DVBD Spotlights

November 2020

CDC’s Yellow Fever Diagnostic Kit Could Lead to Faster Outbreak Response, Fewer Deaths

Yellow fever is one of the oldest-recognized mosquito-borne diseases in the world. Those who become infected are at risk for severe liver disease with bleeding and jaundice. Between 30 to 60% of those who develop this severe form of the disease will die. Despite having an effective vaccine since the 1930s, outbreaks continue to occur, particularly in Africa and South America.

Being able to quickly identify yellow fever infections is crucial to stopping an outbreak. However, recognizing cases of yellow fever can be difficult. Not everyone has symptoms. For those who do, symptoms are similar to other diseases that cause fever, aches, and pains.

Diagnosing yellow fever can be difficult. Traditional diagnostic testing is technically challenging, particularly in resource-limited settings. The traditional test requires skilled staff and takes days to perform. To address these technical challenges, Jane Basile and Christin Goodman led a team of DVBD researchers to create pre-measured, calibrated test components that allow the traditional serologic test (YF IgM ELISA) to be performed easily in resource-limited settings. This new diagnostic kit, the Yellow Fever M-antibody Capture-half Day (YF MAC-HD), cuts processing time from 3 days to just 4 hours. The most critical kit components are freeze dried to improve stability, and the user simply adds water. Each kit can test up to 24 samples and can be refrigerated for at least one year.

CDC validated the new YF MAC-HD test kits during the 2016 Angola outbreak. Professional laboratory staff found the test easy to use and provided results comparable to the serologic test. Recent trainings in both Africa and South America included attendees from 46 countries. Trainings are crucial for national laboratories across Africa and South America. As a result, laboratories are better prepared to assist with surveillance efforts across the continents.

Since most yellow fever outbreaks occur in resource-limited countries, where electricity, water, and even reliable shipping can be an issue, this new diagnostic kit is a valuable tool in combatting yellow fever outbreaks. Basile hopes when the next outbreak happens, laboratory staff will not only have easy-to-use tests but also the training to use them. CDC is working with an external manufacturer to create a consistent supply of the YF MAC-HD kits. Now the biggest hurdle researchers have is how to distribute large numbers of kits.

October 2020

DVBD Uses Advanced Molecular Detection to Better Understand Tickborne Diseases

Advanced molecular detection (AMD) integrates the latest next-generation genomic sequencing technologies with bioinformatics and epidemiology expertise across CDC and the nation to help us find, track, and stop disease-causing pathogens faster than ever before. Scientists at DVBD are using AMD to uncover, detect more of, and advance knowledge of pathogens spread through tick bites and about the ticks that are responsible for spreading these pathogens.

DVBD scientists, Luke Kingry, Stephanie Oatman, Sarah Sheldon, and partners used an AMD method called 16S metagenomics to analyze over 13,000 samples from patients who were suspected of having a tickborne illness. Twelve tickborne species of bacteria that cause illness in people were detected, including two not previously known to cause illness in people. The AMD method increased the number of tickborne bacteria identified by 100 percent as compared to using typical diagnostic testing methods.

DVBD scientists, Maria Galletti, Joy Hecht, and Chris Paddock, are using another AMD method to reveal new information about ticks that could help us better understand tickborne pathogens and how ticks spread those pathogens. The AMD method is known as MALDI-TOF, matrix-assisted laser desorption/ionization time-of-flight. This method will complement currently used methods and expand understanding of tick life stages and how certain germs adapt to become more or less capable of infecting people. The data collected will be used to establish a database of genetic information about the pathogens spread by ticks; the first of its kind in the Western Hemisphere. Scientists worldwide can use the database to improve the accuracy and speed of tick identification and tickborne disease surveillance. The team says, “We are excited to see what new information MALDI will reveal about the identification of medically relevant ticks that could be associated to pathogen prevalence in geographical areas with important disease burden. The results might help us better understand tick-borne disease dynamics in those areas.”

AMD activities at DVBD are improving tickborne disease detection, discovery, and surveillance, and are improving our understanding of how ticks spread germs. For more information about AMD activities across CDC, visit the CDC AMD website.