Study of hematological and parasitological findings in goats infected with Haemonchus contortus. Differences between different-trial immunized withthiol-proteinases from adult worms and non-immunized goats.

Abstract

The current situation of Haemonchosis in small ruminants cattle all over the world due to its pathogenicity and prolificacy and de develop of resistance to the conventional control methods such as anthelminthic drugs creates the need to search for new ways to reduce the impact of the parasite activity in the animals and the consequent echonomic loses related to the decrease of the production. In this context, cysteine proteases of Haemonchus spp. seems to be interesting for the develop of vaccines despite the unknown aspects related to its phisiology. In this experimental study, using different antigen doses and adjuvants as Freund and Dextran we tried to compare different group-trials basing on their immune response against an experimental infection with a Haemonchus contortus strain. A total of 36 kids the Canarian Majorera goat breed were divide in groups with different immunization trials and two non-immunized groups as controls. Weekly samplings of feces and blood were taken both before and after the challenger with L3 of the parasite the week 7 of the experiment- At the end of the study the animals were euthanized and removed the abomasa to make a count of adult worms of Haemonchus. Results were analyzed to make a comparison usign various stathistical methods. Parasitological parameters, FEC (fecal egg count) and adult worms in the abomasa seemed to be lower in immunized groups in comparison with the non immunized ones, regardless the adjuvant and antigen doses used. Hematological parameters were selected due to their importance related to the blood-feeding condition of the parasite. Some of these hematological parameters showed significative differences as observed in parasitological parameters between immunized and non-immunized groups. In the other hand, parasitological and hematological paramters seems to describe a negative correlation after the inoculation of the parasite. This immunization trials seems to have some protecting effect as the previous experimental studies made with thiol-proteinases based vaccines and continues the investigating way for future experiments in the search for an effective vaccine against haemonchosis.