Yellow fever, Zika virus, and lessons we have to keep learning

By | 2016-05-26T16:18:42+00:00 May 26th, 2016|5 Comments

Last week, the World Health Organization stopped short of declaring a yellow fever outbreak centered in Angola to be a public health emergency of international concern, but its emergency advisory committee “emphasized the serious national and international risks posed by urban yellow fever outbreaks.” Angola has reported more than 2,000 suspected cases of the disease and nearly 300 deaths. Cases among travelers from Angola have also been reported in China, the Democratic Republic of Congo, and Kenya.

Like Zika, yellow fever is a flavivirus spread by Aedes mosquitos. Typical symptoms include fever, muscle pain, and vomiting; a small percentage of affected individuals develop a toxic form with high fever and liver and kidney problems, and half of these patients die. Forty-seven countries (34 in Africa, 13 in the Americas) are or have regions that are endemic. The good news is that a safe, highly effective, affordable vaccine is available.

Because yellow fever hasn’t been circulating worldwide, many countries’ populations are unvaccinated. STAT’s Helen Branswell explains, “Yellow fever has never taken off in Asia, but if it were to take root there, it would be a disaster. The region has the right mosquitoes, teeming megacities, and is a critical engine of the global economy.” Baylor College of Medicine’s Peter Hotez and Kristy Murray noted back in 2013, “We need to seriously evaluate the risks of the major southern cities of the US, including Houston, but also New Orleans, Tampa, and Miami for their vulnerability to Aedes-transmitted arbovirus infections, such as yellow fever.”

The existence of an effective vaccine is a plus when it comes to fighting yellow fever, but existing stores and production capacity wouldn’t be sufficient in the face of a widespread epidemic. Branswell notes that low demand for yellow fever vaccine over the past decades has had a predictable result:

Vaccine manufacturers don’t make what they can’t sell. So, currently, there are only four producers in the world, and they make between 35 million and 40 million doses a year, according to Dr. Thomas Monath, a yellow fever vaccine expert who leads infectious disease research and operations for NewLink Genetics, which is developing an Ebola vaccine.

… Earlier this year, the WHO emptied [its emergency] stockpile and sent 6 million doses of the yellow fever vaccine to Angola. That has since been replenished; a WHO spokesperson said Wednesday the agency currently has around 6.3 million doses. But if the entire population of Kinshasa needs to be vaccinated, the emergency stockpile won’t do the job.

Targeted use of the emergency stockpile appears to have helped. Donald G. McNeil, Jr. reports in the New York Times, “After more than five million Angolans were vaccinated, cases in Luanda dropped. New clusters appeared in several of the country’s provinces and spread to other countries and China, but vaccination now appears to be containing them.” Based on these results, the WHO’s advisory committee decided not to recommend giving diluted doses of the vaccine to stretch supplies (a step some experts have suggested when need is great).

Missing opportunities for prevention

When it comes to the Zika virus, we don’t have a vaccine to deploy strategically, but we still have an opportunity to invest in prevention – and potentially spare thousands of families from suffering. Ashish Jha wrote in USA TODAY on Mother’s Day:

We are doing better on Zika than we did on Ebola. We are sharing information better, WHO has been more responsive and international response has been better coordinated. But that is not enough. We need stronger, faster action and greater resources — particularly for research on disease diagnostics and vaccine development. Even on the verge of mosquito season, with millions of Americans at risk, Congress has failed to approve $1.9 billion in emergency Zika funding.

I honestly can’t understand why the House Appropriations Committee is only willing to spend $622 million to address something that has the potential to devastate so many families (and so many state Medicaid budgets) in the southern half of this country. The extent of the disease’s devastation will depend largely on the speed with which we improve our fragmented mosquito-control efforts and develop diagnostics and vaccines. Ask Kim noted earlier this month, “preparing for Zika is no time for political games” – but three months of Congressional foot-dragging haven’t helped public-health efforts.

In the Los Angeles Times, Noam N. Levey considers the big picture of public-health funding:

Government investment in public health has been declining for years. So too has the nation’s public health workforce, which is almost 20% smaller than it was in 2008, according to health authorities.

… Chronic underfunding for public health has forced Congress to repeatedly pass emergency measures in the face of crises, as lawmakers did in 2014 to respond to Ebola and in 2005 and 2006 to respond to a pandemic flu outbreak.

This form of crisis funding slows public health responses to disease outbreaks as agencies often must hire staff, train volunteers and take other steps to ramp up, said James Blumenstock, who oversees health security programs for the Assn. of State and Territorial Health Officials.

“We are much better off if we maintain a public health system that has a higher state of preparedness,” he said.

At Vox, Julia Belluz shares the perspectives of officials and experts who’ve become all too familiar with the “looming-health-disaster money scramble.” Here’s one of the suggestions she got:

Ron Klain, the “Ebola czar” who coordinated the US response to Ebola, has also thought long and hard about how to prepare for outbreaks. The Federal Emergency Management Agency (FEMA) was established to respond to natural disasters, he pointed out, but there’s still no equivalent for health. So he’s been advocating for a new federal response agency to help us organize for and rapidly deploy in the event of a major epidemic.

“We should have an agency doing for epidemics what FEMA does for hurricanes — and then, yes, we would have some common response items prepositioned and some immediate funds for action and contracting in the response,” he said. But, like FEMA, even if a health fund existed it might need to be supplemented with emergency funding if a particularly bad epidemic were to hit.

Hotez also favors the creation of a new funding agency to manage infectious disease emergencies. While each epidemic looks a little different, having some sort of mechanism in place that could trigger an immediate release of money would be extremely useful and probably lifesaving.

“You could even make those funds time-sensitive — use them for the first 30 days, then go back to Congress to continue funding,” said Hotez. “But at least the first tranche of money is there to begin [responding to the outbreak].”

These sound like promising ideas to pursue once we have a Congressional majority that appropriately values public health.

Forgotten lessons

The first “irrefutable” outbreak of yellow fever in North America hit Boston in 1693, and periodic deadly outbreaks in US coastal cities continued until the turn of the 20th century. In 1900, Army major and physician Walter Reed announced findings of the US Army Yellow Fever Commission at the annual meeting of the American Public Health Association in Indianapolis. His team demonstrated that mosquitoes spread yellow fever, and do so after an incubation period. The University of Virginia’s Historical Collections at the Claude Moore Health Sciences Library explains that government officials switched from a quarantine policy to a mosquito-control policy on the basis of these findings, and concludes: “The control of Aedes and the subsequent elimination of yellow fever in America saved innumerable lives and millions of dollars in commercial losses.”

Federal investment in controlling infectious diseases has saved lives and averted economic losses in the past. But without sustained support for public health and preparedness, we’ll remain at risk. I hope it doesn’t take the births of hundreds of Zika-infected US babies for the US government to re-learn that we have to invest appropriately in public health.

Update, 5/27: Congress left town for its Memorial Day recess without approving Zika funding.

About the Author:

Liz Borkowski
Liz Borkowski, MPH is the managing editor of the journal Women's Health Issues and a researcher at the Jacobs Institute of Women's Health at the Milken Institute School of Public Health at George Washington University. Her blog posts are her own and do not necessarily represent the views of her employer.


  1. JustaTech May 26, 2016 at 6:06 pm - Reply

    1) Death to the A aegyptes! Down with that mosquito!
    2) Congress is pretty much the definition of “penny-wise and pound-foolish”. Also, disastrously short-sighted.
    3) If anyone remembers the old Disney live-action movie of the Swiss Family Robinson, the family initially fends off the pirates by flying the Yellow Fever Quarantine flags.

    I didn’t know that yellow fever hasn’t taken hold in Asia – I assumed that since it was so old, it had gotten everywhere.

  2. Paul Murray May 26, 2016 at 8:26 pm - Reply

    “I honestly can’t understand why the House Appropriations Committee is only willing to spend $622 million to address something that has the potential to devastate so many families”

    Racism. Everything in the USA that doesn’t make sense can be instantly understood when you factor race into it. Just ask yourself what color those devastated families are likely to be, and it all explains itself.

  3. GregH May 27, 2016 at 3:36 pm - Reply

    Great article, thanks!

    What do you think about the idea that Zika (and yellow fever) transmission in post-Olympics travellers returning to countries where Aedes is endemic represents a major health risk?

    Off the Podium: Why Public Health Concerns for Global Spread of Zika Virus Means That Rio de Janeiro’s 2016 Olympic Games Must Not Proceed

  4. Liz May 28, 2016 at 6:37 pm - Reply

    Greg, I do think there’s a strong case for postponing or moving the Olympics — due not just to Zika, but to drug-resistant pathogens in the water where athletes will compete, as Judy Stone has pointed out in Forbes ( It’s not a move to undertake lightly, though, and if countries suffer economically for being transparent about public health concerns, that could discourage future transparency.

  5. G June 1, 2016 at 5:39 pm - Reply

    Liz, thanks for keeping us up to date on these developments.

    We all understand the politics of this well enough to know what we need to do about it: replace irresponsible Representatives in the House with science-aware responsible ones.

    The reason this is difficult is that Congressional districts have been relentlessly gerrymandered to make them non-competitive. This favors incumbents and particularly favors anti-science irresponsible types in certain states.

    The solution to this is to target the worst of the worst for replacement, based on sound analyses of which of them are vulnerable.

    Everyone who is aware of urgent science-based issues including novel infectious agents, climate change, etc., can pitch in and do their part right now. Register new voters, help voters get their “papers” in “voter ID” states, and participate in “GOTV” or “Get Out The Vote” campaigns.

    Also we should not be above giving the public a realistic scare about what is likely to happen, and tying that message directly to the political message, for example: “If Zika strikes your family, hold Congress accountable.”

    As for the Olympics, I can’t help but see a catastrophe in the making there, for all the reasons y’all have cited: Zika, resistant pathogens in the water, etc.; all of which will be getting on airplanes and spreading around the world. WHO needs to get onboard with moving or postponing the games.

    This almost feels like a John Brunner novel: an epidemic of microcephaly looms, because tax cuts for billionaires to buy more toys, and because expensive games. Brain damaged babies because adults have to have their toys and games. If you wrote the screenplay and took it to Hollywood fifty years ago, you’d have been laughed out of the producer’s office: “that’s not even believable!”

    Yet here we are. Microcephalic babies because adult toys and games.

    Get out the vote, folks. Every vote counts.

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