Johannesburg: Alarmed that an outbreak of yellow fever in southwest Africa could spread if not quickly contained, medical experts will convene this week to consider whether to declare an international health emergency.
Though the panel convened by the World Health Organisation (WHO) may not make the declaration — a move taken with Ebola and Zika outbreaks — the session to be held in Geneva on Thursday speaks to the seriousness of the disease’s spread in Angola. Yellow fever infections tied to Angola already have been reported in China.
“In my view, calling an emergency committee for yellow fever is clearly the right thing to do,” Lawrence Gostin, faculty director of Georgetown University’s O’Neill Institute for National and Global Health Law, said in an email.
“First, there is the potential for rapid spread to other countries and regions, threatening the health of large populations in Africa, Asia and elsewhere,” Gostin said. “Second, as the crisis escalates, global supplies of the yellow fever vaccine are dwindling and we could easily face a critical shortage. What this new emergency committee demonstrates is that mosquito-borne diseases — Zika and now yellow fever — pose major threats. This requires a war against mosquito vectors with resources and a full range of technologies, as well as health education.”
In a paper published this month in the Journal of the American Medical Association, Gostin and his colleague Daniel Lucey, an immunologist at the O’Neill Institute, called for WHO to “urgently convene an emergency committee to mobilise funds, coordinate an international response, and spearhead a surge in vaccine production.”
The disease emerged last December in Angola, which had not had an outbreak in almost 30 years. Since then, 2,267 suspected infections have been reported and 293 people have died from the virus, according to WHO.
Meanwhile, the disease has been imported by travellers from Angola to Kenya, China and the Democratic Republic of Congo, raising the alarm in other nations, including Namibia and Zambia that share a long border with Angola.
An unrelated bout of yellow fever has also taken hold in Uganda.
“The risks for other countries really depend on how fast the cases are detected and the density of mosquitoes,” Sylvie Briand, WHO’s director of the pandemic and epidemic diseases department, told reporters at a briefing in Geneva last week. “We are concerned for other countries that may have high density of mosquitoes.”
Yellow fever is transmitted by Aedes aegypti mosquitoes, which also carry Zika, the virus linked to severe birth defects that have swept South America in recent months.
Patients with severe infection from yellow fever experience high temperatures, jaundice, bleeding and eventually shock and failure of multiple organs. Between 20 per cent and 50 per cent of those who become jaundiced, entering what is known as the “yellow” phase of the disease, die from the virus, WHO officials said.
The outbreak in Angola is particularly worrisome because it is happening in urban areas such as the capital city Luanda, where the first cases in the country were detected, health officials said.
“You have trillions of mosquitoes and millions of people, so the capacity of transmission of the virus is multiplied enormously,” said Briand. The virus is far easier to fight in sparsely populated rural areas, she said.
While there is no treatment for yellow fever, the vaccination used to prevent the disease is highly effective. But the global supply of the vaccine is limited, according to information published WHO. The agency said that because of the current outbreak, shipments of the vaccine that would ordinarily be used in routine immunisation programmes in other countries where yellow fever is endemic were being used in Angola and other affected countries.
Ray Arthur, director of the Global Disease Detection Operations Centre at the Centres for Disease Control and Prevention (CDC), said in emailed comments that there had been no local transmission of yellow fever in the US since the early 1900s. And while many areas in the country have mosquitoes that can become infected and transmit yellow fever virus, the agency was “not expecting local transmission of yellow fever in the continental United States, “ Arthur said.
However, the CDC is “concerned about travellers going to Africa and South America,” where yellow fever is endemic, Arthur said. “Travellers can return to the United States with a yellow fever virus infection.”
The agency is advising travellers to countries with yellow fever to review the vaccine recommendations and requirements to determine their need for vaccinations.