Very low helminth infection in sheep grazed on pastures fertilised by sewage sludge or cattle slurry.

Helminth infection acquired by lambs grazing on pastures fertilised either by urban sewage sludge or cattle slurry were studied in temperate Central Western France. The aim was to assess the risk of larval cestodoses in lambs after sewage application and of digestive tract nematode infection following the slurry application. Twenty-six sheep were allocated on two paddocks of 0.7 ha, one fertilised with sludge and the other with cattle slurry. The delay between application and actual grazing was 6 weeks; grazing on these paddocks extended from mid July to beginning of November 2002. The herbage biomass was slightly increased in the sludge paddock but it did not result in an increase of lamb live weight, compared with the slurry paddock. The lambs did not acquire cysticercosis or any other larval cestodoses in the sewage sludge group and only very limited infections with Cooperia spp. and Nematodirus spp. were observed in the slurry group. It was concluded that in our conditions the helminth risk was extremely low and was not a cause of restriction of the use of these biowastes.

Limited role of lagomorphs (Oryctolagus cuniculus and Lepus capensis) in the dispersion of parasite nematodes of ruminants.

Rabbits (Oryctolagus cuniculus) and hares (Lepus capensis) were investigated under natural conditions for infection with ruminant nematodes, either in the condition of close contact with sheep (south-east of France) or unknown contact with ruminants (central region and French Champaign). Rabbits and hares were poorly infected with sheep digestive tract nematodes: Trichostrongylus colubriformis (second record) was encountered in one site and Trichostrongylus capricola (a first record) in another site, at very low intensity. Small sheep lungworms (Neostrongylus linearis and Cystocaulus ocreatus) were not recorded in rabbits grazing common pasture with sheep. Although transmission remained limited between lagomorphs and ruminants, it could play a role in the transfer of nematode isolates resistant to anthelmintics from one farm to another.

[Biological cycle of Paralibyostrongylus hebrenicutus (Nematoda: Trichostrongylidae)]. / Cycle biologique de Paralibyostrongylus hebrenicutus (Nematoda: Trichostrongylidae).

Paralibyostrongylus hebrenicutus accomplishes its life cycle spontaneously in captive Atherurus africanus, its natural host, and in experimentally infected guinea pigs and rabbits. Morphogenesis and larval morphology were studied in the guinea pig and described herein. Host infection were achieved either by subcutaneous or by oral inoculation. The entsheathed infective larvae moult soon after penetration in the vertebrate host. Following subcutaneous inoculation, they reach the lungs very probably through the lymphatic vessels and the right heart at H8, and the stomach as soon as D2. However, a possible direct migration by the mesenteric lymphatic vessels and crossing of the digestive wall cannot be excluded as a few larvae were found in the peristomachal mesentery. Following ingestion, L3 larvae reached the stomach directly. 24 hours post-ingestion, they were localized deep inside the gastric mucosa crypts lumen. The same larval localization was observed at D3 after a subcutaneous inoculation. At D5, regardless of the inoculation route, larvae reached their definitive position, embedded in the gastric mucosa mucus lining, where they underwent the 3rd moulting (L3-L4) followed by the 4th moulting (L4-Ad) at D19. Eggs appeared at D28. Except for the inflammatory granuloma seen in the lungs and the mesentery from H24 to D3, the nematode induced no tissue lesion. The genus Paralibyostrongylus is one of the most primitive in the Libyostrongylinae-Cooperiinae line. The double transmission route, may have made possible the transition from primitive cycles by cutaneous penetration to more specialized cycles by the oral route, the latter being responsible for the evolutionary success of the group in large herbivores.