Dogs and Guinea worm eradication
2016; Elsevier BV; Volume: 16; Issue: 11 Linguagem: Inglês
10.1016/s1473-3099(16)30380-2
ISSN1474-4457
AutoresMark L. Eberhard, Ernesto Ruiz‐Tiben, Donald R. Hopkins,
Tópico(s)Malaria Research and Control
ResumoTeresa Galán-Puchades, in her Correspondence on dogs and Guinea worm eradication,1Galán-Puchades MT Dogs and Guinea worm eradication.Lancet Infect Dis. 2016; 16: 770Summary Full Text Full Text PDF PubMed Scopus (7) Google Scholar noted several critical points about the Guinea Worm Eradication Program (GWEP) in Chad. We would like to clarify several of the issues. Dog infections have been addressed programmatically in Chad for the past 4 and a half years. The situation in Chad is different from previous reports of sporadic Guinea worm infections in dogs. What is not made clear by Galán-Puchade is that human Guinea worm has infected dogs occasionally, but when eliminated from the human population, dog infections disappear.2Muller R Dracunculus and dracunculiasis.Adv Parasitol. 1971; 9: 73-151Crossref PubMed Scopus (116) Google Scholar, 3Cairncross S Muller R Zagaria N Dracunculiasis (Guinea worm disease) and the eradication initiative.Clin Micro Rev. 2002; 15: 223-246Crossref PubMed Scopus (108) Google Scholar By contrast, in Chad, dog infections are probably responsible for the small number of cases in human beings.4Eberhard ML Ruiz-Tiben E Hopkins DR et al.The peculiar epidemiology of dracunculiasis in Chad.Am J Trop Med Hyg. 2014; 90: 61-70Crossref PubMed Scopus (98) Google Scholar We expect human infections in Chad to stop once transmission of Guinea worms among dogs is interrupted. Lastly, all evidence suggests transmission is not occurring via common drinking water sources, but via a paratenic aquatic host that people and dogs are eating raw or only partly cooked.4Eberhard ML Ruiz-Tiben E Hopkins DR et al.The peculiar epidemiology of dracunculiasis in Chad.Am J Trop Med Hyg. 2014; 90: 61-70Crossref PubMed Scopus (98) Google Scholar Previous laboratory studies have shown that dogs (and cats and monkeys) are good experimental hosts for Dracunculus medinensis.5Moorthy VN Sweet WC Further notes on the experimental infection of dogs with dracontiasis.Am J Hyg. 1938; 27: 301Google Scholar, 6Muller R Experimental dracontiasis in animals.Parasitology. 1968; 58: 7-8Google Scholar Hence, the ease with which this infection was established in dogs is not surprising. The reward paid to dog owners probably has a key role in dog infections being reported by owners, which is exactly what was hoped for. However, the increase in dog infection rates has resulted from active surveillance undertaken in larger and larger areas within Chad by the GWEP. Residents of endemic villages have been interviewed to learn what is known about Guinea worm disease. Discussions have also been held with former officials of Chad's GWEP from 1993–98 to gain some insight and perspective on the matter. None of these reliable sources ever encountered a Guinea worm infection in a dog during years of working in endemic areas when hundreds of cases in human beings were being reported.4Eberhard ML Ruiz-Tiben E Hopkins DR et al.The peculiar epidemiology of dracunculiasis in Chad.Am J Trop Med Hyg. 2014; 90: 61-70Crossref PubMed Scopus (98) Google Scholar We recently showed that tadpoles were readily infected with D medinensis and harboured larvae that were infectious to ferrets.7Eberhard ML Yablsey MJ Zirimwabagabo H et al.Possible role of fish and frogs as paratenic hosts of Dracunculus medinensis Chad.Emerg Inf Dis. 2016; 22: 1428-1430Crossref PubMed Scopus (38) Google Scholar Tadpoles have been shown to harbour those larvae into the adult frog stage, and that these larvae were infective in mammalian definitive hosts.8Beverley-Burton M CrichtonVFJObservations on the seasonal prevalence, pathology and transmission of Dracunculus insignis (Nematoda: Dracunculoidea) in the raccoon, Procyon lotor in Ontario.J Wildl Dis. 1977; 13: 273-280Crossref PubMed Scopus (21) Google Scholar, 9Eberhard ML Brandt FH The role of tadpoles and frogs as paratenic hosts in the life cycle of Dracunculus insignis (Nematoda: Dracunculoidea).J Parasitol. 1995; 81: 792-793Crossref PubMed Scopus (20) Google Scholar We recently discovered the occurrence of a D medinensis larva in a wild-caught frog in Chad.10Eberhard ML Cleveland CA Zirimwabagabo H Yabsley MJ Ouakou PT Ruiz-Tiben E Guinea worm (Dracunculus medinensis) infection in a wild-caught frog, Chad.Emerg Infect Dis. 2016; (published online Nov 15.)https://doi.org/10.3201/eid2211.161332Crossref Scopus (30) Google Scholar In Chad, most water bodies are too large to treat with chemical larvicide, so it is applied to cordoned areas suspected of being contaminated, thus preventing new infections in the following year. D medinensis from dogs and human beings in Chad are genetically indistinguishable, hence interventions in place now and in the near future aim to interrupt transmission from both hosts. We declare no competing interests. The findings and conclusions in this Correspondence are our own and do not necessarily represent the official position of the US Centers for Disease Control and Prevention. Dogs and Guinea worm eradicationAfter 30 years of control campaigns, guinea worm faces eradication.1 However, dogs are expected to thwart the eradication of dracunculiasis as they act as alternative hosts of the worm.1,2 The health community undoubtedly have to recognise the success of the Guinea Worm Eradication Program (GWEP), although some flaws cannot be overlooked. One of the most essential points when trying to achieve the control of parasitic infections is to determine the role of reservoirs that could maintain the disease. Full-Text PDF
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