Contortus Resistance Research Articles

To trace the active compound in mengkudu (morinda citrifolia) with anthelmintic acvtivity against Haemonchus contortus

Intestinal parasites such Haemonchus contortus is usually controlled by management improvement and regular administration of anthelmintic. However, there is an indication of H. contortus resistance to several anthelmintic available in the market, which makes medicinal plants as an alternative anthelmintic and mengkudu or noni fruit (Morinda citrifolia) have been reported as an effective anthelmintic. To trace the active compounds responsible for anthelmintic activity against H. contortus, the mengkudu fruit was continuosly extracted into hexane, chloroform, metanol and water, followed by in-vitro study on the anthelmintic activity. The in-vitro anthelmintic activity was base on the ability of the extracts to kill the worm and the ability of the extracts to prevent egg development. The study suggested that chloroform fraction which contains alkaloid and anthraquinon have the highest anthelmintic activity and showed significant different compared to control (P≤ 0.05). Key words : Morinda citrifolia, anthelmintic, Haemonchus contortus

A search for associations between major histocompatibility complex restriction fragment length polymorphism bands and resistance to Haemonchus contortus infection in sheep

Polymorphic bands were detected within the DQB and DRB regions of the ovine major histocompatibility complex by probing TaqI digested DNA from three large sheep half-sib families derived from a highly resistant ram. All animals were phenotypically assessed for Haemonchus contortus resistance by faecal egg counts and associations with RFLP bands and haplotypes were estimated using mixed model, best linear unbiased prediction statistical methods. Although the highly resistant sire was homozygous at the MHC, no significant associations were found between any band or haplotype and faecal egg count.

Haemonchus contortus resistance to ivermectin and netobimin in Brazilian sheep

Suffolk, Texel, Hampshire Down and Ile de France sheep from the municipalities of Porto Amazonas, Piraquara and Araucaria in the State of Paraná, and Bagé in the State of Rio Grande do Sul were brought to Sobral, State of Ceará, to be used in a cross-breeding project. On arrival they had clinical signs of nematode parasitosis, and one Suffolk female died. The animals were treated orally with ivermectin (0.2 mg kg −1) and fifteen days later with netobimin (20.0 mg kg −1). Neither drug reduced the egg counts (measured in eggs per gram, EPG) significantly, and this suggested that the nematodes in the sheep were resistant to the anthelmintics used. Haemonchus contortus was the species involved. The egg counts were reduced after oral treatment with trichlorfon (100.0 mg kg −1). Haemonchus contortus larvae obtained from these animals before trichlorfon treatment and passaged through two nematode-free sheep were used in a further experiment. Twenty 6- to 9-month-old nematode-free lambs were infected with the H. contortus larvae (10 000 per animal) and, after the infection was confirmed, were randomly divided into four groups of five animals. Group I was orally treated with ivermectin at 0.2 mg kg −1, Group II with oral netobimin at 20.0 mg kg −1, Group III with oral trichlorfon at 100.0 mg kg −1 and Group IV was a non-treated control. Egg counts and faecal cultures were taken before dosing on the day of treatment and seven days later when all animals were necropsied and the nematodes were collected from the abomasa and counted. Drug efficacy measured by the reduction in adult H. contortus numbers was 99.9% for trichlorfon, 38.9% for netobimin and 17.6% for ivermectin. The results demonstrated the resistance of this strain of H. Contortus to ivermectin and netobimin.