Polio, a diseases that can be eradicated by vaccination
|Dr. Ali Mzige|
Daily News; Sunday,August 31, 2008 @08:38
Since the development of effective vaccines in the 1950s, polio has virtually been eliminated from most developed countries, although cases still occur in people who have not been fully vaccinated. It is for this reason that in the last pilgrimage to Mecca, Saudi Arabia, those who came from Nigeria were requested to be immunized against polio. In Tanzania the last polio case was reported in 1996. In the coming integrated measles campaign which will be conducted nationally, only 18 districts will conduct polio immunization to children of six months to five years.
Those districts are either on the border with neighbouring countries which have polio virus in circulation or their immunization coverage was low. This effort must be applauded by the Tanzanian community, as it puts us with the rest of the world to be certified a polio free country, if the neighbouring countries achieve the same.
During the time when the health personnel in the communities were investigating cases of acute flaccid paralysis (ulemavu wa ghafla) in children below the age of 15 years (selective criteria), the cases were only reported in those hospitals where there were physiotherapists (baba cheza au mama cheza-mtaalamu wa kunyoosha viungo na misuli). The traditional healers in most communities were the ones who were first approached. The reasons are obvious; here is a child who was well, walking up and about, only to be reported early next morning he/she cannot walk. Out of panic for not knowing the immediate cause, a traditional healer who is closest to the community will be consulted.
The Ministry of Health by then, in the 1990s had to do social mobilization and advocacy with the traditional healers, to strike a balance for them to refer the children to the nearest health facility for further investigations. The history of not being immunized against polio may give a clue but the confirmatory test was to send stools to a public health laboratory for polio virus isolation.
There are three closely related polio viruses. Infected people pass large numbers of virus particles in their faeces, from where they may be spread indirectly or directly via fingers, to food and thus infect others. Airborne transmission also occurs.
In countries where standards of hygiene and sanitation are low, like Tanzania, most children become infected early in life, when the infection rarely causes serious illness and develop immunity. In countries with better standards of hygiene, children do not become immune in this manner; if they are not vaccinated, disastrous epidemics occur. Immunization is thus of vital importance.
The only effective means of controlling and or eradicating this disease of polio is to immunize children immediately when they are borne. The dose given within the first day and at most in less than two weeks after delivery to the baby is called polio zero. Subsequent doses will be given at intervals of one month up to three doses within the first three/four months of life. A booster dose again at five years. These campaigns which are conducted are a good opportunity to strengthen (zindiko) the immunity of these children to chase away the polio virus from circulation.
The vaccine given contains all three types of polio virus and immunity develops against each of them. There are two alternatives of vaccine, the one given in Tanzania is Oral Polio Vaccine (given as drops by mouth) and this oral polio virus vaccine contains live but harmless strains of polio virus. In a child where there is immune deficiency syndrome, not necessarily due to HIV, because immune deficiency syndromes have been existing even before HIV, polio immunizations were given by using Salk vaccine (polio vaccine given by injection). The vaccine is also called IPV (Inactivated polio vaccine).
The community is assured that, there is an extremely small risk (about one in five million doses) that live vaccine will cause polio in the vaccinated person or in someone who is a close contact.
Symptoms and signs in minor forms of polio are by far the most common. About 85 per cent of children infected with the polio virus have no symptoms at all. In the rest, after an incubation period of three to four days, there is a short illness with slight fever, sore throat, headache and vomiting. This lasts for a few days, after which most children recover completely.
In some children, however, after a short period of apparent health, there is a major illness with symptoms caused by inflammation of the meninges (membranes covering the brain and spinal cord -- 'uti wa mgongo'). These symptoms are fever, severe headache, stiffness of the neck and back and aching in the muscles, sometimes with widespread twitching. In some cases the condition progresses, often in the course of a few hours, to extensive paralysis of muscles. The legs and lower trunk are the most frequently paralyzed. If infection spreads to the brainstem (the lowest part of the brain), the result may be swallowing and breathing problems or even total loss of these faculties.
Diagnosis in our set up is to send stools for polio virus isolation in special packing materials to the polio lab in Dar and or to another country like Uganda for comparing notes. Our laboratory in Tanzania has in all cases given similar results of no polio finding so far. At times polio vaccine virus can be isolated from stools, in medical terms it is harmless. Throat swabs and cerebro spinal fluid obtained by lumbar puncture may capture the polio virus in some centres. However, a good clinician cannot miss a case of polio, it is so typically presented-muscle paralysis combined with acute fever is characteristic of severe polio and enables an immediate diagnosis to be made.
There is no effective drug treatment for polio. Those children without paralysis bed rest with pain killers may assist. Health personnel are advised to stop giving injections in children suspected to have polio. The children with paralyzed muscles will need physiotherapy. Physiotherapy is essential to prevent muscle damage while virus is active. Later, if disease process is subsiding, physiotherapy is needed to help retain muscle function.
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