Anthelmintics resistance; How to overcome it?

Many parasitic helminthes of veterinary importance have genetic features that favor development of anthelmintic resistance, this becoming a major worldwide constrain in livestock production. The development of anthelmintic resistance poses a large threat to future production and welfare of grazing animals. Development of variable degrees of resistance among different species of gastrointes final nematodes has been reported for all the major groups of anthelmintic drugs. It has been observed that frequent usage of the same group of anthelmintic; use of anthelmintics in sub-optimal doses, prophylactic mass treatment of domestic animals and frequent and continuous use of a single drug have contributed to the widespread development of anthelmintic resistance in helminthes. The degree and extent of this problem especially with respect to multidrug resistance in nematode populations is likely to increase. Maintaining parasites in refugia and not exposed to anthelmintics, seems to be a key point in controlling and delaying the development of resistance, because the susceptible genes are preserved. Targeted selective treatments attract the interest of scientists towards this direction. Additionally, adoption of strict quarantine measures and a combination drug strategy are two important methods of preventing of anthelmintic resistance. Experience from the development of anthelmintic resistance suggests that modern control schemes should not rely on sole use of anthelmintics, but employ other, more complex and sustainable recipes, including parasite resistant breeds, nutrition, pasture management, nematode-trapping fungi, antiparasitic vaccines and botanical dewormers. Most of them reduce reliance on the use of chemicals and are environmental friendly. Finally, if new anthelmintic products are released, an important question will be raised about how they should be used. It is suggested that slowing the development of resistance to a new class are likely to be gained by releasing it in combination with one or more of the older anthelmintic classes, especially where efficacy of the older active[s] remains high

Efficacy of volatile oils [curzerene, furanoeudesma-1, 3-diene and lindestrene] on avian coccidiosis under laboratory conditions

The coccidicidal efficacy of volatile oils [curzerene, furanoeudesma-1, 3- diene and lindestrene] against unsporulated and sporulated chicken Eimeria species oocysts was tested in three concentrations: 1, 2 and 3 micro g/ml. Marked reduction in the number of living oocysts was recorded in exposed groups. The concentration of 3 micro g/ml volatile oils induced the highest destructive effect. 58.1% of viable unsporulated oocysts were destroyed. A mean number of 153,800 oocysts was the difference between the total number of the produced oocysts per gram faeces in the group infected with exposed oocysts and that of the group infected with nonexposed oocysts being less in the exposed group with more reduction in the vitality of shedding oocysts in the former group. At the meantime, the postmortem and histopathological microscopical examination of the intestine and caecum of' the tested group revealed a reduction in the intestinal lesions in the group infected with the exposed oocysts

diagnostic efficacy of Fasciola gigantica coproantigen in naturally infected cattle and buffaloes

Monoclonal antibody sandwich ELISA was used detect F. gigantica coproantigen in 33 selected animals according to the faecal history to evaluate sensitivity and specificity by using three different rabbit hyper-immune sera; Copro HIS, Egg HIS and ES HIS. The results showed that Copro HIS and ES HIS detected F. gigantica coproantigen in faecal of naturally infected cattle and buffaloes, but egg HIS failed. The 26-28 KDa coproantigen proved sensitivity [81.8%] and specificity [90.9%] in diagnosis of fascioliasis. Also, there was a positive statistical significance between number of F. gigantica egg per gm faeces [EPG] and mean sandwich ELISA OD. values for copro antigen. For diagnostic value of F. gigantica coproantigen in comparison with ES antigen, EITB was done on field sera of cattle and buffaloes of known faecal history. The F. gigantica coproantigen bands of 27.6 and 72.1 KDa were specific for diagnosis animal fascioliasis, but the 72.1 KDa was less sensitive than the 27.6 KDs. The immunoblotting reaction was more intensive than with fractionated ES antigen than with fractionated coproantigen

Efficacy of some Fasciola gigantica antigens

The present study tested the antigenic relationship between the three Egyptian strain of Fasciola gigantica antigens; coproantigen, excretory-secretory and egg antigens, versus their related hyper-immune sera and select the most specific one. By using SDS-PAGE, a structural homology was demonstrated in F. gigantica ES and egg antigens. This homology was resided in the components of the similar molecular weights between both antigens. When no cross-reaction was recorded with the coproantigen, the intense cross-reaction occurred between ES and egg antigens in ELISA technique. This was attributed to the presence of common bands at 18.0, 20.4 and 27.6 KDa in between them. Consequently, the F. gigantica coproantigen and Copro HIS reflected the lowest level of the cross-reaction with the other evaluated F. gigantica antigens. The cross-reaction elucidated in the present study between the F. gigantica ES and egg antigens was mainly at the low serum dilutions. The distinction between the specific and the cross-reactive binding activities was clearly marked with the highly diluted sera