Progress Toward Global Eradication of Dracunculiasis, January 2016–Jun

Country Reports

Chad. After a decade with no reported cases, Chad reported 10 indigenous cases in 2010. After indigenous cases were confirmed during 3 consecutive years, dracunculiasis was declared to be endemic in 2012 (6,7). In 2016, Chad reported 16 cases (nine contained) in 12 villages, compared with nine cases (none contained) in 2015. During the first half of 2017, eight cases (six contained) were reported in eight villages. One of 12 villages that reported a case in 2016, and one of eight reporting a case during January–June 2017, had reported a case previously.

In 2012, Guinea worm infections were first reported in domestic dogs in Chad (6), and since then, more dogs than humans have been identified with emerging Guinea worms. This substantial number of nonhuman infections has not occurred in any other country during the eradication campaign. Worm specimens obtained from dogs were determined to be genetically indistinguishable from D. medinensis worms removed from humans in Chad (6). A majority of infections during the current outbreak have occurred in communities along the Chari River. The Carter Center has assisted the ministry of health in implementing active village-based surveillance for the disease in approximately 1,700 villages in the at-risk zone. The working hypothesis, on the basis of biologic, environmental, and epidemiologic investigations by CDC and the Carter Center, is that the cases in humans and infected dogs are associated with the domestic and commercial fishing industry along the Chari River and involve fish, frogs, or other aquatic hosts that serve as paratenic hosts (intermediate hosts in which no development of the parasite occurs). New infections are thought to occur when humans consume inadequately cooked paratenic hosts and when such hosts are consumed raw by dogs (6). Overall, 1,011 infected dogs (and 11 infected domestic cats) were reported during 2016, which was twice the number of infected dogs (503) reported in 2015. However, during January–June 2017, 537 infected dogs were reported, which is an 18% decrease from the 653 reported during the same period of 2016. This is the first such half-yearly reduction since infected dogs were first reported in 2012, and it reflects consecutive months of declining dog infections that began in November 2016 (3).

Beginning in October 2013, Chad’s Guinea Worm Eradication Program urged villagers to cook their fish well, bury fish entrails, and prevent dogs from eating fish entrails. By June 2017, according to monthly sample surveys, this intervention was being implemented by approximately 81% of respondents in surveyed communities with populations at risk. In February 2014, health education measures began to persuade villagers to tether infected dogs until the worms emerged, to prevent contamination of water and infection of copepods. In February 2015, the program introduced a reward equivalent to US$20 for reporting and tethering an infected dog. Whereas 40%, 68%, and 68% of infected dogs were tethered in 2014, 2015, and 2016, respectively, 78% of 537 infected dogs reported during January–June 2017 were tethered.

Beginning before 2010, Chad has offered a cash reward equivalent to US$100 for reporting a human case of dracunculiasis. In areas under active surveillance, 69% of 383 residents surveyed during January–June 2017 knew of the cash reward for reporting a case of dracunculiasis, and 60% of 363 persons surveyed knew of the cash reward for reporting and tethering an infected dog.

As of June 2017, 68% of villages with endemic dracunculiasis had safe water (i.e., water sources free of copepods, such as rapidly flowing rivers, protected hand dug wells, and borehole wells). Temephos use is limited by the extremely large lagoons used for fishing and as sources of drinking water. Starting in August 2014, an innovative technique of applying temephos to smaller cordoned sections of the lagoons at entry points used by infected humans or dogs was introduced and used to protect 19, 29, 61, and 51 villages in 2014, 2015, 2016, and January–June 2017, respectively.

The Carter Center and WHO Collaborating Center for Dracunculiasis Eradication at CDC are supporting research to better understand the unusual epidemiology of the current outbreak of dracunculiasis in Chad, assess antihelminthic treatment of dogs to prevent maturation of worms, and study the food sources and movements of dogs in an area of Chad with endemic disease. In collaboration with researchers from the University of Georgia, this initiative has demonstrated that D. medinensis can use an amphibian (frog) (8) as a paratenic host in the laboratory (8) and has recovered, for the first time, a Dracunculus larva from a frog captured in the wild in Chad (9).

Ethiopia. In 2016, Ethiopia reported three cases of dracunculiasis (two contained), in two villages of the Gog district and one village of the Lare district of Gambella Region. This is the same number of cases that Ethiopia reported in 2015 and in 2014. (The origin of the third case, which was reported in September 2016, is unclear, because the patient entered Ethiopia from South Sudan approximately 1 year before emergence of his Guinea worm). Ethiopia also reported 14 infected domestic dogs and two infected baboons in 2016, compared with 13 infected dogs and one infected baboon in 2015, all in the same area of the Gog district. During January–June 2017, Ethiopia reported no human case, eight infected dogs, and four infected baboons. However, in the same area of the Gog district, there were two cases in humans, two infected dogs, and no infected baboons during the same period of 2016. The program applied temephos monthly to almost all water sources known to have been used by humans in the at-risk area throughout 2015, increased coverage threefold to include numerous smaller water sources in 2016, and is addressing additional gaps in identification of water sources related to a particular stream in the at-risk area in 2017. A cash reward, equivalent to US$20 for reporting an infected animal was introduced, and the ministry of health held three press conferences to publicize the eradication effort during 2016. There are 152 villages under active surveillance in three districts of Gambella Region. Ethiopia offers a cash reward equivalent to US$100 for reporting a case of dracunculiasis. Among 11,712 persons surveyed in the Gog district during January–June 2017, 82% were aware of the reward for reporting an infected person; 61% of 2,123 surveyed knew of the reward for reporting an infected animal.

Mali. In 2016, Mali reported no human cases of dracunculiasis for the first time since its eradication program began, compared with five cases reported from three villages in 2015. Mali reported one infected dog for the first time in 2015 and 11 infected dogs (eight contained) in 2016. Two infected dogs (one contained) were reported during January–June 2017, compared with one dog (contained), during the same period of 2016. All infected dogs were detected in the Tominian district of Segou Region, but many had been imported from other areas of Segou or adjacent Mopti Region, in which certain areas were inaccessible to the program because of insecurity. Mali has 455 villages under active surveillance. Mali offers a cash reward equivalent to US$100 for reporting a case of dracunculiasis and US$20 for reporting and tethering an infected dog. In areas under active surveillance, 79% of 23,943 persons surveyed in 2016 were aware of the cash reward for reporting a case. During January–June 2017, 80% of 2,190 persons surveyed were aware of the reward for reporting a case, and 88% of 819 persons surveyed were aware of the reward for reporting and tethering an infected dog.

South Sudan. South Sudan reported six cases of dracunculiasis (three contained) from four villages in 2016, all west of the Nile, compared with five cases (three contained) reported from five villages in 2015. The country reported no infected dogs in 2016, compared with one in 2015, which has been the only infected dog found in South Sudan to date. South Sudan has reported no cases during January–June 2017, compared with four cases (three contained) reported during the same period of 2016. South Sudan has 3,860 villages under active surveillance. In April 2014, South Sudan began offering a cash reward equivalent to approximately US$125 for reporting a case of dracunculiasis (10). The overall level of reward awareness among 495 persons queried in active surveillance areas in 2016 was 76%. In March 2017, the ministry of health doubled its cash reward for reporting a case of dracunculiasis to 10,000 South Sudanese pounds (approximately US$139) to adjust for inflation and introduced a cash reward (approximately US$20) for reporting and tethering an infected animal. Coverage with interventions in villages with endemic disease remains high (except for provision of safe sources of drinking water) (Table 2), despite increased insecurity having forced the evacuation of most expatriate staff members assisting the South Sudan Guinea Worm Eradication Program since early July 2016.