Eradication of dracunculiasis
Dracunculiasis or Guinea-worm disease (GWD), is an infection by the Guinea worm. In 1986, there were an estimated 3.5 million cases of Guinea worm in 20 endemic nations in Asia and Africa. Ghana alone reported 180,000 cases in 1989. The number of cases has since been reduced by more than 99.999% to 22 in 2015 — in the five remaining endemic nations of Africa: South Sudan, Chad, Mali, Ethiopia, and Angola.
The World Health Organization (WHO) is the international body that certifies whether a disease has been eliminated from a country or eradicated from the world. The Carter Center, a nongovernmental, not-for-profit organization founded by former U.S. President Jimmy Carter, also reports the status of the Guinea worm eradication program by country.
As of 2019, the WHO goal for eradication in humans and animals is 2030 (previously targets have been set at 1991, 2009, 2015, and 2020).
Since humans are the principal host for Guinea worm, and there is no evidence that D. medinensis has ever been reintroduced to humans in any formerly endemic country as the result of non-human infections, the disease can be controlled by identifying all cases and modifying human behavior to prevent it from recurring. Once all human cases are eliminated, the disease cycle will be broken, resulting in its eradication.
The eradication of Guinea worm disease has faced several challenges:
- Inadequate security in some endemic countries
- Lack of political will from the leaders of some of the countries in which the disease is endemic
- The need for change in behavior in the absence of a magic bullet treatment like a vaccine or medication
- Inadequate funding at certain times
In January 2012 the WHO meeting at the Royal College of Physicians in London launched the most ambitious and largest coalition health project ever, known as London Declaration on Neglected Tropical Diseases which aims to end/control dracunculiasis by 2020, among other neglected tropical disease. This project is supported by all major pharmaceutical companies, the Bill & Melinda Gates Foundation, the governments of the United States, United Kingdom DFID and United Arab Emirates and the World Bank.
In August 2015, when discussing his diagnosis of melanoma metastasized to his brain, Jimmy Carter stated that he hopes the last Guinea worm dies before he does.
Countries certified free
Endemic countries must report to the International Commission for the Certification of Dracunculiasis Eradication and document the absence of indigenous cases of Guinea worm disease for at least three consecutive years to be certified as Guinea worm-free by the World Health Organization.
The results of this certification scheme have been remarkable: by 2007, Benin, Burkina Faso, Chad, Ivory Coast, Kenya, Mauritania, Togo, and Uganda had stopped transmission, and Cameroon, Central African Republic, India, Pakistan, Senegal, Yemen were WHO certified. Nigeria was certified as having ended transmission in 2013, followed by Ghana in 2015.
With the current eradication campaign the areas that dracunculiasis are found in are shrinking. In the early 1980s, the disease was endemic in Pakistan, Yemen and 17 countries in Africa with a total of 3.5 million cases per year. In 1985, 3.5 million cases were still reported annually, but by 2008, the number had dropped to 5,000. This number further dropped to 1058 in 2011. At the end of 2015, South Sudan, Mali, Ethiopia and Chad still had endemic transmissions. For many years the major focus was South Sudan (independent after 2011, formerly the southern region of Sudan), which reported 76% of all cases in 2013.
Timeline of events
In 1984, the WHO asked the United States Centers for Disease Control and Prevention (CDC) to spearhead the effort to eradicate dracunculiasis, an effort that was further supported by the Carter Center, former U.S. President Jimmy Carter's not-for-profit organization. In 1986, Carter and the Carter Center began leading the global campaign, in conjunction with CDC, UNICEF, and WHO. At that time the disease was endemic in Pakistan, Yemen and 17 countries in Africa, which reported a total of 3.5 million cases per year.
Carter made a personal visit to a Guinea-worm endemic village in 1988. He said, "Encountering those victims first-hand, particularly the teenagers and small children, propelled me and Rosalynn [his wife] to step up the Carter Center's efforts to eradicate Guinea worm disease."
In 1991, the World Health Assembly (WHA) agreed that Guinea worm disease should be eradicated. At this time there were 400,000 cases reported each year. The Carter Center has continued to lead the eradication efforts, primarily through its Guinea Worm Eradication Program.
In the 1980s, Carter persuaded President Zia-ul-Haq of Pakistan to accept the proposal of the eradication program, and by 1993, Pakistan was free of the disease. Key to the effort was, according to Carter, the work of "village volunteers" who educated people about the need to filter drinking water.
Other countries followed the example of Pakistan, and by 2004, Guinea worm was eradicated in Asia.
In December 2008, The Carter Center announced new financial support totaling $55 million from the Bill & Melinda Gates Foundation and the United Kingdom Department for International Development. The funds will help address the higher cost of identifying and reporting the last cases of Guinea worm disease. Since the worm has a one-year incubation period, there is a very high cost of maintaining a broad and sensitive monitoring system and providing a rapid response when necessary.
One of the most significant challenges facing Guinea worm eradication has been the civil war in Southern Sudan, which was largely inaccessible to health workers due to violence. To address some of the humanitarian needs in Southern Sudan, in 1995, the longest ceasefire in the history of the war, and the longest humanitarian cease-fire in history, was achieved through negotiations by Jimmy Carter. Commonly called the "Guinea worm cease-fire," both warring parties agreed to halt hostilities for nearly six months to allow public health officials to begin Guinea worm eradication programming, among other interventions.
Public health officials cite the formal end of the war in 2005 as a turning point in Guinea worm eradication because it has allowed health care workers greater access to Southern Sudan's endemic areas. In 2006, there was an increase from 5,569 cases in 2005 to 15,539 cases, as a result of better reporting from areas that were no longer war-torn. The Southern Sudan Guinea Worm Eradication Program (SSGWEP) has deployed over 28,000 village volunteers, supervisors and other health staff to work on the program full-time. The SSGWEP was able to slash the number of cases reported in 2006 by 63% to 5,815 cases in 2007. Since 2011, at the time that South Sudan became an independent nation-state, its northern neighbour Sudan had reported no endemic cases of dracunculiasis .
Sporadic insecurity or widespread civil conflict could at any time ignite, thwarting eradication efforts. The remaining endemic communities in South Sudan are remote, poor and devoid of infrastructure, presenting significant hurdles for effective delivery of interventions against disease. Moreover, residents in these communities are nomadic, moving seasonally with cattle in pursuit of water and pasture, making it very difficult to know where and when transmission occurred. The peak transmission season coincides with the rainy season, hampering travel by public health workers.
Another remaining area in Africa remained challenging to ending Guinea worm: northern Mali, where Tuareg rebels made some affected areas unsafe for health workers. Four of Mali's regions—(Kayes, Koulikoro, Ségou, and Sikasso)—have eliminated dracunculiasis, while the disease is still endemic in the country's other four regions (Gao, Kidal, Mopti, and Timbuktu). Late detection of two outbreaks, due to inadequate surveillance resulted in a meager 36% containment rate in Mali in 2007. The years 2008 and 2009 were more successful, however, with containment rates of 85% and 73% respectively. The civil war prevented accurate information from being gathered in northern Mali in 2012.
In Ghana, after a decade of frustration and stagnation, in 2006 a decisive turnaround was achieved. Multiple changes can be attributed to the improved containment and lower incidence of dracunculiasis: better supervision and accountability, active oversight of infected people daily by paid staff, and an intensified public awareness campaign. After Jimmy Carter's visit to Ghana in August 2006, the government of Ghana declared Guinea worm disease to be a public health emergency. The overall rate of contained cases has increased in Ghana from 60% in 2005, to 75% in 2006, 84% in 2007, 85% in 2008, 93% in 2009, and 100% in 2010.
In 2012, 1,060 human cases were reported—1,030 in South Sudan, 12 in Mali, 10 in Chad, and 8 in Ethiopia. The majority of cases in South Sudan were in Kapoeta East County, and Kapoeta North County. These adjacent counties are in the state of Eastern Equatoria. Of the 70 counties in South Sudan, 56 (80%) are considered free of dracunculiasis.
The cases reported in Chad were part of an outbreak that was originally identified in 2010 as part of a pre-certification process. Chad had not reported any cases between 2001 and 2009. Two of the cases in Ethiopia were imported from South Sudan. Ghana appears to have eradicated guinea worm. In August 2011, their public health officials reported that Ghana was free of reported cases for over 14 months. While promising, given the incubation period, it will be some time before the WHO certifies Ghana as free of this disease. After South Sudan separated from Northern Sudan, Northern Sudan has been free of guinea worm disease since 2002 and it has been certified free of this disease by the WHO. Burkina Faso and Togo were both certified free of dracunculiasis in 2011, as the last endemic cases were in November 2006 and December 2006, respectively.
In 2012, 542 human cases were reported—521 in South Sudan, 10 in Chad, 7 in Mali, and 4 in Ethiopia. This represents a 49% reduction compared to 2011. The containment rate was 64%.
However, since March 2012, Mali's Guinea Worm Eradication Program workers have had limited access to northern Mali due to the Tuareg rebellion (2012), and were not able to investigate cases there. Médecins du Monde reported rumours of a further 5 unconfirmed cases in northern Mali since March.
In 2013, 148 human cases were reported—113 in South Sudan, 14 in Chad, 11 in Mali and 7 in Ethiopia, and 3 in Sudan (imported from South Sudan). This represents a 73% reduction over 2012. Due to civil insecurity in South Sudan, monitoring was suspended in parts of the country in December. Containment was 66%. After a decade without any reported cases, it is clear that dracunculiasis has since reestablished itself in Chad. There were concerns that surveillance vigilance has decreased, and renewed efforts were made to increase monitoring. This includes coordinating monitoring with its neighbours Nigeria and Cameroon.
In 2014, 126 human cases were reported—70 in South Sudan, 40 in Mali, 13 in Chad, and 3 in Ethiopia. 13% fewer Guinea worms emerged from humans in 2014 compared to 2013 (172 vs. 197), and 57% fewer villages had indigenous cases (30 vs. 69). The figure for total worms emerging is larger than new cases because a person may be infected by more than 1 worm, and it may emerge many months later than when the case is first reported. The big drop in cases was again in South Sudan. Containment increased from 66% to 73%, mainly due to Mali's 24% improvement to 88%. The increase of the reward for reporting cases of the disease in South Sudan, Ethiopia and Mali from the equivalent of about US$50 to about US$100 has improved reporting, as did the campaign to advertise this reward in Mali. In Mali, part of the increase has been caused by improved security allowing more of the country to be monitored. While parts of the country were still not monitored, all known endemic areas were covered. Advertising the increased reward for reporting cases may have allowed cases to be found earlier, and so contained before the victims become a risk of spreading the parasite.
A report from the WHO Collaborating Center for Research, Training and Eradication of Dracunculiasis, CDC noted 2 specific problems encountered while eliminating the last few cases in Chad – some dogs seemed to be infected with the parasite, and the large number, size and heavy vegetation of lagoons used by fishermen reducing the effectiveness of the Abate larvicide. It is likely that the disease is being caused by eating undercooked fish from these sources. The Carter Center reported the general consensus that in Chad the disease has found an alternate host in dogs, and will have to be eradicated from both humans and dogs.
In 2015, 22 human cases were reported—9 in Chad, 3 in Ethiopia, 5 in Mali, and 5 in South Sudan. The proportion of people contained was 36%, compared to 73% in 2014. That means 14 cases were not contained in 2015, compared to 34 cases in 2014. Nine of these 14 cases not contained were in Chad. Ghana was certified free of dracunculiasis in 2015, as the last endemic case was in May 2010.
A significant change from 2014 was the increased effort being used to identify and treat infected dogs—mainly in Chad where the vast majority of cases of dogs hosting the worm were found, but also significantly in Ethiopia. In 2015, 483 infected dogs were identified and treated in Chad—more than 20 times the number reported in humans worldwide. This was more than four times larger than the number treated in 2014 (114 dogs). A major factor in this increase was probably the financial reward started in January for reporting an infected dog. 68% of dogs treated were also contained, compared to 40% in 2014. Dogs are now believed to be the major source of the parasite infecting humans in Chad, a country in which no indigenous cases of guinea worm were reported in the decade leading up to 2010. 15 dogs outside Chad were also been identified and treated, as well five cats and one baboon. The August Carter Center report predicts that Chad may be the last country that eliminates dracunculiasis, and reports on further ongoing research into the relationship between the parasite and dogs there, and some different treatments for dogs.
In 2016, 25 human cases were reported—16 in Chad, 6 in South Sudan, and 3 in Ethiopia. No cases were reported in Mali. This was the first increase in yearly case count. The 2016 Juba clashes in South Sudan led to the evacuation of all expatriate SSGWEP staff. Members of the local staff were given the option of continuing to work if possible. It is unclear what impact the evacuation had.
The efforts against infected dogs continue to increase in Chad, with 498 dogs being identified and treated up to 31 May, compared to 196 cases in the same period the previous year. The level of containment of infected dogs before they become a risk of spreading the parasite has improved to 81% compared to 67% last year. By the end of 2016, Chad reported provisional totals of 1,011 infected domestic dogs (66% contained), 11 infected domestic cats (55% contained), and one infected wild frog. Mali reported 11 infected dogs (8/11 contained) in 2016, and Ethiopia reported 14 infected dogs (71% contained), and two infected baboons.
In 2017, 30 human cases were reported—15 in Chad, and 15 in Ethiopia; 13 of which were fully contained. For the first time ever, South Sudan reported no human infections for a whole calendar year: the last reported case was on 20 November 2016. No human cases were reported in Mali for the second year in a row.
In addition to their human cases, Chad reported 817 infected dogs and 13 infected domestic cats, and Ethiopia reported 11 infected dogs and 4 infected baboons. Despite no human infections, Mali reported 9 infected dogs and 1 infected cat.
In 2018, 28 human cases were reported worldwide: 17 in Chad, 10 in South Sudan and 1 in Angola. In terms of animal cases Chad has so far reported 832 infections in dogs and 17 infections in domestic cats, Mali reported 6 infected dogs and 2 infected domestic cats, and Ethiopia reported 8 infected dogs and 3 infected domestic cats.
At the end of 2018 28 human cases and 1,102 animal cases were reported. Of the animal cases 1,069 were in dogs, 32 in cats and one in a baboon.
- A human case was reported in Angola in January.
- Angola reported a single animal case in April.
- Mali reported a single case in an animal in May.
- As of the end of May Chad has reported nine human cases and 1055 cases in dogs.
- Chad has also reported three cases in cats.
- Ethiopia reported a single suspected case in a baboon in June.
A trial of flubendazole to treat dogs has been started.
The World Health Organization revised its target date for eradication from 2020 to 2030, citing civil conflicts and new information about transmission between humans and dogs. The new goal includes eradication in both humans and animals.
By the end of October 2019 the total number of human cases had risen to 49. There was one case each in Angola and Cameroon, four cases in South Sudan and 43 cases in Chad.
At the same time a number of cases in animals were also reported. Angola reported 1 case, Ethiopia reported 8 cases, Mali 9 cases while Chad reported 1899 cases.
Notes and references
- Including 3 exported to Sudan.
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