Progress Toward Global Eradication of Dracunculiasis, January 2010--June 2011

In 1986, the World Health Assembly (WHA) called for the elimination of dracunculiasis (Guinea worm disease), a parasitic infection in humans caused by Dracunculus medinensis (1). At the time, an estimated 3.5 million cases were occurring annually in 20 countries in Africa and Asia, and 120 million persons were at risk for the disease (1,2). Because of slow mobilization in countries with endemic disease, the 1991 WHA goal to eradicate dracunculiasis globally by 1995 was not achieved (3). In 2004, WHA established a new target date of 2009 for global eradication*; despite considerable progress, that target date also was not met. This report updates published (4--6) and previously unpublished data and describes progress towards global eradication of dracunculiasis since January 2010. The number of indigenous cases of dracunculiasis worldwide decreased 44%, from 3,185 cases in 2009 to 1,793 in 2010. As of June 2011, dracunculiasis remained endemic in three countries (Ethiopia, Mali, and South Sudan). Of the 814 cases that occurred during January--June 2011, a total of 801 (98%) were reported from 358 villages in South Sudan. By October 2010, Ghana had gone 12 months without an indigenous case, thereby interrupting transmission; Ethiopia and Mali are close to interrupting transmission, as indicated by the small and declining numbers of cases in these two countries. An outbreak of 10 cases was discovered in Chad in 2010. The current target is to interrupt transmission in the remaining countries as soon as possible. Insecurity (e.g., sporadic violence or civil unrest) in areas of South Sudan and Mali, where dracunculiasis is endemic, poses the greatest threat to the success of the global dracunculiasis eradication campaign.

Persons become infected with the parasite by drinking water from stagnant sources (e.g., ponds) containing copepods (water fleas) that harbor D. medinensis larvae. Currently, no effective drug to treat or vaccine to prevent the disease is available, and persons who contract D. medinensis infections do not become immune. After a 1-year incubation period, adult female worms 24--40 inches (60--100 centimeters) long migrate under the skin to partially emerge, usually through the skin of the foot or lower leg. On contact with water, these worms release larvae that can then be ingested by copepods and infect persons who drink the water. The emerging worm can be removed by manual traction and rolling it up on a stick or gauze a few centimeters each day. Complete removal requires an average of approximately 4 weeks. Disabilities caused by dracunculiasis are secondary to bacterial infections that frequently develop in the skin, causing pain and swelling (7,8).

Dracunculiasis can be prevented by 1) educating persons from whom worms are emerging to avoid immersing affected parts in sources of drinking water, 2) filtering potentially contaminated drinking water through a cloth filter, 3) treating potentially contaminated surface water with the larvicide temephos (Abate), and 4) providing safe drinking water from bore-hole or hand-dug wells (3). Containment of transmission,† achieved through 1) voluntary isolation of each patient to prevent contamination of drinking water sources, 2) provision of first aid, 3) manual extraction of the worm, and 4) application of occlusive bandages, is complementary to the four main interventions.

Countries enter the World Health Organization (WHO) precertification stage of eradication approximately 1 year (i.e., one incubation period for D. medinensis) after reporting of their last indigenous case. A case of dracunculiasis is defined as occurring in a person exhibiting a skin lesion or lesions with emergence of one or more Guinea worms. Each person is counted only once during a calendar year. An imported case is an infection acquired in a place (another country or village within the same country) other than the community where it is detected and reported. Eight countries where transmission of dracunculiasis previously was endemic (Burkina Faso, Cote d'Ivoire, Ghana, Kenya, Niger, Nigeria, Sudan,§ and Togo) are in the precertification stage of eradication.

In each country affected by dracunculiasis, a national eradication program receives monthly reports of cases from each village that has endemic transmission. Reporting rates are calculated by dividing the number of villages with endemic dracunculiasis that report each month by the total number of villages with endemic disease. All villages with endemic dracunculiasis are kept under active surveillance, with daily searches of households for persons with signs and symptoms suggestive of dracunculiasis. This is done to ensure that detection occurs within 24 hours of worm emergence so that patient management can begin to prevent contamination of water. Villages where endemic transmission of dracunculiasis is interrupted (i.e., zero cases reported for ≥12 consecutive months) also are kept under active surveillance for 3 consecutive years.

WHO certifies a country free from dracunculiasis after it maintains adequate nationwide surveillance for 3 consecutive years and demonstrates that no cases of indigenous dracunculiasis occurred during that period. As of the end of 2010, WHO had certified 187 countries and territories as free from dracunculiasis (4); 18 African countries, including three with endemic disease and one with an outbreak of dracunculiasis, remained to be certified.

Country Reports

South Sudan. After a referendum held in January 2011, the 10 southern states of Sudan became the independent Republic of South Sudan on July 9, 2011. Since 2002, all indigenous cases of dracunculiasis in Sudan were reported from the states that are now in the Republic of South Sudan, making the northern states the newest dracunculiasis-free country (Sudan), which is awaiting certification. The South Sudan Guinea Worm Eradication Program (SSGWEP) reported 1,698 cases of dracunculiasis in 2010, of which 1,264 (74%) were contained (Table 1). In January--June 2011, SSGWEP reported a provisional total of 801 cases (77% contained, compared with 72% contained during January--June 2010), an increase of 8% compared with the 745 cases reported for the same period in 2010 (Table 2). All of South Sudan's increase in cases occurred in the state of Eastern Equatoria, which had 27% more cases than the same period a year before. Endemic areas outside of Eastern Equatoria reported 72% fewer cases during January--June 2011. In June 2011, South Sudan's cases were fewer than the same month the previous year for the first time this year (171 cases in June 2011 compared with 241 cases in June 2010, a reduction of 29%). During 2010, a total of 732 villages reported one or more indigenous cases; during January--June 2011, a total of 366 villages reported indigenous cases. During January--June 2011, three security incidents (e.g., civil disorder, banditry, and other violence) disrupted Guinea worm program operations in South Sudan, compared with 14 such incidents during January--June 2010. The peak transmission season in South Sudan is March through October.

Mali. Mali's Guinea Worm Eradication Program reported 57 indigenous cases in 2010, which was a reduction of 69% from the 186 indigenous cases reported in 2009. Of the 57 cases reported for 2010, 45 (79%) were contained. Mali reported three cases, of which one was contained, during January--June 2011, compared with one case reported during January--June 2010. The two uncontained cases were detected more than 24 hours after the worms began to emerge, but neither patient appears to have contaminated water. Insecurity attributed to Al Qaeda--associated groups is an increasing problem in the areas of Mali that are endemic or previously endemic. Mali's peak Guinea worm transmission season is June through October.

Ethiopia. Ethiopia reported 20 indigenous cases and one imported case from South Sudan in 2010, of which 19 (90%) were contained. This was a reduction of 17% from the 24 indigenous cases reported in 2009. During January--June 2011, Ethiopia reported six indigenous cases and two cases imported from South Sudan, of which seven cases (88%) were contained, for a reduction of 54% from the 13 indigenous cases reported during January--June 2010. All of the indigenous cases in 2010 and so far in 2011 were from Gog District in the Gambella Region. The program extended surveillance to all 71 known inhabited settlements in Gog District beginning in January 2010. The peak transmission season in Ethiopia is March through May.

Ghana. Ghana reported eight indigenous cases in 2010, all of which were contained. Ghana has reported no case of dracunculiasis since May 2010. The peak transmission season in Ghana was October through March.

Chad. After a decade with no reported cases and three assessments by WHO teams in 2001, 2006, and 2008, a visiting WHO team in 2010 investigated rumors of cases and confirmed an outbreak that involved a total of 10 known indigenous cases in eight villages during 2010. None of the cases were contained. Worm specimens taken from several patients in 2010 were confirmed at CDC as D. medinensis. Two cases were reported during January--June 2011 (compared with two cases during January--June 2010), of which one was contained, in two additional villages. A total of 36 villages are associated (i.e., visited by or the residence of a patient 10--14 months before the emergence of the worm) with the 12 cases reported during January 2010--June 2011. WHO staff members and two CDC Epidemic Intelligence Service officers conducted an investigation during January--February 2011, the outcomes of which were reported in June 2011 (9). The Carter Center opened an office in Chad in March 2011, and has provided a resident technical advisor and two expatriate technical advisors to assist the program. Active surveillance and outbreak control measures are being taken to help ensure rapid detection and containment of cases. The peak transmission season in Chad appears to be June through August.

Reported by

Donald R. Hopkins, MD, Ernesto Ruiz-Tiben, PhD, The Carter Center, Atlanta, Georgia. World Health Organization Collaborating Center for Research, Training, and Eradication of Dracunculiasis. Mark L. Eberhard, Div of Parasitic Diseases and Malaria, Center for Global Health; Sharon L. Roy, Div of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, CDC. Corresponding contributor: Sharon L. Roy, slroy@cdc.gov, 404-718-4698.

Editorial Note

With fewer than 1,800 cases reported in 2010 (the lowest annual total ever), only three endemic countries remaining, and 98% of cases in shrinking endemic areas of South Sudan, the global Guinea Worm Eradication Program is closer than ever to the goal of stopping transmission by the end of 2012. Since last year's update, Guinea worm disease transmission has ended in Ghana, once the country with the second highest dracunculiasis prevalence in the world. Unfortunately, Chad experienced an outbreak after more than 10 years in the precertification stage. The source of that outbreak, whether it originated from an externally imported case or was the result of undetected endemic transmission, is still unknown and likely will never be known. The outbreak in Chad follows the previous setback in Ethiopia in 2008, after 20 consecutive months with no reported indigenous cases there. The setbacks in Chad and Ethiopia (10) underscore the perils of inadequate vigilance after transmission of dracunculiasis is believed to have been interrupted, as well as the importance of adequate surveillance and response to suspected cases in Guinea worm--free areas of endemic countries. Other remaining challenges include the problem of insecurity in Guinea worm--endemic areas of South Sudan and Mali, and the need to focus improvements in safe water supplies on priority endemic villages.

In May 2011, the WHA adopted a resolution (WHA64.16) on eradication of dracunculiasis,¶ its first since 2004. This resolution requires the secretariat of WHO to report on the status of Guinea worm eradication to the WHA annually until the disease is eradicated.

References

1. World Health Assembly. Resolution WHA 39.21. Elimination of dracunculiasis: resolution of the 39th World Health Assembly. Geneva, Switzerland: World Health Organization; 1986.
2. Watts SJ. Dracunculiasis in Africa: its geographic extent, incidence, and at-risk population. Am J Trop Med Hyg 1987;37:119--25.
3. Ruiz-Tiben E, Hopkins DR. Dracunculiasis (Guinea worm disease) eradication. Adv Parasitol 2006;61:275--309.
4. World Health Organization. Dracunculiasis eradication: global surveillance summary, 2010. Wkly Epidemiol Rec 2011;86:189--98.
5. World Health Organization. Monthly report on dracunculiasis cases, January--December 2010. Wkly Epidemiol Rec 2011;86:91--2.
6. CDC. Progress towards dracunculiasis eradication Jan 2009--June 2010. MMWR 2010;59:1239--42.
7. Imtiaz R, Hopkins DR, Ruiz-Tiben E. Permanent disability from dracunculiasis. Lancet 1990;336:630.
8. Ruiz-Tiben E, Hopkins DR. Dracunculiasis. In: Guerrant RL, Walker DH, Weller PF, eds. Tropical infectious diseases: principles, pathogens, and practice. 2nd ed. New York, NY: Elsevier; 2006:1204--7.
9. CDC. Renewed transmission of dracunculiasis---Chad, 2010. MMWR 2011;60:744--8.
10. World Health Organization. Dracunculiasis eradication---global surveillance summary, 2008. Wkly Epidemiol Rec 2009; 84:162--71.