Migration behaviour and pathogenesis of five ascarid nematode species in the Mongolian gerbilMeriones unguiculatus

Abstract

AbstractTo understand the characteristic features of the Mongolian gerbil,Meriones unguiculatus,as an animal model of ascarid infections, the migration behaviour and pathogenesis of larvae were investigated in experimentally infected gerbils. Embryonated eggs from each ofToxocara canis,Baylisascaris procyonis, B. transfuga, Ascaris suum, andA. lumbricoideswere orally inoculated into gerbils and larvae were recovered from various organs at designated periods. InT. canis-infected gerbils, larvae were present in the liver 3 days after infection and in the skeletal muscle and brain via the heart and lungs at a similar rate. InB. procyonis- andB. transfuga-infected gerbils, larvae were present in the lungs within 24 h after infection, with some having reached the brain by that time. After 24 h, larvae ofB. procyonistended to accumulate in the brain, while those ofB. transfugaaccumulated in skeletal muscles. InA. suum- andA. lumbricoides-infected gerbils, larvae remained in the liver on day 5 post-infection and elicited pulmonary haemorrhagic lesions, which disappeared 7 days after initial infection. Thereafter, no larvae of any type were recovered. Ocular manifestations were frequently observed inT. canis- andB. procyonisinfected gerbils, but were rare inB. transfuga-infected gerbils. In the cases ofA. suumandA. lumbricoides, migration to the central nervous system and eyes was extremely rare, and larvae had disappeared by 2 weeks post-infection. Fatal neurological disturbances were observed inB. procyonis-infected gerbils, whereas irreversible non-fatal neurological symptoms were observed in the case ofB. transfuga.