PCR for the Diagnosis of Abdominal Angiostrongyliasis in Formalin-Fixed Paraffin-Embedded Human Tissue

Abstract

To date the diagnosis of abdominal angiostrongyliasis (AA) depends on the histological identification of Angiostrongylus costaricensis (AC) in surgical specimens. However, microscopic evaluation is time consuming and often fails in identifying the parasite. We tested whether PCR might help in the diagnosis of AA by identifying parasite DNA in formalin-fixed paraffin-embedded (FFPE) tissue. We used primers based on DNA from Angiostrongilus cantonensis. Four groups of FFPE intestinal tissue were tested: (1) confirmed cases (n = 20), in which AC structures were present in the target tissue; (2) presumptive cases (n = 20), containing changes secondary to AC infection in the absence of AC structures; (3) negative controls (n = 3), consisting of normal colonic tissue; and (4) tissue affected by other parasitoses (n = 7), including strongyloidiasis, ascaridiasis, schistosomiasis, and enterobiasis. Most lesions of confirmed cases were located in small and/or large bowel (90%), as compared with presumptive cases, in which 70% of lesions were in appendix (P = 0.0002). When confronted with cases of other parasitoses, PCR showed sensitivity of 55%, specificity of 100% and positive predictive value of 100%. In presumptive cases PCR was positive in 4 (20%). All specimens from negative controls and other parasitoses were negative. In conclusion, the PCR technique showed intermediate sensitivity and optimal specificity, being clinically relevant when positive for abdominal angiostrongyliasis. It allowed a 20% gain in diagnosis of presumptive cases. PCR might help in the diagnosis of abdominal angiostrongyliasis, particularly when the pathologists are not experienced with such disease.

First case report of nematode parasitic myelopathy in a wild feline in Brazil

“…Therefore, to ascertain a possible role of G. paralysans in the lung pathology, the paraffin embedded tissues were subjected to nested PCR (Muñoz et al, 2017). Unfortunately, however, the samples did not amplify due to DNA and rRNA degradation, possibly because of prolonged formalin fixation, paraffin embedding time and conservation, processing temperature or PCR inhibitors in the samples (Merkelbach et al, 1997;Macabeo-Ong et al, 2002;Malik et al, 2013;Rodriguez et al, 2014).…”

Angiostrongylus costaricensisinfection in Martinique, Lesser Antilles, from 2000 to 2017

“…Better specificity is observed when antigens are derived from A. costaricensis eggs or the reproductive organs of females [ 4 , 15 ]. New tools are now being used to improve the diagnosis in countries in which the disease is endemic, such as Brazil, particularly PCR on paraffin-embedded biopsy tissue or sera, which can lead to a 20% increase in the rate of presumptive diagnoses [ 8 , 53 ]. Unfortunately, such biological tools are not yet available in the French territories.…”

Rapid Differentiation of Filariae in Unstained and Stained Paraffin-Embedded Sections by a High-Resolution Melting Analysis PCR Assay

“…A molecular-based assay for the identification of other intact parasites in FFPE human tissues was recently reported using both conventional PCR and real-time PCR with probes (Koonmee et al 2011, Rodriguez et al 2014. The HRM-PCR assay provides a low-cost, fast, and sensitive molecular technique that allows the detection of DNA in a single step.…”