|
|
|
|
Eradication of infectious diseases
|
| |
|
| |
Eradication is the reduction of an infectious disease's prevalence in the global human population to zero. A number of world organizations together with local governments are working to fully eradicate various diseases. It is sometimes confused with elimination, which describes the reduction of an infectious disease's prevalence in a regional population to zero, or the reduction of the global prevalence to a negligible amount.
Discussion
Ask a question about 'Eradication of infectious diseases' Start a new discussion about 'Eradication of infectious diseases' Answer questions from other users |
Encyclopedia
Eradication is the reduction of an infectious disease's prevalence in the global human population to zero. A number of world organizations together with local governments are working to fully eradicate various diseases. It is sometimes confused with elimination, which describes the reduction of an infectious disease's prevalence in a regional population to zero, or the reduction of the global prevalence to a negligible amount. Also, the term eradication is sometimes used in the context of HIV to describe the sought-after total removal of HIV infection from an individual (i.e. a cure).
Eradicated
Smallpox
Smallpox is the only disease to have been eradicated as of December 2008. It became one of the first diseases for which there was an effective vaccination when Edward Jenner demonstrated in 1798 that inoculation of humans with cowpox could protect against smallpox.
The virus causing smallpox, Variola vera, has two variants: variola major, with a mortality rate around 30%, and variola minor, with a mortality rate less than 1%. The last naturally occurring case of variola major was diagnosed in October 1975 in Bangladesh, and the last naturally occurring case of variola minor was diagnosed in October 1977 in Somalia. The global eradication of smallpox was certified by a commission of scientists on December 9, 1979 and endorsed by the World Health Assembly on May 8, 1980.
Global eradication underway
Poliomyelitis (polio)
A dramatic reduction of the incidence of poliomyelitis in industrialized countries followed the development of a vaccine in the 1950s. In 1960, Czechoslovakia became the first country certified to have eliminated polio.
In 1988, the World Health Organization (WHO), Rotary International, the United Nations Children's Fund (UNICEF), and the U.S. Centers for Disease Control and Prevention (CDC) passed the Global Polio Eradication Initiative. Its goal was to eradicate polio by the year 2000. The updated strategic plan for 2004–2008 expects to achieve global eradication by interrupting poliovirus transmission, using the strategies of routine immunization, supplementary immunization campaigns, and surveillance of possible outbreaks. The WHO estimates that global savings from eradication, due to forgone treatment and disability costs, could exceed one billion U.S. dollars.
The following world regions have been declared polio-free:
The lowest annual polio prevalence seen so far was in 2001, with 483 reported cases. However, following interruption of vaccination in Nigeria in 2003-4 and a reduction in immunisation in India in 2001-2, there was a resurgence of polio transmission: in the period of 2002 to 2008, the number of global reported cases has remained between 750 and 2000 per year, with 1,654 cases in 2008. Some of these cases were the result of new importations in 27 countries which had previously interrupted transmission, leading to many subsequent outbreaks; 13 of these countries are believed to have still had active transmission in 2008. Four further countries remain in which poliovirus transmission has never been interrupted - Nigeria, India, Pakistan, and Afghanistan.
Dracunculiasis
Dracunculiasis, also called Guinea Worm Disease, is a painful and disabling parasitic disease caused by a worm, Dracunculus medinensis. It is spread through consumption of drinking water infested with copepods hosting Dracunculus eggs. The Carter Center has led the effort to eradicate the disease, along with the CDC, the WHO, UNICEF, and the Bill and Melinda Gates Foundation.
Unlike diseases such as smallpox and polio, there is no vaccine nor drug therapy for dracunculiasis. Eradication efforts have been based on making drinking water supplies safer and through educating people where it is endemic on safe drinking water practices. These strategies have proved successful: two decades of eradication efforts have reduced its global incidence to 4,619 cases in 2008 (provisional figures, March 2 2009), down from an estimated 3.5 million in 1986, although success has not been as quick as was hoped, given that the original goal for eradication was 1995. The WHO has certified 180 countries free of the disease, and only six countries—Sudan, Ghana, Mali, Nigeria, Niger and Ethiopea—are reported to have had endemic guinea worm in 2008.
Global eradication proposed
The Carter Center International Task Force for Disease Eradication are one of the leading groups who discuss candidates for eradication; as of April 2008, their current recommendations were that, in addition to Polio and Guinea Worm, five further diseases could be considered as candidates for eradication - Measles, Mumps, Rubella, Lymphatic Filariasis and pork tapeworm. In addition to these, however, two other diseases - Malaria and Human African Trypanosomiasis - have also been seriously proposed for eradication since the year 2000 by other parties.
Malaria
At the Gates Foundation Malaria Forum in October 2007, Bill and Melinda Gates called for a new plan for malaria eradication, by going as far as possible with existing tools while also investing in new ones. Nearly a year later, on September 25, 2008, the Roll Back Malaria partnership unveiled the Global Malaria Action Plan, in which a series of measures were proposed to eliminate malaria as a global public health concern by 2015, eliminate all malaria transmission within 8–10 countries by the same deadline, and build towards its eventual global eradication.
Human African Trypanosomiasis
The Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC), launched in July 2000, aims to eradicate the trypanosomes which cause Human African Trypanosomiasis (also known as sleeping sickness) and the cattle disease nagana, primarily by eradicating their vector, the tsetse fly. As of the end of 2007, a full scale eradication effort had not yet been rolled out, but regional elimination campaigns are planned in a number of countries.
Regional/sub-regional elimination established or under way
Some diseases have already been eliminated from parts of the world, and/or are currently being targetted for regional elimination. These have been grouped together under one section here because often, even after regional elimination is successful, interventions need to continue to prevent a disease becoming re-established.
Malaria
Malaria elimination has already been achieved in the USA, Australia and Western Europe. The WHO define elimination as having no domestic transmission for the past three years. They also define an "elimination stage" when a country is on the verge of eliminating malaria, as being <1 case per 1000 people at risk per year. According to the 2008 WHO world malaria report, 10 countries were in the elimination stage by July 2008 (Algeria, Argentina, Armenia, Egypt, El Salvador, Iraq, Paraguay, Republic of Korea, Saudi Arabia and Turkmenistan) with a further 11 in the pre-elimination stage (<5 cases per 1000 people at risk per year). Some countries that are not yet in the elimination stage are also moving towards elimination. For instance, the elimination of malaria from the last remaining island in the Caribbean to have endemic transmission, Hispaniola, is under way. The main tools are malaria treatment, mosquito nets, and vector control. Of the two countries on the island, malaria is currently endemic to most of Haiti but only parts of the Dominican Republic. China is also shifting focus from control to elimination, with an initial focus on elimination in the island province of Hainan.
Lymphatic filariasis
Lymphatic filariasis is an infection of the lymph system by mosquito-borne microfilarial worms which can cause elephantiasis. Studies have demonstrated that transmission of the infection can be broken when a single dose of combined oral medicines is consistently maintained annually for approximately seven years. The strategy for eliminating transmission of lymphatic filariasis is mass distribution of medicines that kill the microfilariae and stop transmission of the parasite by mosquitoes in endemic communities. In sub-Saharan Africa, albendazole (donated by GlaxoSmithKline) is being used with ivermectin (donated by Merck & Co.) to treat the disease, whereas elsewhere in the world albendazole is used with diethylcarbamazine. Using a combination of treatments better reduces the number of microfilariae in blood. The use of insecticide-treated mosquito bed nets also reduces the transmission of lymphatic filariasis as well as malaria, which is prevalent in many of the same communities in Africa.
The efforts of the Global Programme to Eliminate LF are estimated to have already prevented 6.6 million new filariasis cases from developing in children, and to have stopped the progression of the disease in another 9.5 million people who have already contracted it. Overall, of 83 endemic countries, mass treatment has been rolled out in 48, and elimination of transmission reportedly achieved in 21.
Measles, mumps and rubella
In the 1990s, the governments of the Americas, along with the Pan American Health Organization, launched a plan to eliminate the three MMR vaccine diseases—measles, mumps, and rubella—from the region. Worldwide eradication of these diseases has also been proposed by some smaller organizations. As of December 2008, the elimination of endemic transmission of measles from the Americas has been all but achieved, with occasional small outbreaks from imported cases, and the WHO regional offices for Europe and for the Western Pacific are aiming to also achieve regional measles elimination by 2010 and 2012 respectively. However, the global goal remains control (a 90% reduction in measles deaths by 2010 from the 757,000 deaths in 2000).
Onchocerciasis
Onchocerciasis (river blindness) is the world's second leading cause of infectious blindness. It is caused by the nematode Onchocerca volvulus, which is transmitted to people via the bite of a black fly. Elimination of this disease is under way in the region of the Americas, where this disease is endemic to Brazil, Colombia, Ecuador, Guatemala, Mexico and Venezuela. The principal tool being used is mass ivermectin treatment. If successful, the only remaining endemic countries would be in Africa. In most endemic African countries, the focus is currently on control, but a few, such as Uganda, are also attempting elimination.
Yaws
Yaws is a disease caused by the spiral-shaped bacterium (spirochete) Treponema pertenue. The global prevalence of this disease was greatly reduced by the Global Control of Treponematoses (TCP) programme between 1952 and 1964. However, it remained at a low prevalence in parts of Asia, Africa and the Americas. This disease is targeted by the South-East Asian Regional Office of the WHO for elimination from the remaining endemic countries in this region (India, Indonesia and East Timor) by 2010.
See also
External links
|
| |
|
|
