Correlates of Variation in Guinea Worm Burden among Infected Domestic Dogs

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  • 1 Parasitic Diseases Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia;
  • 2 Guinea Worm Eradication Program, The Carter Center, Atlanta, Georgia;
  • 3 Southeastern Cooperative Wildlife Disease Study, University of Georgia, Athens, Georgia;
  • 4 Guinea Worm Eradication Program, Ministry of Public Health, N’Djamena, Chad

The Guinea Worm Eradication Program has been extraordinarily successful—in 2019, there were 53 human cases reported, down from the estimated 3.5 million in 1986. Yet the occurrence of guinea worm in dogs is a challenge to eradication efforts, and underlying questions about transmission dynamics remain. We used routine surveillance data to run negative binomial regressions predicting worm burden among infected dogs in Chad. Of 3,371 infected dogs reported during 2015–2018, 38.5% had multiple worms. A multivariable model showed that the number of dogs in the household was negatively associated with worm burden (adjusted incidence rate ratio [AIRR] = 0.95, 95% CI: 0.93–0.97, P < 0.0001) after adjusting for dog age (AIRR = 0.99, 95% CI: 0.96–1.01, P > 0.1). This could relate to the amount of infective inocula (e.g., contaminated food or water) shared by multiple dogs in a household. Other significant univariable associations with worm burden included dog history of guinea worm infection (IRR = 1.30, 95% CI: 1.18–1.45) and dog owners who were hunters (IRR = 0.78, 95% CI: 0.62–0.99, P < 0.05) or farmers (IRR = 0.83, 95% CI: 0.77–0.90, P < 0.0001). Further analysis showed that the number of dogs in the household was significantly and positively correlated with nearly all other independent variables (e.g., owner occupation: farmer, fisherman, or hunter; dog age, gender, and history of guinea worm). The associations we identified between worm burden and dogs per household, and dogs per household and owner characteristics should be further investigated with more targeted studies.

Author Notes

Address correspondence to Sarah Anne J. Guagliardo, U.S. Centers for Disease Control and Prevention, Atlanta, GA. E-mail: sguagliardo@cdc.gov

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the U.S. Department of Health and Human Services, the CDC, or the authors’ affiliated institutions.

Authors’ addresses: Sarah Anne J. Guagliardo, Ryan Wiegand, and Sharon L. Roy, Centers for Disease Control and Prevention, Atlanta, GA, E-mails: sguagliardo@cdc.gov, fwk2@cdc.gov, and str2@cdc.gov. Christopher A. Cleveland, Southeastern Cooperative Wildlife Disease Study, University of Georgia, Athens, GA, E-mail: ccleve@uga.edu. Hubert Zirimwabagabo and Elisabeth Chop, Guinea Worm Eradication Program, The Carter Center Chad Office, N’Djamena, Chad, E-mails: hubert.zirimwabagabo@cartercenter.org and echop711@gmail.com. Philippe Tchindebet Ouakou, Guinea Worm Eradication Program, Ministry of Public Health, N’Djamena, Chad, E-mail: tchindebetouakou14@gmail.com. Ernesto Ruiz-Tiben, Donald Hopkins, and Adam Weiss, Guinea Worm Eradication Program, The Carter Center, Atlanta, GA, E-mails: eruizti@emory.edu, shandal.sullivan@cartercenter.org, and adam.weiss@cartercenter.org.

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