?

A long-held assumption has been that nearly all malaria deaths in high-transmission areas are of children younger than 5 years and pregnant women. Most global malaria mortality estimates incorporate this assumption in their calculations. In 2010, the Indian Million Death Study, which assigns cause of death by verbal autopsy (VA), challenged the reigning perception, producing a U-shaped mortality age curve, with rates rising after age 45 years in areas of India with substantial malaria transmission. Similar patterns are seen in Africa in the International Network for the Demographic Evaluation of Populations and Their Health (INDEPTH) network, also relying on VA. Whether these results are accurate or are misidentified deaths can be resolved by improving the evidence for assigning causes for adult acute infectious deaths in high malaria transmission areas. The options for doing so include improving the accuracy of VA and adding postmortem biological evidence, steps we believe should be initiated without delay.

Description of Plasmodium falciparum infections in central Gabon demonstrating high parasite densities among symptomatic adolescents and adults

BACKGROUND

Malaria remains a public health issue, particularly in sub-Saharan Africa with special features of seriousness in young children and pregnant women. Adolescents and adults are reported to have acquired a semi-immune status and, therefore, present with low parasitaemia. Children are understood to present with a much higher parasitaemia and severe malaria. It is a concern that effective malaria control programmes targeting young children may lead to a delay in the acquisition of acquired immunity and, therefore, causing a shift in the epidemiology of malaria. Prevalence and parasitaemia were explored in adolescents and adults with Plasmodium falciparum infections compared to young children in the area of Lambaréné, Gabon as an indicator for semi-immunity.

METHODS

A cross-sectional study was conducted at the Centre de Recherches Médicales de Lambaréné (CERMEL) during a 6-month period in 2018. Symptomatic patients, of all ages were screened for malaria at health facilities in Lambaréné and Fougamou and their respective surrounding villages in the central region of Gabon. Plasmodium falciparum infections were determined either by rapid diagnostic test (RDT) or by microscopy. Descriptive analysis of data on parasite densities, anaemia, and fever are presented.

RESULTS

1589 individuals screened were included in this analysis, including 731 (46%) adolescents and adults. Out of 1377 assessed, the proportion of P. falciparum positive RDTs was high among adolescents (68%) and adults (44%), compared to young children (55%) and school children (72%). Out of 274 participants assessed for malaria by microscopy, 45 (16%) had a parasite count above 10,000/µl of which 9 (20%) were adults.

CONCLUSION

This study shows a high rate of P. falciparum infections in adolescents and adults associated with high-level parasitaemia similar to that of young children. Adolescents and adults seem to be an at-risk population, suggesting that malaria programmes should consider adolescents and adults during the implementation of malaria prevention and case management programmes with continuous care, since they also act as reservoirs for P. falciparum.

Effects of insecticide-treated net access and use on infant mortality in Malawi: A pooled analysis of demographic health surveys

Malaria continues to be among the top causes of death in children and insecticide-treated nets (ITNs) are considered among the most effective malaria control methods. However, information on the association between universal ITN coverage and infant mortality is limited. A Cox proportional hazard model was applied to Malawi Demographic and Health Surveys to determine the association between ITN access and use and infant mortality between 2004 and 2015-2016. The overall infant mortality rate for the entire period was 47.9/1000 live births. Infants from the ITN-user households exhibited a lower risk of mortality [adjusted Hazard Ratio (aHR) = 0.61, 95% Confidence Interval (CI) = 0.44-0.85] than those from the ITN-nonuser households. Similarly, the infants from the high-access households exhibited a lower risk of death (aHR = 0.63, 95% CI = 0.46-0.86) than those from the no-access households. Infants from the ITN-user and high-access households exhibited a significantly lower risk of death (aHR = 0.57, 95% CI = 0.40-0.82) than those from the ITN-nonuser and no-access households. The relationship between ITN access and use and infant mortality was significant among female infants with a second or higher birth order and interval of ≥2 years. The findings of the present population-based study emphasized the importance of ITN access and use in providing optimal protection against malaria to infants in Malawi. Malaria control programs should ensure high ITN access and use in Malawi to reduce infant mortality.

Modelling the relationship between malaria prevalence as a measure of transmission and mortality across age groups

Background

Parasite prevalence has been used widely as a measure of malaria transmission, especially in malaria endemic areas. However, its contribution and relationship to malaria mortality across different age groups has not been well investigated. Previous studies in a health and demographic surveillance systems (HDSS) platform in western Kenya quantified the contribution of incidence and entomological inoculation rates (EIR) to mortality. The study assessed the relationship between outcomes of malaria parasitaemia surveys and mortality across age groups.

Methods

Parasitological data from annual cross-sectional surveys from the Kisumu HDSS between 2007 and 2015 were used to determine malaria parasite prevalence (PP) and clinical malaria (parasites plus reported fever within 24 h or temperature above 37.5 °C). Household surveys and verbal autopsy (VA) were used to obtain data on all-cause and malaria-specific mortality. Bayesian negative binomial geo-statistical regression models were used to investigate the association of PP/clinical malaria with mortality across different age groups. Estimates based on yearly data were compared with those from aggregated data over 4 to 5-year periods, which is the typical period that mortality data are available from national demographic and health surveys.

Results

Using 5-year aggregated data, associations were established between parasite prevalence and malaria-specific mortality in the whole population (RR_malaria = 1.66; 95% Bayesian Credible Intervals: 1.07–2.54) and children 1–4 years (RR_malaria = 2.29; 1.17–4.29). While clinical malaria was associated with both all-cause and malaria-specific mortality in combined ages (RR_all-cause = 1.32; 1.01–1.74); (RR_malaria = 2.50; 1.27–4.81), children 1–4 years (RR_all-cause = 1.89; 1.00–3.51); (RR_malaria = 3.37; 1.23–8.93) and in older children 5–14 years (RR_all-cause = 3.94; 1.34–11.10); (RR_malaria = 7.56; 1.20–39.54), no association was found among neonates, adults (15–59 years) and the elderly (60+ years). Distance to health facilities, socioeconomic status, elevation and survey year were important factors for all-cause and malaria-specific mortality.

Conclusion

Malaria parasitaemia from cross-sectional surveys was associated with mortality across age groups over 4 to 5 year periods with clinical malaria more strongly associated with mortality than parasite prevalence. This effect was stronger in children 5–14 years compared to other age-groups. Further analyses of data from other HDSS sites or similar platforms would be useful in investigating the relationship between malaria and mortality across different endemicity levels.

Electronic supplementary material

The online version of this article (10.1186/s12936-019-2869-9) contains supplementary material, which is available to authorized users.

Cause-specific mortality in the Kombewa health and demographic surveillance systems site, rural Western Kenya from 2011-2015

BACKGROUND

The vast majority of deaths in the health and Kombewa demographic surveillance system (HDSS) study area are not registered and reported through official systems of vital registration. As a result, few data are available regarding causes of death in this population.

OBJECTIVES

To describe causes of death among residents of all ages in the Kombewa HDSS, located in rural Western Kenya.

METHODS

Verbal autopsy (VA) interviews at the site were conducted using the modified 2007 and later 2012 standardized WHO questionnaires. Assignment of causes of death was made using the InterVA-4 model version 4.02. Cox regression model, adjusted for sex, was built to evaluate the influence of age on mortality.

RESULTS

There were a total of 5196 deaths recorded between 2011 and 2015 at the site. VA interviews were successfully completed for 3903 of these deaths (75.1%). Mortality rates were highest among neonates HR = 38.54 (<0.001) and among Infants HR = 2.07 (<0.006) in the Kombewa HDSS. Among those deaths in which VA was performed, the top causes of death were HIV/AIDS (12.6%), Malaria (10.3%), Pneumonia (10.1%), Acute abdomen (7.0%), Stroke (5.2%) and TB (4.9%) for the whole population in general. Stroke, acute abdomen heart diseases and Pneumonia were common causes of death (CODs) among the elderly over the age of 65.

CONCLUSIONS

The analysis established the main CODs among people of all ages within the area served by the Kombewa HDSS. We hope that information generated from this study will help better address preventable deaths in the surveyed community as well as help mitigate negative health impacts in other rural communities throughout the Western Kenya region.

Age, exposure and immunity

The acquisition of immunity to malaria by an individual depends on their age and the number of infectious mosquito bites they have received.

Elimination of Falciparum Malaria and Emergence of Severe Dengue: An Independent or Interdependent Phenomenon?

The global malaria burden, including falciparum malaria, has been reduced by 50% since 2000, though less so in Sub-Saharan Africa. Regional malaria elimination campaigns beginning in the 1940s, up-scaled in the 1950s, succeeded in the 1970s in eliminating malaria from Europe, North America, the Caribbean (except Haiti), and parts of Asia and South- and Central America. Dengue has grown dramatically throughout the pantropical regions since the 1950s, first in Southeast Asia in the form of large-scale epidemics including severe dengue, though mostly sparing Sub-Saharan Africa. Globally, the WHO estimates 50 million dengue infections every year, while others estimate almost 400 million infections, including 100 million clinical cases. Curiously, despite wide geographic overlap between malaria and dengue-endemic areas, published reports of co-infections have been scarce until recently. Superimposed acute dengue infection might be expected to result in more severe combined disease because both pathogens can induce shock and hemorrhage. However, a recent review found no reports on more severe morbidity or higher mortality associated with co-infections. Cases of severe dual infections have almost exclusively been reported from South America, and predominantly in persons infected by Plasmodium vivax. We hypothesize that malaria infection may partially protect against dengue – in particular falciparum malaria against severe dengue – and that this inter-species cross-protection may explain the near absence of severe dengue from the Sub-Saharan region and parts of South Asia until recently. We speculate that malaria infection elicits cross-reactive antibodies or other immune responses that infer cross-protection, or at least partial cross-protection, against symptomatic and severe dengue. Plasmodia have been shown to give rise to polyclonal B-cell activation and to heterophilic antibodies, while some anti-dengue IgM tests have high degree of cross-reactivity with sera from malaria patients. In the following, the historical evolution of falciparum malaria and dengue is briefly reviewed, and we explore early evidence of subclinical dengue in high-transmission malaria areas as well as conflicting reports on severity of co-morbidity. We also discuss examples of other interspecies interactions.

Framework for Evaluating the Health Impact of the Scale-Up of Malaria Control Interventions on All-Cause Child Mortality in Sub-Saharan Africa

Concerted efforts from national and international partners have scaled up malaria control interventions, including insecticide-treated nets, indoor residual spraying, diagnostics, prompt and effective treatment of malaria cases, and intermittent preventive treatment during pregnancy in sub-Saharan Africa (SSA). This scale-up warrants an assessment of its health impact to guide future efforts and investments; however, measuring malaria-specific mortality and the overall impact of malaria control interventions remains challenging. In 2007, Roll Back Malaria's Monitoring and Evaluation Reference Group proposed a theoretical framework for evaluating the impact of full-coverage malaria control interventions on morbidity and mortality in high-burden SSA countries. Recently, several evaluations have contributed new ideas and lessons to strengthen this plausibility design. This paper harnesses that new evaluation experience to expand the framework, with additional features, such as stratification, to examine subgroups most likely to experience improvement if control programs are working; the use of a national platform framework; and analysis of complete birth histories from national household surveys. The refined framework has shown that, despite persisting data challenges, combining multiple sources of data, considering potential contributions from both fundamental and proximate contextual factors, and conducting subnational analyses allows identification of the plausible contributions of malaria control interventions on malaria morbidity and mortality.

The long road to elimination: malaria mortality in a South African population cohort over 21 years

Background

Malaria elimination is on global agendas following successful transmission reductions. Nevertheless moving from low to zero transmission is challenging. South Africa has an elimination target of 2018, which may or may not be realised in its hypoendemic areas.

Methods

The Agincourt Health and Demographic Surveillance System has monitored population health in north-eastern South Africa since 1992. Malaria deaths were analysed against individual factors, socioeconomic status, labour migration and weather over a 21-year period, eliciting trends over time and associations with covariates.

Results

Of 13 251 registered deaths over 1.58 million person-years, 1.2% were attributed to malaria. Malaria mortality rates increased from 1992 to 2013, while mean daily maximum temperature rose by 1.5 °C. Travel to endemic Mozambique became easier, and malaria mortality increased in higher socioeconomic groups. Overall, malaria mortality was significantly associated with age, socioeconomic status, labour migration and employment, yearly rainfall and higher rainfall/temperature shortly before death.

Conclusions

Malaria persists as a small but important cause of death in this semi-rural South African population. Detailed longitudinal population data were crucial for these analyses. The findings highlight practical political, socioeconomic and environmental difficulties that may also be encountered elsewhere in moving from low-transmission scenarios to malaria elimination.

Malaria mortality characterization and the relationship between malaria mortality and climate in Chimoio, Mozambique

BACKGROUND

The United Nation's sustainable development goal for 2030 is to eradicate the global malaria epidemic, primarily as the disease continues to be one of the major concerns for public health in sub-Saharan Africa. In 2015, the region accounted for 90% of malaria deaths. Mozambique recorded a malaria mortality rate of 42.75 (per 100,000). In Chimoio, Mozambique's fifth largest city, malaria is the fourth leading cause of death (9.4%). Few data on malaria mortality exists in Mozambique, particularly in relation to Chimoio. The objective of this study was to characterize malaria mortality trends and its spatial distribution in Chimoio.

METHODS

Malaria mortality data and climate data were extracted from the Chimoio Civil Registration records, and the Regional Weather station, from 2010 to 2014. The malaria crude mortality rate was calculated. ANOVA, Tukey's, Chi square, and time series were carried out and an intervention analysis ARIMA model developed.

RESULTS

A total of 944 malaria death cases were registered in Chimoio, 729 of these among Chimoio residents (77%). The average malaria mortality by gender was 44.9% for females and 55.1% for males. The age of death varied from 0 to 96 years, with an average age of 25.9 (SE = 0.79) years old. January presented the highest average of malaria deaths, and urban areas presented a lower crude malaria mortality rate. Rural neighbourhoods with good accessibility present the highest malaria crude mortality rate, over 85 per 100,000. Seasonal ARMA (2,0)(1,0)₁₂ fitted the data although it was not able to capture malaria mortality peaks occurring during malaria outbreaks. Intervention effect properly fit the mortality peaks and reduced ARMA's root mean square error by almost 25%.

CONCLUSION

Malaria mortality is increasing in Chimoio; children between 1 and 4 years old represent 13% of Chimoio population, but account for 25% of malaria mortality. Malaria mortality shows seasonal and spatial characteristics. More studies should be carried out for malaria eradication in the municipality.

Under-five mortality rate variation between the Health and Demographic Surveillance System (HDSS) and Demographic and Health Survey (DHS) approaches

BACKGROUND

Several low and middle-income countries (LMIC) use Demographic and Health Surveys (DHS) and/or Health and Demographic Surveillance System (HDSS) to monitor the health of their population. The level and trends of under-five mortality rates could be different in the HDSS sites compared to the DHS reports. In this study, we investigated the change in under-five mortality rates overtime in the HDSS sites and the corresponding DHS reports in eight countries and 13 sites.

METHODS

Under-five mortality rates in the HDSS sites were determined using number of under-five deaths (numerator) and live births (denominator). The trends and annualized rate of change (ARC) of under-five mortality rates in the HDSS sites and the DHS reports were compared by fitting exponential function.

RESULTS

Under-five mortality rates declined substantially in most of the sites during the last 10-15 years. Ten out of 13 (77 %) HDSS sites have consistently lower under-five mortality rates than the DHS under-five mortality rates. In the Kilifi HDSS in Kenya, under-five mortality rate declined by 65.6 % between 2003 and 2014 with ARC of 12.2 % (95 % CI: 9.4-15.0). In the same period, the DHS under-five mortality rate in the Coastal region of Kenya declined by 50.8 % with ARC of 6 % (95 % CI: 2.0-9.0). The under-five mortality rate reduction in the Mlomp (78.1 %) and Niakhar (80.8 %) HDSS sites in Senegal during 1993-2012 was significantly higher than the mortality decline observed in the DHS report during the same period. On the other hand, the Kisumu HDSS in Kenya had lower under-five mortality reduction (15.8 %) compared to the mortality reduction observed in the DHS report (27.7 %) during 2003-2008. Under-five mortality rate rose by 27 % in the Agincourt HDSS in South Africa between 1998 to 2003 that was contrary to the 18 % under-five mortality reduction in the DHS report during the same period.

CONCLUSIONS

The inconsistency between HDSS and DHS approaches could have global implication on the estimation of child mortality and ethical issues on mortality inequalities. Further studies should be conducted to investigate the reasons of child mortality variation between the HDSS and the DHS approaches.

Community-Based Surveillance to Monitor Mortality in a Malaria-Endemic and Ebola-Epidemic Setting in Rural Guinea

Multiple community-based approaches can aid in quantifying mortality in the absence of reliable health facility data. Community-based sentinel site surveillance that was used to document mortality and the systems utility for outbreak detection was evaluated. We retrospectively analyzed data from 46 sentinel sites in three sous-préfectures with a reinforced malaria control program and one sous-préfecture without (Koundou) in Guinea. Deaths were recorded by key informants and classified as due to malaria or another cause. Malaria deaths were those reported as due to malaria or fever in the 3 days before death with no other known cause. Suspect Ebola virus disease (sEVD) deaths were those due to select symptoms in the EVD case definition. Deaths were aggregated by sous-préfecture and analyzed by a 6-month period. A total of 43,000 individuals were monitored by the surveillance system; 1,242 deaths were reported from July 2011-June 2014, of which 55.2% (N = 686) were reported as due to malaria. Malaria-attributable proportional mortality decreased by 26.5% (95% confidence interval [CI] = 13.9-33.1, P < 0.001) in the program area and by 6.6% (95% CI = -17.3-30.5, P = 0.589) in Koundou. Sixty-eight deaths were classified as sEVD and increased by 6.1% (95% CI = 1.3-10.8, P = 0.021). Seventeen sEVD deaths were reported from November 2013 to March 2014 including the first two laboratory-confirmed EVD deaths. Community surveillance can capture information on mortality in areas where data collection is weak, but determining causes of death remains challenging. It can also be useful for outbreak detection if timeliness of data collection and reporting facilitate real-time data analysis.

Diverse Empirical Evidence on Epidemiological Transition in Low- and Middle-Income Countries: Population-Based Findings from INDEPTH Network Data

Background

Low- and middle-income countries are often described as being at intermediate stages of epidemiological transition, but there is little population-based data with reliable cause of death assignment to examine the situation in more detail. Non-communicable diseases are widely seen as a coming threat to population health, alongside receding burdens of infection. The INDEPTH Network has collected empirical population data in a number of health and demographic surveillance sites in low- and middle-income countries which permit more detailed examination of mortality trends over time.

Objective

To examine cause-specific mortality trends across all ages at INDEPTH Network sites in Africa and Asia during the period 1992–2012. Emphasis is given to the 15–64 year age group, which is the main focus of concern around the impact of the HIV pandemic and emerging non-communicable disease threats.

Methods

INDEPTH Network public domain data from 12 sites that each reported at least five years of cause-specific mortality data were used. Causes of death were attributed using standardised WHO verbal autopsy methods, and mortality rates were standardised for comparison using the INDEPTH standard population. Annual changes in mortality rates were calculated for each site.

Results

A total of 96,255 deaths were observed during 9,487,418 person years at the 12 sites. Verbal autopsies were completed for 86,039 deaths (89.4%). There were substantial variations in mortality rates between sites and over time. HIV-related mortality played a major part at sites in eastern and southern Africa. Deaths in the age group 15–64 years accounted for 43% of overall mortality. Trends in mortality were generally downwards, in some cases quite rapidly so. The Bangladeshi sites reflected populations at later stages of transition than in Africa, and were largely free of the effects of HIV/AIDS.

Conclusions

To some extent the patterns of epidemiological transition observed followed theoretical expectations, despite the impact of the HIV pandemic having a major effect in some locations. Trends towards lower overall mortality, driven by decreasing infections, were the general pattern. Low- and middle-income country populations appear to be in an era of rapid transition.

Remotely Sensed Environmental Conditions and Malaria Mortality in Three Malaria Endemic Regions in Western Kenya

Background

Malaria is an important cause of morbidity and mortality in malaria endemic countries. The malaria mosquito vectors depend on environmental conditions, such as temperature and rainfall, for reproduction and survival. To investigate the potential for weather driven early warning systems to prevent disease occurrence, the disease relationship to weather conditions need to be carefully investigated. Where meteorological observations are scarce, satellite derived products provide new opportunities to study the disease patterns depending on remotely sensed variables. In this study, we explored the lagged association of Normalized Difference Vegetation Index (NVDI), day Land Surface Temperature (LST) and precipitation on malaria mortality in three areas in Western Kenya.

Methodology and Findings

The lagged effect of each environmental variable on weekly malaria mortality was modeled using a Distributed Lag Non Linear Modeling approach. For each variable we constructed a natural spline basis with 3 degrees of freedom for both the lag dimension and the variable. Lag periods up to 12 weeks were considered. The effect of day LST varied between the areas with longer lags. In all the three areas, malaria mortality was associated with precipitation. The risk increased with increasing weekly total precipitation above 20 mm and peaking at 80 mm. The NDVI threshold for increased mortality risk was between 0.3 and 0.4 at shorter lags.

Conclusion

This study identified lag patterns and association of remote- sensing environmental factors and malaria mortality in three malaria endemic regions in Western Kenya. Our results show that rainfall has the most consistent predictive pattern to malaria transmission in the endemic study area. Results highlight a potential for development of locally based early warning forecasts that could potentially reduce the disease burden by enabling timely control actions.

Analysis of Trend of Malaria Prevalence in the Ten Asian Countries from 2006 to 2011: A Longitudinal Study

Background. To control the malaria mortality, the global and national communities have worked together and produced impressive results in the world. Some of the Asian counties' malaria mortality rate is more compared to countries with high health facilities around the world. This paper's main aim is to describe trend of malaria cases and mortality in 10 Asian countries using the World Health Organization data. Methods. Malaria mortality data was collected systematically from WHO and UN database for the period 2006-2011. We estimated malaria mortality by age and countries. We also explored the dynamic relationships among malaria death rate, total populations, and geographical region using a map. During 2006-2011, the average malaria death per 10,000 population of all ages was 0.239 (95% CI 0.104 to 0.373), of children aged less than 5 year 1.143 (0.598 to 1.687), and of age greater than 5 years 0.089 (0.043 to 0.137) in Asian countries. Malaria prevalence per 10,000 populations steadily decreased from 486.7 in 2006 to 298.9 in 2011. Conclusion. The findings show that malaria mortality is higher for children aged less than 5 years compared with with adults selected in Asian countries except Sri Lanka.

Causes of death in the Taabo health and demographic surveillance system, Côte d'Ivoire, from 2009 to 2011

BACKGROUND

Current vital statistics from governmental institutions in Côte d'Ivoire are incomplete. This problem is particularly notable for remote rural areas that have limited access to the health system.

OBJECTIVE

To record all deaths from 2009 to 2011 and to identify the leading causes of death in the Taabo health and demographic surveillance system (HDSS) in south-central Côte d'Ivoire.

DESIGN

Deaths recorded in the first 3 years of operation of the Taabo HDSS were investigated by verbal autopsy (VA), using the InterVA-4 model. InterVA-4 is based on the World Health Organization 2012 VA tool in terms of input indicators and categories of causes of death.

RESULTS

Overall, 948 deaths were recorded, of which 236 (24.9%) had incomplete VA data. Among the 712 deaths analyzed, communicable diseases represented the leading causes (58.9%), with most deaths attributed to malaria (n=129), acute respiratory tract infections (n=110), HIV/AIDS (n=80), and pulmonary tuberculosis (n=46). Non-communicable diseases accounted for 18.9% of the deaths and included mainly acute abdomen (n=38), unspecified cardiac diseases (n=15), and digestive neoplasms (n=13). Maternal and neonatal conditions accounted for 8.3% of deaths, primarily pneumonia (n=19) and birth asphyxia (n=16) in newborns. Among the 3.8% of deaths linked to trauma and injury, the main causes were assault (n=6), accidental drowning (n=4), contact with venomous plants/animals (n=4), and traffic-related accidents (n=4). No clear causes were determined in 10.0% of the analyzed deaths.

CONCLUSIONS

Communicable diseases remain the predominant cause of death in rural Côte d'Ivoire. Based on these findings, measures are now being implemented in the Taabo HDSS. It will be interesting to monitor patterns of mortality and causes of death in the face of rapid demographic and epidemiological transitions in this part of West Africa.

Cause-specific mortality at INDEPTH Health and Demographic Surveillance System Sites in Africa and Asia: concluding synthesis

This synthesis brings together findings on cause-specific mortality documented by means of verbal autopsies applied to over 110,000 deaths across Africa and Asia, within INDEPTH Network sites.

Cause-specific mortality in Africa and Asia: evidence from INDEPTH health and demographic surveillance system sites

BACKGROUND

Because most deaths in Africa and Asia are not well documented, estimates of mortality are often made using scanty data. The INDEPTH Network works to alleviate this problem by collating detailed individual data from defined Health and Demographic Surveillance sites. By registering all deaths over time and carrying out verbal autopsies to determine cause of death across many such sites, using standardised methods, the Network seeks to generate population-based mortality statistics that are not otherwise available.

OBJECTIVE

To build a large standardised mortality database from African and Asian sites, detailing the relevant methods, and use it to describe cause-specific mortality patterns.

DESIGN

Individual demographic and verbal autopsy (VA) data from 22 INDEPTH sites were collated into a standardised database. The INDEPTH 2013 population was used for standardisation. The WHO 2012 VA standard and the InterVA-4 model were used for assigning cause of death.

RESULTS

A total of 111,910 deaths occurring over 12,204,043 person-years (accumulated between 1992 and 2012) were registered across the 22 sites, and for 98,429 of these deaths (88.0%) verbal autopsies were successfully completed. There was considerable variation in all-cause mortality between sites, with most of the differences being accounted for by variations in infectious causes as a proportion of all deaths.

CONCLUSIONS

This dataset documents individual deaths across Africa and Asia in a standardised way, and on an unprecedented scale. While INDEPTH sites are not constructed to constitute a representative sample, and VA may not be the ideal method of determining cause of death, nevertheless these findings represent detailed mortality patterns for parts of the world that are severely under-served in terms of measuring mortality. Further papers explore details of mortality patterns among children and specifically for NCDs, external causes, pregnancy-related mortality, malaria, and HIV/AIDS. Comparisons will also be made where possible with other findings on mortality in the same regions. Findings presented here and in accompanying papers support the need for continued work towards much wider implementation of universal civil registration of deaths by cause on a worldwide basis.

Cause-specific childhood mortality in Africa and Asia: evidence from INDEPTH health and demographic surveillance system sites

Background

Childhood mortality, particularly in the first 5 years of life, is a major global concern and the target of Millennium Development Goal 4. Although the majority of childhood deaths occur in Africa and Asia, these are also the regions where such deaths are least likely to be registered. The INDEPTH Network works to alleviate this problem by collating detailed individual data from defined Health and Demographic Surveillance sites. By registering deaths and carrying out verbal autopsies to determine cause of death across many such sites, using standardised methods, the Network seeks to generate population-based mortality statistics that are not otherwise available.

Objective

To present a description of cause-specific mortality rates and fractions over the first 15 years of life as documented by INDEPTH Network sites in sub-Saharan Africa and south-east Asia.

Design

All childhood deaths at INDEPTH sites are routinely registered and followed up with verbal autopsy (VA) interviews. For this study, VA archives were transformed into the WHO 2012 VA standard format and processed using the InterVA-4 model to assign cause of death. Routine surveillance data also provided person-time denominators for mortality rates. Cause-specific mortality rates and cause-specific mortality fractions are presented according to WHO 2012 VA cause groups for neonatal, infant, 1–4 year and 5–14 year age groups.

Results

A total of 28,751 childhood deaths were documented during 4,387,824 person-years over 18 sites. Infant mortality ranged from 11 to 78 per 1,000 live births, with under-5 mortality from 15 to 152 per 1,000 live births. Sites in Vietnam and Kenya accounted for the lowest and highest mortality rates reported.

Conclusions

Many children continue to die from relatively preventable causes, particularly in areas with high rates of malaria and HIV/AIDS. Neonatal mortality persists at relatively high, and perhaps sometimes under-documented, rates. External causes of death are a significant childhood problem in some settings.

Pregnancy-related mortality in Africa and Asia: evidence from INDEPTH Health and Demographic Surveillance System sites

Background

Women continue to die in unacceptably large numbers around the world as a result of pregnancy, particularly in sub-Saharan Africa and Asia. Part of the problem is a lack of accurate, population-based information characterising the issues and informing solutions. Population surveillance sites, such as those operated within the INDEPTH Network, have the potential to contribute to bridging the information gaps.

Objective

To describe patterns of pregnancy-related mortality at INDEPTH Network Health and Demographic Surveillance System sites in sub-Saharan Africa and southeast Asia in terms of maternal mortality ratio (MMR) and cause-specific mortality rates.

Design

Data on individual deaths among women of reproductive age (WRA) (15–49) resident in INDEPTH sites were collated into a standardised database using the INDEPTH 2013 population standard, the WHO 2012 verbal autopsy (VA) standard, and the InterVA model for assigning cause of death.

Results

These analyses are based on reports from 14 INDEPTH sites, covering 14,198 deaths among WRA over 2,595,605 person-years observed. MMRs varied between 128 and 461 per 100,000 live births, while maternal mortality rates ranged from 0.11 to 0.74 per 1,000 person-years. Detailed rates per cause are tabulated, including analyses of direct maternal, indirect maternal, and incidental pregnancy-related deaths across the 14 sites.

Conclusions

As expected, these findings confirmed unacceptably high continuing levels of maternal mortality. However, they also demonstrate the effectiveness of INDEPTH sites and of the VA methods applied to arrive at measurements of maternal mortality that are essential for planning effective solutions and monitoring programmatic impacts.