Epidemiology of malaria in the Taabo health and demographic surveillance system, south-central Côte d'Ivoire

Perceived water-related risk factors of Buruli ulcer in two villages of south-central Côte d'Ivoire

BACKGROUND

Buruli ulcer, caused by Mycobacterium ulcerans, is a neglected tropical skin disease that is primarily endemic in West and Central Africa, including Côte d'Ivoire. Studies indicate that M. ulcerans infections are caused by contact with an environmental reservoir of the bacteria, governed by specific human biological conditions. Yet, the nature of this reservoir and the exact mode of transmission remain unknown.

METHODOLOGY

To identify ecologic risk factors of Buruli ulcer in south-central Côte d'Ivoire, we pursued a qualitative study matched with geo-referencing inquiry. Embedded in a broader integrated wound management research project, we (i) mapped households and water sources of laboratory confirmed Buruli ulcer cases and (ii) interviewed 12 patients and four health care workers to assess exposure to surface water and to deepen the understanding of perceived transmission pathways.

PRINCIPAL FINDINGS

Water availability, accessibility, and affordability were reported as key determinants for choosing water resources. Furthermore, perceived risks were related to environmental, structural, and individual factors. Despite the presence of improved water sources (e.g., drilled wells), communities heavily relied on unprotected surface water for a multitude of activities. The nearby Bandama River and seasonal waterbodies were frequently used for washing, bathing, and collection of water for drinking and cooking. Many residents also reported to cross the river on a daily basis for agricultural chores, and hence, are exposed to stagnant water during farming activities.

CONCLUSIONS/SIGNIFICANCE

Our study in two Buruli ulcer endemic villages in south-central Côte d'Ivoire revealed a wide range of water-related domestic activities that might expose people to an increased risk of contracting the disease. Environmental, biological, social, and cultural risk factors are closely interlinked and should be considered in future investigations of Buruli ulcer transmission. Active participation of the communities is key to better understand their circumstances to advance research and fight against Buruli ulcer and other neglected tropical diseases.

Spatiotemporal analysis of malaria incidence in Côte d'Ivoire from 2015 to 2019

Background

The collection of malaria cases over time allows the identification of areas with the highest incidence. Our objective was to characterize the spatial distribution of malaria in Côte d’Ivoire from 2015 to 2019 at the health district level.

Methods

Data on the number of reported malaria cases confirmed by rapid diagnostic test (RDT) in the general population, the number of patients attending medical consultations and the total population by health district and year were collected from the National Malaria Control Program in Côte d’Ivoire. Crude and adjusted incidence rates were estimated for each health district and year. Adjusted incidence rates were used to perform global (Moran's index) and local indicators of spatial autocorrelation (LISA) analyses.

Results

Between 2015 and 2019, mean crude incidence rates increased from 155.5‰ to 229.8‰. We observed significant heterogeneity in malaria incidence rates across the study period and within a given year. The overall Moran index showed spatial autocorrelation for every year analysed except 2017. The LISA analysis showed that the health districts with high incidence rates were concentrated in the western zone of Côte d'Ivoire.

Conclusions

The use of spatial analyses to identify the areas with the highest malaria incidence rates is a relevant approach to optimize control measures in targeted areas.

Prevalence of Schistosoma mono- and co-infections with multiple common parasites and associated risk factors and morbidity profile among adults in the Taabo health and demographic surveillance system, South-Central Côte d'Ivoire

Background

Schistosomiasis remains an important public health problem, also among adults, and infected individuals not treated serve as a reservoir for continued transmission. Despite this fact, evidence on the epidemiology of schistosomiasis in adults in Côte d’Ivoire is scanty. This study aimed to determine the prevalence and risk factors of Schistosoma infection and co-infection with other helminth species and Plasmodium among adults in the Taabo region in the south-central part of Côte d’Ivoire.

Methods

A cross-sectional survey was carried out in April and May 2017 in the frame of the “Côte d’Ivoire Dual Burden of Disease Study” (CoDuBu). A total of 901 randomly selected individuals, aged 18–90 years, provided blood, stool and urine samples for the diagnosis of malaria and helminth infections. Stool samples were subjected to the Kato-Katz technique for detection of Schistosoma mansoni and soil-transmitted helminth eggs, while urine samples were examined for eggs of Schistosoma haematobium and circulating cathodic antigen of S. mansoni. Risk factors and morbidity profiles were assessed using health examination and questionnaires. Multinomial logistic regressions were employed to identify risk factors and morbidity patterns associated with S. mansoni mono- and co-infections.

Results

The prevalence of S. mansoni and S. haematobium was 23.2% and 1.0%, respectively. Most S. mansoni were mono-infections (81.3%). Independent determinants of S. mansoni infection were young age, low socioeconomic status (mono- and co-infection) and poor hygiene practices (co-infection) (P < 0.05). S. mansoni infection was independently associated with higher pain and symptom scores (mono-infection), poor self-rated health and low healthcare use (co-infection) (P < 0.05).

Conclusions

This study showed that adults represent a substantial reservoir of S. mansoni. To sustain schistosomiasis control and improve people’s wellbeing, it is important to expand preventive chemotherapy from school-aged children to adults, coupled with hygiene and health education.

Seasonal prevalence of Plasmodium falciparum infection and use of insecticide-treated nets among children in three agroecosystems in Aboisso, Côte d'Ivoire

Agroecosystems have been associated with risk of malaria. The aim of this study was to determine the relationship between three agroecosystems: (i) rubber plantation (RP); (ii) oil palm plantation (OPP); (iii) no cash crop plantation (NCCP) and the prevalence of Plasmodium falciparum infection among children living in the Aboisso region. In the three villages within (Ehania-V5) or close (N'zikro) or far from (Ayébo) to each agroecosystem (RP, OPP, and NCCP), two cross-sectional parasitological surveys were carried out during the dry and the peak of the long wet seasons. A total of 586 children aged 1-14 years were recruited in the three villages to determine the prevalence of malaria using conventional microscopy. Plasmodium falciparum was the dominant species with an overall infection prevalence of 40.8%. There was a significant difference in prevalence between agroecosystems, during both the dry (p = 0.002) and wet seasons (p < 0.001), which was higher in agricultural settings compared with the NCCP environment, whatever the season. The prevalence of P. falciparum infection increased from the dry to the wet season in agricultural settings (RP and OPP), whereas no difference was noted for NCCP. Less than 18% of children use insecticide-treated nets (ITNs) in the three villages, ranging from 6 (in RP) to 30% (in OPP). Multivariate analysis indicated that age (1-4; 5-9; and 10-14 years) was not associated with malaria risk, but the season and living in agricultural villages were associated with a greater risk of malaria infection. Risk of malaria exposure was fourfold higher in children from agricultural villages than their counterpart from the non-agricultural area. Our findings highlight significant variations in the prevalence of P. falciparum according to agroecosystem and season. The findings will be useful in designing and implementing malaria control interventions by the National Malaria Control Program.

Assessment of the burden of malaria and bacteraemia by retrospective molecular diagnosis in febrile illnesses and first-line anti-infectives in Côte d'Ivoire

BACKGROUND

The aetiologies of fever are poorly understood in sub-Saharan Africa. We aimed to assess the burden of malaria and bacteria in Côte d'Ivoire.

METHODS

Blood samples from 438 febrile and 346 afebrile people were screened using molecular tools.

RESULTS

Plasmodium falciparum was the most common microorganism associated with fever (46.8% in febrile, 23.4% in afebrile people; p < 0.001). Bacteraemia was detected in 21.7% of febrile people and 12.7% of afebrile people (p = 0.001). Streptococcus pneumoniae was the main cause of bacteraemia (7.1% of febrile and 0.6% of afebrile individuals; p < 0.001). Non-typhoidal Salmonella spp. was detected in 4.5% of febrile people and 1.2% of afebrile individuals (p < 0.001). Salmonella enterica Typhi and S. enterica Paratyphi were only detected in febrile subjects (1.4% and 2.1%), as well as Tropheryma whipplei (0.9%), Streptococcus pyogenes (0.7%), and Plasmodium ovale (4.6%). The prevalence in febrile and afebrile people was similar for Staphylococcus aureus (3.6-4.9%), Rickettsia felis (5.5-6.4%), Mansonella perstans (3.0-3.2%), and Plasmodium malariae (1.6-2.3%). Comorbidities were higher in febrile than in afebrile subjects (10.3% versus 5.5%; p = 0.01); 82% involving P. falciparum. All patients co-infected with P. falciparum and S. pneumoniae were febrile whereas 30% of those infected by P. falciparum alone were not (p = 0.02). Among febrile participants, 30.4% with malaria and 54.7% with bacteraemia had received neither antimalarial nor antibiotic therapy.

CONCLUSION

Identification of etiologies of acute febrile diseases in sub-Saharan Africa proposes keys to successful treatment and prevention of infectious diseases. Vaccination campaigns may decrease the morbidity of mono- and co-infections by preventable microorganisms.

Epidemiological links between malaria parasitaemia and hypertension: findings from a population-based survey in rural Côte d'Ivoire

Background:

Although potential links between malaria parasitaemia and hypertension have been hypothesized, there is paucity of epidemiologic evidence on this link. We investigated in a population-based survey, the association between malaria parasitaemia and hypertension in Ivorian adults.

Methods:

We estimated the adjusted odds ratios (OR) and 95% confidence intervals (CI) of hypertension in relation to malaria parasitaemia using multinomial regression, in 997 randomly selected adults in the ‘Côte d’Ivoire Dual Burden of Disease Study’ (CoDuBu), in south-central Côte d’Ivoire. We defined malaria parasitaemia as a positive rapid diagnostic test or identification of Plasmodium spp. on microscopy. Using the mean of the last two of three blood pressure (BP) measurements and questionnaire data, we defined hypertension as SBP at least 140 mmHg or DBP at least 90 mmHg or clinician-diagnosed hypertension.

Results:

Prevalence of malaria parasitaemia and hypertension were 10 and 22%, respectively. Malaria parasitaemia was negatively associated with hypertension in participants with body temperature 36.5 °C or less [OR 0.23 (95% CI 0.06–0.84)]. Contrastingly, microscopic malaria parasitaemia showed positive associations with hypertension in participants with elevated body temperature [>36.5 °C; OR: 2.93 (95% CI 0.94–9.14)]. Participants having microscopic malaria parasitaemia with elevated body temperature had three-fold higher odds of hypertension [OR: 3.37 (95% CI 1.12–10.0)] than malaria parasitaemia-negatives with lower body temperature.

Conclusion:

Malaria parasitaemia and hypertension are prevalent and seemingly linked comorbidities in African settings. This link may depend on malaria parasitaemia symptomaticity/latency where individuals with more latent/asymptomatic malaria parasitaemia have lower risk of hypertension and those with more acute/symptomatic malaria parasitaemia have a tendency toward higher BP. The cross-sectional nature of the study limited the distinction of short-term BP elevation (interim pathophysiological stress) from hypertension development. Future longitudinal studies considering malaria/hypertension phenotypes and host molecular variations are needed to clarify involved biological mechanisms, toward comorbidity management.

Asymptomatic Plasmodium infection and glycemic control in adults: Results from a population-based survey in south-central Côte d'Ivoire

AIMS

We investigated the cross-sectional associations of Plasmodium infection (PI) with fasting glucose (FG) and glycated hemoglobin (HbA1c) in malaria-endemic south-central Côte d'Ivoire.

METHODS

We studied 979 participants (non-pregnant; no treated diabetes; 51% males; 18-87 years) of the Côte d'Ivoire Dual Burden of Disease study. Fasting venous blood was obtained for PI, FG, and HbA1c assessment. We defined PI as a positive malaria rapid diagnostic test (RDT) or microscopic identification of Plasmodium species. We applied multivariable linear regressions to assess beta coefficients (β) and 95% confidence intervals (CIs) of PI positivity for FG and HbA1c independent of diabetes risk factors.

RESULTS

Prevalence of PI was 10.1% (5.5% microscopy; 9.7% RDT) without clinical fever. Prevalence of FG-based prediabetes (45.8%) and diabetes (3.6%) were considerably higher than HbA1c-based values (2.7% and 0.7%, respectively). PI was independently associated with FG among participants with higher body temperature (β 0.34, 95% CI 0.06-0.63, p_{heterogeneity} = 0.028), or family history of diabetes (β 0.88, 95% CI 0.28-1.47, p_{heterogeneity} = 0.009). Similar patterns observed with HbA1c were obliterated on accounting for FG. We also observed consistent associations with parasite density.

CONCLUSIONS

FG-based diabetes diagnosis in the presence of asymptomatic PI may misclassify or overestimate diabetes burden in malaria-endemic settings. Longitudinal studies are needed to confirm these findings and determine the risk for diabetes.

Evaluation de la capacité opérationnelle des établissements sanitaires de première ligne dans la prise en charge du paludisme en Côte d’Ivoire

Introduction

Les établissements de santé (ES) possèdent-ils les ressources de base pour la prise en charge des cas de paludisme? L’objectif de notre étude était d’analyser la Capacité Opérationnelle (CO) des ES de première ligne de la Côte d’Ivoire dans la prise en charge du paludisme.

Méthodes

La méthodologie SARA a été utilisée pour réaliser une étude transversale descriptive du 10 au 30 juillet 2016. La CO pour la prise en charge du paludisme a exprimé la disponibilité moyenne de 9 éléments traceurs répartis en 3 domaines: (i) personnel et directives; (ii) capacité de diagnostic; (iii) médicaments et produits. Cette CO a été évaluée par le calcul d’un indice puis comparé entre les ES selon l’instance gestionnaire et la zone géographique à l’aide du test du Chi2 pour un risque de première espèce α fixé à 0,05.

Résultats

Parmi les 818 ES, 651(79,6%) étaient du secteur public et 487(59,5%) situés en zone rurale. La CO des ES de première ligne était de 74,5%. Cette CO était plus élevée dans le public (81,3%) que dans le privé (48,8%) (p < 10^-3) ainsi qu’en zone rurale (82,7%) par rapport à la zone urbaine (62,9%) (p < 10^-3).

Conclusion

Les ES de première ligne de la Côte d’Ivoire disposaient en 2016 des ressources de base pour une prise en charge des cas de paludisme. Il est nécessaire de mettre l’accent sur le renforcement du système de santé dans son ensemble en plus de la prévention.

Antagonistic effects of Plasmodium-helminth co-infections on malaria pathology in different population groups in Côte d'Ivoire

Introduction

Plasmodium spp. and helminths are co-endemic in many parts of the tropics; hence, co-infection is a common phenomenon. Interactions between Plasmodium and helminth infections may alter the host’s immune response and susceptibility and thus impact on morbidity. There is little information on the direction and magnitude of such interactions and results are conflicting. This study aimed at shedding new light on the potential interactions of Plasmodium and helminth co-infections on anemia and splenomegaly in different population groups in Côte d’Ivoire.

Methodology

Parasitologic and clinical data were obtained from four cross-sectional community-based studies and a national school-based survey conducted between 2011 and 2013 in Côte d’Ivoire. Six scenarios of co-infection pairs defined as Plasmodium infection or high parasitemia, combined with one of three common helminth infections (i.e., Schistosoma mansoni, S. haematobium, and hookworm) served for analysis. Adjusted logistic regression models were built for each scenario and interaction measures on additive scale calculated according to Rothman et al., while an interaction term in the model served as multiplicative scale measure.

Principal findings

All identified significant interactions were of antagonistic nature but varied in magnitude and species combination. In study participants aged 5–18 years from community-based studies, Plasmodium-hookworm co-infection showed an antagonistic interaction on additive scale on splenomegaly, while Plasmodium-Schistosoma co-infection scenarios showed protective effects on multiplicative scale for anemia and splenomegaly in participants aged 5–16 years from a school-based study.

Conclusions/Significance

No exacerbation from co-infection with Plasmodium and helminths was observed, neither in participants aged 5–18 years nor in adults from the community-based studies. Future studies should unravel underlying mechanisms of the observed interactions, as this knowledge might help shaping control efforts against these diseases of poverty.

Malaria (due to infection with Plasmodium spp.) and parasitic worms (for example soil-transmitted helminths and Schistosoma spp.) are common in the tropics. Hence, people are often co-infected, depending on various factors. Interactions between Plasmodium and helminth infections may alter immune response and susceptibility of the infected host, and thus impact on morbidity by either making it worse (synergism) or by reducing it (antagonism). Although these co-infections are common, little is known about the direction and magnitude of such interactions. To deepen the understanding of how co-infection could affect morbidity in infected people, we looked at clinical data (i.e., anemia and splenomegaly) in different population groups in Côte d’Ivoire. We did not observe any exacerbation from co-infection with Plasmodium and helminths; all identified significant interactions were of antagonistic nature but varied in magnitude and parasite combination. In the light of enhanced control efforts targeting helminthiases, a better understanding about potential effects on susceptibility to malaria in co-endemic areas should be gained and intervention strategies against the two type of diseases be planned in a more integrative manner.

Low rates of Plasmodium falciparum Pfcrt K76T mutation in three sentinel sites of malaria monitoring in Côte d'Ivoire

Despite efforts to eliminate it, malaria remains a major public health concern, particularly in Côte d'Ivoire. Chloroquine (CQ) was one of the first drugs used for its treatment, but was officially withdrawn from the market in 2007 following reports of high levels of chloroquine resistance. The present study was carried out after the withdrawal of CQ and provides an update on the rates of CQ resistance in Côte d'Ivoire. Samples were collected between September 2013 and March 2014 in Abidjan and from January to May 2016 in Abengourou and San Pedro through cross-sectional studies. Parasitemia was assessed by microscopy, and single nucleotide polymorphism in the Pfcrt (codon 76) gene was analyzed by nested PCR and restriction fragment length polymorphism. A total of 343 samples were analyzed: 119, 106 and 118 were from Abidjan, Abengourou, and San Pedro, respectively. The sex ratio of patients was 0.92. The mean age of patients enrolled was 9.6 years (SD = 10.8). The geometric mean of parasite density was 21,337 parasites/μL (SD = 49,508; range, 2,000-200,000). Molecular analysis revealed 57 K76T mutants (16.6%): 33, 9, and 15 in Abidjan, Abengourou and in San Pedro, respectively. Most of these were found in patients aged ≤15 years (42/57) who had parasitemia greater than 10,000 parasites/μL (40/57). This is the first study conducted in Côte d'Ivoire reporting a decline in Pfcrt K76T mutation rate. Thus, our results indicate the importance of following up on the observed trend also at a national level.

Repeated doses of Praziquantel in Schistosomiasis Treatment (RePST) - single versus multiple praziquantel treatments in school-aged children in Côte d'Ivoire: a study protocol for an open-label, randomised controlled trial

Background

Large scale administration of the anthelminthic drug praziquantel (PZQ) to at-risk populations is the cornerstone of schistosomiasis control, although persisting high prevalence of infections in some areas and growing concerns of PZQ resistance have revealed the limitations of this strategy. Most studies assessing PZQ efficacy have used relatively insensitive parasitological diagnostics, such as the Kato-Katz (KK) and urine-filtration methods, thereby overestimating cure rates (CRs). This study aims to determine the efficacy of repeated PZQ treatments against Schistosoma mansoni infection in school-aged children in Côte d’Ivoire using the traditional KK technique, as well as more sensitive antigen- and DNA-detection methods.

Methods

An open-label, randomised controlled trial will be conducted in school-aged children (5 to 18 years) from the region of Taabo, Côte d’Ivoire, an area endemic for S. mansoni. This 8-week trial includes four two-weekly standard doses of PZQ in the “intense treatment” intervention group and one standard dose of PZQ in the “standard treatment” control group. The efficacy of PZQ will be evaluated in stool samples using the KK technique and real-time PCR as well as in urine using the point-of-care circulating cathodic antigen test and the up-converting phosphor, lateral flow, circulating anodic antigen assay. The primary outcome of the study will be the difference in CR of intense versus standard treatment with PZQ on individuals with a confirmed S. mansoni infection measured by KK. Secondary outcomes include the difference in CR and intensity reduction rate between the intense and standard treatment groups as measured by the other diagnostic tests, as well as the accuracy of the different diagnostic tests, and the safety of PZQ.

Discussion

This study will provide data on the efficacy of repeated PZQ treatment on the clearance of S. mansoni as measured by several diagnostic techniques. These findings will inform future mass drug administration policy and shed light on position of novel diagnostic tools to evaluate schistosomiasis control strategies.

Trial registration

The study is registered at EudraCT (2016–003017-10, date of registration: 22 July 2016) and (NCT02868385, date of registration: 16 August 2016).

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3554-2) contains supplementary material, which is available to authorized users.

Pregnancy-related morbidity and risk factors for fatal foetal outcomes in the Taabo health and demographic surveillance system, Côte d'Ivoire

Background

Reliable, population-based data on pregnancy-related morbidity and mortality, and risk factors for fatal foetal outcomes are scarce for low- and middle-income countries. Yet, such data are essential for understanding and improving maternal and neonatal health and wellbeing.

Methods

Within the 4-monthly surveillance rounds of the Taabo health and demographic surveillance system (HDSS) in south-central Côte d’Ivoire, all women of reproductive age identified to be pregnant between 2011 and 2014 were followed-up. A questionnaire pertaining to antenatal care, pregnancy-related morbidities, delivery circumstances, and birth outcome was administered to eligible women. Along with sociodemographic information retrieved from the Taabo HDSS repository, these data were subjected to penalized maximum likelihood logistic regression analysis, to determine risk factors for fatal foetal outcomes.

Results

A total of 2976 pregnancies were monitored of which 118 (4.0%) resulted in a fatal outcome. Risk factors identified by multivariable logistic regression analysis included sociodemographic factors of the expectant mother, such as residency in a rural area (adjusted odds ratio (aOR) = 2.87; 95% confidence interval (CI) 1.31–6.29) and poorest wealth tertile (aOR = 1.79; 95% CI 1.02–3.14), a history of miscarriage (aOR = 23.19; 95% CI 14.71–36.55), non-receipt of preventive treatment such as iron/folic acid supplementation (aOR = 3.15; 95% CI 1.71–5.80), only two doses of tetanus vaccination (aOR = 2.59; 95% CI 1.56–4.30), malaria during pregnancy (aOR = 1.94; 95% CI 1.21–3.11), preterm birth (aOR = 4.45; 95% CI 2.82–7.01), and delivery by caesarean section (aOR = 13.03; 95% CI 4.24–40.08) or by instrumental delivery (aOR = 5.05; 95% CI 1.50–16.96). Women who paid for delivery were at a significantly lower odds of a fatal foetal outcome (aOR = 0.39; 95% CI 0.25–0.74).

Conclusions

We identified risk factors for fatal foetal outcomes in a mainly rural HDSS site of Côte d’Ivoire. Our findings call for public health action to improve access to, and use of, quality services of ante- and perinatal care.

Distribution of Plasmodium spp. infection in asymptomatic carriers in perennial and low seasonal malaria transmission settings in West Africa

Background

Since 2000, substantial progress has been made in reducing malaria worldwide. However, some countries in West Africa remain a hotspot for malaria with all age groups at risk. Asymptomatic carriers of Plasmodium spp. are important sources of infections for malaria vectors and thus contribute to the anchoring of the disease in favourable eco-epidemiological settings. The objective of this study was to assess the asymptomatic malaria case rates in Korhogo and Kaedi, two urban areas in northern Côte d’Ivoire and southern Mauritania, respectively.

Methods

Cross-sectional surveys were carried out during the rainy season in 2014 and the dry season in 2015 in both settings. During each season, 728 households were randomly selected and a household-based questionnaire was implemented to collect demographic and epidemiological data, including of malaria preventive methods used in communities. Finger-prick blood samples were obtained for biological examination using microscopy and rapid diagnostic tests (RDTs).

Results

Overall, 2672 households and 15 858 consenting participants were surveyed. Plasmodium spp. infection was confirmed in 12.4% (n = 832) and 0.3% (n = 22) of the assessed individuals in Korhogo and Kaedi, respectively. In Korhogo, the prevalence of asymptomatic malaria was 10.5% (95% CI: 9.7–11.2) as determined by microscopy and 9.3% (95% CI: 8.6–10.0%) when assessed by RDT. In Kaedi, asymptomatic malaria prevalence was 0.2% (95% CI: 0.1–0.4%) according to microscopy, while all RDTs performed were negative (n = 8372). In Korhogo, asymptomatic malaria infection was significantly associated with age and season, with higher risk within the 5–14 years-old, and during the rainy season. In Kaedi, the risk of asymptomatic malaria infection was associated with season only (higher during the dry season; crude OR (cOR): 6.37, 95% CI: 1.87–21.63). P. falciparum was the predominant species identified in both study sites representing 99.2% (n = 825) in Korhogo and 59.1% (n = 13) in Kaedi. Gametocytes were observed only in Korhogo and only during the rainy season at 1.3% (95% CI: 0.7–2.4%).

Conclusions

Our findings show a low prevalence of clinical malaria episodes with a significant proportion of asymptomatic carriers in both urban areas. National policies for malaria infections are focused on treatment of symptomatic cases. Malaria control strategies should be designed for monitoring and managing malaria infections in asymptomatic carriers. Additional measures, including indoor residual spraying, effective use of long-lasting insecticidal nets is strongly needed to reduce the number of Plasmodium spp. infections in Korhogo and Kaedi.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0412-9) contains supplementary material, which is available to authorized users.

Epidemiology of intestinal parasite infections in three departments of south-central Côte d'Ivoire before the implementation of a cluster-randomised trial

Hundreds of millions of people are infected with helminths and intestinal protozoa, particularly children in low- and middle-income countries. Preventive chemotherapy is the main strategy to control helminthiases. However, rapid re-infection occurs in settings where there is a lack of clean water, sanitation and hygiene. In August and September 2014, we conducted a cross-sectional epidemiological survey in 56 communities of three departments of south-central Côte d'Ivoire. Study participants were invited to provide stool and urine samples. Stool samples were examined for helminth and intestinal protozoa infections using the Kato-Katz technique and a formalin-ether concentration method. Urine samples were subjected to a filtration method for the diagnosis of Schistosoma haematobium. Information on sociodemographic characteristics, knowledge, attitude, practices and beliefs with regard to hygiene, sanitation and intestinal parasitic diseases were collected using a questionnaire administered to household heads. Multivariable logistic regression models were employed to analyse associations between parasite infections and risk factors. Overall, 4,305 participants had complete parasitological and questionnaire data. Hookworm was the predominant helminth species (21.2%), while Ascaris lumbricoides, Trichuris trichiura, Schistosoma mansoni and S. haematobium showed prevalences below 10%. Infections with pathogenic intestinal protozoa (e.g. Entamoeba histolytica/E. dispar and Giardia intestinalis) were similarly prevalent in the three departments. Hookworm infection was associated with open defecation and participants' age and sex. Entamoeba coli infection was negatively associated with the use of tap water at home (odds ratio (OR) = 0.66; p = 0.032). Disposal of garbage in close proximity to people's home was positively associated with G. intestinalis (OR = 1.30; p = 0.015). Taken together, helminth and intestinal protozoa infections affected a considerable proportion of rural dwellers in south-central Côte d'Ivoire at the onset of a cluster-randomised intervention trial. Our results will serve as baseline to monitor the effect of a package of interventions, including preventive chemotherapy, sanitation and health education on re-infection with helminths and intestinal protozoa.

TRIAL REGISTRATION

ISRCTN53102033 (date assigned: 26 March 2014).

Côte d'Ivoire Dual Burden of Disease (CoDuBu): Study Protocol to Investigate the Co-occurrence of Chronic Infections and Noncommunicable Diseases in Rural Settings of Epidemiological Transition

BACKGROUND

Individual-level concomitance of infectious diseases and noncommunicable diseases (NCDs) is poorly studied, despite the reality of this dual disease burden for many low- and middle-income countries (LMICs).

OBJECTIVE

This study protocol describes the implementation of a cohort and biobank aiming for a better understanding of interrelation of helminth and Plasmodium infections with NCD phenotypes like metabolic syndrome, hypertension, and diabetes.

METHODS

A baseline cross-sectional population-based survey was conducted over one year, in the Taabo health and demographic surveillance system (HDSS) in south-central Côte d'Ivoire. We randomly identified 1020 consenting participants aged ≥18 years in three communities (Taabo-Cité, Amani-Ménou, and Tokohiri) reflecting varying stages of epidemiological transition. Participants underwent health examinations consisting of NCD phenotyping (anthropometry, blood pressure, renal function, glycemia, and lipids) and infectious disease testing (infections with soil-transmitted helminths, schistosomes, and Plasmodium). Individuals identified to have elevated blood pressure, glucose, lipids, or with infections were referred to the central/national health center for diagnostic confirmation and treatment. Aliquots of urine, stool, and venous blood were stored in a biobank for future exposome/phenome research. In-person interviews on sociodemographic attributes, risk factors for infectious diseases and NCDs, medication, vaccinations, and health care were also conducted. Appropriate statistical techniques will be applied in exploring the concomitance of infectious diseases and NCDs and their determinants. Participants' consent for follow-up contact was obtained.

RESULTS

Key results from this baseline study, which will be published in peer-reviewed literature, will provide information on the prevalence and co-occurrence of infectious diseases, NCDs, and their risk factors. The Taabo HDSS consists of rural and somewhat more urbanized areas, allowing for comparative studies at different levels of epidemiological transition. An HDSS setting is ideal as a basis for longitudinal studies since their sustainable field work teams hold close contact with the local population.

CONCLUSIONS

The collaboration between research institutions, public health organizations, health care providers, and staff from the Taabo HDSS in this study assures that the synthesized evidence will feed into health policy towards integrated infectious disease-NCD management. The preparation of health systems for the dual burden of disease is pressing in low- and middle-income countries. The established biobank will strengthen the local research capacity and offer opportunities for biomarker studies to deepen the understanding of the cross-talk between infectious diseases and NCDs.

TRIAL REGISTRATION

International Standard Randomized Controlled Trials Number (ISRCTN): 87099939; http://www.isrctn.com/ISRCTN87099939 (Archived by WebCite at http://www.webcitation.org/6uLEs1EsX).

Iron Fortified Complementary Foods Containing a Mixture of Sodium Iron EDTA with Either Ferrous Fumarate or Ferric Pyrophosphate Reduce Iron Deficiency Anemia in 12- to 36-Month-Old Children in a Malaria Endemic Setting: A Secondary Analysis of a Cluster-Randomized Controlled Trial

Iron deficiency anemia (IDA) is a major public health problem in sub-Saharan Africa. The efficacy of iron fortification against IDA is uncertain in malaria-endemic settings. The objective of this study was to evaluate the efficacy of a complementary food (CF) fortified with sodium iron EDTA (NaFeEDTA) plus either ferrous fumarate (FeFum) or ferric pyrophosphate (FePP) to combat IDA in preschool-age children in a highly malaria endemic region. This is a secondary analysis of a nine-month cluster-randomized controlled trial conducted in south-central Côte d'Ivoire. 378 children aged 12-36 months were randomly assigned to no food intervention (n = 125; control group), CF fortified with 2 mg NaFeEDTA plus 3.8 mg FeFum for six days/week (n = 126; FeFum group), and CF fortified with 2 mg NaFeEDTA and 3.8 mg FePP for six days/week (n = 127; FePP group). The outcome measures were hemoglobin (Hb), plasma ferritin (PF), iron deficiency (PF < 30 μg/L), and anemia (Hb < 11.0 g/dL). Data were analyzed with random-effect models and PF was adjusted for inflammation. The prevalence of Plasmodium falciparum infection and inflammation during the study were 44-66%, and 57-76%, respectively. There was a significant time by treatment interaction on IDA (p = 0.028) and a borderline significant time by treatment interaction on iron deficiency with or without anemia (p = 0.068). IDA prevalence sharply decreased in the FeFum (32.8% to 1.2%, p < 0.001) and FePP group (23.6% to 3.4%, p < 0.001). However, there was no significant time by treatment interaction on Hb or total anemia. These data indicate that, despite the high endemicity of malaria and elevated inflammation biomarkers (C-reactive protein or α-1-acid-glycoprotein), IDA was markedly reduced by provision of iron fortified CF to preschool-age children for 9 months, with no significant differences between a combination of NaFeEDTA with FeFum or NaFeEDTA with FePP. However, there was no overall effect on anemia, suggesting most of the anemia in this setting is not due to ID. This trial is registered at clinicaltrials.gov (NCT01634945).

Asymptomatic and sub-microscopic malaria infection in Kayah State, eastern Myanmar

Background

Myanmar has the heaviest burden of malaria in the Greater Mekong Sub-region. Asymptomatic Plasmodium spp. infections are common in this region and may represent an important reservoir of transmission that must be targeted for malaria elimination.

Methods

A mass blood survey was conducted among 485 individuals from six villages in Kayah State, an area of endemic but low transmission malaria in eastern Myanmar. Malaria infection was screened by rapid diagnostic test (RDT), light microscopy and real-time polymerase chain reaction (PCR), and its association with demographic factors was explored.

Results

The prevalence of asymptomatic Plasmodium spp. infection was 2.3% (11/485) by real-time PCR. Plasmodium vivax accounted for 72.7% (8/11) and Plasmodium falciparum for 27.3% (3/11) of infections. Men were at greater risk of infection by Plasmodium spp. than women. Individuals who worked as farmers or wood and bamboo cutters had an increased risk of infection.

Conclusion

A combination of RDT, light microscopy and PCR diagnostics were used to identify asymptomatic malaria infection, providing additional information on asymptomatic cases in addition to the routine statistics on symptomatic cases, so as to determine the true burden of disease in the area. Such information and risk factors can improve malaria risk stratification and guide decision-makers towards better design and delivery of targeted interventions in small villages, representative of Kayah State.