When I heard that Africa had been certified free of wild polio, I was elated. It means millions of children, including my three, will grow up without experiencing what I went through due to lack of access to the polio vaccine, my parents incurred a lot of costs both financially and emotionally.
One might easily dismiss my paralysis as the result of an accident or any other disease, but polio, because it is extremely rare to meet someone who suffered paralysis because of the viral ailment.
My name is Dr Riro Mwita. I am 44 years old, a consultant physician at Kiambu Level Five hospital, married and a father of three. At the age of one, I developed a flu-like illness, coupled with fever which progressed to weakness in my lower limbs. The progression of the disease from weakness to partial paralysis was so fast that at some point, my father thought I was dead.
I was born in Makarangwe, Kuria, a kilometre from the Kenya-Tanzania border. Back then, immunisation campaigns against many of the vaccine-preventable diseases were not as aggressive as they are now. This is why I am in this state of physical disability because I was not among the lucky ones who were immunised against poliomyelitis. In fact, those of us who were born in the 60s and 70s were could not access vaccines like polio. Even hospitals were not as many as they are now.
I did not attend nursery school because I had a problem with my leg after the polio attack. Later, when I joined school, my father had to escort me there. The virus that causes polio infects the cells of the throat and intestine. It can also infect a person’s spinal cord, causing paralysis (one cannot move parts of the body), as in my case.
So, within a week, at least according to my mother, my legs were weak and floppy. The poliovirus affects the front cells of the spinal cord (anterior horn cells), which are important in controlling motor functions.
Initially, because of the fever and stiffness of my back, my parents thought it was meningitis. Weeks later, the fever went down, but my lower limbs were still floppy. They did not know what it was and sent me to a herbalist.
Dr Riro Mwita, a consultant physician at Kiambu Level Five Hospital. Polio paralysed him.
Photo credit: Sila Kiplagat | Nation Media Group
Eventually, at the age of nine, some clinical officers picked up that I had polio and I started physiotherapy. But, the damage had already been done and the weakness on my right leg persisted, leaving me with semi-paralysis. Naturally, the impact of polio is asymmetrical affecting the muscles of one side of the body.
I had to drop out of school because I could not walk or stretch my ankle joint. My father had to take me to a rehabilitation centre in Nyabondo, South of Kisumu, where the doctors fixed my Achilles tendon, which had developed a contracture (hardening of the tendons).
The Achilles tendon is a strong fibrous cord that connects the muscles in the back of your calf to the heel bone. Partial or complete disruption of the tendon just above the heel results in inability to raise the foot.
I was walking on the tips of my toes and on November 11, 1985, the doctors fixed the tendon and put me on callipers for more than 10 years. I also developed a condition known as scoliosis, where my back appears to be curved sideways. Scoliosis is a sideways curvature of the spine that occurs most often during the growth spurt just before puberty. I count myself lucky because I did not develop full paralysis and I can go about my life.
Of course, the disease left me with wasted muscles and partial paralysis, which means I have to frequently walk as part of regular physiotherapy. I also have to incur extra costs like paying for my shoes to be adjusted so for every shilling I spend on shoes, I add an extra Sh1,000 for the adjustment. I also pay for membership at a golf course just to walk because I do not want to be knocked down by a moving vehicle or motorcycle while I am walking.
Beyond health and finances, the disease impacts your self-esteem. For instance, I cannot wear shorts because you do not want to display your atrophied muscle, which results from unused muscles that waste away when I was not active.
A poliovirus injection can provide lifelong immunity against the disease, but this protection is limited to the particular type of poliovirus involved (Type 1, 2, or 3). Infection with one type does not protect an individual against infection with the other two types. The development of effective vaccines to prevent paralytic polio was one of the major medical breakthroughs of the 20th century. Two different kinds of vaccine are available: An inactivated polio vaccine (IPV) developed by Dr Jonas Salk and first used in 1955, and a live attenuated (weakened) oral polio vaccine developed by Dr Albert Sabin and first used in 1961.
Polio, also known as poliomyelitis, is an infectious disease transmitted from person to person mainly by ingesting food or water contaminated with faecal matter from an infected person. Children younger than five years old are more likely to contract the virus than any other group. The virus infects the cells of the throat and intestine.
One in 200 infections leads to irreversible paralysis. Among those paralysed, WHO estimates that five to 10 per cent die when their breathing muscles become immobilised.
The declaration of Africa as free of wild poliovirus is the result of a decades-long eradication campaign. It ends a 30-year battle to eradicate the debilitating disease that at one point paralysed about 75, 000 children annually.
This makes the highly contagious disease the second virus to be eradicated from the face of the continent since smallpox 40 years ago, the World Health Organization’s (WHO’s) Africa director said last week. However, a minor strain still infects hundreds. “Now, future generations of African children can live free of wild polio,” said Dr Matshidiso Moeti, WHO Regional Director for Africa.
Through massive vaccination efforts, polio occurrence has gone down 99 per cent since 1988.
To achieve this success, health workers, traditional and religious leaders traversed the continent, moving from one house to the next, even in conflict zones, to counter misinformation and vaccinate children.
The certification comes four years after Nigeria – the last polio-endemic country in Africa – recorded its last case of wild polio. “Africa has demonstrated that despite weak health systems, significant logistical and operational challenges across the continent, African countries have collaborated very effectively in eradicating wild polio virus,” said Dr Pascal Mkanda, coordinator of WHO Polio Eradication Programme in the African Region.
In Kenya, the national launch of the polio vaccination campaigns has been used to increase herd immunity among children.
A child receives the polio vaccine in Makongeni Estate, Nairobi.
Photo credit: File | Nation Media Group
Despite getting the certification, Africa is still not out of the woods. Dr Moeti warned that people must remain vigilant. “The certification implies that the continent has completely gotten rid of wild poliovirus, but we cannot be certified polio free because we still have polio that is caused by other groups of polioviruses which do not occur naturally,” explained Dr Peter Borus, who heads the Kenya Medical Research Institute (Kemri) polio laboratory, and a WHO lab scientist.
Both the original polio vaccines included all three types of poliovirus. The Salk vaccine, which is injected, is composed of killed viruses; the Sabin vaccine, taken orally, contains live but weakened viruses.
The oral vaccine is both more effective and easier to administer than the injected one, and so it has been the primary weapon for worldwide eradication of polio. Shortly after the oral vaccine became widely used in the early 1960s, researchers discovered that some shed viruses had reacquired ability to cause paralysis.
Every year, hundreds of people across Africa are still being infected with circulating vaccine-derived poliovirus, which can infect people in areas where there is only partial vaccination. There are still pockets of children who are not getting the polio vaccine, leading to outbreaks of circulating vaccine-derived poliovirus.
When a vaccine-derived poliovirus is detected, a country cannot be certified polio-free as the WHO only considers a country to be clear if it goes12 months without a case – or a positive environmental sample. Because of this risk, most developed countries, including the US, stopped using the oral Sabin vaccine, relying instead on several injections of the Salk vaccine.
However, oral polio vaccine is still the most available, and reliable one in developing countries.
African cases of the vaccine-derived strain, which results in the same symptoms as the wild kind, increased to 320 last year from 68 in 2018 and could rise again in 2020 because many vaccination campaigns were paused during coronavirus lockdowns.
When a child is immunised with the oral vaccine, the weakened virus replicates in the intestine for a limited period, thereby developing immunity by building up antibodies. During this time, the vaccine-virus is also excreted. 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), before eventually dying out.
On rare occasions, if a population is seriously under-immunised, an excreted vaccine-virus can continue to circulate for an extended period of time. Through genetic changes, the weakened vaccine virus can reacquire the ability to cause paralytic polio.
Research is underway to understand how the weakened virus reactivates itself and how to prevent it. One of the ways to prevent this is by introducing a new vaccine deliberately constructed to prevent the poliovirus from reactivating itself to become infectious, says Dr Borus, adding that a novel of such a vaccine should be ready by the end of the year.
In 2018, experts from Kemri and Centres for Disease Control and Prevention reported finding traces of vaccine-derived poliovirus in environmental samples from Eastleigh, Nairobi. “Since then, we are yet to detect any other incidence, but we are remaining vigilant especially because Kenya remains vulnerable due to its porous borders,” says Dr Borus.
For this reason and the proximity to Somalia, Ethiopia and Sudan where cases of the disease have been detected, Kenya is classified by the International Health Regulations as a state vulnerable to re-infection by wild poliovirus or circulating vaccine-derived poliovirus, with potential risk of internation.
“The detection of poliovirus from sample collection to getting results is long and laborious. We are trying to see if we can use molecular PCR to shorten the detection period,” said Dr Borus, adding that the result should be out in January 2021.
