<b>Ultrastructural morphology of second and third stage larvae of <i>Toxocara cati</i> inside paratenic host tissue</b>

Background: Toxocara cati is a known cause of a zoonotic infectious illness called toxocariasis. Parathenic hostsare important as they can transmit larvae 2 (L2) through direct transmission. Scanning electron microscope (SEM)techniques are needed to provide a three-dimensional image of each stage of T. cati larvae.Aim: The aim of this study was to determine the morphology of L2 and L3 T. cati in parathenic host tissue for etiologicaldiagnosis using SEM.Methods: Mice were used as suitable paratenic hosts for this experiment. A total of 786 embryonated eggs (16 eggs/gram body weight) containing L2 were inoculated into pregnant mice at day 11–13 of its gestation period. Afterdelivery, L2 was transmitted to the off-spring. After 14 days, L2 was collected from mice, and L3 was collected from itsoff-spring. Data were analyzed descriptively based on ultrastructure examination using SEM.Results: SEM examination results indicate that the size of L2 is smaller than L3. Results also showed differencesbetween L2 and L3 based on middle and posterior observations. In the middle of the larval body, the number of L2 bodyrings was observed to be narrower and more than that of L3. In addition, the distance between L2 body rings was muchlarger than that of L3. Posteriorly, the tail tip of L3 was more curved than L2.Conclusion: Ultrastructural examination using SEM has the ability to show differences in L2 and L3 body rings of T.cati by observing the middle and posterior parts of its larvae.