A meta-analysis of symptomatic visceral leishmaniasis diagnosis by in-house polymerase chain reaction assays

Danica Helb

Graduate Student Researcher, Rosenthal Lab, UC Berkeley

Abstract

Leishmaniasis is the third most important vector-borne disease worldwide. Identification of Leishmania amastigotes in bone marrow, spleen, or lymph node aspirates has conventionally been used to diagnose visceral disease. However, these methods are relatively insensitive and time consuming. In-house polymerase chain reaction tests are being developed to rapidly diagnose visceral leishmaniasis (VL) infections with high sensitivity and specificity. Meta-analytical methods were used to determine assay design parameters that were associated with higher estimates of diagnostic accuracy of in-house PCR assays to detect VL. PUBMED and EMBASE databases were searched for articles employing PCR to diagnose VL. Only studies that compared results of in-house PCR to a gold standard (microscopy or culture) were included. Sensitivity and specificity were used as measures of diagnostic accuracy, the outcome of interest, in a bivariate/hierarchical summary receiver operating characteristic model. After stratification by study design, clinical follow-up, PCR sample type, sample storage method, amplification and detection methods, and target gene, the data were re-analyzed. PCR-based diagnosis of VL appeared to be a promising alternative to microscopy, culture, and serology. Higher estimates of diagnostic accuracy were achieved when samples were stored in tubes than when samples were stored on filter paper prior to DNA extraction. Conventional PCR methods can be employed, reducing the costs associated with newer PCR techniques. Whole blood-based PCR detection of VL was highly sensitive and specific, and has the potential to eliminate the need for bone marrow samples and the invasive procedures associated with its collection.

Speaker Biography

Danica received her undergraduate degree in Biology from Bates College in Maine in 2002. Working in the Alland Lab at the University of Medicine & Dentistry of New Jersey after graduation, she was responsible for the research, development, and initial testing of the GeneXpert MTB/RIF. Developed in collaboration with Cepheid and the Foundation for Innovative New Diagnostics, the Xpert MTB/RIF assay, which integrates sputum processing, diagnosis of tuberculosis, and detection of drug resistance into a hands-free test, has recently been approved for use by the World Health Organization. Danica also worked as a consultant for FIND, performing testing and feasibility studies of Eiken’s TB-LAMP assay for diagnosis of tuberculosis in Vietnam. Danica received an MPH in Epidemiology in 2010, and is now a PhD student in Infectious Diseases & Immunity at UC Berkeley. She is currently investigating a potential new antimalarial drug target in the Rosenthal Lab at UC San Francisco.

About the Point-of-Care Diagnostics Idea Lab

The Point-of-Care Diagnostics (POCDx) Idea Lab was created as a forum for graduate students who are working in the areas of medical diagnostics and global health to discuss topics relevant to their research.  Students working in the areas of engineering, science, policy, and healthcare are encouraged to attend.  The bi-weekly meetings will be informal and will usually include one or two short presentations by graduate students, followed by discussion.  Students may choose to present their work or a recent journal article.

This video was originally recorded on March 8th, 2011 in 621 Stanley Hall, UC Berkeley