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Tropical Diseases In The Bullseye At UC San Diego Lab

Reported by Katie Schoolov

Most people have heard of malaria. But how about Chagas disease or Amybiasis? These and other so-called “neglected” tropical diseases infect more than one billion people worldwide. Pharmaceutical companies don’t pay much attention to these infections. But KPBS Health Reporter Kenny Goldberg says a new lab at U-C San Diego is trying to discover new treatments.

Photo credit: Katie Schoolov

Dr. James McKerrow stands in the UCSD drug discovery lab holding a flask of liquid containing the parasite that causes amebiases, on August 20, 2015.

A new lab at UC San Diego is trying to discover new drugs to treat some of the world's most vexing tropical diseases.

There's not many laboratories that have 10 of the world's most notorious parasites.

But the drug discovery lab at UC San Diego does.

Lab director James McKerrow reaches into one of the lab’s incubators and takes out a flask of gold-colored liquid. You wouldn’t want to take sip.

“This is the organism that causes amebiases, which is one of the leading causes of diarrheal disease worldwide," Dr. McKerrow said.

Or how about this container? Swimming inside of it is a different parasite that causes Chagas disease. That’s one of the major causes of heart failure in South America. You get it from being bitten by what’s called a kissing bug.

You can see this parasite in action by looking into a microscope. It’s literally invading the host cell and replicating.

“So what happens to you is, if you get infected with this parasite, they will invade your heart muscle cells, and over a period of about 10 years, they’ll destroy them," McKerrow said.

The lab also has a special room for a parasite that currently infects 240 million people.

Photo credit: Katie Schoolov

A microscopic view of the worms that cause schistosomiasis, taken on August 20, 2015.

“The reason there’s a door here, if you go in, it’s temperature controlled. So it’s like the tropics,” McKerrow said.

This closet-size room has a number of tanks filled with fresh-water snails. These snails are found in water sources throughout the tropical world. They produce parasitic larvae.

“They find you by swimming through the water, following your body heat, and then they penetrate right through your skin," McKerrow said.

In about six weeks, the larvae grow into worms that infect the body with schistosomiasis. The disease causes anemia in children, and chronic ill health in adults.

Taken together, the parasites in this lab cause widespread suffering and death. But because the victims are primarily in poor countries, drug companies aren’t interested in developing new treatments. That's why they're called neglected tropical diseases.

That’s where this lab comes in. It’s well equipped to handle the process of identifying potential drugs.

The lab has robots that screen parasites against hundreds of chemical compounds at a time. The goal is to find a compound that kills the parasites.

Once the machines identify a hit, the compound goes through a series of other steps in the lab.

“So we can actually take the hits from these robots, and if they look promising enough, can put them into an animal model of infection, and ask, do they actually cure the disease? Because that’s what we really want to know," McKerrow said.

The $2 million seed money for the lab came from a combination of philanthropy, grants, and university funding. The lab has 14 core researchers, and a variety of students and interns.

The lab's activities are all part of the process that takes place before a drug can go into clinical trials.

UCSD infectious disease specialist Sanjay Mehta said the lab is doing important work.

“The current drugs are somewhat effective, depending on the disease, and oftentimes very toxic, particularly for things like sleeping sickness," Dr. Mehta said. "Sometimes the treatment can be more toxic than the actual disease. And people used to die from the treatment. So we clearly need better treatments for a lot of diseases."

Photo credit: Katie Schoolov

Post-doctor fellow Laura-Isabel McCall operates a drug discovery robot inside the UCSD lab, on August 20, 2015.

Post-doctoral fellow Laura-Isabel McCall works in McKerrow’s lab. She’s studying a variety of parasites, including the ones that cause Chagas disease and sleeping sickness.

McCall said finding one drug that made it all the way to the clinic would be a dream come true. But she said she wouldn’t stop there.

“I’d probably keep on trying to find better ones," McCall said. "But it would be an achievement.”

McKerrow said his lab has identified two drugs that are ready to move into clinical trials. The odds against them being successful are extremely high.

But that's the nature of the drug development business.


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