Poliomyelitis

Clinical manifestation:

• Few suffer from minor illness, very few suffer from meningitis and less than 1% suffer from major paralytic disease

1. Asymptomatic illness:

• In most of the infection is asymptomatic and self-limiting
• 99% cases

2. Abortive poliomyelitis:

• Non-specific symptoms such as headache, fever, sore throat, loss of appetite
• Disease last for 5 days

3. Non paralytic poliomyelitis

• Very few patients suffer from non-paralytic poliomyelitis
• Stiffness of neck
• Pain in back and neck
• Disease last for 2-10 days

4. Paralytic Poliomyelitis:

• Less than 1% patients suffer from major paralytic poliomyelitis
• Paralysis in polio is asymmetric, descending, non-progressive and LMN type.
• It damages the motor nerves causing oedema and muscle paralysis
• Malaise
• Anorexia
• Nausea and vomiting
• Sore throat
• Constipation
• Abdominal pain
• Headache and fever
• Flaccid paralysis: motor neuron damage
•  Lower motor neuron lesion of the anterior horn cells of the spinal cord and affects the muscles of the legs, arms and/ or trunk
• Bulbar paralysis: respiratory paralysis

5. Post-poliomyelitis muscle atrophy:

• Muscle wasting
• Loss of neuromuscular function
• Physically Disabled

6. Death is rare. And if occur it is due to respiratory paralysi 

Lab diagnosis:

• Specimen: nasal secretion, faecal samples, throat swab, CSF

1. Electron Microscopy: virus detection
2. Virus isolation from stool: 

• Culture on monkey kidney cell line, Human amnion, HeLa, Hep-2, Buffalo green monkey (BGM), MRC-5 cell line

1. Antibody detection: ELISA, complement fixation test
2. Antigen detection: neutralization test
3. Molecular diagnosis: PCR 

Treatment: no antiviral drugs

Prevention and control:

1. Vaccination

i. Inactivated Polio Vaccine (Salk type – killed):

• Prepared by Jonas Salk in 1956
• Also known as Inactivated poliovirus vaccine (IPV)
• Prepared by formalin inactivation of poliovirus
• It is injected deep subcutaneous or intramuscular
• Given to child at age of 2 months, 4 months, at school entry age
• Effective against all serotype of poliovirus
• Produces circulatory antibody
• Does NOT require stringent refrigeration
• NOT effective in an epidemic

ii. Oral Polio Vaccine (Sabin type – live):

• Developed by Albert Sabin in 1962
• Contains live attenuated strain of all serotypes of poliovirus

• On administration, the virus multiplies in the intestine 
• Induces intestinal and systemic immunity 
• Intestinal immunity prevents infection of intestine by Poliovirus
• Vaccine virus is excreted in the feces and can infect the unimmunized and induce immunity
• Thus widespread herd immunity results, even if only approximately 66% of the community is immunized (100% coverage is not required).
• It is administered Orally at 2 months of age simultaneously with first DPT
• It is recommended for all children below 5 years
• In endemic countries monovalent oral poliovirus type I vaccine (MOPvI) is introduced to eliminate the last reservoir of poliovirus
• Colostrum produced in the first three days after child-birth contains secretory IgA antibody which might interfere with the production of immune response to OPV
• Nevertheless, several studies show that among breastfed infants who are fed OPV in the first three days of life, 20-40 percent develop serum antibodies and 30-60 percent excrete vaccine virus.
• Molar concentration of certain salts MgC12, Na2So4 protect polio virus from heat inactivation  
• As it prevents heat inactivation mgCl2 can be added to polio vaccine so that it can be stored at a higher temperature. 

Complications of OPV

• Being living viruses, the vaccine viruses, particularly type 3 do mutate 
• In the course of their multiplication in vaccinated children, and rare cases of vaccine associated paralytic polio have occured in – 

1. Recipients of the vaccine
2. Thier contacts 

Contraindiations of OPV

• Immunocompromized individuals
• Patients suffering from leukaemias & malignancy or AIDS.
• Persons receiving corticosteroids.
• In pregnancy. 

2. Proper sanitation

3. Safe drinking water 

Vaccine derived polio virus (VDPV) 

Types of VDPV: 

• c-VDPV: Person-to-person transmission in community
• i-VDPV: Isolates from immunodeficient persons
• a-VDPV: Ambiguous from health person or sewage isolates

Diagnosis: 

• VDPV is diagnosed by Real-time Reverse transcription-PCR nucleic acid amplification 

Key risk factors for cVDPV emergence