Identifying correlates of Guinea worm (Dracunculus medinensis) infection in domestic dog populations

PLoS Negl Trop Dis. 2020 Sep 14;14(9):e0008620. doi: 10.1371/journal.pntd.0008620. eCollection 2020 Sep.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Chad / epidemiology
  • Climate
  • Disease Eradication / statistics & numerical data
  • Dog Diseases / epidemiology*
  • Dog Diseases / parasitology
  • Dogs
  • Dracunculiasis / epidemiology*
  • Dracunculiasis / transmission
  • Dracunculiasis / veterinary*
  • Dracunculus Nematode / isolation & purification
  • Geography
  • Machine Learning

Grants and funding

This study was financially supported by The Carter Center (https://www.cartercenter.org) and members of this organization were involved in the study. Ernesto Ruiz-Tiben from The Carter Center helped to conceive the study to serve the needs of the Guinea Worm Eradication Program. The Carter Center curated data which were collected by the Guinea Worm Eradication Program in coordination with the Chadian Ministry of Health. Adam Weiss and Ernesto Ruiz-Tiben from The Carter Center provided substantive comments on the manuscript prior to submission. No representatives from The Carter Center were involved in the design of the statistical methodology, statistical analysis, or preparation of the original manuscript draft. RLR was supported by a National Science Foundation Graduate Research Fellowship (https://www.nsfgrfp.org/) [grant number 2017203341]. Additional support for CAC was received from the ARCS Atlanta chapter (https://atlanta.arcsfoundation.org/). NSF and ARCS had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.