Can thick-shelled eggs of Capillaria philippinensis embryonate within the host?

Intestinal capillariasisis is a newly emerging parasitic disease and its outcome may be fatal if not diagnosed and treated in the proper time. The main diagnosis of intestinal capillariasis is made by identifying eggs, larvae and/or adults in the stools of infected cases. This study aimed to describe a different type of developmental stages, which is the detection of adult females carrying embryonated thick-shelled eggs in their uteri in the fecal samples of infected cases. The study included 40 Capillaria philippinensis patients admitted to the hospitals of Kasr Al-Ainy Faculty of Medicine, Cairo University and Beni-Suef University. Stool examination was performed using direct smear and the formalin-ether concentration methods. The adult stages of the parasite were detected in 35 stool samples, eggs were detected in 33 cases, 5 of them were diagnosed by detecting eggs only. We could identify three types of eggs of C. philippinensis: non-embryonated thick-shelled eggs in feces of cases, embryonated thin-shelled and embryonated thick-shelled eggs in the uteri of female worms. Only in 2 cases we were able to identify female worms with embryonated thick-shelled eggs inside their uteri. This finding has never been mentioned and may point out to a missing point in the known life cycle.