Everything about Poliomyelitis Eradication totally explained
The
global eradication of poliomyelitis is a
public health effort to eliminate all cases of poliomyelitis infection. The global effort, begun in 1988 and led by the
World Health Organization,
UNICEF and
The Rotary Foundation, has reduced the number of annual diagnosed cases from the hundreds of thousands to around a thousand. Should the effort be successful, the eradication of polio will represent only the second time a disease has been eradicated, after
smallpox.
Factors influencing eradication
Eradication of polio has been defined in various ways -- as elimination of the occurrence of a poliomyelitis even in the absence of human intervention, as
extinction of
poliovirus, such that the infectious agent no longer exists in nature or in the laboratory, as control of an infection to the point at which
transmission of the disease ceased within a specified area,
In theory, if the right tools were available, it would be possible to eradicate all infectious diseases. In reality there are distinct biological features of the organisms and technical factors of dealing with them that make their potential eradicability more or less likely. Three indicators however, are considered of primary importance in determining the likelihood of successful eradication: That effective interventional tools are available to interrupt transmission of the agent, such as a
vaccine. That diagnostic tools, with sufficient sensitivity and
specificity, be available to detect infections that can lead to transmission of the disease, and that humans are required for the life-cycle of the agent, which has no other
vertebrate reservoir and can't amplify in the environment.
Strategy
The most important step in eradication of polio is interruption of
transmission of poliovirus. Stopping polio transmission has been pursued through a combination of routine
immunization, supplementary immunization campaigns and surveillance of possible outbreaks. The four key strategies outlined by the World Health Organization for stopping polio transmission are:
- High infant immunization coverage with four doses of oral polio vaccine (OPV) in the first year of life in developing and endemic countries, and routine immunization with OPV and/or IPV elsewhere.
- Organization of “National immunization days” to provide supplementary doses of oral polio vaccine to all children less than five years of age.
- Active surveillance for wild poliovirus through reporting and laboratory testing of all cases of acute flaccid paralysis among children less than fifteen years of age.
- Targeted "mop-up" campaigns once wild poliovirus transmission is limited to a specific focal area.
Vaccination
Among the factors that have bolstered efforts to eradicate polio is that the oral polio vaccine is both highly effective and cheap (about
US$0.10 per dose, or
US$0.30 per child);
vaccination generally provides lifelong
immunity to the virus. Because the
immune response to oral polio vaccine is very similar to natural polio infection, it's expected that oral polio vaccination provides similar long term immunity.
Contact immunity to polio can occur when
attenuated poliovirus derived from the oral polio vaccine is excreted, and infects and indirectly vaccinates unvaccinated individuals.
Herd immunity
Polio vaccination is also important in the development of
herd immunity. For polio to occur in a population, there needs to be an infecting organism (
poliovirus), a susceptible human population, and a cycle of
transmission. Poliovirus is transmitted only through person-to-person contact and the transmission cycle of polio is from one infected person to another person susceptible to the disease, and so on.
Herd immunity is an important supplement to vaccination. Among those individuals who receive oral polio vaccine, only 95 percent will develop immunity. That means 5 of every 100 given the vaccine won’t develop any immunity and will be susceptible to developing polio. According to the concepts of herd immunity this population whom the vaccine fails, are still protected by the immunity of those around them. Herd immunity can only be achieved when vaccination levels are high.
Obstacles
Among the greatest obstacles to global polio eradication are the lack of basic health infrastructure, which limits vaccine distribution, the crippling effects of civil war and internal strife, and a philosophical objection to vaccination based on religious reasons in the remaining polio endemic countries. Another challenge has been maintaining the
potency of live (attenuated) vaccines in extremely hot or remote areas. The oral polio vaccine must be kept at 2-8° Celsius for vaccination to be successful.
|-
| 2001 || - || 498
|-
| 2002 || - || 1,922
|-
| 2003 || - || 784
|-
| 2004 || - || 1,258
|-
| 2005 || - || 1,998
|-
| 2006 || - || 1,985
|-
| 2007 || - || 1,307
|-
| colspan="3" |References:
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Following the widespread use of poliovirus vaccine in the mid-1950s, the incidence of poliomyelitis declined rapidly in many industrialized countries. In 1962 — just one year after
Sabin's oral polio vaccine (OPV) was licensed in most industrialized countries —
Cuba began using the oral vaccine in a series of nationwide polio campaigns. The early success of these mass vaccination campaigns suggested that polioviruses could be globally eradicated. The Pan American Health Organization (
PAHO), under the leadership of
Ciro de Quadros, launched an initiative to eradicate polio from the
Americas in 1985.
1988–1991
In 1988, the
World Health Organization, together with
Rotary International,
UNICEF, and the U.S.
Centers for Disease Control and Prevention passed the Global Polio Eradication Initiative, with the goal of eradicating polio by the year 2000. The Initiative was inspired by
Rotary International's 1985 pledge to raise $120 million toward immunising all of the world's children against the disease. This achievement was a milestone in efforts to eradicate the disease.
In 1994 the Indian Government launched the
Pulse Polio Campaign to eliminate polio. The current campaign involves annual vaccination of all children under age five. Most families have allowed their children to take the vaccine.
In 1995 Operation Mecacar (Mediterranean, Caucasus, Central Asian Republics and Russia) were launched; National Immunization Days were coordinated in 19
European and
Mediterranean countries. In 1998, Melik Minas of
Turkey became the last case of polio reported in Europe. In 1997 Mum Chanty of
Cambodia became the last person to contract polio in the
Indo-West Pacific region. In 2000 the Western Pacific Region (including
China) was certified Polio-free.
In 2002, an outbreak of polio in India occurred after the number of planned polio vaccination campaigns was reduced and the state of
Uttar Pradesh accounted for nearly two-thirds of total worldwide cases reported. (See .)
In the
Kano province in Northern
Nigeria, which operates under
Sharia (
Muslim religious law), the immunization campaign was suspended in September 2003 when prominent Muslim leaders claimed vaccines supplied by Western donors were
adulterated to reduce fertility and spread
HIV as part of a
U.S.-led drive against
Islam. On
June 30, 2004, after a 10-month ban on polio vaccinations, the WHO announced that Kano had pledged to restart the campaign in early July. During the ban the virus spread across Nigeria and into 12 neighboring countries that had previously been polio-free.
Eradication efforts in the Indian sub-continent have met with a large measure of success. Using the
Pulse Polio campaign to increase polio immunization rates,
India recorded just 66 cases in 2005; down from 135 cases reported in 2004, 225 in 2003, and 1,600 in 2002.
The first case of the polio outbreak in Sudan was detected in May 2004. The reemergence of polio led to stepped up vaccination campaigns. In the city of
Darfur; 78,654 children were immunized and 20,432 more in southern Sudan (Yirol and Chelkou).
In the
United States it was reported that "on
September 29,
2005 the Minnesota Department of Health (MDH) identified poliovirus type 1 in an unvaccinated, immunocompromised infant girl aged 7 months (the index patient) in an
Amish community whose members predominantly were unvaccinated for polio. The patient has no paralysis; the source of the patient's infection is unknown. Subsequently, poliovirus infections in three other children within the index patient's community have been documented."
2006–present
In 2006 only four countries in the world (Nigeria, India, Pakistan, and Afghanistan) were reported to have endemic poliomyelitis. Cases in other countries are attributed to importation. A total of 1,997 cases worldwide were reported in 2006; of these the majority (1,869 cases) occurred in countries with endemic polio. (See: )
In 2007 there were 1,307 cases of poliomyelitis reported worldwide.
Pakistan and Afghanistan reported 32 and 17 cases respectively in 2007. In Pakistan's tribal areas, immunization campaigns were hindered by
Muslim clerics who claim that immunizations are part of an American conspiracy designed to sterilize the local Muslim population. In February 2007, physician Abdul Ghani, who was in charge of polio immunizations in a key area of disease occurrence in northern Pakistan, was killed in a
terrorist bombing. In July 2007, a student traveling from Pakistan imported the first polio case to
Australia in over 20 years. Other countries with significant numbers of wild polio virus cases include, the
Democratic Republic of the Congo which reported 41 cases, Chad with 11 cases; Niger and
Myanmar each reported 11 cases.
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