Ask a Doc: What is being done to track the spread of infectious disease?

Ask a Doc: What is being done to track the spread of infectious disease?

Health and Safety

Ask a Doc: What is being done to track the spread of infectious disease?

Question:

From cholera in Haiti, to Valley Fever in Arizona, to an especially cruel flu season this winter throughout the nation, the world is awash in pathogens. What is being done to track down, monitor and combat infectious disease?

Answer:

One of the many global missions of TGen, the Translational Genomics Research Institute, is to develop technology derived from the Human Genome Project. Molecular-level tests have become some of the most powerful tools in epidemiology, a branch of science dealing with the occurrence, spread and control of diseases.

For example, the TGen technology and scientific analysis was recently called upon by health officials in Washington, Oregon and British Columbia to find out how a deadly tropical fungus known as Cryptococcus gattii spread to the temperate environs of the Pacific Northwest.

How did it get here?

C. gattii can cause deadly lung and brain infections in both people and animals. It is usually found in places like Australia, New Guinea and Brazil. So how did this disease cause a deadly 1999 disease outbreak on B.C.’s Vancouver Island?

In what is being described as “The Teddy Roosevelt effect,” C. gattii may have arrived in the Pacific Northwest from Brazil via the Panama Canal, according to a new study.

Working under grants from the U.S. Centers for Disease Control and Prevention, and the National Institutes of Health, TGen researchers and collaborators used genomic analysis and advanced statistics to trace the likely evolution of the disease, correlating it in time to the 1914 opening of the Panama Canal and a surge of shipping trade between Brazil and the Pacific Northwest. The results were published Jan. 17 in the scientific journal mSphere.

 

Symptoms of C. gattii infection

C. gattii infections first appeared in Washington in 2007, and in Oregon in 2010, with isolated incidences in Idaho and California.

Symptoms include cough, shortness of breath, chest pain, fever, headache, neck pain, nausea, vomiting, sensitivity to light and confusion or changes in behavior. Treatment can include months of intravenous and oral anti-fungal drugs, and in some cases surgical removal from the lungs and central nervous system.

Understanding the emergence and continual evolution of this pathogen into a new environment is critical to the understanding of the ongoing spread of cryptococcal disease, and may be important to studying the evolution of other emerging health threats.

Researchers performed whole genome sequencing on 134 C. gattii samples. They then estimated fungal mutation rates and used evolutionary analysis to calculate the arrival of C. gattii in the Pacific Northwest within the past 60 to 100 years, which the authors posit, “makes a strong case for an anthropogenic (human-caused) introduction.”

The importance of tracing origins

Nearly 3 million years ago, the Isthmus of Panama rose to create a land bridge between North and South America, and a barrier between the Atlantic and Pacific oceans. The study results suggest that the completion of the Panama Canal in 1914 may have provided the perfect migratory path for the fungus.

As North American populations of C. gattii continue to evolve and disperse, it will be useful to continually apply genomic dating to understand the nature of these events and the expanding impact of these fungi on human and veterinary health.

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