Seasonal variation in child mortality in rural Guinea-Bissau

Discovering Subgroups of Children With High Mortality in Urban Guinea-Bissau: Exploratory and Validation Cohort Study

BACKGROUND

The decline in global child mortality is an important public health achievement, yet child mortality remains disproportionally high in many low-income countries like Guinea-Bissau. The persisting high mortality rates necessitate targeted research to identify vulnerable subgroups of children and formulate effective interventions.

OBJECTIVE

This study aimed to discover subgroups of children at an elevated risk of mortality in the urban setting of Bissau, Guinea-Bissau, West Africa. By identifying these groups, we intend to provide a foundation for developing targeted health interventions and inform public health policy.

METHODS

We used data from the health and demographic surveillance site, Bandim Health Project, covering 2003 to 2019. We identified baseline variables recorded before children reached the age of 6 weeks. The focus was on determining factors consistently linked with increased mortality up to the age of 3 years. Our multifaceted methodological approach incorporated spatial analysis for visualizing geographical variations in mortality risk, causally adjusted regression analysis to single out specific risk factors, and machine learning techniques for identifying clusters of multifactorial risk factors. To ensure robustness and validity, we divided the data set temporally, assessing the persistence of identified subgroups over different periods. The reassessment of mortality risk used the targeted maximum likelihood estimation (TMLE) method to achieve more robust causal modeling.

RESULTS

We analyzed data from 21,005 children. The mortality risk (6 weeks to 3 years of age) was 5.2% (95% CI 4.8%-5.6%) for children born between 2003 and 2011, and 2.9% (95% CI 2.5%-3.3%) for children born between 2012 and 2016. Our findings revealed 3 distinct high-risk subgroups with notably higher mortality rates, children residing in a specific urban area (adjusted mortality risk difference of 3.4%, 95% CI 0.3%-6.5%), children born to mothers with no prenatal consultations (adjusted mortality risk difference of 5.8%, 95% CI 2.6%-8.9%), and children from polygamous families born during the dry season (adjusted mortality risk difference of 1.7%, 95% CI 0.4%-2.9%). These subgroups, though small, showed a consistent pattern of higher mortality risk over time. Common social and economic factors were linked to a larger share of the total child deaths.

CONCLUSIONS

The study's results underscore the need for targeted interventions to address the specific risks faced by these identified high-risk subgroups. These interventions should be designed to work to complement broader public health strategies, creating a comprehensive approach to reducing child mortality. We suggest future research that focuses on developing, testing, and comparing targeted intervention strategies unraveling the proposed hypotheses found in this study. The ultimate aim is to optimize health outcomes for all children in high-mortality settings, leveraging a strategic mix of targeted and general health interventions to address the varied needs of different child subgroups.

Overall effect of a campaign with measles vaccine on the composite outcome mortality or hospital admission: A cluster-randomized trial among children aged 9-59 months in rural Guinea-Bissau

OBJECTIVES

Campaigns with measles vaccine (C-MV) are conducted to eradicate measles, but prior studies indicate that MV reduces non-measles mortality and hospital admissions too. We hypothesized that C-MV reduces death/hospital admission by 30%.

METHODS

Between 2016-2019, we conducted a non-blinded cluster-randomized trial randomizing village clusters in rural Guinea-Bissau to a C-MV targeting children aged 9-59 months. In Cox proportional hazards models, we assessed the effect of C-MV, obtaining hazard ratios (HR) for the composite outcome (death/hospital admission). We also examined potential effect modifiers.

RESULTS

Among 18,411 children (9636 in 111 intervention clusters/8775 in 110 control clusters), 379 events occurred (208 intervention/171 control) during a median follow-up period of 22 months. C-MV did not reduce the composite outcome (HR 1.12, 95% confidence interval 0.88-1.41). Mortality among enrolled children (5.3 intervention and 4.6 control, per 1000 person-years) was approximately half the pre-trial mortality rate (11.1 intervention and 8.9 control, per 1000 person-years). Neither planned nor explorative analyses of potential effect modifiers explained the contrasting results to prior studies.

CONCLUSION

C-MV did not reduce overall mortality or hospital admission. This might be explained by changes in disease patterns, baseline differences in health status, and/or modifying effects of other campaigns during follow-up.

Understanding the child mortality decline in Guinea-Bissau: the role of population-level nutritional status measured by mid-upper arm circumference

BACKGROUND

Malnutrition is considered an important contributing factor to child mortality, and the mid-upper arm circumference (MUAC) is regarded as one of the better anthropometric predictors of child mortality. We explored whether the decline in child mortality over recent decades could be explained by changes in children's MUAC.

METHODS

This prospective study analysed individual-level data from 47 731 children from the capital of Guinea-Bissau followed from 3 months until 36 months of age over 2003 to 2016. We used standardization to compare the mortality rate as if only the MUAC distribution had changed between an early period (2003-05) and a late period (2014-16). We adjusted the analyses for age, sex, socioeconomic-related possessions and maternal education.

RESULTS

A total of 949 deaths were included in the analysis. The adjusted mortality rate was 18.9 [95% confidence interval (CI) 14.3-23.3] deaths per 1000 person-years (pyrs) in the early period and declined to 4.4 (95% CI 2.9-6.0) deaths per 1000 pyrs in the late period, a 77% (95% CI 71-83%) reduction in the mortality rate. At all calendar years, the MUAC distribution in the population was close to the WHO reference population. MUAC below -1 z-score was associated with increased child mortality. The change in MUAC distribution from the early period to the late period (in the early period mortality standardization) corresponded to 1.5 (95% CI 1.0-2.2) fewer deaths per 1000 pyrs, equivalent to 11% (95% CI 7-14%) of the observed change in child mortality.

CONCLUSIONS

From 2003 to 2016, child mortality in urban Guinea-Bissau declined considerably but, though a low MUAC was associated with increased mortality, changes in the MUAC distribution in the population explained little of the decline. Understanding the driving factors of child mortality decline can help scope tomorrow's interventions.

Prevalence, risk factors and health consequences of soil-transmitted helminth infection on the Bijagos Islands, Guinea Bissau: A community-wide cross-sectional study

Soil-transmitted helminths (STH) are endemic and widespread across Sub-Saharan Africa. A community wide soil-transmitted helminth (STH) prevalence survey was performed on the island of Bubaque in Guinea-Bissau using both Kato-katz microscopy and qPCR methodology. Predictors of infection and morbidity indicators were identified using multivariable logistic regression, and diagnostic methods were compared using k statistics. Among 396 participants, prevalence of STH by microscopy was 23.2%, hookworm was the only species identified by this method and the mean infection intensity was 312 eggs per gram. qPCR analysis revealed an overall prevalence of any STH infection of 47.3%, with the majority A. duodenale (32.3%), followed by N. americanus (15.01%) and S. stercoralis (13.2%). A. lumbricoides, and T. trichiura infections were negligible, with a prevalence of 0.25% each. Agreement between diagnostic tests was k = 0.22, interpreted as fair agreement, and infection intensity measured by both methods was only minimally correlated (Rs = -0.03). STH infection overall was more common in females and adults aged 31-40. STH infection was associated with open defaecation, low socio-economic status and further distance to a water-source. The prevalence of anaemia (defined as a binary outcome by the WHO standards for age and sex) was 69.1%, and 44.2% of children were malnourished according to WHO child growth standards. Hookworm infection intensity by faecal egg count showed no statistically significant association with age (Rs 0.06) but S. Stercoralis infection intensity by qPCR cycle threshold was higher in pre-school aged children (Rs = 0.30, p-value 0.03) There was no statistically significant association between STH infection and anaemia (OR 1.0 p = 0.8), stunting (OR 1.9, p-value 0.5) and wasting (OR 2.0, p-value 0.2) in children. This study reveals a persistent reservoir of STH infection across the community, with high rates of anaemia and malnutrition, despite high-coverage of mebendazole mass-drug administration in pre-school children. This reflects the need for a new strategy to soil-transmitted helminth control, to reduce infections and ultimately eliminate transmission.

Effect of Seasonal Variations on Infant Mortality Rate of Some Selected Districts of Jammu Division

BACKGROUND

The infant and child mortality rates are considered as sensitive indicators of living and socioeconomic conditions of a country. The infant mortality rate is regarded as most of the revealing measures of how well a society is meeting the needs of its people.

OBJECTIVE

The purpose of the study is to determine the effect of seasonal variations on the infant mortality in some selected districts of Jammu Division, J&K.

METHODOLOGY

In the present study, infant mortality data were collected for the 6 consecutive years (2013-2018) from different health centers of four districts of Jammu Division and Jammu Municipal Corporation (JMC), J&K. The seasonal variations of overall infant deaths were analyzed using the monthly mortality data collected for the study period. Poisson regression model was employed to measure the seasonal effects on the overall infant deaths. Data analysis was done using software IBM SPSS 24.0.

RESULTS

In this study, a total of 4443 infant deaths were recorded from selected districts of Jammu Division, J&K, from the year 2013-2018. The prevalence of infant deaths was extremely high in the month of January as compared to the reference month June. Furthermore, the parameter estimates for each of the months along with 95% Wald confidence interval were calculated.

CONCLUSIONS

The present study concludes that seasonal variations significantly affect the infant mortality in Jammu Division, J&K, India. The policymakers must consider the effect of seasons on infant mortality as children in their 1st year of life are more susceptible toward environmental conditions.

Seasonal variation in the non-specific effects of BCG vaccination on neonatal mortality: three randomised controlled trials in Guinea-Bissau

The BCG vaccine protects non-specifically against other diseases than tuberculosis. Three randomised controlled trials of early BCG in Guinea-Bissau found a 38% reduction in all-cause neonatal mortality. Little is known about the underlying mechanisms. In Guinea-Bissau, prevalent infectious diseases display distinct seasonality. Revisiting the three trials (>6500 infants) comparing early BCG versus no early BCG in low weight infants on all-cause neonatal mortality over 12 consecutive years, we explored the seasonal variation in BCG’s effect on mortality. In a subgroup of participants, adaptive and innate cytokine responses were measured 4 weeks after randomisation. Consistently over the course of the three trials and 12 years, the effect of BCG on all-cause neonatal mortality was particularly beneficial when administered in November to January, coincident with peaking malaria infections. During these months, BCG was also associated with stronger proinflammatory responses to heterologous challenge. Recent studies have suggested a protective effect of BCG against malaria. BCG may also ameliorate immune-compromising fatal effects of placental malaria in the newborn.

Research protocol of two concurrent cluster-randomized trials: Real-life Effect of a CAMPaign with Measles Vaccination (RECAMP-MV) and Real-life Effect of a CAMPaign with Oral Polio Vaccination (RECAMP-OPV) on mortality and morbidity among children in rural Guinea-Bissau

BACKGROUND

Measles and oral polio vaccinations may reduce child mortality to an extent that cannot be explained by prevention of measles and polio infections; these vaccines seem to have beneficial non-specific effects. In the last decades, billions of children worldwide have received measles vaccine (MV) and oral polio vaccine (OPV) through campaigns. Meanwhile the under-five child mortality has declined. Past MV and OPV campaigns may have contributed to this decline, even in the absence of measles and polio infections. However, cessation of these campaigns, once their targeted infections are eradicated, may reverse the decline in the under-five child mortality. No randomized trial has assessed the real-life effect of either campaign on child mortality and morbidity. We present the research protocol of two concurrent trials: RECAMP-MV and RECAMP-OPV.

METHODS

Both trials are cluster-randomized trials among children registered in Bandim Health Project's rural health and demographic surveillance system throughout Guinea-Bissau. RECAMP-MV is conducted among children aged 9-59 months and RECAMP-OPV is conducted among children aged 0-8 months. We randomized 222 geographical clusters to intervention or control clusters. In intervention clusters, children are offered MV or OPV (according to age at enrolment) and a health check-up. In control clusters, children are offered only a health check-up. Enrolments began in November 2016 (RECAMP-MV) and March 2017 (RECAMP-OPV). We plan 18,000 enrolments for RECAMP-MV with an average follow-up period of 18 months and 10,000 enrolments for RECAMP-OPV with an average follow-up period of 10 months. Data collection is ongoing. The primary outcome in both trials is non-accidental death or non-accidental first non-fatal hospitalization with overnight stay (composite outcome). Secondary outcomes are: non-accidental death, repeated non-fatal hospitalizations with overnight stay, cause-specific primary outcome, outpatient visit, and illness. We obtained ethical approval from Guinea-Bissau and consultative approval from Denmark.

DISCUSSION

Cluster randomization and minimum risk of loss to follow-up are strengths, and no placebo a limitation. Our trials challenge the understanding that MV and OPV only prevent measles and polio, and that once both infections are eradicated, campaigns with MV and OPV can be phased out without negative implications on child health and survival.

TRIAL REGISTRATION

NCT03460002.

A Two-Center Randomized Trial of an Additional Early Dose of Measles Vaccine: Effects on Mortality and Measles Antibody Levels

Background

In addition to protecting against measles, measles vaccine (MV) may have beneficial nonspecific effects. We tested the effect of an additional early MV on mortality and measles antibody levels.

Methods

Children aged 4-7 months at rural health and demographic surveillance sites in Burkina Faso and Guinea-Bissau were randomized 1:1 to an extra early standard dose of MV (Edmonston-Zagreb strain) or no extra MV 4 weeks after the third diphtheria-tetanus-pertussis-hepatitis B-Haemophilus influenzae type b vaccine. All children received routine MV at 9 months. We assessed mortality through home visits and compared mortality from enrollment to age 3 years using Cox proportional hazards models, censoring for subsequent nontrial MV. Subgroups of participants had blood sampled to assess measles antibody levels.

Results

Among 8309 children enrolled from 18 July 2012 to 3 December 2015, we registered 145 deaths (mortality rate: 16/1000 person-years). The mortality was lower than anticipated and did not differ by randomization group (hazard ratio, 1.05; 95% confidence interval, 0.75-1.46). At enrollment, 4% (16/447) of children in Burkina Faso and 21% (90/422) in Guinea-Bissau had protective measles antibody levels. By age 9 months, no measles-unvaccinated/-unexposed child had protective levels, while 92% (306/333) of early MV recipients had protective levels. At final follow-up, 98% (186/189) in the early MV group and 97% (196/202) in the control group had protective levels.

Conclusions

Early MV did not reduce all-cause mortality. Most children were susceptible to measles infection at age 4-7 months and responded with high antibody levels to early MV.

Clinical Trials Registration

NCT01644721.

Prevalence and potential risk factors for gastrointestinal parasitic infections in children in urban Bissau, Guinea-Bissau

BACKGROUND

Gastrointestinal (GI) parasitic infections cause significant morbidity and mortality in tropical and subtropical countries. We aimed to investigate the prevalence of GI parasitic infections in children from Bissau, Guinea-Bissau and to identify the possible risk factors for these infections.

METHODS

We performed an observational study on two comparable cohorts of children 2-15 y of age: one study covering health care-seeking children (n=748) and one study covering children from the background population (n=851). A total of 1274 faecal samples from the two cohorts were investigated for parasites by microscopy and the risk factors for infection were identified by logistic regression.

RESULTS

Intestinal parasitic infections were found in 54.8% of health care-seeking children and 55.5% of children from the background population. Helminth infections were more common among health care-seeking children and were mainly due to hookworms. Pathogenic protozoa included Entamoeba histolytica/dispar and Giardia lamblia. The risk factors for infections included increasing age, household crowding and poor sanitation and water supply.

CONCLUSIONS

We found a high prevalence of intestinal parasites among both health care-seeking children and children from the background population. Compared with previous studies, we found a decreasing prevalence of intestinal helminths. This study further identifies potential risk factors for infections, including inadequate sanitation and water supply.

Cohort profile : Bandim Health Project's (BHP) rural Health and Demographic Surveillance System (HDSS)-a nationally representative HDSS in Guinea-Bissau

PURPOSE

Bandim Health Project (BHP) monitors health and survival of women and children in a nationally representative rural Health and Demographic Surveillance System (HDSS) in Guinea-Bissau. The HDSS was set up in 1989-1990 to collect data on health interventions and child mortality.

PARTICIPANTS

The HDSS covers 182 randomly selected clusters across the whole country. The cohort is open, and women and children enter the cohort, when they move into the selected clusters, and leave the cohort, when they move out or die, or when children reach 5 years of age. Data are collected through biannual or more frequent household visits. At all village visits, information on pregnancies, vital status, vaccination status, arm circumference, use of bed nets and other basic information is collected for women and children. Today, more than 25 000 women and 23 000 children below the age of 5 years are under surveillance.

FINDINGS TO DATE

Research from the BHP has given rise to the hypothesis that vaccines, in addition to their targeted effects, have important non-specific effects altering the susceptibility to other infections. Initially, it was observed that mortality among children vaccinated with the live BCG or measles vaccines was much lower than the mortality among unvaccinated children, a difference, which could not be explained by prevention of tuberculosis and measles infections. In contrast, mortality tended to be higher for children who had received the non-live Diphtheria-Tetanus-Pertussis vaccine compared with children who had not received this vaccine. Since the effect differed for the different vaccines, no bias explained the contrasting findings.

FUTURE PLANS

New health interventions are introduced with little assessment of real-life effects. Through the HDSS, we can describe both the implementation of interventions (eg, the vaccination programme) and their effects. Furthermore, the intensive follow-up allows the implementation of randomised trials testing potential better vaccination programmes.