Towards global Guinea worm eradication in 2015: the experience of South Sudan

Guinea Worm Disease: A Neglected Diseases on the Verge of Eradication

Background: Dracunculiasis, also known as Guinea worm disease (GWD), is a neglected tropical disease (NTD) caused by a parasite (Dracunculus medinensis). In the past, dracunculiasis was known as “the disease of the empty granary” because of the difficulties patients had in going to work in fields or to school when affected by this disease. In tropical areas, the condition has been widespread in economically disadvantaged communities, and has been associated with reduced economic status and low levels of education. Methods: we searched PubMed, Scopus, Google Scholar, EMBASE, Cochrane Library, and WHO websites for literature addressing dracunculiasis published in the last 50 years. Results: by development and optimization of multi-layered control measures, transmission by the vector has been interrupted, but there are foci in several African countries with a high risk of compromising the results obtained in the control of this neglected disease. Conclusion: this review features state-of-the-art data on the infection prevalence, geographical distribution, diagnostics, parasite–host interactions, and the pathology of dracunculiasis. Also described are the current state and future perspectives for vector control and elimination strategies.

Seasonal fishery facilitates a novel transmission pathway in an emerging animal reservoir of Guinea worm

Exploitation of natural resources is a driver of human infectious disease emergence. The emergence of animal reservoirs of Guinea worm Dracunculus medinensis, particularly in domestic dogs Canis familiaris, has become the major impediment to global eradication of this human disease. 93% of all Guinea worms detected worldwide in 2020 were in dogs in Chad. Novel, non-classical pathways for transmission of Guinea worm in dogs, involving consumption of fish, have been hypothesized to support the maintenance of this animal reservoir. We quantified and analyzed variation in Guinea worm emergence in dogs in Chad, across three climatic seasons, in multiple villages and districts. We applied forensic stable isotope analyses to quantify dietary variation within and among dogs and GPS tracking to characterize their spatial ecology. At the end of the hot-dry season and beginning of the wet season, when fishing by people is most intensive, Guinea worm emergence rates in dogs were highest, dogs ate most fish, and fish consumption was most closely associated with disease. Consumption of fish by dogs enables a non-classical transmission pathway for Guinea worm in Chad. Seasonal fisheries and the facilitation of dogs eating fish are likely contributing to disease persistence and to this key impediment to human disease eradication. Interrelated natural resource use, climatic variation, companion animal ecology, and human health highlight the indispensability of One Health approaches to the challenges of eradicating Guinea worm and other zoonotic diseases.

Challenges in the last mile of the global guinea worm eradication program

OBJECTIVE

The objective of this study was to identify the existing challenges in the last mile of the global Guinea Worm Eradication Program.

METHODS

Systematic Review of articles published from 1 January 2000 until 31 December 2019. Papers listed in Cochrane Library, Google Scholar, ProQuest PubMed and Web of Science databases were searched and reviewed.

RESULTS

Twenty-five articles met inclusion criteria of the study and were selected for analysis. Hence, relevant data were extracted, grouped and descriptively analysed. Results revealed 10 main challenges complicating the last mile of global guinea worm eradication: unusual mode of transmission; rising animal guinea worm infection; suboptimal surveillance; insecurity; inaccessibility; inadequate safe water points; migration; poor case containment measures, ecological changes; and new geographic foci of the disease.

CONCLUSION

This systematic review shows that most of the current challenges in guinea worm eradication have been present since the start of the campaign. However, the recent change in epidemiological patterns and nature of dracunculiasis in the last remaining endemic countries illustrates a new twist. Considering the complex nature of the current challenges, there seems to be a need for a more coordinated and multidisciplinary approach of dracunculiasis prevention and control measures. These new strategies would help to make history by eradicating dracunculiasis as the first ever parasitic disease.

Cooking copepods: The survival of cyclopoid copepods (Crustacea: Copepoda) in simulated provisioned water containers and implications for the Guinea Worm Eradication Program in Chad, Africa

INTRODUCTION

The global Guinea Worm Eradication Program has reduced numbers of human infections of Guinea worm disease (dracunculiasis) to 49 cases in four countries. However, infections of domestic animals (dogs and cats) have recently been recognized and are increasing. Typically, Guinea worm (Dracunculus medinensis) transmission occurs via the ingestion of copepods from water. Despite several interventions, including tethering of dogs while worms emerge, the number of infected dogs continue to increase. One hypothesis is that dogs could be infected through the ingestion of copepods in provisioned water.

OBJECTIVES

The purpose of this study was to determine whether copepods can survive in water containers under typical Chadian temperatures.

METHODS

Four container types (plastic, glass, gourd, and metal) were seeded with copepods and exposed to simulated Chadian temperatures.

RESULTS

All copepods in the metal containers died within 4 h. Conversely, after 8 h live copepods were still present in plastic, glass, and gourd containers.

CONCLUSIONS

If provisioned water is provided to potential hosts of D. medinensis, metal containers create the most inhospitable environment for copepods. Plastic containers have little effect on copepod mortality. The use of metal containers for water provisions could be a useful tool assisting with the interruption of D. medinensis transmission among dogs.

Engineered nanomaterials for water decontamination and purification: From lab to products

Clean water is vital for life; it is required not only for drinking but also for the preparation of food and proper hygiene. Unfortunately, more than fifty percent of the world population mainly in China and India face a severe scarcity of water. Around 1.8 billion people inevitably drink water from sources having fecal contamination resulting in the death of about a million children every year. Scientists are developing various economic technologies to decontaminate and purify water. Nanomaterials-based technology offers an economic and effective alternative for water purification and decontamination. As nanomaterials are available globally, have remarkable antimicrobial activity and the ability to effectively remove organic and inorganic pollutants from water. This review discusses the potential role of nanomaterials in the purification of drinking water. As nanomaterials exhibit remarkable antimicrobial and antiparasitic activities against waterborne pathogens and parasites of primary concern like Shigella dysenteriae, Vibrio cholera, and Entamoeba histolytica. Nanomaterials also demonstrate the ability to absorb toxic chemicals like mercury and dyes from polluted water. However, for successful commercialization of the technology, some inherent bottlenecks need to be addressed adequately. These include nanoparticles aggregation, their seepage into drinking water and adverse effects on human health and the environment. Nanocomposites are being developed to overcome these problems and to combine two or more desirable properties for water purification. Widespread and large-scale use of nanomaterials for water purification soon may become a reality. Products containing nanomaterials such as Karofi, Lifestraw, and Tupperware for water purification are already available in the market.

Not every worm wrapped around a stick is a guinea worm: a case of Onchocerca volvulus mimicking Dracunculus medinensis

BACKGROUND

Despite being certified guinea worm free in 2007, Cameroon continues surveillance efforts to ensure rapid verification of any suspected reoccurrence. This includes the investigation of every rumor and confirmation of each suspicious expulsed worm. This paper presents fieldwork carried out to investigate a guinea worm rumor in Cameroon which turned out to be an Onchocerca volvulus mimicking Dracunculus medinensis.

METHODS

The investigation included a field visit to the subsistence farming community where the rumor was reported. During the visit, interviews were conducted with health staff who managed the case and the elderly farmer from whom the worm was retrieved. An investigation of any potential missed guinea worm cases was also conducted through interviews with community residents and reviews of the health facility's medical records. This was combined with laboratory analyses of water samples from the community's water sources and the retrieved worm which was removed from the patient via wrapping it around a stick.

RESULTS

Microscopy and molecular analyses of the retrieved worm revealed a female Onchocerca volvulus whose expulsion strongly mimicked guinea worm. In addition to presenting findings of our investigation, this paper discusses distinguishing elements between the two parasites and gives an overview of guinea worm eradication efforts in Cameroon as well as current challenges to the worm's eradication globally.

CONCLUSIONS

The investigation findings suggest the evolving Onchocerca volvulus worm tropisms' adaptive survival behavior worth further investigation. Strategies used to successfully control guinea worm in Cameroon could be adapted for Onchocerca volvulus control.

Pan-phylum Comparison of Nematode Metabolic Potential

Nematodes are among the most important causative pathogens of neglected tropical diseases. The increased availability of genomic and transcriptomic data for many understudied nematode species provides a great opportunity to investigate different aspects of their biology. Increasingly, metabolic potential of pathogens is recognized as a critical determinant governing their development, growth and pathogenicity. Comparing metabolic potential among species with distinct trophic ecologies can provide insights on overall biology or molecular adaptations. Furthermore, ascertaining gene expression at pathway level can help in understanding metabolic dynamics over development. Comparison of biochemical pathways (or subpathways, i.e. pathway modules) among related species can also retrospectively indicate potential mistakes in gene-calling and functional annotation. We show with numerous illustrative case studies that comparisons at the level of pathway modules have the potential to uncover biological insights while remaining computationally tractable. Here, we reconstruct and compare metabolic modules found in the deduced proteomes of 13 nematodes and 10 non-nematode species (including hosts of the parasitic nematode species). We observed that the metabolic potential is, in general, concomitant with phylogenetic and/or ecological similarity. Varied metabolic strategies are required among the nematodes, with only 8 out of 51 pathway modules being completely conserved. Enzyme comparison based on topology of metabolic modules uncovered diversification between parasite and host that can potentially guide therapeutic intervention. Gene expression data from 4 nematode species were used to study metabolic dynamics over their life cycles. We report unexpected differential metabolism between immature and mature microfilariae of the human filarial parasite Brugia malayi. A set of genes potentially important for parasitism is also reported, based on an analysis of gene expression in C. elegans and the human hookworm Necator americanus. We illustrate how analyzing and comparing metabolism at the level of pathway modules can improve existing knowledge of nematode metabolic potential and can provide parasitism related insights. Our reconstruction and comparison of nematode metabolic pathways at a pan-phylum and inter-phylum level enabled determination of phylogenetic restrictions and differential expression of pathways. A visualization of our results is available at http://nematode.net and the program for identification of module completeness (modDFS) is freely available at SourceForge. The methods reported will help biologists to predict biochemical potential of any organism with available deduced proteome, to direct experiments and test hypotheses.

We reconstructed metabolic pathways of 23 organisms including 13 nematode species, using their complete deduced protein coding sequences and compared them to 10 non-nematodes. We observed that metabolic potential availability is concomitant with phylogenetic and/or ecological similarity, with the exceptions providing interesting case studies. We also studied changes in metabolic profiles under different developmental stages of 4 nematode species using stage-specific transcriptomic data. A comparison of the variation patterns in these profiles led to recognition of modules that share metabolic profiles at various life-cycle stages or during development. The undertaken analysis improved genome annotation and the obtained results provided insight into parasitism, resulting in identification of taxonomically-restricted pathways and enzymes that may provide new mechanisms for control of nematode infections.

Public, environmental, and occupational health research activity in Arab countries: bibliometric, citation, and collaboration analysis

BACKGROUND

The objective of this study was to analyze quantity, assess quality, and investigate international collaboration in research from Arab countries in the field of public, environmental and occupational health.

METHODS

Original scientific articles and reviews published from the 22 Arab countries in the category "public, environmental & occupational health" during the study period (1900 - 2012) were screened using the ISI Web of Science database.

RESULTS

The total number of original and review research articles published in the category of "public, environmental & occupational health" from Arab countries was 4673. Main area of research was tropical medicine (1862; 39.85%). Egypt with 1200 documents (25.86%) ranked first in quantity and ranked first in quality of publications (h-index = 51). The study identified 2036 (43.57%) documents with international collaboration. Arab countries actively collaborated with authors in Western Europe (22.91%) and North America (21.04%). Most of the documents (79.9%) were published in public health related journals while 21% of the documents were published in journals pertaining to prevention medicine, environmental, occupational health and epidemiology.

CONCLUSION

Research in public, environmental and occupational health in Arab countries is in the rise. Public health research was dominant while environmental and occupation health research was relatively low. International collaboration was a good tool for increasing research quantity and quality.

Assessment of research productivity of Arab countries in the field of infectious diseases using Web of Science database

BACKGROUND

To meet the future challenges of infectious diseases and limit the spread of multidrug resistant microorganisms, a better understanding of published studies in the field of infectious diseases is needed. The objective of this study was to analyze the quantity and quality of research activity in the field of infectious diseases in Arab countries and compare it with that in non-Arab countries.

METHODS

Documents published in Arab countries within the research category of "infectious diseases" were extracted and analyzed using the Web of Science database. The data analyzed represent research productivity during the time interval between 1900 - 2012.

RESULTS

Worldwide, the total number of documents published in the field of infectious diseases up to 2012 was 227,188. A total of 2,408 documents in the field of infectious diseases were published in Arab countries, which represents 1.06% of worldwide research output. Research output from Arab countries in the field of infectious diseases was low for decades. However, approximately a five-fold increase was observed in the past decade. Arab countries ranked 56(th) to 218(th) on the standard competition ranking (SCR) in worldwide publications in the field of infectious diseases. Egypt, with a total publication of 464 (19.27%) documents ranked first among Arab countries, while Kuwait University was the most productive institution with a total of 158 (6.56%) documents. Average citation per document published in Arab countries was 13.25 and the h-index was 64. Tuberculosis (230; 9.55%), malaria (223; 9.26%), and hepatitis (189; 7.8%) were the top three infectious diseases studied as according to the retrieved documents.

CONCLUSION

The present data reveals that some Arab countries contribute significantly to the field of infectious diseases. However, Arab countries need to work harder to bridge the gap in this field. Compared with non-Arab countries in the Middle East, research output from Arab countries was high, but more efforts are needed to enhance the quality of this output. Future research in the field should be encouraged and correctly directed.

Absence of Wolbachia endobacteria in the human parasitic nematode Dracunculus medinensis and two related Dracunculus species infecting wildlife

BACKGROUND

Wolbachia endosymbionts are a proven target for control of human disease caused by filarial nematodes. However, little is known about the occurrence of Wolbachia in taxa closely related to the superfamily Filarioidea. Our study addressed the status of Wolbachia presence in members of the superfamily Dracunculoidea by screening the human parasite Dracunculus medinensis and related species from wildlife for Wolbachia.

FINDINGS

D. medinensis, D. lutrae and D. insignis specimens were all negative for Wolbachia colonization by PCR screening for the Wolbachia ftsZ, 16S rRNA and Wolbachia surface protein (wsp) sequences. The quality and purity of the DNA preparations was confirmed by amplification of nematode 18S rRNA and cytochrome c oxidase subunit I sequences. Furthermore, Wolbachia endobacteria were not detected by whole mount fluorescence staining, or by immunohistochemistry using a Wolbachia-specific antiserum. In contrast, positive control Brugia malayi worms were shown to harbour Wolbachia by PCR, fluorescence staining and immunohistochemistry.

CONCLUSIONS

Three examined species of Dracunculus showed no evidence of Wolbachia endobacteria. This supports that members of the superfamily Dracunculoidea are free of Wolbachia. Within the order Spirurida, these endosymbionts appear restricted to the Filarioidea.