Evaluation of complement and lysozyme activity and determination of antibody titers in the sera of Linguatula serrata -infected intermediate hosts by indirect hemagglutination

This study was performed to determine the prevalence of Linguatula serrata in sheep and goats by observing the parasite in the mesenteric lymph nodes and measuring the antibody titer by indirect haemagglutination test and also evaluating the activity of serum complement activity by classical method and lysozyme. 791 samples of blood and mesenteric lymph nodes from sheep (456) and goats (335) were collected in the slaughterhouse of Ahvaz (Khuzestan province). The results showed that 7.8% of all ruminants in the present study were infected with L. serrata. There was no significant difference in the level of complement activity by classical method and lysozyme activity between infected and non-infected animals. Also, using an indirect haemagglutination test, in addition to accurately identifying infected samples from non-infected animals, the levels of IgG and IgM antibodies against L. serrata were estimated. IgG levels in infected samples were higher than IgM levels and the levels of these antibodies were significantly lower in non-infected samples. Overall, the present study suggests that this parasite in the intermediate host may escape from some important components of the innate immune system (such as the complement and lysozyme). Although the results of the present study showed that infection with the parasite increased the level of some antibodies, but these changes do not seem to provide the conditions for the eradication of the parasite.