Editor's note: Gen. Stanley McChrystal is the former commander of the United States Forces in Afghanistan and a senior fellow at the Yale University Jackson Institute for International Affairs. Follow him on Twitter @StanMcChrystal. Kristina Talbert-Slagle is the senior scientific officer of the Yale Global Health Leadership Institute and a lecturer at the Yale University School of Public Health. Follow her on Twitter @KTalbertSlagle. The opinions expressed in this commentary are solely those of the writers.
(CNN) -- Over the past several months, about 3,100 people have died from Ebola infection in western Africa. Now, we have a confirmed case of Ebola in the United States, making this global health security threat all the more real. Thousands of miles away, an unknown number of people have died at the hands of members of the Islamic State in Iraq and Syria, or ISIS.
Although the Ebola outbreak is a global health crisis caused by a virus, and ISIS is an international security crisis caused by an insurgent group, the two have much in common.
Each poses serious threats to the health and safety of people not only in their own nations, but also to populations around the world. Both Ebola and ISIS were threats that were initially underestimated, even denied, by national and international political powers. Both have persisted, and now require a complex, multisectoral strategy that includes political, military, infrastructural, and humanitarian interventions.
The response to these threats is challenging and expensive. It is also late: Earlier intervention arguably could have saved lives in both cases. Finally, and most important, Ebola and ISIS are serious global health security challenges that mask deeper, more complex problems. They are, in essence, opportunistic infections taking advantage of weakened, vulnerable systems.
We have seen this before.
The opportunism of Ebola and ISIS in many ways mirrors that of the opportunistic infections that prey upon people with AIDS, exploiting their long-weakened systems. Several lessons from the long, painful struggle of the AIDS epidemic can inform our approach to Ebola and ISIS as global health security crises.
The host can't be brought back to health unless the opportunistic infections are treated. For patients living with AIDS, the ideal standard of care is to address infections with state-of-the-art, targeted therapy. The same is true for the immediate threats posed by Ebola and ISIS. By deploying targeted approaches in Liberia, Iraq and Syria, the United States has demonstrated strategic leadership in addressing these invasive threats.
But unless the underlying immunodeficiency is treated, people with AIDS will be vulnerable to ongoing waves of infection. The same is true with Ebola and ISIS. Unless we address the underlying causes of national immunodeficiency that facilitated their emergence, more infectious disease outbreaks, other insurgencies, or to-be-determined threats will recur.
Stemming the spread of Ebola requires not only treating people infected with the virus, but also addressing the weakened or broken health systems that have allowed it to take hold so rampantly. Similarly, combating ISIS, an insurgent group, requires not only targeted attacks on the opportunistic threat, but also sustained efforts to rebuild the health of national systems and regain the trust of the population.
These efforts, like the multiyear struggle to identify and treat the underlying cause of AIDS, are difficult, resource-intense, and fraught with political challenges. But as we have learned from AIDS, we have no choice.
Third, we must overcome our instincts for denial. Although the first AIDS cases were reported in 1981, not until the mid- to late-1980s did the AIDS epidemic garner widespread public recognition as a health crisis. By then, many people had died. Denial of the problem was extraordinarily powerful and surprisingly easy: AIDS affected a group of people who felt like the "other," the problem seemed far away, addressing it would be costly. Political leaders did not want to talk about it.
We have long been aware of huge challenges posed by vulnerable systems in Sierra Leone, Guinea, Liberia, Iraq and Syria; we know that such national immunodeficiency needs to be addressed.
After the frustrations we've experienced following 9/11, it is tempting to adopt a defensive crouch and respond only to the threats before us, allowing the remainder of the problem to fester. That is a mistake. And the history of the AIDS epidemic argues that ultimately, it won't work.
Restoring a nation to health will require not only targeted efforts to address Ebola and ISIS, but also rebuilding systems—not just defense, but also infrastructure, health care and government—through sustainable, well-funded and comprehensive approaches.
Admittedly, this is not a popular strategy for a war-weary nation, or with the allies with whom we must partner, but in a globally connected world, we may not have a choice. As Ebola and ISIS are teaching us—and as we have learned before from AIDS -- treating only the opportunistic infections that take hold in a weakened system does not make the problem go away. Let's learn from experience.