1,115 research outputs found
Introduction
No full textThe geographical focus of this book pertains to Europe and Central Asia, while thematically, the seven chapters concentrate on a group of diseases, collec tively termed neglected tropical diseases (NTDs). Geographically, Europe and Central Asia are a contiguous area. Yet, this vast territory is characterized by considerable heterogeneity and enormous cultural, ecological, economic, political, and social diversity, which, in turn, govern people's health and well-being. For the purpose of this book, Europe and Central Asia are defined as the continent of Europe plus the Asian part of the former Soviet Union, namely Siberia, the Caucasus region, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. Essentially, this overlaps with the World Health Organization (WHO) European Region (EURO). The bio-eco-geographical diversity of this region is reflected in widely varying biomes, including arctic tundra, extensive forests, steppes, deserts, mountains, and Mediterranean areas. Of note, this region does not include tropical areas in a strict geographical or climatological sense
A research and development agenda for the control and elimination of human helminthiases
No full textIntroduction
No full textNeglected tropical diseases (NTDs) are a group of diseases frequently found in impoverished communities in tropical and sub-tropical countries. The risk for many of the NTDs is high in both deprived urban and rural areas of East Asia. Adapted to the endemic settings and characteristics of the diseases, a range of tools and strategies are currently being rolled out for the large-scale control of many NTDs. Both vector control measures and community sensitization programmes have for example been used to control dengue in urbanized settings. Challenges posed by yaws and lymphatic filariasis are being addressed by mass drug administration, while rabies requires the involvement of the veterinary public health sector for disease control. For leprosy, an elimination target has been defined; however, achieving this goal remains a considerable challenge. Food-borne trematodiases, on the other hand, are emerging and require a deeper understanding of its burden in East Asia and how these diseases can be tackled in a cost-effective manner. Finally, factors, such as an increase of non-communicable diseases due to changing lifestyles which accompany economic growth, the spreading HIV epidemic as well as climate change and the occurrence of natural disasters can potentially affect the epidemiology and control of NTDs. This volume discusses the mentioned topics in detail with contributions by experts in the respective research areas from different working environments
Three years of Geospatial Health online: a review of the Journals’ internet website usage
No full textMoustiquaires imprégnées d'insecticides longue durée et tests diagnostiques rapides du paludisme : implication dans le contrôle du paludisme au centre de la Côte d'Ivoire
No full textMalaria is a vector-borne disease that primarily affects rural dwellers in the tropics and subtropics. In areas of high transmission, the highest mortality and morbidity rates are found in rural settings with seasonal variations that might be governed by irrigated rice farming. The use of long-lasting insecticidal nets (LLINs), adequate case management facilitated by rapid diagnostic tests (RDTs) and prompt treatment with artemisinin-based combination therapy are key tools for malaria control. The effectiveness of these control measures might be further enhanced by the implementation of communication strategies aiming at increasing population LLINs ownership. We evaluated the effect of routine LLINs monitoring and active surveillance of Plasmodium falciparum infection using RDTs and treatment administration at the community level on malaria transmission, infection and morbidity. Additionally, the acceptability of RDTs for malaria was investigated.
Goal and specific objectives
This PhD pursued four specific objectives: (i) to evaluate the effect of LLINs on species composition and abundance of wild Culicidae; (ii) to evaluate the impact of LLINs routine monitoring on transmission indicators; (iii) to evaluate the impact of LLINs routine monitoring associated with the detection of malaria cases using RDTs on malaria prevalence and morbidity; and (iv) to determine socio-economic factors impacting the use of LLINs and identify attitudes and beliefs affecting RDTs acceptability.
Methods
The study was carried out between July 2009 and May 2012 in three villages (N’dakonankro, Yoho and Bozi) in central Côte d’Ivoire. In Bozi, 150 households were given LLINs free of charge. Five entomological surveys (collection of larvae and adult mosquitoes) were conducted: two before and three after free distribution of LLINs at 3-month intervals. Three parasitological surveys (examination of Giemsa-stained thick and thin blood films and RDTs) were carried out: one prior to and two after free LLIN distribution at 6-month intervals. Additionally, two socio-cultural and economic surveys using a questionnaire were carried out.
Results
The results of our study showed that longitudinal monitoring and implementing a locally adapted communication strategy at the household level were associated with reduced malaria transmission and lower P. falciparum prevalence rates. The adherence of the population to properly use LLINs increased net utilization to very high levels (95-100%). While a rapid decrease in malaria transmission in Bozi was observed, declines in malaria incidence and prevalence required longer time. Our results highlight the scope and limitations of implementing local malaria control measures. A significant relationship between people’s educational attainment, socio-economic position and nets ownership have been observed. In addition social representations about malaria, blood and blood-related diseases preventing an efficient introduction and routine use of RDTs have been found.
Conclusions
In central Côte d’Ivoire, scaling up and sustained use of LLINs should be carefully monitored at the household level. Moreover, the integration of larval control holds promise to significantly reducing malaria transmission. Specific health messages tailored to the local context should be used to raise awareness about the use of RDTs for malaria. Remaining challenges (e.g. strategies adapted to the local conditions of information, education and communication, and diagnosis and prevention) must be overcome for integrated control and eventual local elimination of malaria
Geospatial (s)tools: integration of advanced epidemiological sampling and novel diagnostics.
No full textLarge-scale control and progressive elimination of a wide variety of parasitic diseases is moving to the fore. Indeed,
there is good pace and broad political commitment. Yet, there are some worrying signs ahead, particularly the anticipated
declines in funding and coverage of key interventions, and the paucity of novel tools and strategies. Further and intensified
research and development is thus urgently required. We discuss advances in epidemiological sampling, diagnostic tools and
geospatial methodologies. We emphasise the need for integrating sound epidemiological designs (e.g. cluster-randomised
sampling) with innovative diagnostic tools and strategies (e.g. Mini-FLOTAC for detection of parasitic elements and pooling
of biological samples) and high-resolution geospatial tools. Recognising these challenges, standardisation of quality procedures,
and innovating, validating and applying new tools and strategies will foster and sustain long-term control and eventual
elimination of human and veterinary public health issues
Epidemiology and diagnosis of schistosomiasis in preschool-aged children in Azaguié, south Côte d'Ivoire
No full textBackground: Classified among the neglected tropical diseases (NTDs), schistosomiasis remains one of the most important parasitic diseases in the tropics and subtropics, and constitutes a major public health problem. Following World Health Assembly (WHA) resolution 54.19, put forth in May 2001, several control programmes have emerged in schistosomiasis-endemic countries with the objective to reduce morbidity due to schistosomiasis and soil-transmitted helminthiasis by regularly treating at least 75% and up to 100% of all school-aged children who are at risk by 2010. By focusing treatment upon the school-aged population, WHA resolution 54.19 neglects preschool-aged children, thus preventing them from benefiting from preventive chemotherapy targeted to their older peers, and hence creating a potential health inequity. Root causes include the belief that very young children would not yet be exposed to infected freshwater bodies, thus an insufficient understanding and documentation of the extent and severity of schistosomiasis in this age class, and a paucity of pharmacokinetic safety data of praziquantel among young children. However, in endemic zones, women are frequently accompanied by their children, even at young age, when they go to ponds, rivers or irrigation canals, all of which may be contaminated with cercariae, the infective stage to humans. Recent studies carried out in East and West Africa showed that intestinal and urogenital schistosomiasis can indeed occur in very early childhood. Pathology due to chronic infection with Schistosoma mansoni includes hepatic perisinusoidal egg granulomas, Symmers’ pipe-stem periportal fibrosis, portal hypertension and, occasionally, embolic egg granulomas in the brain or spinal cord. Schistosoma haematobium infection may cause haematuria, scarring, calcification, squamous cell carcinoma and, occasionally, embolic egg granulomas in the brain or spinal cord.
Goal and specific objectives: The overarching goal of this Ph.D. thesis is to deepen our understanding of the epidemiology of schistosomiasis in preschool-aged children. The thesis pursued five specific objectives in Azaguié district, south Côte d’Ivoire. First, to characterize intestinal parasitic infections at the Azaguié district level. Second, to assess the accuracy of a commercially available urine circulating cathodic antigen (CCA) cassette test (CCA-A) and an experimental formulation (CCA-B) for the diagnosis of S. mansoni among school-aged children in different endemicity settings. Third, to assess the accuracy of CCA-A for the diagnosis of S. mansoni in preschool-aged children before and after praziquantel administration. Fourth, to study the epidemiology and risk factors for schistosomiasis in preschool-aged children. Fifth, to assess the efficacy and safety of crushed praziquantel tablets in preschool-aged children in a co-endemic setting of S. mansoni and S. haematobium.
Methods: The fieldwork for this Ph.D. thesis was split into two parts. In order to address the first two objectives, in mid-2010, a cross-sectional study was carried out in seven schools from four locations of Azaguié district, including more than 600 schoolchildren. Multiple stool and urine samples were collected from each schoolchild over three consecutive days. Stool samples were examined with the Kato-Katz technique for the diagnosis of S. mansoni and soil-transmitted helminths (Trichuris trichiura, Ascaris lumbricoides and hookworm). Stool samples from the first day of collection were preserved in sodium acetate-acetic acid-formalin (SAF) and examined one month later using an ether-concentration method for the diagnosis of intestinal protozoa. Urine samples were examined with CCA tests (CCA-A on three days and CCA-B once) for the diagnosis of S. mansoni. In addition, urine samples were analysed with the urine filtration technique and reagent strips for the diagnosis of S. haematobium.
In order to address objectives 3-5, a cross-sectional study was implemented as a baseline survey in 2011 in two villages of Azaguié district, namely Azaguié Makouguié and Azaguié M’Bromé, where S. mansoni and S. haematobium coexist. About 300 preschool-aged children (<6 years) were involved in this study. Multiple stool and urine samples were collected over two consecutive days and subjected to the same laboratory procedures as the samples of the schoolchildren in 2010. Anthropometric measures (weight, height and arm circumference) and clinical features (temperature, haemoglobin level) from each preschool-aged child were recorded. Focus group discussions were performed with the mothers of the preschool-aged children and questionnaires administered for a risk factor assessment. Subsequently, preschool-aged children were treated with crushed praziquantel tablets and three weeks posttreatment, drug efficacy was determined following the same field and laboratory procedures as during the baseline study. Adverse events (within 3 and 24 hours posttreatment were recorded by interviewing the mothers of the preschoolers.
Results: The results of this PhD thesis can be structured as follows:
Intestinal parasitic infections in Azaguié: We showed that the selection of intervention settings by control programmes based on a single stool sample examined with duplicate Kato-Katz thick smears or a single urine sample subjected to a standard urine filtration method considerably underestimate the prevalence of Schistosoma infection. This led to a misclassification of intervention settings as defined by the World Health Organization (WHO) guidelines. Hence, in such a context, more sensitive diagnostic tools are needed to select the intervention settings with high accuracy. In addition, we found a small-scale heterogeneity in the distribution of helminth and intestinal protozoa infections. We also confirmed that polyparasitism is common in the Azaguié district.
Accuracy of urine CCA tests in different endemicity settings in schoolchildren: The prevalence of S. mansoni in the three different endemicity settings was 32.9%, 53.1% and 91.8%, respectively. In all three settings, the sensitivity of a single CCA-A test was similar to triplicate Kato-Katz thick smears and was 56.3% and 47.9% in setting A (S. mansoni prevalence, 32.9%), 69.6% and 73.9% in setting B (S. mansoni prevalence, 53.1%), and 89.6% and 94.2% in setting C (S. mansoni prevalence, 91.8%). The specificity of the CCA-A test was moderate (76.9–84.2%). The likelihood of a CCA-A test color reaction increased with higher S. mansoni faecal egg counts (odds ratio = 1.07, p <0.001). A concurrent S. haematobium infection or the presence of microhaematuria did not influence the CCA test results for S. mansoni diagnosis.
Accuracy of the urine CCA test in preschool-aged children: Before treatment, the prevalence of S. mansoni, as determined by quadruplicate Kato-Katz thick smears, duplicate CCA(t-) test considering “trace” as negative results, and CCA(t+) test with “trace” as positive, was 23.1%, 45.0% and 76.5%, respectively. Irrespectiv of the ‘gold’ standard, a single CCA test (CCA(t+) or CCA(t-)) was more sensitive than quadruplicate Kato-Katz thick smears before and after treatment. The specificity of a single CCA test ranged between 59.3% and 100% before and after treatment. The intensity of the CCA test band reaction was correlated with S. mansoni egg burden (odds ratio = 1.2, p = 0.04).
Epidemiology and risk factors of schistosomiasis in preschoolers: The prevalence of S. mansoni in preschool-aged children was 25.5% in Azaguié Makouguié and 21.6% in Azaguié M’Bromé and the prevalence of S. haematobium 17.3% and 5.9%, respectively. Most infections were of light intensity. Mothers’ occupation and older siblings played important roles in the epidemiology of schistosomiasis in preschool-aged children.
Efficacy and safety of crushed praziquantel in preschoolers: According to the Kato-Katz and urine filtration results, we found high efficacy of crushed praziquantel against S. mansoni (cure rate (CR) = 88.6%, egg reduction rate (ERR) = 96.7%) and S. haematobium (CR = 88.9%, ERR = 98.0%). Treatment was generally well tolerated, but moderate adverse events (i.e. body and face inflammation), which required close supervision by the study physician, were observed in four non-infected children.
Conclusions: More sensitive diagnostic tools and rigorous sampling approaches are needed to select schistosomiasis-endemicity settings with high accuracy. The observed small-scale heterogeneity of helminth and intestinal protozoa infections should be carefully considered by control programmes. A single urine CCA test is more sensitive than multiple Kato-Katz thick smears in school-aged as well as in preschool-aged children. The urine CCA test can be recommended for rapid identification of high risk communities. However, its application for monitoring the impact of control interventions needs further investigation. In our study settings, preschool-aged children are at risk of schistosomiasis and can be infected very early in childhood. Integrated control approaches including improvement of safe water supply, sanitation, health facilities, and health education are needed in our study communities. Crushed praziquantel is efficacious against S. mansoni and S. haematobium and can be recommended for the treatment of infected children at young age, but only if they are unambiguously diagnosed. Nevertheless, further research is needed to deepen our understanding on the safety of praziquantel in this age group
How long can stool samples be fixed for an accurate diagnosis of soil-transmitted helminth infection using mini-FLOTAC?
No full textKato-Katz is a widely used method for the diagnosis of soil-transmitted helminth infection. Fecal samples cannot be preserved, and hence, should be processed on the day of collection and examined under a microscope within 60 min of slide preparation. Mini-FLOTAC is a technique that allows examining fixed fecal samples. We assessed the performance of Mini-FLOTAC using formalin-fixed stool samples compared to Kato-Katz and determined the dynamics of prevalence and intensity estimates of soil-transmitted helminth infection over a 31-day time period.; The study was carried out in late 2013 on Pemba Island, Tanzania. Forty-one children were enrolled and stool samples were subjected on the day of collection to a single Kato-Katz thick smear and Mini-FLOTAC examination; 12 aliquots of stool were fixed in 5% formalin and subsequently examined by Mini-FLOTAC up to 31 days after collection.; The combined results from Kato-Katz and Mini-FLOTAC revealed that 100% of children were positive for Trichuris trichiura, 85% for Ascaris lumbricoides, and 54% for hookworm. Kato-Katz and Mini-FLOTAC techniques found similar prevalence estimates for A. lumbricoides (85% versus 76%), T. trichiura (98% versus 100%), and hookworm (42% versus 51%). The mean eggs per gram of stool (EPG) according to Kato-Katz and Mini-FLOTAC was 12,075 and 11,679 for A. lumbricoides, 1,074 and 1,592 for T. trichiura, and 255 and 220 for hookworm, respectively. The mean EPG from day 1 to 31 of fixation was stable for A. lumbricoides and T. trichiura, but gradually declined for hookworm, starting at day 15. The findings of our study suggest that for a qualitative diagnosis of soil-transmitted helminth infection, stool samples can be fixed in 5% formalin for at least 30 days. However, for an accurate quantitative diagnosis of hookworm, we suggest a limit of 15 days of preservation. Our results have direct implication for integrating soil-transmitted helminthiasis into transmission assessment surveys for lymphatic filariasis
FLOTAC: new multivalent techniques for qualitative and quantitative copromicroscopic diagnosis of parasites in animals and humans.
No full textAccurate diagnosis of parasitic infections is of pivotal importance for both individual patient management and population-based studies, such as drug efficacy trials and surveillance of parasitic disease control and elimination programs, in both human and veterinary public health. In this study, we present protocols for the FLOTACLOTACLOTACLOTACLOTAC basic, dual and double techniques, which are promising new multivalent, sensitive, accurate and precise methods for qualitative and quantitative copromicroscopic analysis. These various methods make use of the FLOTACLOTACLOTACLOTACLOTAC apparatus, a cylindrical device with two 5-ml flotation chambers, which allows up to 1 g of stool to be prepared for microscopic analysis. Compared with currently more widely used diagnostic methods for parasite detection in animals (e.g., McMaster and Wisconsin techniques) and humans (e.g., Kato-Katz and ether-based concentration techniques), the FLOTACLOTACLOTACLOTACLOTAC techniques show higher sensitivity and accuracy. All FLOTACLOTACLOTACLOTACLOTAC techniques can be performed on fresh fecal material as well
as preserved stool samples, and require approximately 12–15 min of preparation time before microscopic analysis
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