A scientist at the University of Wisconsin at Madison works with a strain of Aedes aegypti mosquito. (Jeff Miller/Associated Press)

Michael Gerson and Raj Shah are senior fellows with Results for America. Gerson, a Post columnist, served as assistant to President George W. Bush for policy and planning and is a senior adviser at the anti-poverty group One. Shah served as administrator of the U.S. Agency for International Development under President Obama.

In the aftermath of the 2014 Ebola crisis, public-health officials, disease experts and politicians said that 11,000 painful, frightening deaths had not been in vain. Images of children dying in their mothers’ arms in Africa and the fear of Ebola transmission here at home should have been a wake-up call to the world.

At least four systematic reviews of the Ebola crisis were conducted (including one by a high-level U.N. panel on which one of us, Raj, served). All these studies called for greater global rapid-response capabilities; clearer lines of authority ending in a single, accountable leader; flexible resources, including a trained workforce that can be called quickly into aggressive action and deployed to whichever countries needed help; and a rapid-response organization capable of reacting to circumstances on the ground.

Now, the response to Zika is revealing many of the same weaknesses, allowing the virus to gain a dangerous momentum that could bring unnecessary tragedy to thousands of families and justified fear to America’s shores.

The world is not mounting a sufficient operational response to Zika in the South and Central American countries that are at risk. Brazil, Colombia and other nations are not applying the scale of resources required to rapidly reduce transmission. Within a year, Puerto Rico could have hundreds of cases of microcephaly, leading to disastrous consequences for its already troubled and tourist-driven economy.

Nearly every Ebola study called for the World Health Organization to create an operational entity prepared to step in and support countries that need help fighting pandemics. Given that this has not yet happened, we need a single authority tasked with the responsibility of coordinating the operational response in foreign countries — such as retired Rear Adm. Tim Ziemer. As U.S. global malaria coordinator under both President George W. Bush and President Obama, Ziemer has helped save millions of lives through mosquito control and could be tasked with one more mission.

We also need clear, evidence-based and comprehensive strategies capable of rapidly interrupting disease transmission in Central and South America. These should include data-driven insecticide spraying campaigns; widespread use of mosquitoes that mate with Zika-spreading mosquitoes and block reproduction; and immediate communications campaigns that promote using protective clothing, bug spray and condoms (because the virus can be transmitted sexually as well). Critical research into better pesticides, more accurate rapid testing and a Zika vaccine have already been prioritized and will improve the effectiveness of at-scale response to end transmission.

To succeed, we need resources — both financial resources and trained people willing to put themselves at risk. But the U.S. budgetary and political process has been irresponsibly slow. The WHO declared a global health emergency early in February. Later that month, the Centers for Disease Control and Prevention sent a detailed request to the White House. The Senate approved a lower amount than the Obama administration proposed. The House came in with a smaller number still and proposed to divert money — with absurd pound-foolishness — from the continuing Ebola response. And now Congress has gone on vacation without passing a funding bill.

This partisan delay is tremendously dangerous. It is precisely at this stage of a pandemic that the eventual shape of an epidemic curve is determined. The effects of even small delays become magnified. And the delays on Zika response are accumulating. As CDC Director Tom Frieden has said, “Anything we don’t do now we will regret later.” That regret will come in the form of personal suffering for families that should not have to hold a young child suffering from severe birth defects.

The fight against Zika requires global leadership to coordinate a coherent, multi-country strategy committed to measurable outcomes, relentless innovation and making good use of data. Only the U.S. government has shown the ability to lead that effort. Bush fought the HIV/AIDS pandemic in Africa with a successful, evidence-based strategy. Obama demonstrated leadership by successfully investing U.S. resources to fight Ebola and creating a global health security partnership with countries around the world.

On health issues such as HIV/AIDS and Ebola, U.S. leadership — our science, technical skill, compassion and political will — has been essential to changing the course of history. On Zika, important preparations, including with federal and state authorities, are ongoing. But a heightened global focus is required to make all our efforts effective. This requires Congress to return from its recess and pass a meaningful funding bill. Each of these pandemics demonstrates how our interests as Americans and our values as the world’s truly exceptional nation lead us in the same direction: to fight with urgency and ambition for the health of the world.