Current status of schistosomiasis and soil-transmitted helminthiasis in Beyla and Macenta Prefectures, Forest Guinea

Neglected tropical diseases in Republic of Guinea: disease endemicity, case burden and the road towards the 2030 target

Neglected tropical diseases (NTDs) predominantly affect vulnerable and marginalized populations in tropical and subtropical areas and globally affect more than one billion people. In Guinea, the burden of NTDs is estimated to be >7.5 disability-adjusted life years per million inhabitants. Currently the Guinea NTDs master plan (2017-2020) has identified eight diseases as public health problems: onchocerciasis, lymphatic filariasis, trachoma, schistosomiasis and soil-transmitted helminthiasis, leprosy, human African trypanosomiasis and Buruli ulcer. In this review we discuss the past and the current case burden of the priority NTDs in Guinea, highlight the major milestones and discuss current and future areas of focus for achieving the 2030 target outlined by the World Health Organization.

Prevalence of Intestinal Parasitosis in Guinea: Systematic Review of the Literature and Meta-Analysis

BACKGROUND

Intestinal parasitosis constitute a major public health issue, particularly in sub-tropical and tropical areas. Even though they are classified as neglected tropical diseases, no national study has been carried out recently in Guinea to estimate the prevalence of intestinal parasitosis.

OBJECTIVE

A systematic review and meta-analysis aimed to determine the overall prevalence of intestinal parasitosis in Guinea.

METHOD

The PRISMA method was used to perform a systematic review and meta-analysis. The studies carried out in order to study intestinal parasitosis in Guinea and published between 2010 and 2020 were searched in online public databases. The prevalence of parasitosis was calculated by a random-effects meta-analysis. Subgroup comparisons were performed using Q-tests. Statistical analyses were performed with the R software. This review was registered with PROSPERO under the identification number CRD42022349743.

RESULTS

69 studies were selected out of 1230 studies identified in online public databases. The meta-analysis involved 44,186 people with an overall prevalence of intestinal parasitic infections of 52%.

CONCLUSIONS

This is the first study in Guinea to assess the prevalence of intestinal parasitic infections in different regions of the country. It was found that intestinal parasitosis are a real health problem in Guinea, hence, the need to put in place national strategies for regular control.

Schistosomiasis with a Focus on Africa

Schistosomiasis is a common neglected tropical disease of impoverished people and livestock in many developing countries in tropical Africa, the Middle East, Asia, and Latin America. Substantial progress has been made in controlling schistosomiasis in some African countries, but the disease still prevails in most parts of sub-Saharan Africa with an estimated 800 million people at risk of infection. Current control strategies rely primarily on treatment with praziquantel, as no vaccine is available; however, treatment alone does not prevent reinfection. There has been emphasis on the use of integrated approaches in the control and elimination of the disease in recent years with the development of health infrastructure and health education. However, there is a need to evaluate the present status of African schistosomiasis, primarily caused by Schistosoma mansoni and S. haematobium, and the factors affecting the disease as the basis for developing more effective control and elimination strategies in the future. This review provides an historical perspective of schistosomiasis in Africa and discusses the current status of control efforts in those countries where the disease is endemic.

Prevalence and risk factors of schistosomiasis among primary school children in four selected regions of The Gambia

BACKGROUND

The Gambia initiated a control programme for schistosomiasis in 2015. In light of this, recent and comprehensive data on schistosomiasis is required to effectively guide the control programme. This study aimed to evaluate the prevalence and associated risk factors of schistosomiasis among primary school children in The Gambia.

METHODS

We utilised data from a previous study conducted in 2015 in 4 regions of The Gambia: North Bank Region (NBR), Lower River Region (LRR), Central River Region (CRR) and Upper River Region (URR). In the parent study, ten schools were selected randomly from each region. Urine and stool samples collected from 25 boys and 25 girls (7-14 years) in each school were examined for urinary schistosomiasis (Schistosoma haematobium infection) and intestinal schistosomiasis (Schistosoma mansoni infection) using urine filtration, dipstick and Kato-Katz methods.

PRINCIPAL FINDINGS

Urinary schistosomiasis had an overall prevalence of 10.2% while intestinal schistosomiasis had a prevalence of 0.3% among the sampled school children. Prevalence of urinary schistosomiasis was significantly different among regions (χ 2 = 279.958, df = 3, p < 0.001), with CRR (27.6%) being the most endemic region, followed by URR (12.0%), then LRR (0.6%), and NBR (0.0%). Prevalence of intestinal schistosomiasis was also significantly variable among regions, with 4 of the 5 positive cases detected in CRR and 1 case in URR. Every school sampled in CRR had at least one student infected with S. haematobium, 50% of schools in URR had S. haematobium infection, and just one school in LRR had S. haematobium infection. While S. haematobium infection was significantly higher in boys (χ 2 = 4.440, df = 1, p = 0.035), no significant difference in infection rate was observed among age groups (χ 2 = 0.882, df = 2, p = 0.643). Two of the 5 students infected with S. mansoni were boys and 3 were girls. Four of these 5 students were in the 10-12 years age group and 1 was in the 7-9 years age group. Macrohaematuria and microhaematuria were found to be statistically associated with presence of S. haematobium eggs in urine. Being a male was a risk factor of S. haematobium infection. Bathing, playing and swimming in water bodies were found to pose less risk for S. haematobium infection, indicating that the true water contact behaviour of children was possibly underrepresented.

CONCLUSION

The findings of this study provide invaluable information on the prevalence of schistosomiasis in The Gambia. This was useful for the schistosomiasis control efforts of the country, as it guided mass drug administration campaigns in eligible districts in the study area. More studies on S. mansoni and its intermediate snail hosts are required to establish its true status in The Gambia. As children sometimes tend to provide responses that potentially please the research or their teacher, data collection frameworks and approaches that ensure true responses in studies involving children should be devised and used.

Relationships Between Gastrointestinal Parasite Infections and the Fecal Microbiome in Free-Ranging Western Lowland Gorillas

Relationships between gastrointestinal parasites (GIPs) and the gastrointestinal microbiome (GIM) are widely discussed topics across mammalian species due to their possible impact on the host's health. GIPs may change the environment determining alterations in GIM composition. We evaluated the associations between GIP infections and fecal microbiome composition in two habituated and two unhabituated groups of wild western lowland gorillas (Gorilla g. gorilla) from Dzanga Sangha Protected Areas, Central African Republic. We examined 43 fecal samples for GIPs and quantified strongylid nematodes. We characterized fecal microbiome composition through 454 pyrosequencing of the V1-V3 region of the bacterial 16S rRNA gene. Entamoeba spp. infections were associated with significant differences in abundances of bacterial taxa that likely play important roles in nutrition and metabolism for the host, besides being characteristic members of the gorilla gut microbiome. We did not observe any relationships between relative abundances of several bacterial taxa and strongylid egg counts. Based on our findings, we suggest that there is a significant relationship between fecal microbiome and Entamoeba infection in wild gorillas. This study contributes to the overall knowledge about factors involved in modulating GIM communities in great apes.

Schistosomiasis and soil-transmitted helminth infections in schoolchildren in north-eastern Democratic Republic of the Congo

BACKGROUND

There is a paucity of epidemiological data pertaining to schistosomiasis and soil-transmitted helminth (STH) infections in the Democratic Republic of the Congo (DRC).

METHODS

A cross-sectional survey was carried out in the north-eastern part of DRC enrolling 400 schoolchildren aged 9-14 years. Stool and urine samples were subjected to standard diagnostic methods and examined under a microscope for helminth eggs.

RESULTS

Four out of five children were infected with at least one helminth species. Schistosoma mansoni was the predominant species (57.8%). Urine examinations were all negative for S. haematobium.

CONCLUSIONS

S. mansoni and STH infections are highly endemic in the surveyed part of the DRC, calling for interventions in school-aged children.

Changing patterns of health in communities impacted by a bioenergy project in northern Sierra Leone

Large private sector investments in low- and middle-income countries are often critically evaluated with regards to their environmental, social, human rights, and health impacts. A health impact assessment, including a baseline health survey, was commissioned by the Addax Bioenergy Sierra Leone project in 2010. As part of the monitoring, a follow-up survey was conducted three years later. A set of health indicators was assessed at six impacted and two control sites. Most of these indices improved, particularly at the impacted sites. The prevalences of stunting, wasting, and Plasmodium falciparum in children under five years of age decreased significantly at impacted sites (all p < 0.05) and non-significantly at control sites. Anemia in children and in women of reproductive age (15–49 years) decreased significantly at impacted and control sites (p < 0.05 and p < 0.001, respectively). Health facility-based deliveries increased significantly at the impacted sites (p < 0.05). The prevalences of helminth infections in children aged 10–15 years remained approximately at the same levels, although focal increases at the impacted sites were noted. Access to improved sanitation decreased significantly (p < 0.05) at control and non-significantly at impacted sites. Water quality remained poor without significant changes. The epidemiologic monitoring of a bioenergy project provides a useful contribution for evidence-based decision-making.

Baseline health conditions in selected communities of northern Sierra Leone as revealed by the health impact assessment of a biofuel project

BACKGROUND

As biofuel projects may be associated with positive and negative effects on people's health and wellbeing, a health impact assessment was performed for the Addax Bioenergy Sierra Leone (ABSL) project. We present data from the baseline health survey, which will provide a point of departure for future monitoring and evaluation activities.

METHODS

In December 2010, a cross-sectional survey was carried out in eight potentially affected communities. A broad set of clinical and parasitological indicators were assessed using standardised, quality-controlled procedures, including anthropometry and prevalence of anaemia, Plasmodium falciparum and helminth infections.

RESULTS

Complete datasets were obtained from 1221 individuals of 194 households and eight schools. Of children aged <5 years (n=586), 41.8% were stunted, 23.2% were underweight and 4.8% were wasted. Very high prevalences of anaemia and P. falciparum were found in children aged 6-59 months (n=571; 86.1% and 74.0%, respectively). Overall, 73.7% of women of reproductive age (n=395) were anaemic. In school-aged children (n=240), 27.9% had light- to moderate-intensity hookworm infections, whereas Ascaris lumbricoides, Trichuris trichiura and Schistosoma mansoni were rare (<3% each).

CONCLUSIONS

The detailed description of the baseline health conditions, in combination with future health surveys, will deepen the understanding of how a biofuel project impacts on community health in a rural setting in sub-Saharan Africa.

[Prevalence of geohelminth infections in children living in Kinshasa]

BACKGROUND

Data on geohelminth infections in children in the Democratic Republic of Congo are sparse. The objective of this study was to document and compare the profile and prevalence in children living in Kinshasa.

METHODS

A prospective cohort study was conducted from May to October 2009 in children in the Biyela health area in Kinshasa, Democratic Republic of Congo. Stool samples were collected from representative members of these two populations and analyzed for geohelminths (GH) using the Kato-Katz technique.

RESULTS

In this series, 438 school-age children were included. There were 235 children recruited in schools and 203 in households (77.8%). Overall prevalence of geohelminths was 66.9%. The specific prevalence was 69.4% in children recruited in schools and 64.0% in children recruited in households. The frequency of Ascaris lumbricoides, Trichuris trichiura, and Ancylostoma species were, respectively, 56.2%, 38.7%, and 1.7% in schools and 39.9%, 51.7%, and 1.0% in households. A. lumbricoides was significantly more prevalent in schools (56.2% vs 39.9%; OR=2.0; 95%CI: 1.3-3.0), T. trichiura was significantly less prevalent in schools (38.7% vs 51.7%; OR=0.6; 95% CI: 0.4-0.9). There were no significant differences in the prevalence of Ancylostoma between schools and households.

CONCLUSION

GH is a health problem among Biyela children. Preventive measures and education of the population need to be emphasized in attempts to reduce the prevalence of geohelminths in these children.

Combined spatial prediction of schistosomiasis and soil-transmitted helminthiasis in Sierra Leone: a tool for integrated disease control

BACKGROUND

A national mapping of Schistosoma haematobium was conducted in Sierra Leone before the mass drug administration (MDA) with praziquantel. Together with the separate mapping of S. mansoni and soil-transmitted helminths, the national control programme was able to plan the MDA strategies according to the World Health Organization guidelines for preventive chemotherapy for these diseases.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 52 sites/schools were selected according to prior knowledge of S. haematobium endemicity taking into account a good spatial coverage within each district, and a total of 2293 children aged 9-14 years were examined. Spatial analysis showed that S. haematobium is heterogeneously distributed in the country with significant spatial clustering in the central and eastern regions of the country, most prevalent in Bo (24.6% and 8.79 eggs/10 ml), Koinadugu (20.4% and 3.53 eggs/10 ml) and Kono (25.3% and 7.91 eggs/10 ml) districts. By combining this map with the previously reported maps on intestinal schistosomiasis using a simple probabilistic model, the combined schistosomiasis prevalence map highlights the presence of high-risk communities in an extensive area in the northeastern half of the country. By further combining the hookworm prevalence map, the at-risk population of school-age children requiring integrated schistosomiasis/soil-transmitted helminth treatment regimens according to the coendemicity was estimated.

CONCLUSIONS/SIGNIFICANCE

The first comprehensive national mapping of urogenital schistosomiasis in Sierra Leone was conducted. Using a new method for calculating the combined prevalence of schistosomiasis using estimates from two separate surveys, we provided a robust coendemicity mapping for overall urogenital and intestinal schistosomiasis. We also produced a coendemicity map of schistosomiasis and hookworm. These coendemicity maps can be used to guide the decision making for MDA strategies in combination with the local knowledge and programme needs.