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Experimental Parasitology Oct 2020Guinea worm Dracunculus medinensis causes debilitating disease in people and is subject to an ongoing global eradication programme. Research and controls are constrained...
Guinea worm Dracunculus medinensis causes debilitating disease in people and is subject to an ongoing global eradication programme. Research and controls are constrained by a lack of diagnostic tools. We developed a specific and sensitive LAMP method for detecting D. medinensis larval DNA in copepod vectors. We were able to detect a single larva in a background of field-collected copepods. This method could form the basis of a "pond-side test" for detecting potential sources of Guinea worm infection in the environment, in copepods, including in the guts of fish as potential transport hosts, enabling research, surveillance and targeting of control measures. The key constraint on the utility of this assay as a field diagnostic, is a lack of knowledge of variation in the temporal and spatial distribution of D. medinensis larvae in copepods in water bodies in the affected areas and how best to sample copepods to obtain a reliable diagnostic sample. These fundamental knowledge gaps could readily be addressed with field collections of samples across areas experiencing a range of worm infection frequencies, coupled with field and laboratory analyses using LAMP and PCR.
Topics: Africa; Animals; Base Sequence; Cats; Copepoda; DNA Primers; DNA, Helminth; Disease Vectors; Dogs; Dracunculus Nematode; Humans; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Papio; Ponds; Sensitivity and Specificity; Time Factors
PubMed: 32755552
DOI: 10.1016/j.exppara.2020.107960 -
International Journal of Infectious... Apr 2021
Topics: Animals; Dracunculiasis; Dracunculus Nematode; Humans; Public Health; Vietnam; Water Supply
PubMed: 33610782
DOI: 10.1016/j.ijid.2021.02.063 -
The American Journal of Tropical... Apr 2021
Topics: Animals; Communicable Disease Control; Disease Eradication; Dracunculiasis; Dracunculus Nematode; Humans
PubMed: 33909595
DOI: 10.4269/ajtmh.21-0433 -
MMWR. Morbidity and Mortality Weekly... Nov 2018Dracunculiasis (Guinea worm disease), caused by the parasite Dracunculus medinensis, is acquired by drinking water containing copepods (water fleas) infected with its...
Dracunculiasis (Guinea worm disease), caused by the parasite Dracunculus medinensis, is acquired by drinking water containing copepods (water fleas) infected with its larvae. The worm typically emerges through the skin on a lower limb approximately 1 year after infection, causing pain and disability (1). The worldwide eradication campaign began at CDC in 1980. In 1986, the World Health Assembly called for dracunculiasis elimination, and the global Guinea Worm Eradication Program (GWEP), led by the Carter Center in partnership with the World Health Organization (WHO), United Nations Children's Fund (UNICEF), CDC, and others, began assisting ministries of health in countries with dracunculiasis. There is no vaccine or medicine to treat the disease; the GWEP relies on case containment* to prevent water contamination and other interventions to prevent infection, including health education, water filtration, chemical treatment of water, and provision of safe drinking water (1,2). In 1986, an estimated 3.5 million cases occurred each year in 20 African and Asian countries (3,4). This report, based on updated health ministry data (3), describes progress during January 2017-June 2018 and updates previous reports (1,4). In 2017, 30 cases were reported from Chad and Ethiopia, and 855 infected animals (mostly dogs) were reported from Chad, Ethiopia, and Mali, compared with 25 cases and 1,049 animal infections reported in 2016. During January-June 2018, the number of cases declined to three cases each in Chad and South Sudan and one in Angola, with 709 infected animals reported, compared with eight cases and 547 animal infections during the same period of 2017. With only five affected countries, the eradication goal is near, but is challenged by civil unrest, insecurity, and lingering epidemiologic and zoologic questions.
Topics: Disease Eradication; Dracunculiasis; Global Health; Humans
PubMed: 30439874
DOI: 10.15585/mmwr.mm6745a3 -
MMWR. Morbidity and Mortality Weekly... Oct 2020Dracunculiasis (Guinea worm disease) is caused by the parasite Dracunculus medinensis and is acquired by drinking water containing copepods (water fleas) infected with...
Dracunculiasis (Guinea worm disease) is caused by the parasite Dracunculus medinensis and is acquired by drinking water containing copepods (water fleas) infected with D. medinensis larvae. The worm typically emerges through the skin on a lower limb approximately 1 year after infection, resulting in pain and disability (1). There is no vaccine or medicine to treat the disease; eradication efforts rely on case containment* to prevent water contamination. Other interventions to prevent infection include health education, water filtration, chemical treatment of unsafe water with temephos (an organophosphate larvicide to kill copepods), and provision of safe drinking water (1,2). The worldwide eradication campaign began in 1980 at CDC (1). In 1986, with an estimated 3.5 million cases occurring each year in 20 African and Asian countries (3), the World Health Assembly (WHA) called for dracunculiasis elimination (4). The global Guinea Worm Eradication Program (GWEP), led by the Carter Center and supported by the World Health Organization (WHO), United Nations Children's Fund, CDC, and other partners, began assisting ministries of health in countries with dracunculiasis. This report, based on updated health ministry data (4), describes progress made during January 2019-June 2020 and updates previous reports (2,4,5). With only 54 human cases reported in 2019, 19 human cases reported during January 2019-June 2020, and only six countries currently affected by dracunculiasis (Angola, Chad, Ethiopia, Mali, South Sudan, and importations into Cameroon), the achievement of eradication is within reach, but it is challenged by civil unrest, insecurity, and lingering epidemiologic and zoologic concerns, including 2,000 reported animal cases in 2019 and 1,063 animal cases in 2020, mostly in dogs. All national GWEPs remain fully operational, with precautions taken to ensure safety of program staff members and community members in response to the coronavirus disease 2019 (COVID-19) pandemic.
Topics: Animals; Disease Eradication; Dog Diseases; Dogs; Dracunculiasis; Global Health; Humans
PubMed: 33119555
DOI: 10.15585/mmwr.mm6943a2 -
Emerging Infectious Diseases Nov 2016A third-stage (infective) larva of Dracunculus medinensis, the causative agent of Guinea worm disease, was recovered from a wild-caught Phrynobatrachus francisci frog in...
A third-stage (infective) larva of Dracunculus medinensis, the causative agent of Guinea worm disease, was recovered from a wild-caught Phrynobatrachus francisci frog in Chad. Although green frogs (Lithobates clamitans) have been experimentally infected with D. medinensis worms, our findings prove that frogs can serve as natural paratenic hosts.
Topics: Animals; Anura; Chad; Dracunculiasis; Dracunculus Nematode; Helminthiasis, Animal; Larva
PubMed: 27560598
DOI: 10.3201/eid2211.161332 -
PLoS Neglected Tropical Diseases Jan 2021A number of neglected tropical diseases are targeted for elimination or eradication. An effective surveillance system is critical to determine if these goals have been... (Review)
Review
Lessons learned for surveillance strategies for trachoma elimination as a public health problem, from the evaluation of approaches utilised by Guinea worm and onchocerciasis programmes: A literature review.
INTRODUCTION
A number of neglected tropical diseases are targeted for elimination or eradication. An effective surveillance system is critical to determine if these goals have been achieved and maintained. Trachoma has two related but morphologically different presentations that are monitored for elimination, the active infectious form of trachoma and trachomatous trichiasis (TT), the progression of the disease. There are a number of lessons learnt from the Guinea worm surveillance system that are particularly compatible for TT surveillance and the onchocerciasis surveillance system which can provide insights for surveillance of the infectious form of trachoma.
METHODS/PRINCIPAL FINDINGS
A literature search of peer-reviewed published papers and grey literature was conducted using PUBMED and Google Scholar for articles relating to dracunculiasis or Guinea worm, onchocerciasis and trachoma, along with surveillance or elimination or eradication. The abstracts of relevant papers were read and inclusion was determined based on specified inclusion and exclusion criteria. The credibility and bias of relevant papers were also critically assessed using published criteria. A total of 41 papers were identified that were eligible for inclusion into the review. The Guinea worm programme is designed around a surveillance-containment strategy and combines both active and passive surveillance approaches, with a focus on village-based surveillance and reporting. Although rumour reporting and a monetary incentive for the identification of confirmed Guinea worm cases have been reported as successful for identifying previously unknown transmission there is little unbiased evidence to support this conclusion. More rigorous evidence through a randomised controlled trial, influenced by motivational factors identified through formative research, would be necessary in order to consider applicability for TT case finding in an elimination setting. The onchocerciasis surveillance strategy focuses on active surveillance through sentinel surveillance of villages and breeding sites. It relies on an entomological component, monitoring infectivity rates of black flies and an epidemiological component, tracking exposure to infection in humans. Challenges have included the introduction of relatively complex diagnostics that are not readily available in onchocerciasis endemic countries and target thresholds, which are practically unattainable with current diagnostic tests. Although there is utility in monitoring for infection and serological markers in trachoma surveillance, it is important that adequate considerations are made to ensure evidence-based and achievable guidelines for their utility are put in place.
CONCLUSIONS/SIGNIFICANCE
The experiences of both the Guinea worm and onchocerciasis surveillance strategies have very useful lessons for trachoma surveillance, pre- and post-validation. The use of a monetary reward for identification of TT cases and further exploration into the use of infection and serological indicators particularly in a post-validation setting to assist in identifying recrudescence would be of particular relevance. The next step would be a real-world evaluation of their relative applicability for trachoma surveillance.
Topics: Animals; Databases, Factual; Disease Eradication; Dracunculiasis; Dracunculus Nematode; Health Surveys; Humans; Onchocerciasis; Prevalence; Public Health; Trachoma; Trichiasis
PubMed: 33507903
DOI: 10.1371/journal.pntd.0009082 -
The American Journal of Tropical... Nov 2020The campaign to eradicate dracunculiasis (Guinea worm [GW] disease) and its causative pathogen (GW) in Chad is challenged by infections in domestic dogs, which far...
The campaign to eradicate dracunculiasis (Guinea worm [GW] disease) and its causative pathogen (GW) in Chad is challenged by infections in domestic dogs, which far outnumber the dwindling number of human infections. We present an agent-based simulation that models transmission of GW between a shared water source and a large population of dogs. The simulation incorporates various potential factors driving the infections including external factors and two currently used interventions, namely, tethering and larvicide water treatments. By defining and estimating infectivity parameters and seasonality factors, we test the simulation model on scenarios where seasonal patterns of dog infections could be driven by the parasite's life cycle alone or with environmental factors (e.g., temperature and rainfall) that could also affect human or dog behaviors (e.g., fishing versus farming seasons). We show that the best-fitting model includes external factors in addition to the pathogen's life cycle. From the simulation, we estimate that the basic reproductive number, , is approximately 2.0; our results also show that an infected dog can transmit the infection to 3.6 other dogs, on average, during the month of peak infectivity (April). The simulation results shed light on the transmission dynamics of GWs to dogs and lay the groundwork for reducing the number of infections and eventually interrupting transmission of GW.
Topics: Animals; Chad; Computer Simulation; Dog Diseases; Dogs; Dracunculiasis; Dracunculus Nematode; Environment; Female; Life Cycle Stages; Models, Theoretical; Seasons; Temperature; Water
PubMed: 32901603
DOI: 10.4269/ajtmh.19-0466 -
International Journal of Molecular... Sep 2023Among the plants that exhibit significant or established pharmacological activity, the genus L. deserves special attention. This genus comprises over 500 species...
Among the plants that exhibit significant or established pharmacological activity, the genus L. deserves special attention. This genus comprises over 500 species belonging to the largest family. Our study aimed at providing a comprehensive evaluation of the phytochemical composition of the ethanol extracts of five different L. species (collected from the southwest of the Russian Federation) and their antimicrobial and nematocide activity as follows: cv. Novichok., cv. Smaragd, cv. Citral, cv. Euxin, and cv. Tavrida. The study of the ethanol extracts of the five different L. species using the methods of gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-MS/MS) allowed establishing their phytochemical profile. The obtained data on the of five different L. species ethanol extracts' phytochemical composition were used to predict the antibacterial and antifungal activity against phytopathogenic microorganisms and nematocidal activity against the free-living soil nematode . The major compounds found in the composition of the L. ethanol extracts were monoterpenes, sesquiterpenes, flavonoids, flavonoid glycosides, coumarins, and phenolic acids. The antibacterial and antifungal activity of the extracts began to manifest at a concentration of 150 µg/mL. The cv. Smaragd extract had a selective effect against Gram-positive and bacteria, whereas the cv. Tavrida extract had a selective effect against Gram-negative and bacteria and , and fungi. The cv. Novichok, cv. Smaragd, and cv. Citral extracts in the concentration range of 31.3-1000 µg/mL caused the death of nematodes. It was established that cv. Novichok affects the UNC-63 protein, the molecular target of which is the nicotine receptor of the N-subtype.
Topics: Animals; Ethanol; Antifungal Agents; Artemisia; Tandem Mass Spectrometry; Anti-Infective Agents; Anti-Bacterial Agents; Antinematodal Agents; Araceae; Caenorhabditis elegans; Flavonoids; Plant Extracts
PubMed: 37762675
DOI: 10.3390/ijms241814372 -
MMWR. Morbidity and Mortality Weekly... Oct 2015Dracunculiasis (Guinea worm disease) is caused by Dracunculus medinensis, a parasitic worm. Approximately 1 year after a person acquires infection from contaminated...
Dracunculiasis (Guinea worm disease) is caused by Dracunculus medinensis, a parasitic worm. Approximately 1 year after a person acquires infection from contaminated drinking water, the worm emerges through the skin, usually on the lower limb. Pain and secondary bacterial infection can cause temporary or permanent disability that disrupts work and schooling. The campaign to eradicate dracunculiasis worldwide began in 1980 at CDC. In 1986, the World Health Assembly called for dracunculiasis elimination, and the global Guinea Worm Eradication Program, led by the Carter Center and supported by the World Health Organization (WHO), United Nations Children's Fund (UNICEF), CDC, and other partners, began assisting ministries of health in countries where dracunculiasis was endemic. In 1986, an estimated 3.5 million cases occurred each year in 20 countries in Africa and Asia. Since then, although the goal of eradicating dracunculiasis has not been achieved, considerable progress has been made. Compared with the 1986 estimate, the annual number of reported cases in 2015 has been reduced by 99% and cases are confined to four endemic countries. This report updates published and unpublished surveillance data reported by ministries of health and describes progress toward dracunculiasis eradication from January 2014 through June 2015. During 2014, a total of 126 cases were reported from four countries (Chad [13 cases], Ethiopia [three], Mali [40], and South Sudan [70]), compared with 148 cases reported in 2013, from the same four countries. The overall 15% reduction in cases during 2013–2014 was less than that experienced in recent years, but the rate of decline increased again to 70% in the first 6 months of 2015 compared with the same period during 2014. Continued active surveillance with aggressive detection and appropriate management of cases are essential program components; however, epidemiologic challenges and civil unrest and insecurity pose potential barriers to eradication.
Topics: Disease Eradication; Dracunculiasis; Global Health; Humans
PubMed: 26492134
DOI: 10.15585/mmwr.mm6441a1