Volume 97, Issue 2
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645

    Recurrence of Guinea Worm Disease in Chad after a 10-Year Absence: Risk Factors for Human Cases Identified in 2010–2011

  • Authors: Nandini Sreenivasan1, Adam Weiss2, Jean-Paul Djiatsa2, Fernand Toe2, Ngarodjel Djimadoumaji3,†, Tracy Ayers1, Mark Eberhard1, Ernesto Ruiz-Tiben2, Sharon L. Roy1
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    *Address correspondence to Sharon L. Roy, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop A-06, Atlanta, GA 30329. E-mail: str2@cdc.gov


    Financial support: The Parasitic Diseases Branch, Division of Parasitic Diseases and Malaria, CDC, serves as the WHO Collaborating Center for Dracunculiasis Eradication, and as such, received a small award from the Neglected Tropical Diseases Department, WHO, in support of these activities. During 2008–2012, The Carter Center’s work to eradicate Guinea worm disease was made possible by financial and in-kind contributions from Next Generation Fund of the Hugh J. Andersen Foundation; Apple Computer, Inc., Arab Fund for Economic and Social Development; Atlanta Woman’s Club; BASF Corporation; Canadian International Development Agency; Chevron Corporation; Children’s Investment Fund Foundation UK; Crawford Family Foundation; Delta Medical Supplies; Edgar O. Dixon Charitable Trust; Elfenworks Foundation; First Congregational Church; Foundation Source; Bill & Melinda Gates Foundation; General Electric Company; Girl Scouts of America Brownie Troop 861; Global Aviation Holdings; Global Health Education Consortium, Inc.; Google, Inc.; Robert and Shirley Harris Family Foundation; Harris myCFO Foundation; Conrad N. Hilton Foundation; John C. and Karyl Kay Hughes Foundation; John P. Hussman Foundation, Inc.; Johns Hopkins University; Johnson and Johnson; Kendeda Fund; Leslie Family Foundation; John D. and Catherine T. MacArthur Foundation; McKenna Foundation; Mid-Continent University; Monsanto Company; Mount Pleasant Lutheran Church; National Democratic Institute for International Affairs; OPEC Fund for International Development; Roman Catholic Diocese of Joliet; Government of Saudi Arabia; Saudi Fund for Development; JV Schiro Zavela Foundation; S.H.O.D. LLC; Stahl Family Foundation; St. Thomas Aquinas Parish; Sultanate of Oman; HH General Sheikh Mohamed Bin Zayed Al Nahyan, Crown Prince of Abu Dhabi, in honor of HH Sheikh Khalifa bin Zayed, President of the United Arab Emirates; UNICEF; United Kingdom Department for International Development; U.S. Agency for International Development; U.S. Centers for Disease Control and Prevention; United Nations World Food Programme; Vanguard Charitable Endowment Program; Vestergaard Frandsen; Women’s Leadership Foundation; YKK Corporation; and many generous individuals.

    fn2Authors’ addresses: Nandini Sreenivasan, Tracy Ayers, Mark Eberhard, and Sharon L. Roy, Centers for Disease Control and Prevention, Atlanta, GA, E-mails: vii2@cdc.gov, eyk6@cdc.gov, mle1@cdc.gov, and str2@cdc.gov. Adam Weiss and Ernesto Ruiz-Tiben, The Carter Center, Atlanta, GA, E-mails: adam.weiss@cartercenter.org and ert@cartercenter.org. Jean-Paul Djiatsa and Fernand Toe, The Carter Center, N’Djamena, Chad, E-mails: jpdjiatsa@gmail.com and fernandtoe@gmail.com.


    Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

  • Publisher: The American Society of Tropical Medicine and Hygiene
  • Source: The American Journal of Tropical Medicine and Hygiene, Volume 97, Issue 2, Aug 2017, p. 575 - 582
  • DOI: https://doi.org/10.4269/ajtmh.16-1026



A decade after reporting its last case of Guinea worm disease (GWD), a waterborne parasitic disease targeted for eradication, Chad reported 20 confirmed human cases from 17 villages—10 cases in 2010 and 10 cases in 2011. In 2012, the first GWD dog infections were diagnosed. We conducted a case-control study during April–May 2012 to identify human transmission risk factors and epidemiologic links. We recruited 19 cases and 45 controls matched by age, sex, time, and location of exposure based on the case patients’ periods of infection 10–14 months earlier. Data were analyzed with simple conditional logistic regression models using Firth penalized likelihood methods. Unusually, GWD did not appear to be associated with household primary water sources. Instead, secondary water sources, used outside the village or other nonprimary sources used at home, were risk factors (matched odds ratio = 38.1, 95% confidence interval = 1.6–728.2). This study highlights the changing epidemiology of GWD in Chad—household primary water sources were not identified as risk factors and few epidemiologic links were identified between the handfuls of sporadic cases per year, a trend that continues. Since this investigation, annual dog infections have increased, far surpassing human cases. An aquatic paratenic host is a postulated mode of transmission for both dogs and humans, although fish could not be assessed in this case-control study due to their near-universal consumption. GWD’s evolving nature in Chad underscores the continued need for interventions to prevent both waterborne and potential foodborne transmission until the true mechanism is established.


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  • Received : 27 Dec 2016
  • Accepted : 11 Apr 2017

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