Anthelmintic activity of chicory (Cichorium intybus): in vitro effects on swine nematodes and relationship to sesquiterpene lactone composition

Chicory is a perennial crop that has been investigated as a forage source for outdoor-reared ruminants and pigs, and has been reported to have anthelmintic properties. Here, we investigated in vitro anthelmintic effects of forage chicory-extracts against the highly prevalent swine parasites Ascaris suum and Oesophagostomum dentatum. Methanol extracts were prepared and purified from two different cultivars of chicory (Spadona and Puna II). Marked differences were observed between the anthelmintic activity of extracts from the two cultivars. Spadona extracts had potent activity against A. suum third (L3) and fourth (L4) - stage larvae, as well as O. dentatum L4 and adults, whereas Puna II extracts had less activity against A. suum and no activity towards O. dentatum L4. Transmission-electron microscopy of A. suum L4 exposed to Spadona extracts revealed only subtle changes, perhaps indicative of a specific anthelmintic effect rather than generalized toxicity. Ultra-high liquid chromatography-mass spectrometry analysis revealed that the purified extracts were rich in sesquiterpene lactones (SL), and that the SL profile differed significantly between cultivars. This is the first report of anthelmintic activity of forage chicory towards swine nematodes. Our results indicate a significant anthelmintic effect, which may possibly be related to SL composition.

New oral linguiform projections and their associated neurons in the third-stage infective larva of the parasitic nematode Oesophagostomum dentatum

The infective larvae (L3i) of the nematode parasite of swine, Oesophagostomum dentatum, are passively ingested by their hosts. The L3i exhibit certain behaviors that are probably selected to increase the likelihood of ingestion, by strategic positioning in the environment. The larvae show positive geotactic behavior and respond to temperature variations in their environment, as shown by their behavior on a thermal gradient. To investigate neuronal control of this behavior, we initiated a study of the structure of the amphidial neurons of this parasite. The same number and types of neuronal dendritic processes are found in the amphids of the O. dentatum L3i as in those of its close relatives Haemonchus contortus and Ancylostoma caninum. Well-developed dendritic processes of wing cells are located in the amphidial sheath cells, these being similar to wing cells AWA in the free-living nematode Caenorhabditis elegans but actually more extensive. Similar to its close relatives just mentioned, and C. elegans as well, O. dentatum L3i has prominent finger cell processes, the finger cell neurons being the thermoreceptors in all 3 of the preceding species. However, unlike the arrangement seen in H. contortus and A. caninum, where the microvilli-like "fingers" of these neurons lie dorsal to the amphidial channel and occupy a very large portion (>50%) of the anterior end of the larva, the dendritic process of the finger cells in O. dentatum extends into unusual linguiform projections that, in turn, extend into the lumen of the mouth tube, a complex structural arrangement that has not been described for any other nematode.

Ultrastructure and development of the body cuticle of Oesophagostomum dentatum (Strongylida, Nematoda)

The ultrastructure, development, and morphogenesis of the body cuticle of adult and juvenile Oesophagostomum dentatum (Strongylida, Nematoda) were investigated by light microscopy, scanning electron microscopy, and transmission electron microscopy. The cuticle of the first 3 juvenile stages consists of a trilaminate epicuticle, an amorphous layer, and a radially striated layer. In the last juvenile stage and the adult worm, the radially striated layer is replaced by a fibrous layer with 3 sublayers of giant fibers and a basal amorphous layer. The new forming cuticle of the 3rd juvenile stage exhibits the epicuticle and amorphous material and, at a later time, the epicuticle and the radially striated layer; finally, amorphous material appears between these layers. Our finding of a structural change in the cuticular morphology between the 3rd and 4th juvenile stage harmonizes with earlier reports about the Strongylida. Such a change occurs at different ontogenetic stages or seems to be missing in other nematodes. Morphogenetic events such as the formation of the radial striation layer from amorphous precursor material agrees with previous observations on strongylids.

Oesophagostomiasis, a common infection of man in northern Togo and Ghana

Infection with Oesophagostomum sp. is normally considered a rare zoonosis and up to this time its diagnosis has been based on the demonstration of larvae and young adult worms in the typical nodules formed in the intestinal wall. Only in Dapaong, in North Togo, and Bawku, North Ghana, have larger series of clinical cases been described. In the rural areas around these towns, a survey was made in which stool samples were collected and cultured. Third-stage larvae of Oesophagostomum sp. could be found after 5-7 days of incubation at room temperature, and the prevalence of infection with this parasite was often high but varied from one village to another. It was over 30% in seven villages out of the 15 villages surveyed. Anthelmintic treatment resulted in the evacuation of adult males and females of O. bifurcum. It is concluded that O. bifurcum is a locally common parasite of humans, not requiring an animal reservoir for completion of its lifecycle.

Cutaneous oesophagostomiasis in man

A case is presented of infection by Oesophagostomum, a nematode worm, producing a cutaneous nodule in man. Of the 70 individual cases reported in man it is believed that this is the first in which the worm has produced a lesion outside the gastro-intestinal tract and without evidence of bowel infection. This finding suggests either that the worm is able to achieve direct skin penetration or that it can be disseminated from the bowel via the bloodstream or the lymphatics. The pathology caused by Oesophagostomum and the possible modes of infection are discussed in relation to studies in animals, particularly simians and cattle.