Epidemiological, clinical and biological features of malaria among children in Niamey, Niger

[Descriptive study of malaria cases in the paediatric population in a reference hospital in Valencia, Spain, between 1993 and 2015]

INTRODUCTION

Malaria is considered to be the fourth leading cause of infant mortality after pneumonia, complications related to premature birth, and perinatal asphyxia.

MATERIAL AND METHODS

A retrospective and descriptive study of cases of malaria confirmed and treated by the Paediatric Infectious Diseases Unit (age lower than 15 years) at the La Fe Hospital, Valencia, over the period 1993 to 2015.

RESULTS

A total of 54 cases of paediatric malaria were diagnosed in the period 1993-2015, with 51.8% of these occurring in males, and 46.2% of patients were aged below 5 years. The majority of children came from Equatorial Guinea (68.5%). Only 5.6% had received antimalarial prophylaxis. Plasmodium falciparum was found to be the causal species in 81.4% of cases. Seven patients (13%) presented with complicated malaria. The most widely used treatment was quinine, either alone or in combination with other drugs. Atovaquone/proguanil was used from 2010 onwards and was indicated in 20.3% of the patients. The combination of artesunate/piperaquine/dihydroartemisinin began to be used in 2013. No deaths or relevant side effects were reported, and the clinical response was favourable in all children (100%).

CONCLUSIONS

Malaria is still a prevalent disease in this population, a consequence of immigration, and tourism to endemic countries. Malaria should be considered as a likely diagnosis in a febrile child who comes from, or has travelled to, an endemic region in the past year.

Clinical and laboratory predictors of death in African children with features of severe malaria: a systematic review and meta-analysis

BACKGROUND

The criteria for defining severe malaria have evolved over the last 20 years. We aimed to assess the strength of association of death with features currently characterizing severe malaria through a systematic review and meta-analysis.

METHOD

Electronic databases (Medline, Embase, Cochrane Database of Systematic Reviews, Thomson Reuters Web of Knowledge) were searched to identify publications including African children with severe malaria. PRISMA guidelines were followed. Selection was based on design (epidemiological, clinical and treatment studies), setting (Africa), participants (children < 15 years old with severe malaria), outcome (survival/death rate), and prognostic indicators (clinical and laboratory features). Quality assessment was performed following the criteria of the 2011 Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). Odds ratios (ORs) were calculated for each study and prognostic indicator, and, when a test was assessed in at least two studies, pooled estimates of ORs were computed using fixed- or random-effects meta-analysis.

RESULTS

A total of 601 articles were identified and screened and 30 publications were retained. Features with the highest pooled ORs were renal failure (5.96, 95% CI 2.93-12.11), coma score (4.83, 95% CI 3.11-7.5), hypoglycemia (4.59, 95% CI 2.68-7.89), shock (4.31, 95% CI 2.15-8.64), and deep breathing (3.8, 95% CI 3.29-4.39). Only half of the criteria had an OR > 2. Features with the lowest pooled ORs were impaired consciousness (0.58, 95% CI 0.25-1.37), severe anemia (0.76, 95% CI 0.5- 1.13), and prostration (1.12, 95% CI 0.45-2.82).

CONCLUSION

The findings of this meta-analysis show that the strength of association between the criteria defining severe malaria and death is quite variable for each clinical and/or laboratory feature (OR ranging from 0.58 to 5.96). This ranking allowed the identification of features weakly associated with death, such as impaired consciousness and prostration, which could assist to improve case definition, and thus optimize antimalarial treatment.

Epidemiological and clinical profile of paediatric malaria: a cross sectional study performed on febrile children in five epidemiological strata of malaria in Cameroon

Background

In the wake of a decline in global malaria, it is imperative to describe the epidemiology of malaria in a country to inform control policies. The purpose of this study was to describe the epidemiological and clinical profile of paediatric malaria in five epidemiological strata of malaria in Cameroon including: the Sudano-sahelian (SS) strata, the High inland plateau (HIP) strata, the South Cameroonian Equatorial forest (SCEF) strata, the High western plateau (HWP) strata, and the Coastal (C) strata.

Methods

This study involved 1609 febrile children (≤15 years) recruited using reference hospitals in the five epidemiological strata. Baseline characteristics were determined; blood glucose level was measured by a glucometer, malaria parasitaemia was assessed by Giemsa microscopy, and complete blood count was performed using an automated hematology analyser. Severe malaria was assessed and categorized based on WHO criteria.

Results

An overall prevalence of 15.0% (95% CI: 13.3–16.9) for malaria was observed in this study. Malaria prevalence was significantly higher in children between 60 and 119 months (p < 0.001) and in Limbe (C strata) (p < 0.001). The overall rate of severe malaria (SM) attack in this study was 29.3%; SM was significantly higher in children below 60 months (p < 0.046). Although not significant, the rate of SM was highest in Maroua (SS strata) and lowest in Limbe in the C strata. The main clinical phenotypes of SM were hyperparasitaemia, severe malaria anaemia and impaired consciousness. The majority (73.2%) of SM cases were in group 1 of the WHO classification of severe malaria (i.e. the most severe form). The malaria case-fatality rate was 5.8%; this was higher in Ngaoundere (HIP strata) (p = 0.034).

Conclusion

In this study, malaria prevalence decreased steadily northward, from the C strata in the South to the SS strata in the North of Cameroon, meanwhile the mortality rate associated with malaria increased in the same direction. On the contrary, the rate of severe malaria attack was similar across the different epidemiological strata. Immunoepidemiological studies will be required to shed more light on the observed trends.

Clinical features and outcome in children with severe Plasmodium falciparum malaria: a meta-analysis

Background

Although global malaria mortality is declining, estimates may not reflect better inpatient management of severe malaria (SM) where reported case fatality rates (CFRs) vary from 1–25%.

Methods

A meta-analysis of prospective studies of SM was conducted to examine i) whether hypothesized differences between clinical features and outcome in Melanesian compared with African or Asian children really exist, and ii) to explore temporal changes in overall and complication-specific CFRs. The proportions of different SM complications and, overall and complication-specific CFRs were incorporated into the meta-analysis. Adjustments were made for study-level covariates including geographic region, SM definition, artemisinin treatment, median age of participants and time period.

Findings

Sixty-five studies were included. Substantial heterogeneity (I²>80%) was demonstrated for most outcomes. SM definition contributed to between-study heterogeneity in proportions of cerebral malaria (CM), metabolic acidosis (MA), severe anemia and overall CFR, whilst geographic region was a significant moderator in for CM and hypoglycemia (HG) rates. Compared with their African counterparts, Melanesian children had lower rates of HG (10% [CI95 7–13%] versus 1% [0–3%], P<0.05), lower overall CFR (2% [0–4%] versus 7% [6–9%], P<0.05) and lower CM-specific CFR (8% [0–17%] versus 19% [16–21%], P<0.05). There was no temporal trend for overall CFR and CM-specific CFR but declining HG- and MA- specific CFRs were observed.

Interpretation

These data highlight that recent estimates of declining global malaria mortality are not replicated by improved outcomes for children hospitalized with SM. Significant geographic differences in the complication rates and subsequent CFRs exist and provide the first robust confirmation of lower CFRs in Melanesian children, perhaps due to less frequent HG.

Predictive value of fever and palmar pallor for P. falciparum parasitaemia in children from an endemic area

INTRODUCTION

Although the incidence of Plasmodium falciparum malaria in some parts of sub-Saharan Africa is reported to decline and other conditions, causing similar symptoms as clinical malaria are gaining in relevance, presumptive anti-malarial treatment is still common. This study traced for age-dependent signs and symptoms predictive for P. falciparum parasitaemia.

METHODS

In total, 5447 visits of 3641 patients between 2-60 months of age who attended an outpatient department (OPD) of a rural hospital in the Ashanti Region, Ghana, were analysed. All Children were examined by a paediatrician and a full blood count and thick smear were done. A Classification and Regression Tree (CART) model was used to generate a clinical decision tree to predict malarial parasitaemia a7nd predictive values of all symptoms were calculated.

RESULTS

Malarial parasitaemia was detected in children between 2-12 months and between 12-60 months of age with a prevalence of 13.8% and 30.6%, respectively. The CART-model revealed age-dependent differences in the ability of the variables to predict parasitaemia. While palmar pallor was the most important symptom in children between 2-12 months, a report of fever and an elevated body temperature of ≥37.5°C gained in relevance in children between 12-60 months. The variable palmar pallor was significantly (p<0.001) associated with lower haemoglobin levels in children of all ages. Compared to the Integrated Management of Childhood Illness (IMCI) algorithm the CART-model had much lower sensitivities, but higher specificities and positive predictive values for a malarial parasitaemia.

CONCLUSIONS

Use of age-derived algorithms increases the specificity of the prediction for P. falciparum parasitaemia. The predictive value of palmar pallor should be underlined in health worker training. Due to a lack of sensitivity neither the best algorithm nor palmar pallor as a single sign are eligible for decision-making and cannot replace presumptive treatment or laboratory diagnosis.

Significance of travel to rural areas as a risk factor for malarial anemia in an urban setting

The epidemiology of malaria in urban environments is poorly characterized, yet increasingly problematic. We conducted an unmatched case-control study of risk factors for malarial anemia with high parasitemia in urban Kisumu, Kenya, from June 2002 through February 2003. Cases (n = 80) were hospital patients with a hemoglobin level < or = 8 g/dL and a Plasmodium parasite density > or = 10,000/microL. Controls (n = 826) were healthy respondents to a concurrent citywide knowledge, attitude, and practice survey. Children who reported spending at least one night per month in a rural area were especially at risk (35% of cases; odds ratio = 9.3, 95% confidence interval [CI] = 4.4-19.7, P < 0.0001), and use of mosquito coils, bed net ownership, and house construction were non-significant, potentially indicating that malaria exposure during rural travel comprises an important element of risk. Control of severe malaria in an urban setting may be complicated by Plasmodium infections acquired elsewhere. Epidemiologic studies of urban malaria in low transmission settings should take travel history into account.

Malaria is associated with poor school performance in an endemic area of the Brazilian Amazon

Background

Approximately 40% of the world's population is at risk for malaria. In highly endemic tropical areas, malaria is a major cause of morbidity and mortality during infancy. There is a complex interrelationship between malaria, malnutrition and intestinal helminths, and this may impair cognitive development in children. The aim of this study was to determine the relationship between malaria and school performance in children living in an endemic area where Plasmodium vivax is the species responsible for most of the cases.

Methods

The study was conducted in the Municipality of Careiro, Amazonas, Brazil, with five to14 year-old children, studying the first eight grades of public school, during the year 2008. After an initial active case detection, during nine months of follow-up, passive malaria cases detection was instituted, through a thick blood smear performed in every child with fever. School performance was evaluated by the final notes in Mathematics and Portuguese Language. Performance was considered poor when either of the final notes in these disciplines was below the 50^th percentile for the respective class and grade.

Results

The total number of students followed-up in the cohort was 198. Malarial attacks were reported in 70 (35.4%) of these students, with no cases of severe disease. Plasmodium vivax was detected in 69.2% of the attacks, Plasmodium falciparum in 25.5% and both species in 5.3%. In the multivariate analysis, adjusting for age, mother's education, time living in the study area and school absenteeism, presenting with at least one episode of malaria independently predicted a poor performance at school [OR = 1.91 (1.04-3.54); p = 0.039].

Conclusion

Non-severe malaria compromises the school performance of children even during a nine-month follow-up, potentially contributing to the maintenance of underdevelopment in countries endemic for malaria. This is the first evidence of such impact in Latin America, where P. vivax is responsible for the majority of the cases.

Field-based evidence of fast and global increase of Plasmodium falciparum drug-resistance by DNA-microarrays and PCR/RFLP in Niger

Background

Over the last years, significant progress has been made in the comprehension of the molecular mechanism of malaria resistance to drugs. Together with in vivo tests, the molecular monitoring is now part of the survey strategy of the Plasmodium sensitivity. Currently, DNA-microarray analysis allows the simultaneous study of many single nucleotide polymorphisms (SNP) of Plasmodium isolates. In December 2005, the International Federation of the Red Cross distributed two million three hundred thousand long-lasting insecticide nets to pregnant women and mothers of under five years children in the whole Niger. Then, Niger adopted artemisinin-based combination therapy as first-line treatment.

Methods

Thirty four SNPs of pfcrt, pfdhfr, pfdhps, pfmdr and pfATPase were analysed by DNA-microarray and PCR/RFLP in two villages – Zindarou and Banizoumbou – with different durations of malaria transmission. The main objective of the study was to measure the dynamics of Plasmodium falciparum resistant strains and associated factors.

Results

This study shows a global and clear increase of the drug-resistance associated molecular markers frequencies during a relatively short-time period of four years. Markers associated with resistance to chloroquine and sulphonamids were more frequently found in the short transmission zone than in the long transmission one. The pfcrt76T mutation is significantly more present at Banizoumbou than Zindarou (38.3% vs 25.2%, p = 0.013).

This work allowed the screening of several field strains for five SNPs of PfATPase6 gene. The pfATPase6S769N, candidate mutation of resistance to artemisinin was not found. However the pfATPsaeA623E mutation was found in 4.7% of samples.

Conclusion

A significant increase of several SNPs frequencies was highlighted over a four-year period. The polymorphism of five PfATPase6 gene SNPs was described. The global, large and fast increase of the molecular resistance is discussed in the context of current changes of health policy and malaria control in Niger.

Age patterns of severe paediatric malaria and their relationship to Plasmodium falciparum transmission intensity

Background

The understanding of the epidemiology of severe malaria in African children remains incomplete across the spectrum of Plasmodium falciparum transmission intensities through which communities might expect to transition, as intervention coverage expands.

Methods

Paediatric admission data were assembled from 13 hospitals serving 17 communities between 1990 and 2007. Estimates of Plasmodium falciparum transmission intensity in these communities were assembled to be spatially and temporally congruent to the clinical admission data. The analysis focused on the relationships between community derived parasite prevalence and the age and clinical presentation of paediatric malaria in children aged 0–9 years admitted to hospital.

Results

As transmission intensity declined a greater proportion of malaria admissions were in older children. There was a strong linear relationship between increasing transmission intensity and the proportion of paediatric malaria admissions that were infants (R² = 0.73, p < 0.001). Cerebral malaria was reported among 4% and severe malaria anaemia among 17% of all malaria admissions. At higher transmission intensity cerebral malaria was a less common presentation compared to lower transmission sites. There was no obvious relationship between the proportions of children with severe malaria anaemia and transmission intensity.

Conclusion

As the intensity of malaria transmission declines in Africa through the scaling up of insecticide-treated nets and other vector control measures a focus of disease prevention among very young children becomes less appropriate. The understanding of the relationship between parasite exposure and patterns of disease risk should be used to adapt malaria control strategies in different epidemiological settings.

A census-weighted, spatially-stratified household sampling strategy for urban malaria epidemiology

BACKGROUND

Urban malaria is likely to become increasingly important as a consequence of the growing proportion of Africans living in cities. A novel sampling strategy was developed for urban areas to generate a sample simultaneously representative of population and inhabited environments. Such a strategy should facilitate analysis of important epidemiological relationships in this ecological context.

METHODS

Census maps and summary data for Kisumu, Kenya, were used to create a pseudo-sampling frame using the geographic coordinates of census-sampled structures. For every enumeration area (EA) designated as urban by the census (n = 535), a sample of structures equal to one-tenth the number of households was selected. In EAs designated as rural (n = 32), a geographically random sample totalling one-tenth the number of households was selected from a grid of points at 100 m intervals. The selected samples were cross-referenced to a geographic information system, and coordinates transferred to handheld global positioning units. Interviewers found the closest eligible household to the sampling point and interviewed the caregiver of a child aged < 10 years. The demographics of the selected sample were compared with results from the Kenya Demographic and Health Survey to assess sample validity. Results were also compared among urban and rural EAs.

RESULTS

4,336 interviews were completed in 473 of the 567 study area EAs from June 2002 through February 2003. EAs without completed interviews were randomly distributed, and non-response was approximately 2%. Mean distance from the assigned sampling point to the completed interview was 74.6 m, and was significantly less in urban than rural EAs, even when controlling for number of households. The selected sample had significantly more children and females of childbearing age than the general population, and fewer older individuals.

CONCLUSION

This method selected a sample that was simultaneously population-representative and inclusive of important environmental variation. The use of a pseudo-sampling frame and pre-programmed handheld GPS units is more efficient and may yield a more complete sample than traditional methods, and is less expensive than complete population enumeration.

Malaria importada: revisión epidemiológica y clínica de una enfermedad emergente cada vez más frecuente

OBJECTIVE

To describe the epidemiology, clinical and laboratory features and outcome of children younger than 15 years with malaria in our hospital.

MATERIAL AND METHODS

A retrospective case review of all children admitted to our hospital with malaria between 1997 and 2005 was performed. The following epidemiological data were analyzed: age, sex, nationality of the child and of the family, country and date of trip, chemoprophylaxis used, clinical features, laboratory parameters (hemogram and biochemistry), type of plasmodium and degree of parasitization, treatment, associated diseases, length of hospital stay, and outcome.

RESULTS

A total of 24 children (16 boys) were diagnosed (median age, 6.5 years). All of the patients were immigrants or were the children of sub-Saharian immigrants. Thirteen patients had traveled to a malaria-endemic country during the summer holidays. Eleven children started chemoprophylaxis, but only two completed the whole course. The most common symptoms were fever (21 patients) and gastrointestinal symptoms (16 patients). Nineteen patients had anemia and six had thrombocytopenia. The most common species identified was Plasmodium falciparum (19 patients). After treatment, outcome was satisfactory in 21 patients. One patient had recurrence at 3 months, another showed sequelae, and one died after 30 days.

CONCLUSIONS

Most children with imported malaria in our area were immigrants or the children of immigrants. Although treatment response is usually satisfactory, rapid diagnosis of this disease in the emergency room of any hospital capable of treating these patients is required.

Field-based evidence for the linkage of pfcrt and pfdhfr drug-resistant malaria genotypes and clinical profiles of severe malaria in Niger

Drug resistance has been shown to increase malaria mortality and morbidity in both community- and hospital-based studies. We investigated the association between two Plasmodium falciparum drug resistance-related molecular markers and clinical profiles of severe malaria in children hospitalised in Niger. PCR-RFLP analysis showed that the codon 108 mutation of the pfdhfr gene was positively linked to severe malarial anaemia. These findings are consistent with persistent parasite infection leading to unbalanced anaemia in young children. No significant relationship was found between the molecular markers and hypoglycaemia or hyperparasitaemia. Conversely, the pfcrt T76 mutation was found to be negatively associated with cerebral malaria and neurological symptoms, such as convulsions and coma. These results have implications for the strain-specific virulence hypothesis and for parasite fitness and evolution. Our findings are discussed in regard to the local malaria transmission level.