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Food and Waterborne Parasitology Sep 2020Waterborne parasitic diseases form one of common and important public health and economic problems in low- and middle-income countries, though little is known on the...
Waterborne parasitic diseases form one of common and important public health and economic problems in low- and middle-income countries, though little is known on the burden and patterns of these diseases in most regions. This systematic scoping review informs on the prevalence and pattern of waterborne parasitic infections in eastern Africa from 1st of January 1941 to 31st of December 2019. The review found limited number of published studies on waterborne parasitic diseases, though 13 of the 15 studied countries in eastern Africa provided one or more published report(s) totalling 47 reports. Focus of studies was mainly on schistosomiasis where 44.8% of the 47 retrieved studies reported it. Other frequently reported diseases were giardiasis (23.4% of reports), soil-transmitted helminths (23.4%) and amoebiasis (21.3%). Rarely reported diseases were malaria, cryptosporidiosis, isosporiasis, dracunculiasis and trichomoniasis. Based on parasitological examinations, schistosomiasis prevalence ranged from 17 to 33% in Burundi, 1.9 to 73.9% in Ethiopia, 2.1 to 18% in Kenya, 7.2 to 88.6% in Uganda, 22.9 to 86.3% in Tanzania, 27.2 to 65.8% in Somalia, 15 to >50% in Mauritius, 2.4% in Eritrea and 5.0 to 93.7% in Madagascar. Amoebiasis prevalence was 4.6-15,3% (Ethiopia), 5.9-58.3% (Kenya), 54.5% (Rwanda), 0.7-2.7% (Sudan), 19.93% (Uganda) and 4.5-5.0% (Seychelles). Giardiasis prevalence was 0.6-55.0% (Ethiopia), 16.6% (Kenya), 3.6% (Rwanda), 21.1% (Sudan), 40.7% (Uganda), 45.0% (Eritrea) and 3.3-6.0% (Seychelles). Soil-transmitted helminths prevalence was 41.7-52.4% (Ethiopia), 32.4-40.7% (Kenya), 9997 cases (Rwanda), 85.0% (Somalia), 4.7% (Madagascar) and 1.1-84% (Seychelles), , and hookworms were the most common helminths detected. Malaria prevalence was 2.9-4.31% (Ethiopia), an annual episode of 9 million people (Sudan), 13.0% (Tanzania), 146 hospital cases (Madagascar), 1.4-2.0% (Seychelles) and <5.0% in Djibouti. It is also observed that >50% of the populations in eastern Africa region lack improved drinking water sources or sanitation facilities. This may account for the observed high prevalence of the diseases. The author also suggests likely underestimation of the prevalence as most waterborne parasitic diseases are neglected and cases likely only recorded and left unpublished in health facilities. Thus for a thorough mapping of burdens of these diseases, grey literature, including hospital records must be reviewed while interventions focusing on improved water and sanitation are likely to reduce the burden considerably.
PubMed: 32995583
DOI: 10.1016/j.fawpar.2020.e00089 -
Tropical Medicine & International... Dec 2020The objective of this study was to identify the existing 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.
Topics: Animals; Communicable Disease Control; Disease Eradication; Dracunculiasis; Dracunculus Nematode; Humans; Water Supply
PubMed: 32946140
DOI: 10.1111/tmi.13492 -
PLoS Neglected Tropical Diseases Sep 2020Few human infectious diseases have been driven as close to eradication as dracunculiasis, caused by the Guinea worm parasite (Dracunculus medinensis). The number of...
Few human infectious diseases have been driven as close to eradication as dracunculiasis, caused by the Guinea worm parasite (Dracunculus medinensis). The number of human cases of Guinea worm decreased from an estimated 3.5 million in 1986 to mere hundreds by the 2010s. In Chad, domestic dogs were diagnosed with Guinea worm for the first time in 2012, and the numbers of infected dogs have increased annually. The presence of the parasite in a non-human host now challenges efforts to eradicate D. medinensis, making it critical to understand the factors that correlate with infection in dogs. In this study, we evaluated anthropogenic and environmental factors most predictive of detection of D. medinensis infection in domestic dog populations in Chad. Using boosted regression tree models to identify covariates of importance for predicting D. medinensis infection at the village and spatial hotspot levels, while controlling for surveillance intensity, we found that the presence of infection in a village was predicted by a combination of demographic (e.g. fishing village identity, dog population size), geographic (e.g. local variation in elevation), and climatic (e.g. precipitation and temperature) factors, which differed between northern and southern villages. In contrast, the presence of a village in a spatial infection hotspot, was primarily predicted by geography and climate. Our findings suggest that factors intrinsic to individual villages are highly predictive of the detection of Guinea worm parasite presence, whereas village membership in a spatial infection hotspot is largely determined by location and climate. This study provides new insight into the landscape-scale epidemiology of a debilitating parasite and can be used to more effectively target ongoing research and possibly eradication and control efforts.
Topics: Animals; Chad; Climate; Disease Eradication; Dog Diseases; Dogs; Dracunculiasis; Dracunculus Nematode; Geography; Machine Learning
PubMed: 32925916
DOI: 10.1371/journal.pntd.0008620 -
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 -
The American Journal of Tropical... Dec 2020The success of the Guinea Worm (GW) Eradication Program over the past three decades has been tempered by the persistence of GW disease in a few African nations and the...
The success of the Guinea Worm (GW) Eradication Program over the past three decades has been tempered by the persistence of GW disease in a few African nations and the potential for a future resurgence in cases. Domestic dogs are now a major concern as a disease reservoir as large numbers of cases of canine GW disease are now reported each year, mainly along the Chari River in Chad. As a first step toward the development of a serologic assay for dogs, archived human plasma samples from dracunculiasis-positive donors from Togo were used to select adult female GW antigens for peptide sequencing and cloning. Eight protein sequences of interest were expressed as recombinant glutathione--transferase (GST) fusion proteins, and the most promising proteins were coupled to carboxylated microspheres for use in multiplex assays. A thioredoxin-like protein (TRXL1) and a domain of unknown function (DUF148) were assessed for total IgG and IgG reactivities using a panel of specimens from GW cases, uninfected donors, and individuals infected with various nematode worms, including . Both the DUF148-GST and the TRXL1-GST assays cross-reacted with sera, but the latter assay was always the more specific. The IgG and total IgG TRXL1-GST assays both had sensitivities > 87% and specificities > 90%. Maximum specificity (> 96%) was obtained with the total IgG assay when reactivity to both antigens was used to define a positive case. Given the good performance of the human assay, we are now working to modify the assay for dog assessments.
Topics: Animals; Antibodies, Helminth; Antigens, Helminth; Blotting, Western; Cross Reactions; Disease Eradication; Disease Reservoirs; Dog Diseases; Dogs; Dracunculiasis; Dracunculus Nematode; Electrophoresis, Polyacrylamide Gel; Glutathione Transferase; Humans; Immunoglobulin G; Onchocerca volvulus; Onchocerciasis; Recombinant Fusion Proteins; Sensitivity and Specificity; Serologic Tests; Thioredoxins
PubMed: 32901602
DOI: 10.4269/ajtmh.20-0511 -
Frontiers in Veterinary Science 2020
PubMed: 32851003
DOI: 10.3389/fvets.2020.00404 -
Emerging Infectious Diseases Aug 2020A fragment of a Dracunculus-like worm was extracted from the hind limb of a 2-year-old dog from Toledo, Spain. Cytochrome oxidase I and rRNA sequences confirmed an...
A fragment of a Dracunculus-like worm was extracted from the hind limb of a 2-year-old dog from Toledo, Spain. Cytochrome oxidase I and rRNA sequences confirmed an autochthonous mammalian Dracunculus worm infection in Europe. Sequence analyses suggest close relation to a parasite obtained from a North American opossum.
Topics: Animals; Dogs; Dracunculiasis; Dracunculus Nematode; Europe; Spain
PubMed: 32687046
DOI: 10.3201/eid2608.201661 -
PLoS Neglected Tropical Diseases May 2020After a ten-year absence of reported Guinea worm disease in Chad, human cases were rediscovered in 2010, and canine cases were first recorded in 2012. In response,...
After a ten-year absence of reported Guinea worm disease in Chad, human cases were rediscovered in 2010, and canine cases were first recorded in 2012. In response, active surveillance for Guinea worm in both humans and animals was re-initiated in 2012. As of 2018, the Chad Guinea Worm Eradication Program (CGWEP) maintains an extensive surveillance system that operates in 1,895 villages, and collects information about worms, hosts (animals and humans), and animal owners. This report describes in detail the CGWEP surveillance system and explores epidemiological trends in canine Guinea worm cases during 2015-2018. Our results showed an increased in the number of canine cases detected by the system during the period of interest. The proportion of worms that were contained (i.e., water contamination was prevented) improved significantly over time, from 72.8% in 2015 to 85.7% in 2018 (Mantel-Haenszel chi-square = 253.3, P < 0.0001). Additionally, approximately 5% of owners of infected dogs reported that the dog had a Guinea worm-like infection earlier that year; 12.6% had a similar worm in a previous year. The proportion of dogs with a history of infection in a previous year increased over time (Mantel-Haenszel chi-square = 18.8, P < 0.0001). Canine cases were clustered in space and time: most infected dogs (80%) were from the Chari Baguirmi (38.1%) and Moyen Chari Regions (41.9%), and for each year the peak month of identified canine cases was June, with 78.5% occurring during March through August. Findings from this report evoke additional questions about why some dogs are repeatedly infected. Our results may help to target interventions and surveillance efforts in terms of space, time, and dogs susceptible to recurrent infection, with the ultimate goal of Guinea worm eradication.
Topics: Animals; Chad; Dog Diseases; Dogs; Dracunculiasis; Dracunculus Nematode; Epidemiological Monitoring; Female; Humans; Male
PubMed: 32463811
DOI: 10.1371/journal.pntd.0008207 -
PLoS Neglected Tropical Diseases Apr 2020Global eradication of human Guinea worm disease (dracunculiasis) has been set back by the emergence of infections in animals, particularly domestic dogs Canis...
Global eradication of human Guinea worm disease (dracunculiasis) has been set back by the emergence of infections in animals, particularly domestic dogs Canis familiaris. The ecology and epidemiology of this reservoir is unknown. We tracked dogs using GPS, inferred diets using stable isotope analysis and analysed correlates of infection in Chad, where numbers of Guinea worm infections are greatest. Dogs had small ranges that varied markedly among villages. Diets consisted largely of human staples and human faeces. A minority of ponds, mostly <200 m from dog-owning households, accounted for most dog exposure to potentially unsafe water. The risk of a dog having had Guinea worm was reduced in dogs living in households providing water for animals but increased with increasing fish consumption by dogs. Provision of safe water might reduce dog exposure to unsafe water, while prioritisation of proactive temephos (Abate) application to the small number of ponds to which dogs have most access is recommended. Fish might have an additional role as transport hosts for Guinea worm, by concentrating copepods infected with worm larvae.
Topics: Animals; Chad; Diet; Disease Reservoirs; Dog Diseases; Dogs; Dracunculiasis; Dracunculus Nematode; Ecology; Family Characteristics; Feces; Female; Fishes; Humans; Water
PubMed: 32310976
DOI: 10.1371/journal.pntd.0008170 -
International Journal of Infectious... Jun 2020The global Guinea Worm Eradication Program has reduced numbers of human infections of Guinea worm disease (dracunculiasis) to 49 cases in four countries. However,...
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.
Topics: Animals; Chad; Copepoda; Dog Diseases; Dogs; Dracunculiasis; Dracunculus Nematode; Infection Control; Water
PubMed: 32173575
DOI: 10.1016/j.ijid.2020.03.016