Discussion
Previous investigations have successfully assessed application of DTS
for HIV, syphilis, and hepatitis B proficiency testing in
resource-limited settings (Mendiratta, 2017, Benzaken, 2014, Ramos,
2013). Experience from many resource-limited countries shows that
traditional EQA programs, when they exist, are only limited to national
and sometimes regional laboratories without participation from lower
tier laboratories. Our intent was to assess stability of DTS as a mean
of proficiency testing panels preparation for serological testing of
brucellosis to overcome the challenges related to expenses for cold
chain maintenance during transportation and storage of liquid samples
and biosafety concerns, as it is one of the limiting factors for
developing countries.
Taking into consideration One Health approach and the challenges with
international EQA in resource-limited settings, we have launched a
national EQA survey for serological tests of brucellosis in Armenia
simultaneously for both human and veterinary laboratories. At the same
time, we have prepared DTS to validate stability to minimize the cost
and ensure long term sustainability of national EQA. The most common
serological screening tests used are RBT also called bufferedBrucella antigen test (OIE, 2018, Chapter 3.1.4) and serum
agglutination test (SAT) which uses serum to detect the presence of
agglutinating antibodies to the smooth lipopolysaccharide (S-LPS) or
O-polysaccharide (OPS) as a mean of initial diagnosis of Brucella
infection, particularly in lower tier laboratories. Secondary
confirmatory tests such as CFT, ELISA and/or FPA are recommended as no
single serological test is appropriate in all epidemiological situations
because all tests have limitations, especially when screening individual
animals (OIE, 2018, Chapter 3.1.4). These led us to use these techniques
for DTS panel validation.
Results obtained in this study validate the long term (105 days)
stability of DTS preparation for brucellosis serological testing.
Therefore, the implementation of the novel approach described in this
study provides a simple solution for organization of brucellosis
serological EQA programs in resource-limited settings. The same strategy
could also be used to prepare laboratory internal quality control
specimens at national level that could be then distributed to the
regional and district laboratories. Moreover, this method could also be
implemented in countries experiencing challenges of storage, cold chain
maintenance, and timely transport of brucellosis clinical samples from
remote areas, point-of-care or lower tier laboratories to the central
level for diagnosis or conformational purposes. Thus, the brucellosis
DTS method has several advantages over traditional methods: 1) it is
easy and cheap to prepare, 2) it is safer and less biohazardous (no
spills risk during transportation), 3) the specimens could be
transported and stored at room temperature without the need for
maintaining expensive cold chain, and 4) as demonstrated here, to have
stability over a long period of time.
In conclusion, brucellosis DTS maintain integrity of serum samples for
serological testing of brucellosis for the indicated period and can be a
powerful tool for EQA providers, as it decreases shipping costs and
avoids challenges of maintaining cold chain shipments between the
provider and recipient laboratories. Moreover, within One Health
context, dried tube specimens have great prospect to enable EQA programs
to reinforce veterinary and human laboratories collaboration. The
utility of this tool also includes increasing coverage of EQA to the
lower tier labs in resource-limited countries, with minimal costs to
monitor and improve the quality and accuracy of brucellosis testing for
veterinary and human laboratories.