Paper-Based Device Detects Pertussis at Point-of-Care
Credit: Laura Trejo / UTEP Communications
A mother lovingly cradles her sick baby in her arms. As the infant coughs and gasps for air, his anguished mother looks up and warns that the safest place for your baby is not always in your arms.
The 30-second commercial by a pharmaceutical company encourages parents to get vaccinated against pertussis – a highly contagious respiratory disease also known as whooping cough. The disease affects people of all ages but can be especially serious, even fatal, for infants.
In 2015, more than 20,000 cases of whooping cough were identified in the United States. The Centers for Disease Control and Prevention estimate that there are 16 million pertussis cases worldwide.
“Pertussis is the only vaccine-preventable infection that still is endemic in the U.S. and worldwide,” said Delfina C. Domínguez, Ph.D., a UTEP professor of clinical laboratory sciences, who has studied pertussis for 10 years. “The disease is very severe in newborns and infants, who may die from the infection.”
Since 2014, Domínguez and XiuJun (James) Li, Ph.D., assistant professor in UTEP’s Department of Chemistry, have collaborated to develop a quicker and less invasive method to detect pertussis in medically underserved and low-resource settings. Recently, they completed testing the biochip on 100 clinical samples with excellent results.
Whooping cough can be difficult to diagnose because its symptoms resemble those of a cold or allergies. After two weeks, symptoms worsen, resulting in a hacking cough that sounds like a “whoop” when a person gasps for air.
Without proper diagnosis and treatment, symptoms may worsen and the infection can quickly spread to others through coughing and sneezing.
Current diagnosis methods are time consuming and require expensive equipment that may not be available in areas with limited access to medical supplies, equipment and medications.
This led Li to develop a paper-based three-dimensional microfluidic point-of-care (POC) device that integrates isothermal DNA amplification, a highly sensitive technique, to diagnose whooping cough.
Similar to a pregnancy test, the handheld device will use a sample from a nasal swab and change color to indicate the presence of the bacteria. Results will be available in less than an hour.
“A major benefit of this low-cost POC biochip is that it can be used in low-resourced settings such as primary care offices and in resource-limited countries to diagnose pertussis,” Li said.
Also known as lab-on-a-chip, microfluidic systems have made point-of-care testing more affordable and accessible, especially in developing nations.
Li expects the patent-pending technology to be available in schools, clinics and other limited-resource environments sometime in the near future.
“Using the innovative microfluidic lab-on-a-chip technique does away with the need for expensive specialized equipment that can cost up to $50,000,” Li said. “We estimate the cost of this device to be a few dollars.”
Li has designed and evaluated the effectiveness of the biochip using 100 clinical samples that Domínguez obtained from Children’s Hospital Los Angeles. So far, the results have been favorable.
“We found that the chip has high sensitivity and specificity and is comparable to real-time PCR – the technology used to diagnose infectious diseases in hospitals,” said Domínguez, who also is the co-investigator on a two-year grant that Li was awarded in 2015 from the National Institute of Allergy and Infectious Diseases to develop the technology.
The researchers also have been assisted by undergraduate and graduate students in Li’s laboratory, including Maowei Dou, Ph.D., who tested the device to see if it could successfully diagnose the Bordetella pertussis bacteria.
“The performance and testing results are very exciting, demonstrating great potential for disease diagnosis in low-resource settings,” said Dou, who worked on the project when he was a doctoral chemistry student at UTEP. He graduated in December 2016.
Dou’s research also was the basis for his dissertation titled, “Paper/polymer hybrid microfluidic biochips for infectious disease diagnosis.”
“As we know, infectious diseases are the leading cause of death in developing countries and often happen in high-poverty locations where the financial and medical resources are usually very limited,” said Dou, a postdoctoral researcher at Pacific Northwest National Laboratory. “I think it is very meaningful to carry out such research projects by developing low-cost point-of-care devices for low-resource settings.”
Li plans to continue testing the device using additional clinical pertussis samples. He also is developing microfluidic biochips for other infectious disease diagnosis such as meningitis.