EPIDEMIOLOGY OF POLIO MYELITIS AND POLIO ERADICATION

PROGRAMME IN INDIA

DR.I.SELVARAJ, I.R.M.SB.Sc.,M.B.B.S.,(M.D COMMUNITY MEDICINE) D.P.H., D.I.H.,P.G.C.H&FW(NIHFW,NEW DELHI)

Sr.D.M.O (ON STUDY LEAVE)

INDIAN RAILWAY MEDICAL SERVICE

•THE AMERICAS WERE CERTIFIED POLIO-FREE IN 1994. (36 COUNTRIES) • THE WESTERN PACIFIC WAS CERTIFIED POLIO-FREE IN 2000. (37 COUNTRIES AND AREAS INCLUDING CHINA) •EUROPE, COMPOSED OF 51 COUNTRIES, WAS CERTIFIED POLIO-FREE IN JUNE 2002. (51 COUNTRIES) • WITH ONLY SIX POLIO ENDEMIC COUNTRIES LEFT IN THE WORLD, POLIO TRANSMISSION COULD BE STOPPED BY END 2005.  THE WORLD COULD THEN BE CERTIFIED POLIO-FREE BY END-2008.

http://en.wikipedia.org/wiki/Image:Rooseveltinwheelchair.jpg

HISTORY1789 - British physician Michael Underwood provides the first clinical description of polio, referring to it as "debility of the lower extremities."1840 - German physician Jacob von Heine publishes a 78-page monograph in 1840 which not only describes the clinical features of the disease, but also notes that its symptoms suggest the involvement of the spinal cord.1908- Austrian physicians Karl Landsteiner and Erwin Popper make the first hypothesis that polio may be caused by a virus.

In 1908, Karl Landsteiner & Erwin Popper discovered a filterable agent as the cause of poliomyelitis. An extract of medula from a fatal human case was injected intraperitoneally in monkeys. He worked then at the Pasteur Institute, because no monkeys were available in the University of Vienna. The lesions that appeared were indistinguishable from those found in humans. They could not pass the disease monkey to monkey, but Simon Flexner & Paul Lewis managed this and found antibodies. Arnold Netter & Constantin Levaditti found antibodies in human convalescents in 1908. Levaditti & Landsteiner demonstrated neutralizing antibodies in monkey serum against active virus. Frank Mcfarland Burnet & Jean MacNamara en 1931 demonstrated serotypes.

In 1936, Albert Sabin & Peter Olitsky cultured poliovirus in embryonic nervous cells. In 1949, John Enders, Thomas Weller & Frederick C. Robbins grew the virus in muscle cells (fibroblasts) human embryonic skin cells, connective tissue cells, intestine and nervous cells, winning the Nobel prize in 1954. The important production point is that the virus grows in nonnervous cells.

Sabin, Albert: (1906-93) Pioneering researcher on viruses and viral diseases who developed the oral live-virus vaccine against polio. Sabin's vaccine came to be preferred over the alternative killed-virus vaccine developed by his bitter rival Dr. Jonas Salk. The Sabin vaccine contains harmless attenuated polio virus. Dr. Sabin first showed that polio virus could grow in human nerve tissue outside the human body. Through research on monkeys he discovered how the polio virus entered the human body. It had been widely thought that the virus entered through the respiratory tract. Sabin proved that the virus first invaded the digestive tract and later attacked nerve tissue. Albert Bruce Sabin was born in Bialystok, Poland. He immigrated with his family to the US in 1921. He graduated from New York University medical school. He trained in pathology, surgery and internal medicine at Bellevue Hospital in New York and spent a year in research at the Lister Institute in London. In 1935 he returned to New York to join the Rockefeller Institute and then in 1939 moved to the University of Cincinnati and its Children's Hospital Research Foundation.

The virion consists of a single strand of RNA containing genetic information and a protein coat. Humans are its only natural host. - The poliovirus is a member of a larger family known as Picornaviruses, which also includes rhinoviruses (such as influenza) and the hepatitis A virus. - Polio belongs to the enterovirus subgroup, made up of over 70 viruses that infect the intestines. - It is one of the smallest RNA viruses, measuring around 25 nm in diameter.

AGENT: POLIO VIRUS

EPIDEMIOLOGY

• AGENT: POLIOVIRUS

• TYPE : THREE SERO TYPES(TYPE-1,TYPE-2,TYPE-3)

• RESERVOIR: MAN

• INFECTIOUS MATERIAL: FAECES, ORO-PHARYNGEAL SECRETIONS

• INCUBATION PERIOD: 7 TO 14 DAYS( 3- 35 DAYS)

• PERIOD OF COMMUNICABILITY: 7 TO 10 DAYS

• HOST : AGE : 6 MONTHS TO 3 YEARS

• ENVIRONMENT : RAINY SEASON (JUNE TO SEPTEMBER)

• MODE OF TRANSMISSION: FAECO – ORAL ROUTE, DROPLET INFECTION

Group: Group IV ((+)ssRNA)

Family: Picornaviridae

Genus: Enterovirus

Species: Poliovirus

Left: Picture of poliovirus. The poliovirus is extremely

small, about 50 nm (nanometer = one-billionth

of a meter) Courtesy of David Belnap and James

Hogle

Right: Cross-section of the poliovirus showing the RNA, capsid, and nerve cell

receptors Illustration courtesy of Link Studio

•Inapperent(sub-clinical) Infection: this occurs approximately in 95 per cent of poliovirus infection. There are no presenting symptoms. Recognition only by isolation. •Abortive Polio Or Minor Illness: occurs approximately in 4-8 per cent of the infection. It causes only a mild or self limiting illness due to viraemia. The patient recovers quickly. •Non paralytic polio: occurs approximately in one per cent of all infections. The presenting features are stiffness and pain in neck and back. The disease lasts for two to ten days. Recovery is rapid. •Paralytic polio: occurs in less then one per cent of infections. The virus enters the brain and causes varying degree of disability.

"Poliomyelitis" comes from the Greek word for gray, polio, and myelo, meaning spinal cord. The Latin suffix itis refers to inflammatory diseases.

Among children who are paralyzed by polio:30% make a full recovery •30% are left with mild paralysis •30% have medium to severe paralysis •10% die

Global Status 1988

GLOBAL STATUS 2004

1988 3,50 000 April 1, 2003, 1,925 polio cases1998 1,9341999 1,186 2000 2652001 2112002 1919 2003 784 2004 1,556 20.12.2005 - 1831

GLOBAL POLIO VIRUS CASES

20051,831 cases of wild poliovirus (excludes vaccine derived polio viruses [8]).727 Nigeria (endemic) 478 Yemen (importation) 299 Indonesia (importation) 154 Somalia (importation) 64 India (endemic) 27 Pakistan (endemic) 27 Sudan (re-established transmission) 20 Ethiopia (importation) 9 Angola (importation) 9 Niger (endemic) 7 Afghanistan (endemic) 4 Nepal (importation) 3 Mali (importation) 1 Chad (re-established transmission) 1 Eritrea (importation) 1 Cameroun (importation) Source: Polio cases from 1 January 2005, as of 17 January 2006

•25 million children are born in India every year.•There is interval of 11 months between two PPIs. •Over emphasis and too-frequent IPPI rounds and other supplemental immunization activities left a grass root health worker completely exhausted and fatigued. •High population densities, poor sanitation, and low routine immunization coverage.•Resistance for OPV immunization amongst Muslim community. OPV is an anti-fertility vaccine and would lead to impotence in male children or infect them with AIDS.• Children in western UP from Muslim community have consistently been missed both during SIAs and for routine immunization. •Significantly almost 66% of polio cases have occurred among Muslim children. •A dwindling public involvement, and lack of commitment of all sectors of local administration have hampered the progress of this mass-campaign in the most populous and political sensitive states of north India.

In 1993, Kerala became the first state in India to conduct statewide immunization day. In 1994 Tamil Nadu became the second state to conduct statewide immunization day. Delhi became the third state, conducting statewide immunization day on 2nd October 1994 and 4th December 1994.First PPI held in 1995-96 all children below 3 years of age were targeted on 9th December 1995 and 20th January 1996.

•Conduct pulse polio immunisation for two days every year for three to four years or until polio is eradicated. •Sustain high level of routine immunisation. •Monitor OPV coverage at district levels and below. •Improve surveillence capable of detecting all cases of polio. •Ensure rapid case investigation, including the collection of stool samples. •Arrange follow-up of all cases of paralytic polio at 60 days to check for residual paralysis. •Conduct outbreak control for cases confirmed or suspected to stop transmission.

POLIO ERADICATION PROGRAMME

National Immunization Days

• 9.12.1995 - I st NID• 20.01.1996• 07.12.1996 – 2nd NID• 18.01.1997• 07.12.1997 – 3rd NID• 18.01.1998• 06.12.1998 – 4th NID• 17.01.1999• 24.10.1999 – 5th NID• 21.11.1999• 19.12.1999• 23.01.2000• 2004 - ( 5- NID, 3SID)• 2005 – ( 2-NID, 6 SID)

GOAL To assist governments in their efforts to immunize every child against polio until polio transmission has stopped, so that the world can be certified polio-free.

From 1996-97 to all children under the age of 5 years were covered.Till 1998-99, the PPI Programme consisted of vaccination of children at fixed booths on two National Immunization Days(NID), separated by six weeks, during the winter season.The strategy for 2000–2001 has been firmed up after studying the epidemiological pattern of the disease in different parts of the country and in consultation with group of national / international experts, specially constituted by WHO at the country’s request. their advice is to adopt a differential approach in response to the varying levels of success already achieved in the different States.

The country has accordingly been divided into three zones : Low Burden Zone (LBZ), Middle Burden Zone (MBZ) and High Burden Zone (HBZ).

Experts have suggested that there should be two national immunization days in the months of December 2000 and January 2001, preceded by one Sub-National Immunization Day for 11 States in the month of November 2000 and another SNID for the 4 States of UP, Bihar, West Bengal and Delhi in the month of September 2000, which are in the HBZ zone.

The experts also advised that the house to house component need not be insisted on the LBZ areas, while the MBZ and HBZ should continue with the house to house search and immunization programme, as some children in these States are missing vaccination in the NIDs.

As regards the LBZ and MBZ areas, experts have advised mop up vaccination around each case of confirmed polio not only in the district in which the case appears but also in the surrounding districts.

The Global Polio Eradication Initiative

OBJECTIVES: • TO INTERRUPT TRANSMISSION OF THE WILD

POLIOVIRUS AS SOON AS POSSIBLE AND CERTIFY ALL WHO REGIONS POLIO-FREE BY THE END OF 2005;

• TO IMPLEMENT THE POLIO ENDGAME PROGRAMME OF WORK, INCLUDING CONTAINMENT OF WILD POLIOVIRUS, GLOBAL POLIO-FREE CERTIFICATION, AND THE DEVELOPMENT OF A POST-ERADICATION IMMUNIZATION POLICY;

• TO CONTRIBUTE TO HEALTH SYSTEMS DEVELOPMENT BY STRENGTHENING ROUTINE IMMUNIZATION AND SURVEILLANCE FOR COMMUNICABLE DISEASES.

Strategies: • HIGH INFANT IMMUNIZATION COVERAGE WITH

FOUR DOSES OF ORAL POLIO VACCINE IN THE FIRST YEAR OF LIFE;

• SUPPLEMENTARY DOSES OF ORAL POLIO VACCINE TO ALL CHILDREN UNDER FIVE YEARS OF AGE DURING NATIONAL IMMUNIZATION DAYS (NIDS);

• SURVEILLANCE FOR WILD POLIOVIRUS THROUGH REPORTING AND LABORATORY TESTING OF ALL CASES OF ACUTE FLACCID PARALYSIS (AFP) AMONG CHILDREN UNDER FIFTEEN YEARS OF AGE;

• TARGETED “MOP-UP” CAMPAIGNS ONCE WILD POLIOVIRUS TRANSMISSION IS LIMITED TO A SPECIFIC FOCAL AREA.

Before a WHO region can be certified polio-free, three conditions must be satisfied:(   A) AT LEAST THREE YEARS OF ZERO POLIO CASES DUE TO WILD POLIOVIRUS( B)  EXCELLENT CERTIFICATION STANDARD SURVEILLANCE ( C) EACH COUNTRY MUST ILLUSTRATE THE CAPACITY TO DETECT, REPORT AND RESPOND TO “IMPORTED” POLIO CASES. LABORATORY STOCKS MUST BE CONTAINED AND SAFE MANAGEMENT OF THE WILD VIRUS IN INACTIVATED POLIO VACCINE (IPV) MANUFACTURING SITES MUST BE ASSURED BEFORE THE WORLD CAN BE CERTIFIED POLIO-FREE.

In THERE ARE FOUR GLOBAL PRIORITIES TO STOP TRANSMISSION OF THE WILD POLIOVIRUS AND OPTIMIZE THE BENEFITS OF POLIO ERADICATION : 1.     1. Substantial external financial resources are required to support the efforts of developing countries to eradicate polio. These financial resources must be secured to purchase oral polio vaccine (OPV), to plan and implement national immunization days and mop-up campaigns, and to cover surveillance and laboratory costs.2.     2. India is the highest priority country, because it has the highest number of cases in the world (83%), and for the first time in the Initiative’s history, previously polio-free areas were reinfected, as the epidemic in the north Indian state of Uttar Pradesh spread into such Indian states as Gujarat, Rajasthan and West Bengal.3.     3. As the world is nearing polio-free status, effective surveillance becomes even more important to quickly identify any potential outbreaks and manage them effectively. Achieving certification standard surveillance is also a requirement for certifying the world polio-free.4.     4. In conjunction with effective surveillance, it is essential that the capacity is in place to rapidly mount massive immunization response campaigns to manage any wild poliovirus importations quickly and efficiently in polio-free areas

FUTURE BENEFITS OF POLIO ERADICATIONONCE POLIO IS ERADICATED, THE WORLD CAN CELEBRATE NOT ONLY THE ERADICATION OF A DISEASE BUT THE DELIVERY OF A GLOBAL PUBLIC GOOD – SOMETHING FROM WHICH EVERY PERSON, REGARDLESS OF RACE, SEX, ETHNICITY, ECONOMIC STATUS OR RELIGIOUS BELIEF, CAN BENEFIT FOR ALL TIME, NO MATTER WHERE THEY LIVE.THE HUMANITARIAN BENEFIT IS TREMENDOUS, AS BETWEEN 2002 AND 2040, OVER TEN MILLION NEW CASES OF POLIO WORLDWIDE WOULD MANIFEST THEMSELVES. ADDITIONALLY, THE SAVINGS OF POLIO ERADICATION ARE POTENTIALLY AS HIGH AS US$ 1.5 BILLION PER YEAR – FUNDS THAT COULD BE USED TO ADDRESS OTHER PUBLIC HEALTH PRIORITIES.

VACCINE VIAL MONITOR

THE MAGNESIUM CHLORIDE STABILISED VACCINE WILL MAINTAIN ADEQUATE IMMUNOGENICITY FOR 18 MONTHS WHEN KEPT IN A REFRIGERATOR AT +2°C TO +8°C, FOR SIX WEEKS AT +25°C AND FOR THREE DAYS AT +37°C.AT -20°C, ALL FORMULATIONS AND PRESENTATIONS ARE VERY STABLE AND NO LOSS OF POTENCY HAS BEEN OBSERVED OVER A PERIOD OF MORE THAN FIVE YEARS.VACCINES SHOULD BE INSPECTED VISUALLY FOR ANY PARTICULATE MATTER AND/OR OTHER COLORATION PRIOR TO ADMINISTRATION.DUE TO MINOR VARIATION OF ITS PH, POLIO SABIN™ (ORAL) MAY VARY IN COLOUR FROM LIGHT YELLOW TO LIGHT RED. CHANGES OF THE COLOUR OF THE VACCINE WITHIN THESE RANGES DO NOT SIGNIFY DETERIORATION OF THE VACCINE.THE VACCINE SHOULD BE STORED IN A REFRIGERATOR BETWEEN +2°C AND +8°C OR IN A FREEZER AT -20°C. FREEZING AND THAWING DOES NOT AFFECT THE TITRE OF THE VACCINE.IN ORDER TO PRESERVE OPTIMAL POTENCY OF POLIO SABIN™ (ORAL), EXPOSURE OF THE VACCINE TO AMBIENT (NON-REFRIGERATED) TEMPERATURES SHOULD BE KEPT TO A MINIMUM AND EXPOSURE TO SUNLIGHT SHOULD BE AVOIDED.

                                                                      

The IEAG also made the following recommendations regarding supplementary immunisation schedule and vaccine:• Use of mOPV1 in Bihar, UP and neighboring districts of Uttaranchal, Delhi, and Mumbai/ Thane/Raigad during the May 2005 NID.• Given the high probability of ongoing low level type 1 poliovirus transmission, and the risk of further spread of this virus with the onset of the rainy season in June, mOPV1 be used in a further round in the full supplementary NID (SNID) area (Bihar, UP and neighboring districts of Uttaranchal, Delhi, and Mumbai/Thane/Raigad). Any areas not covered with mOPV1 in the June SNID should use mOPV1 in the August SNID.• Trivalent OPV should be used for the SNIDs during the three remaining SNID rounds in 2005 (August, October and November), except in areas where wild poliovirus type 1 persists, in which case mOPV1 should be used in appropriate districts for two sequential rounds.• The geographic extent of the four SNIDs should be expanded to include any additional areas or state where a wild poliovirus is isolated. If wild poliovirus type 1 is isolated, mOPV1 should be used for at least two rounds in these areas.• Trivalent OPV should be used for SIAs in 2006-2007 unless wild poliovirus is isolated, in which case mOPV should be used in at least two sequential rounds in an appropriate area.

Accurate surveillance for polio is essential for eradication.Surveillance systems for polio have been developed under the guidance of the global polio eradication initiative and use a combination of (1) identification of all potential cases of acute flaccid paralysis (AFP), the most obvious manifestation of polio infection and (2) laboratory evaluation of stools from these cases to confirm poliovirus as the cause.Surveillance of cases of acute flaccid paralysis among children less than 15 years of age is a key component for a well functioning polio surveillance system. The surveillance system works through a network of surveillance medical officers, the responsibility of them lies in assisting the health services departments of all states and maintaining a network of acute flaccid paralysis reporting sites and rapidly investigating the cases.AFP is defined as sudden onset of weakness and floppiness in any part of the body in a child less than 15 years of age. In addition, paralysis in a person of any age in whom polio is suspected is also reported. AFP surveillance is used to detect cases of suspected polio to initiate investigation and control measures. Any case meeting the case definition should be investigated and stool specimens collected.

Case Definition:In the Global Polio Eradication Initiative (PEI), acute flaccid paralysis is defined as:Any case of AFP in a child aged <15 years, or any case of paralytic illness in a person of any age when polio is suspected.Acute: rapid progression of paralysis from onset to maximum paralysisFlaccid: loss of muscle tone, “floppy” – as opposed to spastic or rigidParalysis: weakness, loss of voluntary movementAny case meeting this definition undergoes a thorough investigation to determine if the paralysis is caused by polio.

Components of AFP Surveillance The objective of AFP surveillance is to detect the exact geographic locations where wild polioviruses are circulating in the human population. All cases of acute flaccid paralysis in children aged <15 years are rigorously investigated by a trained medical officer, with collection of stool specimens to determine if poliovirus is the cause of the paralysis. Analysis of the location of polioviruses isolated from AFP cases allows programme managers to plan immunization campaigns (Pulse Polio Immunization) to prevent continuing circulation of virus in these areas.

COMPONENTS OF AFP SURVEILANCE

1.The AFP surveillance network and case notification2.Case and laboratory investigation3.Outbreak response and active case search in the community4.60-day follow-up, cross-notification and tracking of cases 5.Data management and case classification6.Virologic case classification scheme7. Surveillance performance indicators

The most important aspect of this classification is the collection of 2 adequate stool samples from all cases. Samples are considered adequate if both the

specimens (1) are collected within 14 days of paralysis onset and at least 24 hours apart; (2) are

of adequate volume (8-10g) and (3) arrives at a WHO-accredited laboratory in good condition (ie,

no desiccation, no leakage), with adequate documentation and evidence of cold-chain

maintenance.

                                                                                       

THE GLOBAL POLIO LABORATORY NETWORK IS A 3-TIER PYRAMIDAL NETWORK OF A TOTAL OF 145 LABORATORIES CLASSIFIED AS NATIONAL, REGIONAL REFERENCE AND GLOBAL SPECIALISED LABORATORIES. THE INDIAN NETWORK IS COMPRISED OF A TOTAL OF EIGHT LABORATORIES WITH ONE GSL AND SEVEN NPL. THESE ARE STRATEGICALLY LOCATED IN DIFFERENT PARTS OF THE COUNTRY FOR QUICK, EASY ACCESS BY THE SURVEILLANCE SYSTEM. A SPECIFIC GEOGRAPHICAL AREA IS SERVED BY EACH LABORATORY. ALL LABORATORIES IN THE GLOBAL POLIO NETWORK FOLLOW STRICT BIO-SAFETY LEVEL 2 FACILITIES. AND ALSO USE (A) IDENTICAL TESTING PROCEDURES AND HIGH QUALITY EQUIPMENT AND REAGENTS, (B) HAVE INSTITUTED QUALITY ASSURANCE PROGRAMMES AND (C) UNDERGO ANNUAL PROFICIENCY TESTING AND ON-SITE EVALUATION BY WHO FOR ACCREDITATION.

Reference:www.who.intwww.mohfw.nic.in www.polioeradication.org www.unicef.org/immunizationSuper course/ Pittsburgh university(www.pitt.edu/~super1)JIMA DECEMBER 2005http://www.polionet.org/vaccine.htmwww.npspindia.org