Hepatobiliary Ascariasis in a Piglet

Acta Parasitologica (2024) 69:785–790 https://doi.org/10.1007/s11686-024-00813-2 ORIGINAL PAPER Hepatobiliary Ascariasis in a Piglet Claudia Tamponi1 · Lia Cavallo1 · Giorgia Dessì1 · Francesco Sardu2 · Carlo Carta1 · Andrea Corda1 · Giovanni Pietro Burrai1 · Antonio Varcasia1 · Antonio Scala1 Received: 31 July 2023 / Accepted: 19 January 2024 / Published online: 29 February 2024 © The Author(s) 2024 Abstract Purpose Ascariasis caused by the helminth Ascaris suum is the most common parasitosis of swine worldwide and it may involve all age categories of pigs. The present study reports an unusual localization of A. suum worms in the biliary system of a piglet slaughtered for human consumption. Methods The liver was subjected to ultrasound scan and pathological examination. The isolated worms were morphologically examined and the DNA was extracted for the molecular identification of the species involved. Results A total of 43 preadult nematodes were found within the gallbladder and the bile ducts. Parasites were morphologically identified as belonging to the genus Ascaris and molecularly as A. suum. At gross examination, the liver was moderately enlarged, with the bile ducts severely dilated. A chronic inflammatory infiltrate was noted, often centered around ectatic bile ducts (up to 5 mm in diameter), lined by hyperplastic epithelium and filled with sections of nematodes. The worm sections showed smooth cuticle, coelomyarian musculature, and an intestinal tract lined by columnar, uninucleated cells within a pseudocoelom. The ex vivo ultrasonographic examination of the liver allowed the visualization of several nematodes in the bile duct lumen and could be suggested for in vivo diagnosis. Unfortunately, the absence of the intestine did not allow to define the pathogenesis of the infection. Conclusion Although, given the unusual nature of this finding, it is difficult to identify predisposing factors for this A. suum localization, it suggests that ascariasis should be considered in the differential diagnosis of pigs with hepatobiliary disease. Keywords Ascaris suum · Pig · Bile ducts · Ultrasound · Parasitology Introduction Ascariasis is the most common parasitosis in pigs worldwide and is mainly caused by the helminth Ascaris suum, which belongs to the Family Ascarididae and which can reach a relevant size, of up to 40 cm in females [1]. Ascaris lumbricoides can also grow in pigs and both parasite species can mature in humans [2]. This parasitosis has a global distribution and is detected in both organic [3, 4] and industrial pig farms, especially in fattening pigs and old sows [5–7]. Ascaris suum infection can affect all age categories of pigs and depends on several factors mainly related to the type of rearing and management * Antonio Varcasia 1 Department of Veterinary Medicine, University of Sassari, Via Vienna, 2, 07100 Sassari, Italy 2 Local Health Unit, Oristano, Italy [8]. High prevalence rates were found in Denmark (25–88%) and Canada (18–82%) [9, 10]. In Spain, the prevalence found in reared pigs varied from 28.7 to 48.7% [11, 12]. The relevant diffusion of the parasitosis is mainly due to the high fecundity of female A. suum worms (up to 200,000 eggs per female per day) and to the strong structure of the eggs, which guarantees their survival in the external environment even up to 4 years [13]. The biological cycle is direct and begins with the ingestion of embryonated eggs containing the infective larva, an early third-stage (L3) larva covered by the cuticle of the second stage larva (L2) [14]. Piglets can become infected shortly after birth by ingesting embrionated eggs smearing the mammary skin of the sow or directly through food and drinking water contaminated with eggs, especially in polluted soil [2]. The eggs hatch in the stomach and small intestine and release the ascarid L3 larvae, which penetrate the intestinal wall and start their hepatic-pulmonary migration, first to the liver via the portal system [15]. In the liver, the Vol.:(0123456789) 786 larvae lose the cuticle and enter the lungs via the systemic circulation, where they embolize in the pulmonary capillaries, enter the alveoli, are coughed up and then swallowed, reaching the small intestine approximately two weeks after infection [16]. Once back in the small intestine, the larvae moult into the fourth-stage (L4) larva, where most or all of the parasites are expelled from the intestine at 14–21 days post-infection (self-cure). Some of these larvae may remain in the small intestine for the rest of their lives, developing into preadult and then adult worms that reach sexual maturity at 6–10 weeks of age [14]. Earthworms and dung beetles may play a role in the transmission, as they can ingest Ascaris eggs while feeding on soil and feces. The eggs can then hatch and infective larvae can remain in the tissues of earthworms and dung beetles until they are eaten by the pig host, acting as potential paratenic hosts in the life cycle of A. suum [17, 18]. The migration of larvae within the liver can lead to the onset of multifocal interstitial hepatitis in sensitized animals, characterized by fibrosis appearing as white spots (milk spots) [19, 20], while pulmonary alterations caused by migrating larvae include pneumonia, pleurisy and allergic asthma in infected pigs [21]. Although the course of ascariasis in pigs is usually subclinical, clinical infections can occur in growing pigs [22]. The pathological effects of adult A. suum in the small intestine are less dramatic than those of larval migration, but they can cause a chronic malabsorption syndrome with atrophy of the intestinal villi, resulting in reduced weight gain and poor feed conversion [23, 24]. In rare cases, obstruction of the intestinal lumen may happen in heavily infested animals, as well as obstruction of the bile ducts due to the migratory tendency of ascarids, resulting in jaundice [2]. The present study reports an unusual localization of A. suum worms in the biliary system of a piglet. Materials and Methods In February 2022, a 30-days-old piglet slaughtered in Milis (Latitude: 40° 00′ 49″ N Longitude: 8° 35′ 53″ E) in the Oristano province (Sardinia—Italy) presented Ascaris worms in the hepatic biliary tree. The piglet was the seventh of a litter born from a 3-year-old Sarda multiparous sow in which Ascaris eggs were found through the copromicroscopical examination. The piglets were raised indoor, in a box with solid concrete flooring together with his mother and the sow before the parturition had access to the paddock outdoor where she could root. At the time of the home slaughtering, according to the Legislative Decree 2 February 2021 n.27 which provides the inspection in only 10% of the home slaughtering, the Acta Parasitologica (2024) 69:785–790 official veterinarian did not attend, and the intestine was discarded. The liver was examined, and transverse cuts were performed to allow the isolation of worms within the b (...truncated)