Nigeria prepares as yellow fever spreads across Africa

• Govt says nation has critical stock to address any outbreaks
• WHO says country has less than 50% vaccination coverage
• 1986 outbreak infected 116,000 people, killed 24,000 nationwide

There are fresh fears that the worst yellow fever outbreak in decades, which has killed 250 people in Angola and is straining global vaccine supplies, posing a dilemma for health officials, could spread further in Africa and possibly into Asia.

Indeed, as the largest outbreak of yellow fever in almost 30 years continues to spread in Angola, scientists are warning that the world is ill-prepared for what would be a public-health calamity: the re-emergence of urban epidemics of the deadly infection, which could overwhelm vaccine stockpiles.

According to a recent report published in Nature, the immediate concern is that the virus might spread to larger African urban centres, as happened in the biggest previous outbreak, which began in 1986 in Nigeria and ultimately infected 116,000 people and killed 24,000.

Coordinator, the World Health Organisation (WHO) Control of Epidemic Diseases Unit in Geneva, Switzerland, William Perea, in the Nature report noted: “For now, the area of most immediate concern is Africa — where some countries, such as Nigeria, have less than 50 per cent yellow fever vaccination coverage. The availability of vaccines has led to ill-founded complacency about the threat posed by yellow fever. It’s a neglected and forgotten disease.”

But Executive Director, National Primary Health Care Development Agency (NPHCDA), which is in charge of immunisation in Nigeria, Dr. Ado Gana Muhammad, told The Guardian that the country has critical stock to address any outbreaks of yellow fever and measles and there are plans for vaccination campaigns in high-risk states during third quarter of 2016.

Muhammad said: “Efforts are ongoing to sustain the improved national immunisation coverage for yellow fever and measles. The country has critical stock to address any reported incidence of outbreaks, no matter how small, through reactive small-scale campaigns.

‘‘Additionally and based on our epidemiology we do conduct follow-up or catch up campaigns. In 2015, we had nationwide measles follow-up campaigns for the 19 northern states in November / December 2015 and for 17 Southern States in February / March 2016. Our national targets were 38.5 million under five-year-old children. At the end, we reached 22.9 million children in the northern states and 19.0 million in the southern cluster of the campaign giving a total of 41.9 million that is 108 per cent.

“Based on the current risk assessment mapping and the recent campaign outcome, Local Government Areas (LGAs) with less than 95 per cent coverage or greater 20 per cent missed children, will be targeted for special patchy campaign to induce additional immunity to avert potential outbreaks.

“Yellow fever campaign is also being planned for the high-risk states during third quarter 2016. There is also active surveillance for the two diseases for early detection and prompt response.”

The NPHCDA boss had told The Guardian that the Federal Government in line with global best practices planned to resuscitate Yaba Yello Fever (YF) vaccine plant using a Public-Private Partnership arrangement. “Since 2005, an MoU was signed between the FMoH and a local pharmaceutical company (May & Baker) that was followed by the signing of a Joint Venture Agreement (JVA) in 2007. This shows how serious the country is committed to the production of YF vaccine both for our domestic use and subsequently for export,” he said.

Yellow fever is transmitted by the same mosquitoes that spread the Zika and dengue viruses, although it is a much more serious disease with death rates as high as 75 percent in severe cases requiring admission in hospital.

The condition, which takes its name from the jaundiced colour of some patients, has spread to the Democratic Republic of Congo and there is concern it could gain a foothold for the first time in Asia.

Yellow fever virus caused devastating outbreaks in cities in the past, but by the 1970s its mosquito carrier in urban areas — Aedes aegypti — had been wiped from large swathes of the globe; vaccination programmes also helped to confine the virus to the jungle.

But now, as a result of the scaling-back of control efforts, Aedes mosquitoes have re-emerged in densely populated tropical and subtropical cities where many people are unvaccinated — and the Angolan situation has renewed fears that the virus might be poised to break out from the jungle.

Yellow fever, which is endemic in parts of South America and Africa, causes at least 60,000 deaths each year. Many people who become infected recover quickly and there are 84,000–170,000 annual infections, more than 90 per cent of them in Africa, but some develop jaundice, bleed from their orifices and sustain fatal organ damage.

Some experts have called for a radical switch in strategy to use just one-tenth of the usual vaccine dose to conserve scarce stocks but the WHO says it cannot be sure this would work.

A retired virologist who formerly worked for the WHO and the United States Centre of Disease Control and Prevention (USCDC), Jack Woodall, in an article in The Lancet medical journal on April 16, said a short-term solution could be to slash the dose, since research suggests just one-tenth can produce the same immune response as a full dose.

“We need to get a low-dose vaccine authorised as soon as possible because if we keep using full doses we will never catch up.”

Woodall and colleagues laid out the case for the emergency use of a one-tenth dose.

The WHO says cases of yellow fever imported into China, which has close commercial ties with oil-rich Angola, show that “this outbreak constitutes a potential threat for the entire world.”

And it is warning that further spread elsewhere in Africa and Asia would increase the squeeze on vaccine supplies and could interrupt routine immunisation.

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