All adults visiting Namibia should be vaccinated against polio, regardless of whether or not they received the vaccine as children.
At a forum held at Tygerberg Health Science Faculty last week to discuss the implications for South Africa of the recent polio outbreak in Namibia, health professionals stressed the importance of preventative measures for travellers to the neighbouring country.
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Vaccine protection may wane in adults
Most adult South Africans have been vaccinated against polio. However, this was also the officially reported situation in Namibia before the recent outbreak. And, even countries with immunization rates of over 90%, as is the case in South Africa, are still at risk for re-infection.
Prof Wolfgang Preiser, Head of Virology at the University of Stellenbosch, says that after two or three decades, the protection afforded by childhood vaccination against polio can start to wane.
“Children – as long as they’ve followed the standard vaccination regimen – would be my least worry,” says Prof Preiser.
Polio typically affects children under the age of 5 years. The Namibian outbreak has been unusual in that the majority of cases have been adults between the age of 20 and 35 years, and the mortality rate has been high.
In the most serious cases (less than 1% of all people who become infected), polio causes permanent paralysis, and can be fatal. There is no cure for the disease.
Even in cases where there are no obvious symptoms, people infected with the polio virus, which is highly contagious, can spread it unknowingly to others. This can result in a ‘silent epidemic’, in which thousands of people can get infected before doctors diagnose the first symptomatic cases.
Prof Preiser explains that the chances of South Africans getting paralytic polio are very low – especially for those of us lucky enough to be living in good socio-economic conditions and following sound hygiene practices.
However, the risk goes up for anyone currently travelling to Namibia.
Recommendations for travellers to Namibia
The National Institute for Communicable Diseases advises the following for travellers to and from Namibia:
The most important preventative measure is to be meticulous about hygiene, especially hand washing with soap and water after using the toilet and before handling food. Drink water and eat food from safe sources only.
All travellers to Namibia (including returning residents) are advised to obtain a booster dose of polio vaccine, at least 10-14 days before travelling. If your trip is scheduled for sooner than that period, then you should still be immunized.
When returning to South Africa from Namibia, see a doctor immediately if you develop any symptoms of weakness in the limbs, or inability to move the limbs. Be sure to tell the doctor that you have recently visited Namibia.
There is no role for vaccination of people returning from Namibia to South Africa; the vaccine will not prevent the disease if a person is already infected. Spread of infection can be prevented through good hygiene practices.
Which vaccine?
The oral polio vaccine (OPV) is the most accessible in South Africa and is provided free of charge at government clinics. It can also be purchased through doctors or travel clinics very cheaply (at about R2-50 a dose).
The other form of the vaccine is the inactivated polio vaccine (IPV), usually available combined with tetanus and diphtheria (TdP, which stands for tetanus, diphtheria and inactivated polio vaccine). The IPV form of the vaccine is recommended for immuno-compromised individuals, and for pregnant women. However, should only oral polio vaccine be available, it is recommended that pregnant women rather take this than go unvaccinated. IPV is more expensive than OPV, and less readily available.
Both of these vaccines are very safe. With OPV, there is a very low risk (one in a million) of vaccine-associated paralytic poliomyelitis (VAPP), in which the vaccine itself causes disease. The risk of VAPP is higher for immuno-compromised individuals, thus IPV is preferable in such cases.
Do I need a booster dose if I’m not travelling?
There are no guidelines for adult re-vaccination in South Africa, but Prof Preiser reckons that, even if you have no plans to travel to Namibia in the near future, it’s a good idea to get a booster dose at some point, or to have the full course if you’ve never been vaccinated.
However, given the low risk for contracting serious disease, South Africans should be in no rush to get vaccinated, especially considering that currently stocks of available vaccine in South Africa appear to be low. Retailers of the vaccine expect to have more stock by mid-July.
Famous polio survivors
Despite the formidable obstacles polio survivors face, many are able to lead normal lives and even excel in their chosen fields. One of the most inspiring polio survivors is South African hurdles champion LJ van Zyl, who was diagnosed with paralytic polio at the age of three.
Other famous figures who had polio include: Franklin Delano Roosevelt, American president; Frida Kahlo, artist; Dorothea Lange, photographer; Ian Dury, rock musician; Mia Farrow, actress; Francis Ford Coppola, film director; Itzhak Perlman, violinist; Joni Mitchell, singer; Robert Oppenheimer, scientist; Sir Walter Scott, writer.
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