Ana Vargas-Calla, DVM, MS, MS(c)

Nominated From: Oregon Health and Sciences University

Research Site: Peru-Universidad Nacional Mayor de San Marcos

Research Area: Epidemiology

Primary Mentors: Dr. Seth O’Neal, Dr. Hector H. Garcia,

Research Project

Evaluation of a new method based on silica for the diagnosis of intestinal helminth in human stool

Intestinal helminths infect up to 2-3 billion people worldwide and cause intellectual and physical retardation, particularly among children. Diagnosis in the developing world relies on microscopic detection of helminth eggs and larvae in stool samples. However, microscopic diagnosis has notoriously low sensitivity, leading to a high level of false negative results and widespread undertreatment. Thus, this proposal aims to standardize laboratory techniques for silica preservation of stool, compare the sensitivity to detect intestinal helminth infection between silica and formalin-preserved human stool samples using a non-inferiority framework and evaluate whether the DNA of intestinal helminths present in silicate-preserved human stool can be detected and quantified by qPCR at 1, 7, 30 and 60 days post-preservation. If this finding is validated, silica treatment could be transformative for helminth diagnosis. Moreover, if detection sensitivity could be increased, screening for eggs and larvae in environmental samples could become feasible, providing a new tool for monitoring regional transmission of soil transmitted helminthes and the progress of control programs.

Research Significance

If the sensitivity of the new method based on silica for the diagnosis of intestinal helminth in human stool is determined to be non-inferior to the conventional technique, this would provide an inexpensive and non-toxic alternative to the current standard. If DNA preservation is also demonstrated, this will convey a substantial additional advantage of the silica protocol as molecular diagnosis techniques could be applied to the same set of samples used for microscopy; the need to collect multiple samples in different preservation media could be avoided. Evaluating this technique for the detection of other intestinal parasites in different endemic settings will be an important next step to validate our results.


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