Progress Toward Eradication of Dracunculiasis

Results

Reported and Laboratory-Confirmed Human and Animal Dracunculiasis Cases Worldwide

During 2022, a total of 13 human dracunculiasis cases were identified worldwide, in Central African Republic, Chad, Ethiopia, and South Sudan; these cases represent a 13% decrease from the 15 cases reported in 2021 (Table 1). During January–June 2023, three human cases were identified (no change from the number reported during the same period in 2022). Angola, Cameroon, Chad, Ethiopia, Mali, and South Sudan reported 686 animal (mostly dog) infections in 2022, a 21% decrease compared with the 862 animal infections reported in 2021. However, the 315 animal infections reported during January–June 2023 represented a 3% increase over the 305 reported during January–June 2022 (Table 2). Epidemiologic investigations identified the probable sources of 85% (11 of 13) of the human cases in 2022 compared with 47% (seven of 15) of cases in 2021.

During January–June 2023, CDC received 15 specimens from humans, and only one (7%) was laboratory-confirmed as D. medinensis*** (Table 3), compared with 20 specimens received and three (15%) laboratory-confirmed during January–June 2022. No human cases were reported for an unprecedented period of 6 consecutive months (November 1, 2022–April 30, 2023). During the first 6 months of 2023, CDC received 131 animal specimens, 114 (87%) of which were laboratory-confirmed as D. medinensis, compared with 10 (83%) confirmed among 12 specimens received during January–June 2022.

Country Reports

Angola. Angola first discovered Guinea worm cases in 2018 (8). Active community-based surveillance began in 54 villages in 2020 and expanded to 61 communities in 2022. Seven infected dogs were detected in 2022, and 32 during January–June 2023 (Table 2), all in the same province as previous infections. Genetic analysis has not linked Angola’s Guinea worms to D. medinensis specimens from other countries (Elizabeth Thiele, PhD, Vassar College, personal communication, September 2023). Angola offers a cash reward equivalent to US$450 for reporting an infected human or animal. In 2023, the Angola program began proactively tethering dogs at risk for infection, (i.e., living in or adjacent to villages with endemic disease) and began using temephos in affected areas in June.

Chad. Chad reported seven human cases in 2022,^††† compared with eight cases in 2021; during January–June 2023, two cases were reported, compared with three during January–June 2022. Chad reported 606 animal infections (521 dogs and 85 cats) in 2022, compared with 832 (767 dogs and 65 cats) in 2021. During January–June 2023, Chad reported 220 infected animals, 18% fewer than the 268 reported during January–June 2022. Transmission of D. medinensis in Chad is hypothesized to result from consumption of inadequately cooked aquatic animals including fish or other transport hosts or paratenic hosts^§§§ (2). The Carter Center helped Chad’s GWEP implement village-based surveillance for animal and human infections in 2,434 villages at risk for Guinea worm exposure by December 2022 (Table 1). Active surveillance generated 41,135 rumors (a report of a possible case) about possible Guinea worm infections among humans or animals during January–June 2022; these reports increased 169%, to 110,784 rumors during January–June 2023.

Since 2010, Chad’s Ministry of Health has offered a reward equivalent to US$100 for reporting a confirmed human dracunculiasis case, and since 2015 a US$20 reward equivalent for reporting an animal infection. Evaluations in areas with established active surveillance indicated that 72% and 57% of residents surveyed during 2022 and January–June 2023, respectively, were aware of the rewards.

Chad launched a nationwide campaign in 2013 to increase Guinea worm awareness and implemented educational interventions to prevent transmission through consumption of uncooked fish or fish entrails. Since June 2017, approximately 81% of households assessed monthly in at-risk communities were burying fish entrails to prevent consumption by dogs.

Chad’s GWEP began tethering dogs with dracunculiasis-compatible signs in 2014; in March 2020, it began proactively tethering all dogs during the 4 months of peak dracunculiasis incidence in all villages with five or more dracunculiasis infections during the previous year, increasing to villages with three or more infections in 2021, and to all villages reporting one or more dog infections in the previous or current year in 2022. As a result, 64% and 75% of eligible dogs were tethered in 2022 and January–June 2023, respectively. Water treatment with temephos reached 94% of 280 villages with dog or human infections by December 2022 and 91% of 125 villages by June 2023. In December 2022, 40% of villages reporting Guinea worm infections had at least one source of copepod-free drinking water (e.g., from a borehole well). In June 2023, Chad’s minister of health visited an area with endemic disease to support the Guinea worm eradication program and advocate for eradication.

Cameroon. Cameroon reported 28 infected dogs in 2022 and one human infection and 56 confirmed infected dogs during January–June 2023 in villages <3 miles (<5 km) from the Chad-Cameroon border. These Guinea worm infections were likely contracted in Chad because the affected villages include families living on both sides of the border and dog owners take their dogs to Chad regularly. Cameroon expanded active surveillance to all villages of concern and began proactive tethering of dogs in the affected area in January 2022.

Ethiopia. Ethiopia reported one human case, two infected baboons, and one infected dog during 2022; and no infected humans or animals during January–June 2023 (Table 2). Ethiopia is the only country that has reported infected baboons. Almost all recent infections have occurred in western Ethiopia, in the Gog district of Gambella Region. With The Carter Center’s assistance, Ethiopia’s public health and wildlife authorities resumed trapping and examining baboons in December 2022 and June 2023. Since 2021, the Ethiopia Dracunculiasis Eradication Program has conducted active surveillance in 198 villages and 223 non-village areas (e.g., farms and fishing and hunting settlements). Surveillance from the examination of baboons found dead or killed by villagers, and from approximately 555 baboons tracked and trapped by researchers (since 2018) detected 20 infected baboons during 2013–2021, two in 2022, and zero in January–June 2023, in an area of about 50 x 25 miles (80 x 40 km) in Gog district and part of adjacent Abobo district.

The reward for reporting human dracunculiasis cases is equivalent to US$360 and for reporting and tethering infected animals is US$40. In 2022, 72% of persons surveyed in active surveillance areas knew of the rewards; in January–June 2023, 97% were aware.

Since April 2018, Ethiopia has supported villager-initiated constant tethering of approximately 1,900 dogs and cats in villages at highest risk, to prevent their exposure in adjacent forests where transmission apparently occurs. The program applies temephos monthly to nearly all water sources known to have been used by humans in the at-risk areas of Gog and adjacent Abobo districts. Beginning in 2022, remote sensing data from Maxar Technologies, a space technology and intelligence company (https://www.maxar.com), has been identifying new water sources that need to be treated. In May 2022, the minister of health visited areas with endemic dracunculiasis to advocate for Guinea worm eradication.

Mali. Mali reported no human dracunculiasis cases in January 2022–June 2023, compared with two cases in 2021 (Table 2). In 2022, a total of 41 infected animals were reported, compared with 17 in 2021. During January–June 2023, seven confirmed infections in dogs were reported, all in Segou Region of central Mali, an increase from two reported during January–June 2022. Among the infected animals identified in 2022, 31 were in Segou Region; and 10 in adjacent Mopti Region, which is partly inaccessible because of civil unrest. Animals from Segou Region apparently became infected in Mopti Region. The infections of all seven dogs in January–June 2023 were reportedly contained.

In 2022, a total of 2,216 villages in Mali were under active surveillance (Table 1), with cash rewards equivalent to US$340 for reporting a human case and US$20 for reporting and tethering an infected animal. In areas under active surveillance in 2022, 82% of persons queried knew about the rewards for reporting an infected person or animal; in January–June 2023, 88% knew about the rewards. Proactive tethering of some dogs was introduced late in 2021, expanded during the June–September peak transmission season in 2022, and extended to include puppies in 2023.

South Sudan. South Sudan reported five human dracunculiasis cases in 2022, compared with four in 2021 (Table 2). No human cases or infected animals were reported during January 2022–June 2023. Only two infected dogs have ever been reported in South Sudan, the first in September 2015 and the second in August 2022. The high mobility of cattle herders and others in South Sudan poses a challenge to GWEP surveillance and interventions as does sporadic insecurity. By December 2022, a total of 2,044 villages in South Sudan were under active surveillance (Table 1). The reward for reporting a case of dracunculiasis or an infected animal is equivalent to about US$380. A 2022 survey found that 78% of respondents were aware of the reward for reporting an infected person. In April 2023, the minister of health visited an area with endemic dracunculiasis to advocate for Guinea worm eradication.