Experimental studies on hookworm infection. III. observations on the acquired induced in the indigenous dogs by repeated experimental infections with Ancylostoma caninum

摘要

Effect of serial sub-lethal infections of local pups with the infective larvae of Ancylostoma caninum were studied in relation to the acquired resistance. Debilitating clinical signs of ancylostomiasis, adult worm expulsion rates,worm egg productionrates, haemotological changes, biochemical changes and the necropsy worm burdens established a higher level of acquired resistance in the primarily infected groups than in the uninfected control group. Also of the two primarily infected groups, the subcutaneously infected group had a higher (P<0.003) level of resistance than the oral group and the infected female pups than the males. The larger tissue migration of worms provided by the subcutaneous route and the reduced number of adult worms reaching the gut to suck blood were speculated to be responsible for the excellence of the subcutaneous group while the larger worm-tissue contact provided by the bigger surface area of the bitches did same for the female pups. The resistance was speculated to bemediated through the antigenic (larvae) stimulation of varied levels of specific immunoglobulins: IgM, IgA and IgG in the infected pups. The higher plasma concentration, longer circulatory life span and its availability in all extravascular spaces whichwere all enhanced by its subcutaneous stimuli, credited much of the resistance to the specific, IgG. antibodies. This study has informed that varied levels of antibody-mediated resistance do follow serial sub-lethal hookworm infection in local dogs, in spite of their pre-experimental exposure to the worm in this endemic zone and opens up the prospect of using the treated hyper-immune sera in the management of the common acute hookworm diseases in local pups.