Migratory route of Strongyloides venezuelensis in Lewis rats: Comparison of histological analyses and PCR

Strongyloides venezuelensis is a parasitic nematode that has been used as a model to study human and animal strongyloidiasis. In this study, we compared the sensitivity between traditional methodologies and PCR assay to characterize the dynamics of S. venezuelensis infection and its migration route in Lewis rats subcutaneously infected with 4000 L3. The dynamics of the infection was determined by counting the number of eggs and by detecting parasite deoxyribonucleic acid in faeces samples. Both techniques similarly detected the infection at day 6 after larvae inoculation. However, PCR performed with the genus primer showed higher sensitivity during the recovery phase. Histological analysis and PCR assay were then used to follow parasite tissue migration. S. venezuelensis migration route included the muscular fibers below the skin, the pulmonary alveoli and the small intestine vilosities. The sensitivity of these two techniques to detect parasite's presence in these tissues was statistically similar.

In experimentally infected Lewis rats, Strongyloides venezuelensis migrated from inoculation site (subcutaneous abdominal region) to the lungs and then to intestinal vilosities. The whole process took 5 days. Eggs were already detected in the faeces on the 6th day. Two major egg count peaks, (8th and 11th days) were observed. A steadly decrease on egg counts was then observed.Research highlights► Lewis rats infected with Strongyloides venezuelensis are a model for human strongyloidiasis. ► Number of eggs and parasite DNA detection (PCR) similarly indicate acute infection. ► PCR is more sensitive for parasite detection during recovery phase. ► PCR and histology are equally sensitive to detect parasite in host tissues.