During an official check to certify that Namibia remained polio-free a decade after it declared it had conquered the disease, officials made a surprising find: a 39-year-old man stricken with the virus.
Since that first case in May, Namibia has detected 185 suspected cases — including 21 deaths — and 17 confirmed cases. Unusually for a disease that mainly strikes children, most of the cases have been adults.
The outbreak has prompted a robust response from the Namibian government. On Tuesday, it launches a three-day nationwide immunisation drive aiming to vaccinate the entire population.
”We realised immediately that this needed a massive reaction, and that’s what we’ve put into place now,” says Dr Norbert Forster, Namibia’s Undersecretary for Health and Social Welfare Policy.
Health officials say about 75% of the suspected cases are over 15 — a reflection of the fact that only children have been vaccinated under a routine immunisation campaign Namibia launched in 1990.
Polio cases have dropped by more than 99% since 1988, when the Global Polio Eradication Initiative was launched by the World Health Organisation (WHO), the Centers for Disease Control and Prevention (CDC) in the United States, the United Nations Children’s Fund and Rotary International.
Ironically, that has raised the risk of seeing outbreaks similar to the one in Namibia. As populations find themselves less exposed to the polio virus, the general level of immunity has been slipping.
”Every country may well have a higher susceptibility for polio than they’ve had at any time in the past,” says Dr Bruce Aylward, coordinator for the WHO’s polio-eradication department.
That is particularly true for adults, in whom polio tends to provoke a higher percentage of complications, paralysis and even death. The 39-year-old man whose case was discovered in May was left paralysed.
The vaccinations are costly. The three-day immunisation will cost about $2-million, and Namibia is putting up about 80% to 90% of the costs — with aid agencies covering the rest. Experts are concerned that expenses may eventually impede poor countries’ ability to respond to outbreaks.
Adult outbreaks have occurred in recent years in isolated populations in Cape Verde, Albania and The Netherlands.
Still, because polio requires several factors to spread, including a population at risk and poor sanitation, it is unlikely that polio poses a big risk to most developed nations.
”I don’t think there’s a multitude of areas with this situation,” says Dr Linda Venczel, deputy director of the polio department at the CDC.
The outbreak in Namibia is ultimately a symptom of the ongoing polio problem in the four countries where it continues to be transmitted: Afghanistan, India, Nigeria and Pakistan. Health experts say the Namibian strain was imported from India.
”Until we actually tackle eradication and get rid of these endemic countries, we are going to inevitably face some outbreaks in other countries,” says Venczel.
The Southern African nation is sending 1 500 teams of vaccinators across the country this week, armed with 2,8-million doses of vaccine. They aim to administer two drops of the oral polio vaccine to every person in the country.
”We are aware that our outbreak affects the whole sub-region, and that what we’re doing here helps other countries as well,” says Forster.
The WHO characterises Namibia’s reaction to the outbreak as a ”model response” for its speed, the decision to vaccinate the entire population and the choice of vaccine.
”What happens in Namibia should tell us how fast you can stop an outbreak if you do the whole population, if you get high coverage, and if you do it this fast,” says Aylward.
Normally, polio outbreaks resulting from imported viruses can take from three to 12 months to contain fully. Given Namibia’s aggressive approach to outbreak response, however, some public health officials are optimistic it might be controlled even sooner. — Sapa-AP