Team:Michigan/Current

Current Disease Detection Methods:
Technological advancements in serological and molecular laboratory techniques have reduced the time and effort required to test for high profile diseases such as malaria, and tuberculosis, as well as neglected tropical diseases such as trypanosomiasis (chagas disease), dengue fever, and cysticercosis.

Parasitic Diseases

Viral Diseases


Immunofluorescence Antibody Assay (IFA) and Indirect Fluorescent Antibody Test (IFAT):
These tests both rely on the use of fluorescently tagged antibodies binding to targets to report antigen presence. In immunofluorescence antibody assays, a specifically chosen primary fluorescently tagged antibody binds directly to an antigen of interest1 antibody tests, a specific primary antibody is bound to a target antigen while another fluorescently tagged secondary antibody binds to the primary antibody1 fluorescent signal would suggest the binding of antibodies to their specific antigens and a diagnosis for that disease could be made.

PCR:
Currently, PCR is one of the most sensitive of the existing methods of detecting microbial pathogens2. It involves DNA extraction from specimens, PCR amplification, and detection of amplicons2. This method of disease detection is particularly useful when pathogens are difficult to culture in vitro or require a long cultivation period2. However, there are also several downfalls to using PCR. For example, PCR is susceptible to inhibitors and contamination2. Additionally, PCR is based on DNA amplification, meaning false-positive or false-negative outcomes can easily occur2. Experimental conditions, such as contamination of reagents, pipettes, and laboratory surfaces can also result in false-positive outcomes2. Thus, PCR as a method of disease detection must be performed in controlled environments and conditions.

Enzyme-Linked Immunosorbent Assay (ELISA):
Enzyme-linked immunosorbent assays are a common procedure used to detect specific antigens or antibodies not only to determine if they are present or not, but also the relative quantity present3. ELISAs are based on an enzyme-mediated color change, which indicates the presence of a specific antigen3. This method of disease detection is useful because in kits, it can be portable, easy to use, and inexpensive, meaning it could be ideal for large population screening or in low-resource settings3. However, ELISAs have some downfalls. For example, the enzyme-mediated color change continues to react over time, so the color strength could inaccurately display the amount of primary antibody present3. Further, nonspecific binding of antibody to the plate can lead to an atypically high positive result3.

The Need for Point of Care Diagnostic Tests:
Advancing technology continually increases the efficiency of these tests. Improvements in PCR, ELISA, and antibody technology improve reliability and reduces testing time, all while simplifying processes. These diagnostic tests have become integral to medical practice in the developed world, allowing clinicians and patients the ability to receive information and make decisions quickly. However, despite advances in technology, the equipment needed for these tests remains centralised to laboratory settings where trained technicians and staff are needed to operate expensive equipment that requires regular maintenance. For this reason, diagnostic tests that may be commonplace in developed countries may prove inaccessible and prohibitive in other less developed countries, creating a large disparity in the ability to quickly detect and treat diseases in its early stages4. It is estimated that the implementation of rapid, laboratory independent diagnostic tests for just four infections (bacterial pneumonia, syphilis, malaria, and tuberculosis) could prevent more than 1.2 million deaths each year in developing countries4. Still, in resource-limited settings, the clinical benefits of these tests need to outweigh their operational costs in order to be implemented. Point-of-care diagnostic tests done near or at the site of patient care provide results without having to wait hours or even days for sample transport or laboratory processing4. This is where Aptapaper comes in.

An ideal diagnostic point-of-care test would fulfill the following criteria4:

  • Allows a quick clinical decision
  • Can be used at the clinical point-of-care by health workers
  • Affordable (low average cost per test)
  • Rapid (provides result during a clinic visit or within a reasonable waiting time)
  • Acceptable test efficacy
  • Cost effective

Aptapaper is designed to meet all of these specifications, although further work is needed to hone the system.

Point-of-care diagnostics in resource limited settings are currently being developed and tested for a number of diseases, including HIV, malaria, syphilis, tuberculosis, and tetanus immunity. However, studies centered around these diagnostic methods typically revolve around their analytical performance and don’t investigate aspects such as costs of implementation in resource limited settings. We hope that as Aptapaper and other devices like it continue to develop, these important factors are taken into consideration.