Are we ever going get rid of poliomyelitis?

A child receives anti-polio vaccination. Photo/FILE

What you need to know:

  • Polio is a viral disease which affects the spinal cord and causes muscle weakness and paralysis. It is caused by the wild poliovirus serotypes 1, 2, or 3 transmitted from person to person via the feacal-oral route

Dear Askadoc,
The first time I heard of Polio was on a poster reading “Kick Polio out of Kenya”. In the past few months I have heard announcements in the media of polio immunisation campaigns.

I thought we had completely eradicated the disease in Kenya. Is polio still a problem in the country? What is being done? What do I need to know to protect my children?

Dear Anne,

Poliomyelitis, commonly referred to as polio, is one of the diseases targeted for eradication globally. Sporadic cases have been reported in the country especially in the refugee camps and the communities neighbouring the camps.

According to the World Health Organisation (WHO), only three countries — namely Afghanistan, Nigeria and Pakistan — remain polio endemic in 2013. Failure to eradicate polio can result to new cases of up to 200,000 in 10 years all over the world.

Globally, until 1999 there had been no report of poliomyelitis caused by the type 2 virus. But in May this year Somalia experienced a wild polio virus type. Shortly after, another case was confirmed in Kenya in Daadab, the first since 2011.

This has led to major immunisation campaigns across the country in order to boost population immunity levels and reduce the risk of further outbreak. Proximity of Somalia to Daadab in Kenya means there is a risk of the infection spreading from the neighbouring country to Kenya.

Polio is a viral disease which affects the spinal cord and causes muscle weakness and paralysis. It is caused by the wild poliovirus serotypes 1, 2, or 3 transmitted from person to person via the feacal-oral route.

In its severity, it can affect the chest muscles, causing difficulty in breathing and sometimes death. The diseased occurs almost exclusively in infants and young children. Most of those infected are normally not aware that they have polio and go around unaware of the infection.

The virus gains access to the body through the mouth usually from hands contaminated with stool of an infected person. The stool comes into the body through contaminated water or food. The virus then multiplies in the intestine.

The person becomes infectious between seven to eight days and the virus remains present and contagious in the throat and feaces. The virus stays in the throat for around one week and is excreted for approximately three to six weeks.

Some of the predisposing factors to polio are overcrowding, poor sanitation, and poor or low standards of personal hygiene.

Identified cases of polio are normally immediately reported to the notification center at the Ministry of Health. One laboratory-confirmed case of polio is considered an outbreak. Weekly reporting continues for purposes of surveillance and monitoring of outbreaks across all medical institutions.

The extent and severity of the disease determines the symptoms. Initial symptoms include fever, fatigue, headache, vomiting, and stiffness in the neck and pain in the limbs.

Paralytic polio has symptoms such as abnormal sensation, difficulty breathing, difficulty swallowing, urinary retention, drooling, constipation, muscle pains and spasms and even mood swings.

Some neurological illnesses such as Guillan Barre and transverse myelitis imitate signs and symptoms of polio and cause acute flaccid paralysis.

Polio varies in type depending on the severity of the disease and the by location in the central nervous system. Non-paralytic polio (abortive polio) normally presents with flu like symptoms like fever, sore throat, and even an upset stomach and is the most recognisable and dramatic. The body becomes paralysed in the arms, legs and other parts of the body.

Paralytic polio has several types, based on the part of your body that’s affected — spinal cord (spinal polio), brainstem (bulbar polio) or both (bulbospinal polio).

Laboratory confirmation of cases of poliomyelitis involves isolating the virus in a stool sample. The sample must be collected, stored and safely transported. A clinical history is also taken as well as a history of exposure and vaccination.

There is no cure for polio. Symptoms are managed as they appear. Those with non-paralytic polio should be monitored, should they progress to paralytic polio. they should be monitored for signs of respiratory failure and therapy given as need arises.

This could be in form of respiratory support when breathing becomes difficult.

For those who survive; polio paralysis remains more or less the same for several days and even weeks before the recovery process, which takes place over several months and even years, begins. Physical therapy, leg braces and even orthopedic surgery may be required in order to improve function.

The Ministry of Health gives out free Oral Polio Virus (OPV) at government clinics across the country at birth, six weeks and at 10 weeks. Polio vaccine given multiple times is capable of protecting a child for life.

Supplemental vaccination is done when there is a suspected case of polio in the country as was done in the recent months by the government following the outbreak of polio in Daadab. Two forms of the vaccine, IPV (Inactivated Polio Vaccine) and OPV (Oral Polio Vaccine) are available.

Heath education on sanitation and hygiene must accompany immunisation campaigns to sensitise the public. Organisations such as GPEI (Global Polio Eradication Initiative), the largest public health initiative in the world; have made strides in responding to outbreaks of polio.

GPEI was adopted 1988 at the World Health Assembly. Since its inception cases of polio fell by over 99 per cent. It ensures large scale immunisation activities in infected countries and this helps prevent it spreading to neighbouring countries.

Polio eradication has a strategy that is four pronged. It includes having national days committed to immunisation, routine immunisation, mop -up of cases and disease surveillance. Kenya has the Polio Eradication program rolled out in order to eradicate polio in collaboration with other organisations.

— By Dr Torooti Mwirigi. Send your health questions to [email protected]


How the polio vaccine works

When a person is exposed to the polio virus, it quickly replicates in the throat and intestines and then enters the bloodstream.

From here the polio virus enters the central nervous system, where it multiplies and attacks the motor neuron cells that control the muscles for the trunk, arms and legs as well as for swallowing, respiration and circulation.The immune system attempts to build a defense against the virus by producing substances known as antibodies and creating a “memory” of this experience.

A successful defense results in the individual developing immunity and the next time the person encounters that virus, the antibodies that circulate in the bloodstream prevent it from causing disease, or decrease the disease’s severity, and eliminate the virus from the body.

The Oral Polio vaccine (OPV) works in two ways. One by producing antibodies in the blood to all three types of poliovirus, and in the event of infection, this protects the individual against polio paralysis by preventing the spread of poliovirus to the nervous system in a manner similar to the immune system response.

Second, the virus also produces a local immune response in the lining of the intestines.

The antibodies produced here inhibit the multiplication of subsequent infections of naturally occurring virus. During this time, the vaccine-virus is also excreted from the body.

In areas of inadequate sanitation, this excreted vaccine-virus can spread in the immediate community and this can offer protection to other children through ‘passive’ immunisation.

The oral polio vaccine is a mixture of live attenuated poliovirus strains of each of the three serotypes. Live attenuated vaccines are derived from the naturally occurring virus.

They are selected for their ability to mimic the immune response following infection with wild polioviruses, but with a significantly reduced incidence of spreading to the central nervous system.

In very rare instances, people can become sick from the vaccine resulting in vaccine associated paralysis. In Kenya, infants receive four doses of trivalent OPV before one year of age with the first dose is given immediately at birth or within two weeks of birth (birth dose) and the other three doses should be given at 6, 10 & 14 weeks of age.