Polio Epidemiology

3rd year BAMS, Swasthavritta, Epidemiology of communicable diseases

1. POLIOMYELITIS Dr. Jasminkumar Viramgami Reader & H.O.D., Dept. of Swasthavritta , Govt. Akhandanand Ayurved College, Ahmedabad , Gujarat

2. Poliomyelitis is… an acute viral infection caused by an RNA virus. word means “ grey spinal cord inflammation ” primarily an infection of the human alimentary tract virus may infect the CNS in about 1 % of cases resulting in varying degrees of paralysis, and possibly death.

3. Problem statement In the pre-vaccination era, poliomyelitis was found in all countries of the world. The extensive use of polio vaccines since 1954 eliminated the disease in developed countries . India has not reported any polio case since January 2011, and has been declared polio-free since 27th March 2014.

4. Agent factors AGENT : poliovirus three serotypes 1,2 and 3. paralytic polio outbreaks mostly due to type-1 virus. faeco -oral route transmission. can survive for long periods in the external environment . rapidly inactivated by pasteurization, and a variety of physical and chemical agents.

5. Epidemiological Characteristics of Polio Serotypes All types cause paralysis Type 1- Most frequent paralysis , Highest epidemic potential, During polio free last serotype to disappear Type 2- Rarely paralytic , during polio free first serotype to disappear Type 3- Paralysis less frequent Less epidemic potential, scattered cases

6. Reservoir of infection : Man is the only known reservoir of infection. Most infections are subclinical . Mild and subclinical infections play a dominant role in the spread. There are no chronic carriers. No animal source has yet been demonstrated.

7. Infectious material : virus is found in the faeces and oro -pharyngeal secretions of an infected person. Period of communicability : The cases are most infectious 7 to 10 days before and after onset of symptoms. virus is excreted for 2 to 3 weeks in the faeces , sometimes as long as 3 to 4 months.

8. Host factors AGE : occurs in all age groups, but children are more susceptible than adults. In India polio is essentially a disease of infancy and childhood. The most vulnerable age is between 6 months and 3 years SEX : Sex differences 3 males to 1 female .

9. RISK FACTORS : Several provocative or risk factors have been found . They include fatigue, trauma, IM injections operative procedures such as tonsillectomy undertaken especially during epidemics of polio administration of immunizing agents particularly alum-containing DPT.

10. IMMUNITY : maternal antibodies - first 6 months of life. Immunity following infection is fairly solid infection with one type does not protect completely against the other two types Type-2 virus appears to be the most effective antigen.

11. Environmental factors more likely during the rainy season. In India during June to September . Environmental sources : contaminated water, food and flies . virus survives for a long time in a cold environment. Overcrowding and poor sanitation provide opportunities for exposure to infection.

12. Mode of transmission FAECAL—ORAL ROUTE : main route of spread . directly through contaminated fingers where hygiene is poor indirectly through contaminated water, milk, foods, flies and articles of daily use. DROPLET INFECTION : Close personal contact with an infected person facilitates droplet spread.

13. Incubation period Usually 7 to 14 days (range 3 to 35 days).

14. Clinical spectrum one of the following responses may occur. Inapparent (Subclinical) Infection Abortive Polio Or Minor Illness Non-paralytic Polio Paralytic Polio

15. Clinical Outcome of Poliovirus Infections Paralytic poliomyelitis Abortive-Clinical illness, no paralysis Asymptomatic infection 90-95% 4-8% 0.1-1%

16. INAPPARENT (SUB-CLINICAL) INFECTION : in 91-96 % of infections . no presenting symptoms. Recognition only by virus isolation or rising antibody titres .

17. ABORTIVE POLIO OR MINOR ILLNESS : 4 to 8 % of the infections. only a mild or self limiting illness due to viraemia . The patient recovers quickly. The diagnosis cannot be made clinically.

18. NON-PARALYTIC POLIO : 1 % of all infections . The presenting features are stiffness and pain in the neck and back. The disease lasts 2 to 10 days . Recovery is rapid. The disease is synonymous with aseptic meningitis.

19. PARALYTIC POLIO : less than 1 % of infections . virus invades CNS and causes varying degrees of paralysis .

20. Prevention Primary Secondary Tertiary A- -Care of exposed person B—Immunization C- Polio eradication Strategies - Symptomatic Rehabilitation

21. Primary Prevention Health Education Improving Sanitation & Hygiene Vaccination

22. Vaccination Immunization is the only effective in preventing poliomyelitis. essential to immunize all infants by 6 months of age to protect them against polio. Two types of vaccines : 1. Inactivated ( Salk ) polio vaccine ( IPV ). 2. Oral ( Sabin ) polio vaccine ( OPV ). Both are safe and effective when used correctly.

23. Inactivated polio vaccine (IPV) (Salk) usually made from selected WPV (wild) strains administered by IM (preferred) or SC injection. refrigerated to ensure no loss of potency. Freezing avoided Available as a stand-alone or in combination.

24. initial course consists of 4 inoculations . 1 st dose - given to infant @ 6 weeks old . The 1 st 3 doses - @ intervals of 1-2 months 4 th dose - 6-12 months after the 3 rd dose .

25. Oral polio vaccine (OPV) (Sabin) contains live attenuated virus (types 1,2 and 3). given as trivalent ( tOPV ) vaccine . primary course of 3 doses @ 1 month intervals , zero dose to all children delivered in the hospital. 1 st dose @ 6 weeks . complete vaccination before 6 months of age. Bcoz most polio cases occur between 6 months and 3 years. One booster dose recommended 12 to 18 months later .

26. Dose = 2 drops or as stated on the label. Vaccine be stored at -20 °C in a deep freeze until used. hot water, hot milk or hot fluids should be withheld for about half an hour after the adm. of the vaccine. However, Breast milk can be given whenever the child is hungry.

27. Vaccine Derived Polio-virus (VDPV) OPV is a safe vaccine on rare occasions adverse events OPV adverse events may occur Vaccine-associated paralytic poliomyelitis (VAPP) occurs in both OPV recipients and their unimmunized child contacts. most frequently associated with type 3 ( sabin ) (60% of cases); followed by type 2 and type 1

28. Indian Scenario In India vaccination against polio started in 1978. it was successful in covering around 40%. Universal immunization programme (UIP) was launched 1995 Pulse polio immunization programme along with UIP

29. Strategies for polio eradication in India PPI days every year until poliomyelitis is eradicated. Sustain high levels of routine immunization coverage. Monitor OPV coverage at district level and below. Improve surveillance - detecting all cases of AFP due to polio and non-polio reason. Rapid case investigation , including the collection of stool samples for virus isolation

30. follow-up of all cases of AFP at 60 days to check for residual paralysis. outbreak control for cases confirmed or suspected to stop transmission. Even a single case is treated as an outbreak. preventive measures initiated within 48 hr of notification of the case. complete and timely reporting of cases is important element for the eradication . Reporting of all cases of AFP in children under 15 years of age is mandatory.

31. Mopping Up Mopping up activities are usually the last stage in polio eradication. "mopping up" involves door to door immunization in high-risk districts , where wild polio virus is known or suspected to be still circulating. This strategy is being implemented in India.

32. Pulse Polio Immunization GOI conducted - the first round of PPI consisting of two immunization days on… 9th December 1995 and 20th January 1996 . The 1 st PPI targeted all children under 3 years irrespective of their immunization status. Later on, as recommended by WHO , the age group increased from under 3 to under 5 years.

33. Mass Immunization campaign ( Pulse Polio Immunization) Pulse meaning - Sudden, Simultaneous, mass administration of OPV… on a single day- to all children 0-5 years of age …irrespective of their previous polio vaccination status It is additional to routine immunization Also known as NIDs (National Immunization Days)

34. T wo rounds 4 -6 wk apart during low transmission season of polio ( between November to February) In India, the peak transmission is from June to September. The dose of OPV during PPIs are EXTRA doses they DO NOT replace the doses during routine immunization .

35. Several strategies utilized: Development of monovalent OPV. (mOPV1 and mOPV3) deployment of additional personel to assist social mobilization to reaching population groups missed previous mobile teams to vaccinate children at transit points (railway and bus stations) increased engagement and accountability of political leaders and of health staff at all levels.

36. Indian Scenario

37. last case of polio in the country was reported from Howrah of West Bengal dated 13 th January 2011. Thereafter no polio case has been reported in the country. On 27th March 2014, India was declared as non-endemic country for polio.

38. Gujarat- Last Case in 2007 Source-polio_frequently_asked_statistics_02_apr2015

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