Archive for January 3, 2020

Use of rapid diagnostic tests (RDTs) for conclusive diagnosis of chronic Chagas disease – field implementation in the Bolivian Chaco region

PLOS Neglected Tropical Diseases December 19, 2019

Chagas disease, caused by the parasite Trypanosoma cruzi, is the neglected tropical disease with a highest burden in Latin America.

Its acute stage is mostly asymptomatic and goes unnoticed.

Symptoms appear at the chronic stage, which is when diagnosis is usually made. This is based on the agreement of two conventional serological tests such as Enzyme-Linked Immunosorbent Assays (ELISAs).

There are commercial kits with good sensitivity and specificity but their use is impractical in many highly endemic regions with poorly equipped laboratories.

Luckily, several rapid diagnostic tests (RDTs) are available for the detection of anti-T. cruzi immunoglobulins.

They are easy to operate, require no cold storage, provide fast turnaround of results, and some can work with a tiny volume of whole blood as sample.

With the aim to field validate their use we compared an alternative algorithm based on a combination of RDTs with the standard based on ELISAs.

In both cases a third test was available in case of discordance. RDTs were implemented by mobile teams in field campaigns to detect chronic T. cruzi-infections in the Chaco region of Bolivia.

ELISAs were made in the reference laboratories located in the main hospitals of Yacuiba and Villa Montes, two major cities of the region.

We enrolled 685 subjects who voluntarily participated in the study and had not been treated against the disease before.

The agreement between the two main RDTs was 93.1% (638/685) (kappa index = 0.86; CI 95% 0.83–0.90). In comparison to the ELISAs algorithm, the combined use of the RDTs provided a sensitivity of 97.7% and a specificity of 96.1%.

These results support the use of RDTs for the diagnosis of chronic Chagas disease in the studied region, and encourage their evaluation in other regions of Bolivia and other endemic countries.



January 3, 2020 at 4:05 pm

A Liquid Biopsy Compatible Approach for Human Papillomavirus–Associated Oropharyngeal Cancer Detection

The Journal of Molecular Diagnostics January 2020 V.22 N.1 P.50-59    

Previous efforts to evaluate the detection of human papilloma viral (HPV) DNA in whole saliva as a diagnostic measure for HPV-associated oropharyngeal cancer (HPV-OPC) have not shown sufficient clinical performance.

We hypothesize that salivary exosomes are packaged with HPV-associated biomarkers, and efficient enrichment of salivary exosomes through isolation can enhance diagnostic and prognostic performance for HPV-OPC.

In this study, an acoustofluidic (the fusion of acoustics and microfluidics) platform was developed to perform size-based isolation of salivary exosomes.

These data showed that this platform is capable of consistently isolating exosomes from saliva samples, regardless of viscosity variation and collection method.

Compared with the current gold standard, differential centrifugation, droplet digital RT-PCR analysis showed that the average yield of salivary exosomal small RNA from the acoustofluidic platform is 15 times higher.

With this high-yield exosome isolation platform, we show that HPV16 DNA could be detected in isolated exosomes from the saliva of HPV-associated OPC patients at 80% concordance with tissues/biopsies positive for HPV16.

Overall, these data demonstrated that the acoustofluidic platform can achieve high-purity and high-yield salivary exosome isolation for downstream salivary exosome–based liquid biopsy applications.

Additionally, HPV16 DNA sequences in HPV-OPC patients are packaged in salivary exosomes and their isolation will enhance the detection of HPV16 DNA. . . . .



January 3, 2020 at 3:50 pm


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