End Polio Now!

“Polio is a crippling and potentially fatal infectious disease, help to prevent it by awareness about its immune. Prevent polio by taking vaccination and care”

Poliovirus

Poliovirus is a member of the enterovirus subgroup, family Picornaviridae. Picornaviruses are small, ether-insensitive viruses with an RNA genome. Enteroviruses are transient inhabitants of the gastrointestinal tract and are stable at acid pH. There are three poliovirus serotypes (type-1, type-2, and type-3). Immunity to one serotype does not produce significant immunity to the other serotypes. It can cause lymphatic meningitis. It is rapidly inactivated by heat, formaldehyde, chlorine, and ultraviolet light. The reservoir is human and transmission is by faecal-oral or oral-oral.

Poliomyelitis

In 1789, Michael Underwood first described poliomyelitis in children, describing a debility of the lower extremities that was recognized as poliomyelitis in England. The first outbreaks in Europe were reported in the early 19th century, and outbreaks in the United States were reported in 1952. Developed countries in the Northern Hemisphere suffered increasingly severe epidemics in the first half of the 20th century. More than 21,000 paralytic cases were reported in the U.S. in 1952. Following the introduction of effective vaccines in 1955 (inactivated polio vaccine, IPV) and 1961 (oral polio vaccine, OPV), polio incidence declined rapidly. The last case of wild poliovirus acquired in the U.S. was in 1979. Eradication-2019-low routine immunization and poor vaccination campaigns resulted in the re-emergence of type 2 VDPV. Up to 95% of all polio infections are apparent or subclinical. Estimates of the ratio of apparent to paralytic illness vary from 50:1 to 1,000:1 (usually 200:1). Infected people who do not exhibit symptoms shed viruses in their stool and can transmit the virus to others.

Pathogenesis

The mouth is the portal of entry for the virus, and the primary multiplication of the virus occurs at the site of implantation in the pharynx and gastrointestinal tract.

1. The virus enters the body through the mouth.
2. It multiplies in the oropharynx and gastrointestinal tract and is usually present in nasopharyngeal secretions for 1 to 2 weeks and can be shed in stools for several weeks after infection.
3. During intestinal replication, the virus invades local lymphoid tissue, may enter the bloodstream, and then infect cells of the central nervous system.
4. The polio virus-induced destruction of motor neurons in the anterior horn of the spinal cord and brain stem cells results in distinctive paralysis. Replication of poliovirus in motor neurons causes the typical manifestations of poliomyelitis.

Symptoms

The incubation period is 3–6 days for non-paralytic poliomyelitis and 7–21 days for the onset of paralysis in paralytic poliomyelitis. Many patients recover fully after a few days of mild fever and headache. In others, there is a recurrence of pyrexia, headache, and meningism. Weakness may start later and can progress to widespread paresis. Respiratory failure may supervene if intercostal muscles or the medullary motor nuclei are involved. Paralysis is often permanent. Paralytic diseases may be caused by wild-type polioviruses, attenuated polioviruses in the oral vaccine, or by vaccine-derived polioviruses.

One out of four people with poliovirus infection will have flu-like symptoms also can happen

Sore throat, Fever, Tiredness, Headache, Nausea, Stomach-pain, but below symptoms also can happen.

Epidemiology

• Reservoir — humans (transmitted most frequently by persons with inapparent infections)
• Transmission — person to person
• Temporal pattern — peaks in summer months
• Communicability — highly infectious with seroconversion rates in susceptible household contacts of children nearly 100% and of adults over 90%.
• Predominant serotype — all epidemics are due to type-1

Risk factors

Risk of severe paralysis increase if, adult, pregnant, and muscle fatigue or trauma during the incubation period.

Polio virus vaccination

1. Grown in monkey kidney (Vero) cells and Inactivated with formaldehyde
2. Contains serotypes 1, 2 and 3
3. Administered by either subcutaneous or intramuscular injection.
4. Contains neomycin, streptomycin, polymyxin B, 2-phenoxyethanol

The minimum interval between doses of Polio Vaccine

Bed rest is imperative, as exercise appears to worsen or precipitate the paralysis. For respiratory difficulties, a tracheostomy and ventilation are required. Subsequent treatment is by physiotherapy and orthopaedic measures.

The minimum interval between the first three doses of IPV, OPV, or any combination of IPV and OPV is four weeks. The majority of Sri Lankan children are vaccinated, which is conducted free of charge, at government clinics, and 5 OPV doses were given at 2 months (OPV 1-pentavalent 1), 4 months (OPV-2-pentavalent 2), 6 months ( OPV 3-pentavalent 3), 18 months (OPV 4), and 5 years (OPV 5). Thus, the Sri Lankan government’s polio vaccine schedule is as follows: (OPV+IPV) — (OPV+IPV) — OPV– OPV– OPV.

Poliovirus vaccines contraindications and precautions

Serious allergic reaction, moderate or severe acute illness, immunodeficiency (OPV), household contact of an immunodeficient person (OPV), pregnancy.

Laboratory diagnosis

Viral isolation: Poliovirus may be recovered from the stool or pharynx of a person with presumed poliomyelitis. Isolation of viruses from the cerebrospinal fluid (CSF) is diagnostic but is rarely accomplished.

Serology: Neutralizing antibodies appear early and maybe at high levels by the time the patient is hospitalized, and, therefore, a two-fold rise may not be demonstrated.

CSF: In poliovirus infection, the CSF typically contains an increased number of white blood cells, a mildly elevated protein concentration of 40 to 50 mg/ml, and normal glucose.

Inactivated Poliovirus Vaccine (IPV) — advantages

Prevention is by immunization with a live (Sabin) vaccine. The killed vaccine is used increasingly in countries where polio is rare. As a result, this vaccination has the advantage of not being replicated or shed in the stool and is used in immunocompromised people and their household contacts.

“ONE DAY-ONE FOCUS — ENDING POLIO”

References

• Alastair Innes, J., 2016. Davidson’s Essentials of Medicine, 2nd edition, Elsevier, Edinburgh, UK, pp-664–665.
• Murray Longmore, Ian B Wilkinson, Andrew Baldwin & Elizabeth Wallin, 2014. Oxford Handbook of Clinical Medicine, 9th edition, Oxford University Press, Tonbridge, UK, pp-432.
• Priyantha Perera, 2017. Moving from oral poliovirus vaccine to inactivated poliovirus vaccine in Sri Lanka: The rationale and challenges, Sri Lanka Journal of Child Health, 46: pp-70–74.
• World Health Organization, 2016. Polio vaccines: WHO position paper (March), Wkly Epidemiol rec 91(12), pp-145–68.
• Estivariz, Ruth, L.-g. & Tom, S., 2021. [Online]
  Available at: http://www.cdc.gov/vaccines/pubs/pinkbook/polio.html
  [Accessed August 2021].

Article by,
Jesintha Jebamal

Editor ial by,
Praba Jalini