Immunotherapeutic Effect of Spiramycin in Experimental Giardiasis.

Giardiasis is a major global cause of water borne diarrheal disease, which contributes greatly to the burden of malnutrition and malabsorption especially in children. There is a great demand for a new effective therapeutic agent against giardiasis that can be used safely during pregnancy, lactation and in infants. In the present study, the therapeutic effect of spiramycin as well as its immunomodulatory mechanism of action in giardiasis had been investigated. 90 Swiss albino mice were used in this study and classified into 3 groups: GI: 40 mice infected with Giardia lamblia cysts, GII: 40 infected mice that received spiramycin treatment in a daily oral dose of 1000 IU/gm body weight for one week starting one week post infection and GIII: 10 control uninfected untreated mice. 20 mice from each infected group were sacrificed 2 weeks post infection (p.i.) and the remaining mice were sacrificed 4 weeks p.i. Mice of the control groups were sacrificed at one time. The antigiardial therapeutic efficacy of spiramycin was assessed 2 and 4 weeks p.i. by counting of Giardia cysts in stool of mice and studying the histopathological changes and disaccharidase activity in small intestine of mice of different groups. Significant reduction in cysts number shedded in stool of treated animals reached 95.73%. The histopathological changes were mild in all infected groups 2 weeks p.i., while 4 weeks p.i. There was also a significant increase in the number of IELs in treated groups denoting the stimulatory effect of spiramycin on lymphocytic proliferation. On studying the disaccharidase activity, there was significant increase in both sucrase and maltase activities in the treated groups as compared with the nontreated groups. The possible immunomodulatory mechanism of action of spiramycin was studied by measuring the local IgA deposition in small intestinal mucosa by PAP technique 4 weeks p.i. The levels of IgA in small intestine were higher in SP-treated group as compared with the non-treated group. The present results suggested that spiramycin has high efficacy as anti-giardial agent possibly by stimulation of local IgA production.