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Conversations with the Director: Tom Chiller, MD, MPHTM

January 10, 2013

Tom Chiller

Photo by María-Belén Moran

Finding and Stopping Fungi to Prevent Severe Disease and Save Lives

Prevention is key in CDC’s 24/7 mission to support domestic and global partners in identifying public health problems and stopping them. And that is exactly what CDC’s fungal experts are doing in South Africa with a program to decrease and eventually stop the number of HIV patients who develop cryptococcal meningitis, a serious fungal disease of the brain and spinal column that can be fatal.

To learn more about it, CDC Director Tom Frieden, MD, MPH, met with Tom Chiller, MD, MPHTM, chief of the Mycotic Diseases Branch, Division of Foodborne, Waterborne, and Environmental Diseases (DFWED), National Center for Emerging and Infectious Zoonotic Diseases (NCEZID) during a Conversation with the Director.

Cryptococcus spp. are fungi found in the environment. Healthy people who breathe them in rarely get sick, but HIV patients, with weakened immune systems, can develop cryptococcal infection that in turn can cause cryptococcal meningitis. Worldwide, approximately 1 million new cases of cryptococcal meningitis occur annually, resulting in as many as 625,000 deaths.

“With over half a million people being killed from this infection each year, we knew we needed to come up with a plan that could help prevent these deaths,” said Chiller, pictured above, who is also the associate director for epidemiologic science for DFWED.

“One of the problems with HIV is that it lowers our immune system’s ability to respond to normal infections. And many of those infections are fungi. I’m a mycologist, I study fungi and in public health we are challenged with being able to prevent fungal infections,” added Chiller. “So, we set out to find the best strategy to prevent life threatening disease or cryptococcal meningitis. Even if we can’t prevent the initial infection— we can stop it from becoming severe disease— so then we can prevent death.”

Detecting Infection before Disease

The strategy is grounded in science, partnership commitment, and technology. A rapid dipstick cryptococcal antigen test, similar to a pregnancy one, can be performed anywhere and provides results in 10 minutes at a cost of $2 per person, Chiller explained, but to see this through will take relentless focus.

Chiller continued enthusiastically, “It turns out that cryptococcal infection is an interesting infectious disease because it has a wonderfully simple diagnostic test …the antigen test becomes positive in your blood in a matter of weeks to months before you get meningitis. So the test allows us to detect infection before you have severe disease, because we know severe disease can mean death in 50 to 70 percent of patients.”

For decades, to find out if cryptococcal infection was present in HIV patients with a CD4 cell count lower than 100, experts relied on a traditional test that Chiller described as “fantastic” but that required a laboratory and some expertise.

In South Africa, CDC partnered with the National Department of Health, the National Health Laboratory Service, USAID, and our local office and in September a program to screen high-risk patients began. To date 1,500 people have been screened. Of those about 5 percent (75 people) have been found to have infection and are now on treatment to prevent meningitis.

“If you can detect infection before disease, you can save lives. This is a winnable battle and so it is important to go out and start screening programs,” said Chiller, who explained that if the fungus is not treated before providing HIV anti-retroviral therapy (ART), patients can experience serious adverse reactions. “It’s important to identify the patients with the fungus early with screening and treat them with oral antifungal medicine. So, (we can) beat down the fungus and then reconstitute the immune system with ART. That is really important in this disease.”

Chiller said that the cost of treating individuals with cryptococcal meningitis “is very high because you have to put them in the hospital and give them costly IV medicines. The alternative is to screen—it costs a couple of dollars per test and might cost less in the future—identify early infection, and then use antifungal medicine pills that can be taken as an outpatient. And those costs are as low as $40 for a 6-month supply. It’s a cost-saving program for countries that have this disease.”

Studies done in Uganda have shown that “If your prevalence for crypto is anywhere above 1 percent, it’s a cost-effective strategy to screen for Cryptococcus,” said Chiller.

Because of the potential for saving thousands of lives, South Africa included in its 2012 National Strategic Plan a program to have high-risk patients screened on a routine basis. When that happens, it is anticipated that between 400,000 to 500,000 people will be screened per year for cryptococcal infection—with a fungus among us, this screening will save lives and protect people from severe disease.

This CDC Connects story by María-Belén Moran.