Project Lead(s): Aaron Wheeler
Measles and rubella are major contributors to childhood mortality and disability, representing a significant global economic and social cost.
In keeping with the Measles and Rubella Initiative, the World Health Organization has developed a five-pronged strategic plan for the global elimination of these diseases by 2020.
Surveillance tools capable of diagnosing infection and determining immunity coverage from vaccination are a key component for elimination, but surveillance is particularly challenging for sparsely populated, rural economies, where the cost of transporting patient samples is significant.
The objective of this project was to develop a field-deployable decentralized disease surveillance system, powered by paper-based digital microfluidics (DMF), to detect measles and rubella viruses using a single drop of blood.
The diagnostic platform is enabled by a digital microfluidic method for immunoassays, relying on virus-immobilized magnetic particles to capture virus-specific immunoglobulins (IgG or IgM), enzyme-labeled antibodies to probe the immunoglobulins and chemiluminescent substrates that emit light in the presence of the enzyme.
The system is intended to be fast and simple to use, and would provide significant savings through reduced reagent consumption and sample transport costs.
In May–June 2016, this system was taken to Kakuma Refugee Camp, Kenya, and used in conjunction with a camp-wide vaccination campaign.
The team successfully developed and optimized DMF rubella IgG and IgM immunoassays and demonstrated 100% sensitivity and 100% specificity using 25 donor serum/plasma samples.
They also successfully optimized measles IgG and IgM immunoassays, validating them using a seroconversion panel comprised of a set of 15 serum samples collected from an individual over the course of 55 days after measles vaccination.
The measles IgG assays performed similarly to a commercial measles immunoassay, with 100% sensitivity and 100% specificity for the 15 samples.
The team successfully designed and constructed four field-deployable prototypes of the disease surveillance system and 600 devices were brought to the refugee camp for field testing.
Field testing with 150 patient samples was completed within three weeks and gold-standard comparator assays are in progress at the Kenyan Medical Research Institute.
The team plans to publish their completed work in an open-access journal when results are available.
In the meantime, this work has been presented at scientific conferences, informing other researchers in the field of advancements made in measles and rubella surveillance tools.
As a part of this project, the team partnered with the U.S. Centers for Disease Control and Prevention (CDC), which provided technical assistance and facilitated the field evaluation in Kakuma Refugee Camp.