about astra

Dr. Astra Bryant is a professor at the University of Washington who studies neuroscience and parasitology. Growing up in Mountain View, California, Astra was an animal lover and a voracious fiction book reader. While she originally wanted to apply her love of animals into becoming a veterinarian, she ultimately decided to become a research scientist. She studied biology at Bryn Mawr College, a women's liberal arts college in Pennsylvania, and went on to get her PhD in neuroscience from Stanford. She became involved in parasitology during her postdoc at UCLA, and eventually came to the University of Washington to start her own lab, conduct research, and mentor students. When she's not working, she likes to take her 1 year old puppy, Gary, to dog parks, bike around Lake Washington, and paint landscapes.

What are parasitic nematodes?

Nematodes are a kind of worm, but they're not the same as earthworms, which is probably what you think of when you see the word "worm". While they may look "worm shaped", they have different anatomy and have been evolving separately for a very long time. A parasitic organism is one that lives on or in another organism for at least part of its life, usually stealing resources like food, water, or even blood from its host. Head lice and tapeworms are examples of parasites. There are also parasitic organisms that rely on other animals to raise their young, like cuckoo birds and some wasps. Strongyloides stercoralis, or S. stercoralis, live in the soil in their larval form. When they find a human host, they enter the human's body and develop into an adult, living out their life in the small intestine. The nematode's eggs and larvae exit the body through feces, and can go back into the soil to infect someone else.

Parasitic, soil-dwelling nematodes in general affect over a billion people worldwide and can cause a variety of negative health impacts; they can even lead to death. These nematode-related health issues disproportionately impact socioeconomically disadvantaged regions of the world. S. stercoralis, the species Astra studies, "infects at least 610 million people globally, nearly three times as many people as malaria", according to her lab's website. Strongyloidiasis, the condition caused by an infection from S. stercoralis, can cause an itchy skin rash where the nematode entered the body, and mild to severe gastrointestinal issues. Some infections don't cause any symptoms at all. In people with weakened immune systems, strongyloidiasis can be fatal (in fact, it's the only parasitic nematode that can be fatal). When a person's body can't put up a strong immune response, the adult nematodes can create very large numbers of larvae that can eventually make their way to other organs and body systems. When this happens, mortality rates can be as high as 90%.

The soil-dwelling larvae of S. stercoralis can detect human body heat and use that to find their host. Once they turn into adults, they adapt to survive in the much hotter environment of a human's body. Astra and her lab hope to better understand how S. stercoralis senses and responds to temperature, both in its behavior and within its nervous system. 

All of these findings are significant because they point researchers in the direction for more effective prevention and treatment of S. stercoralis. Currently, the best course of treatment is to treat the patient with a de-worming medication, but that leaves them susceptible to reinfection and it may be hard to tell they even need treatment if the infection is asymptomatic. Additionally, it may not be a good enough option for immune-compromised people like infants, the elderly, and people taking certain kinds of immune-suppressing medication.