Hybrid ascaris suum/lumbricoides (ascarididae) infestation in a pig farmer: a rare case of zoonotic ascariasis.

We present a case of the 42-year-old pig farmer from the province of Cuneo in Northwest Italy who was infected by the soil-transmitted nematode Ascaris sp. In November 2010 the patient found one worm in his stool, subsequently identified as female specimen of Ascaris sp. After a first anthelmintic treatment, another worm was found in his stool, that was later identified as male Ascaris sp. Blood tests prescribed by the patient's family physician, as suggested by a parasitologist, found nothing abnormal. A chest x-ray was negative for Loeffler's syndrome and an ultrasound of the abdomen was normal with no evidence of hepatic problems. The nematode collected from the patient was genetically characterized using the ribosomal nuclear marker ITS. The PCR-RFLP analysis showed a hybrid genotype, intermediate between A. suum/lumbricoides. It was subsequently ascertained that some pigs on the patient's farm had A. suum infection; no other family member was infected. A cross-infestation from the pigs as source was the likely way of transmission. This conclusion is further warranted by the fact, that the patient is a confirmed nail-biter, a habit which facilitates oral-fecal transmission of parasites and pathogens.