From Wikipedia, the free encyclopedia - View original article
|Classification and external resources|
A method used to extract a guinea worm from the leg of a human
|Classification and external resources|
A method used to extract a guinea worm from the leg of a human
Dracunculiasis ( //), also called guinea worm disease (GWD), is a nodular dermatosis produced by the development of Dracunculus parasite in the subcutaneous tissue of mammals. Dracunculus medinensis has been reported in humans, dogs, cats, horses, cattle, and other animals in Africa and Asia. A similar species of the Dracunculus genus, D. insignis, is a parasite which causes Dracunculiasis in dogs, raccoons, mink, fox, otter, and skunks of North America. Dracunculus medinensis is a long and very thin nematode (roundworm). The parasite enters a host by way of host ingestion of stagnant water contaminated with copepods infested with guinea worm larvae. Approximately one year later, the disease presents with a painful, burning sensation as the female worm forms a blister, usually on the lower limb.
The guinea worm is one of the best historically documented human parasites, with tales of its behaviour reaching as far back as the 2nd century BC in accounts penned by Greek chroniclers. It is also mentioned in the Egyptian medical Ebers Papyrus, dating from 1550 BC. The name dracunculiasis is derived from the Latin "affliction with little dragons" while the common name "guinea worm" appeared after Europeans saw the disease on the Guinea coast of West Africa in the 17th century.
The Carter Center has predicted that guinea worm disease "will be the first parasitic disease to be eradicated and the first disease to be eradicated without the use of vaccines or medical treatment".
The primary mode of prevention is through behaviour change, alongside the provision of clean water sources and the treatment of contaminated drinking water with larvicides. There is no animal or environmental reservoir of D. medinensis and thus the parasite must pass through a host each year to survive.
As the worm moves downwards, usually to the lower leg, through the subcutaneous tissues it leads to intense pain localized to its path of travel. The painful, burning sensation experienced by infected people has led to the disease being called "the fiery serpent". Other symptoms include fever, nausea, and vomiting.
Guinea worm disease used to thrive in some of the world's poorest areas, particularly those with limited or no access to clean water. In these areas stagnant water sources may still host microscopic arthropods known as copepods, which can carry the larvae of the guinea worm.
The larvae develop for approximately two weeks inside the copepods. At this stage the larvae can cause guinea worm disease if the infected copepods are not filtered from drinking water. The male guinea worm is typically much smaller (12–29 mm or 0.47–1.1 in) than the female, which, as an adult, can grow to 2–3 feet (0.61–0.91 m) long and be as thick as a spaghetti noodle.
Once inside the body, stomach acid digests the water flea, but not the guinea worm larvae that are sheltered inside. These larvae find their way to the body cavity where the female mates with a male guinea worm. This takes place approximately three months after infection. The male worm dies after mating and is absorbed.
Approximately one year after the infection began, the worm creates a blister in the human host's skin—usually on the leg or foot. Within 72 hours the blister ruptures, exposing one end of the emergent worm. This blister causes a very painful burning sensation as the worm emerges. Infected persons often immerse the affected limb in water to relieve the burning sensation. Once the blister or open sore is submerged in water, the adult female releases hundreds of thousands of guinea worm larvae, contaminating the water supply.
During the next few days, the female worm is capable of releasing more larvae whenever it comes in contact with water as it extends its posterior end through the hole in the host's skin. These larvae contaminate the water supply and are eaten by copepods, thereby repeating the life-cycle of the disease. Infected copepods can live in the water for only two to three weeks if they are not ingested by a person. Infection does not create immunity, so people can repeatedly experience guinea worm disease throughout their lives.
In drier areas just below the Sahara desert, cases of the disease often emerge during the rainy season, which for many agricultural communities is also the planting or harvesting season. Elsewhere, the emerging worms are more prevalent during the dry season, when ponds and lakes are smaller and copepods are thus more concentrated in them. Guinea worm disease outbreaks can cause serious disruption to local food supplies and school attendance .
Guinea worm disease can be transmitted only by drinking contaminated water, and can be completely prevented through two relatively simple measures:
2. Preventing people with emerging Guinea worms from entering water sources used for drinking.
There is no vaccine or medicine to treat or prevent Guinea worm disease.. Once a Guinea worm begins emerging, the first step is to do a controlled submersion of the affected area in a bucket of water. This causes the worm to discharge many of its larva, making it less infectious. The water is then discarded on the ground far away from any water source. Submersion results in subjective relief of the burning sensation and makes subsequent extraction of the worm easier. To extract the worm, a person must wrap the live worm around a piece of gauze or a stick. The process can be long, taking anywhere from hours to months. Gently massaging the area around the blister can help loosen the worm up a bit. This is nearly the same treatment that is noted in the famous ancient Egyptian medical text, the Ebers papyrus from 1550 BC Some people have said that extracting a Guinea worm feels like the afflicted area is on fire. However, if the infection is identified before an ulcer forms, the worm can also be surgically removed by a trained doctor in a medical facility.
Although Guinea worm disease is usually not fatal, the wound where the worm emerges could develop a secondary bacterial infection such as tetanus, which may be life-threatening—a concern in endemic areas where there is typically limited or no access to health care. Analgesics can be used to help reduce swelling and pain and antibiotic ointments can help prevent secondary infections at the wound site. At least in the Northern region of Ghana, the Guinea worm team found that antibiotic ointment on the wound site caused the wound to heal too well too quickly making it more difficult to extract the worm and more likely that pulling would break the worm. The local team preferred to use something called "Tamale oil" (after the regional capital) which lubricated the worm and aided its extraction. As a practical matter, many patients were also given prophylactic oral antibiotics.
It is of great importance not to break the worm when pulling it out. Broken worms have a tendency to putrefy or petrify. Putrefaction leads to the skin sloughing off around the worm. Petrification is a problem if the worm is in a joint or wrapped around a vein or other important area.
In 1986, there were an estimated 3.5 million cases of Guinea worm in 20 endemic nations in Asia and Africa. The number of cases has been reduced by more than 99% to 3,190 in 2009, 3,185 of them in the four remaining endemic nations of Africa: Sudan, Ghana, Mali and Ethiopia. This is the lowest number of cases since the eradication campaign began. As of 2010, however, the WHO predicted it will be "a few years yet" before eradication is achieved, on the basis that it took 6–12 years for the countries that have so far eliminated Guinea worm transmission to do so after reporting a similar number of cases to that reported by Sudan in 2009. The total for 2010 was 1,797 cases. All four remaining endemic countries succeeded in reducing their case totals further during this period, with Ghana in particular achieving a 97% reduction from 242 cases in 2009 to 8 cases in 2010, all of them contained. However, Chad unfortunately reported its first cases since 1998, with ten cases reported from 7 villages in 5 districts. The source of these cases is not yet clear.
The World Health Organization is the international body that certifies whether a disease has been eliminated from a country or eradicated from the world. The Carter Center also reports the status of the Guinea worm eradication program by country.
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, Côte d'Ivoire, Kenya, Mauritania, Togo, and Uganda had stopped transmission, and Cameroon, CAR, India, Pakistan, Senegal, Yemen were WHO certified.
At the end of 2010, Sudan, Mali and Ethiopia still had endemic transmission, Ghana appeared to have just succeeded in eliminating domestic transmission, and low-level transmission had just been discovered in Chad, although it has not yet been ascertained whether this was from hidden ongoing transmission or a new importation. The major focus is southern Sudan, which reported 94% of all cases in 2010. (97% in 2011)
|South Sudan||5,815||3,618||2,733||1,698||1,028||Sudan increased its efforts at eradication from 2005 when the Comprehensive Peace Agreement was signed, ending a more than two-decade long civil war. 2006 saw an increase to 15,539 cases of Guinea Worm disease, from 5,569 cases in 2005, as a result of reporting from endemic 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. Northern Sudan had reported no endemic cases of dracunculiasis since 2011 at the time that South Sudan became independent.|
|Mali||313||417||186||57||12||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, in 2007 resulted in a meager 36% containment rate in Mali in 2007. 2008 and 2009 were more successful, however, with containment rates of 85% and 73% respectively.|
|Ethiopia||0||41||24||21||8||Prior to March 2008, there had been no cases reported in Ethiopia since June 2006.|
|Chad||0||0||0||10||10||Prior to 2010, Chad had not reported any indigenous cases of guinea worm in over 10 years.|
|Ghana||3,358||501||242||8||0||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 patients 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.|
Ghana appears to have eradicated guinea worm with their public health officials reporting in August 2011 that the country has been 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.
To the end of June 2011 the number of cases were: Chad 2 cases; Ethiopia 6 cases; Mali 3 cases: and South Sudan 806 cases. After the separation of South Sudan from Northern Sudan, the territory of Northern Sudan has been free of guinea worm disease for several years and it has been certified free of this disease by the WHO.
To the end of August 2011 the number of cases reported were: Chad 7 cases; Ethiopia 8 cases; Mali 9 cases: and South Sudan 944 cases. These occurred in a total of 440 villages. One possible case has been reported from India: investigation into this is ongoing. India has been certified free since 2000 and it is suspected that this possible case may be an imported one. The majority of cases (78%) in South Sudan were located in adjacent two counties of the Eastern Equatoria state: Kapoeta East County (561 cases) and Kapoeta North County (146 cases). Aside from 2 cases imported from South Sudan, no cases were reported in Ethiopia in July and August from the single focus (Gog District) from which all cases in the last few years have been found. Although it is now possible that transmission in Ethiopia has been interrupted official confirmation will not be forthcoming for several months.
Up to September 2011 the number of uncontained cases were: South Sudan - 241; Chad - 6; Mali - 6; Ethiopia - 1. Of the 70 counties in South Sudan, 56 (80%) are considered free of dracunculiasis.
The total number of cases in 2011 was 1060. Of these 1030 were reported from South Sudan. Mali reported 12; Chad reported 10; and Ethiopia 8. The cases 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.
According to the WHO the number of reported cases of dracunculiasis has continued to drop to 143 cases between 1 January and 30 April 2012 compared with 382 cases during the same period in 2011. South Sudan alone reported 142 cases, or 99% of the global total, and Ethiopia reported 1 case.
A slightly more recent report from the WHO Collaborating Center for Research, Training and Eradication of Dracunculiasis, says that the number of reported cases between 1 January and 30 June 2012 has dropped to 391 from 807 cases in the same period in 2011 - a 52% improvement. By country the number of reported cases are South Sudan 387, Ethiopia 2, Mali 1 and Chad 1. In the same period of 2011 the number of reported cases were South Sudan 794, Ethiopia 8, Mali 3 and Chad 2.
The global campaign to eradicate Guinea worm disease began at the U.S. Centers for Disease Control and Prevention (CDC) in 1980. In 1986, former U.S. President Jimmy Carter and his not-for-profit organization, The Carter Center, began leading the global campaign, in conjunction with CDC, UNICEF, and WHO. At this time India, Pakistan, Yemen and 17 countries in Africa were endemic for this disease and 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 to step up the Carter Center's efforts to eradicate Guinea worm disease."
President Carter also recruited two African former heads of state to the battle against Guinea worm disease. Then-former head of state of Mali, General Amadou Toumani Toure (since elected President of Mali) has been a strong advocate of Guinea worm eradication in Mali and all other French-speaking African endemic countries since 1992. Since 1999, former Nigerian head of state General (Dr.) Yakubu Gowan has played a similar role in Nigeria, which at the eradication campaign's start had more cases than any other country.
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.
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. Other major actors in the eradication of Guinea worm disease include: World Health Organization, U.S. Centers for Disease Control and Prevention, Bill & Melinda Gates Foundation, and UNICEF, but the global coalition now includes dozens of other donors, nongovernmental organizations, and institutions, most especially the ministries of health of the affected countries themselves.
In December 2008, The Carter Center announced new financial support totaling US$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. According to The Carter Center, surveillance of countries, including the smallest communities in the most remote areas, needs to be intensified to prevent outbreaks and setbacks. In the case of Guinea worm disease, which 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.
The eradication of Guinea worm disease has faced several challenges:
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 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. One remaining area in West Africa outside of Ghana remains challenging to ending Guinea worm: northern Mali, where Tuareg rebels have made some affected areas unsafe for health workers.
One of the greater challenges ahead in eradicating dracunculiasis will be confronted in Sudan: there is much uncertainty with future political benchmarks in Sudan (national elections in 2009 and the referendum on the status of southern Sudan in 2011). Sporadic insecurity or widespread civil conflict could at any time ignite, thwarting eradication efforts. The remaining endemic communities in 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.
The pain caused by the worm's emergence—which typically occurs during planting and harvesting seasons—prevents many people from working or attending school for as long as three months. In heavily burdened agricultural villages fewer people are able to tend their fields or livestock, resulting in food shortages and lower earnings. A study in southeastern Nigeria, for example, found that rice farmers in a small area lost US$20 million in just one year due to outbreaks of Guinea worm disease.
Dracunculiasis has been a recognized disease for thousands of years:
In modern times, the first to describe dracunculiasis and its pathogenesis was the Bulgarian physician Hristo Stambolski, during his exile in Yemen (1877–1878). His theory was that the cause was infected water which people were drinking.