PCR for the diagnosis of abdominal angiostrongyliasis in formalin-fixed paraffin-embedded human tissue.
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.
Programa de Pós-Graduação: Ciências em Gastroenterologia e Hepatologia, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil; Faculdade de Medicina, Universidade de Passo Fundo, Passo Fundo-RS, Brazil.
Rubens
R
Rodriguez
Laboratórios de Biologia Parasitária e Parasitologia Molecular, Pontifíca Universidade Católica do Rio Grande do Sul, Porto Alegre-RS, Brazil.
Ana Cristina Aramburú
AC
da Silva
Laboratórios de Biologia Parasitária e Parasitologia Molecular, Pontifíca Universidade Católica do Rio Grande do Sul, Porto Alegre-RS, Brazil.
Carla Aristonara
CA
Müller
Laboratórios de Biologia Parasitária e Parasitologia Molecular, Pontifíca Universidade Católica do Rio Grande do Sul, Porto Alegre-RS, Brazil.
Silvana Lunardini
SL
Alves
Laboratórios de Biologia Parasitária e Parasitologia Molecular, Pontifíca Universidade Católica do Rio Grande do Sul, Porto Alegre-RS, Brazil.
Carlos
C
Graeff-Teixeira
Programa de Pós-Graduação: Ciências em Gastroenterologia e Hepatologia, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre-RS, Brazil; Faculdade de Medicina, Universidade de Passo Fundo, Passo Fundo-RS, Brazil.
Fernando
F
Fornari
D000801:Angiostrongylus / Q000235:genetics*; D000818:Animals; D017931:DNA Primers / Q000235:genetics; D005557:Formaldehyde; D006801:Humans; D016612:Paraffin Embedding; D016133:Polymerase Chain Reaction / Q000379:methods*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D017206:Strongylida Infections / Q000175:diagnosis*; D016707:Tissue Fixation
D017931:DNA Primers; D005557:Formaldehyde