The efficacy of the crude Origanum genus (Lamiaceae) essential oils on experimentally infected mice with Blastocystis spp.

Blastocystis spp. is a common intestinal protozoan with a controversial role in gastrointestinal disease, and the variable efficacy of conventional therapies has prompted the search for alternative treatment options. This study evaluated the therapeutic effects of crude Origanum essential oil in experimentally infected mice compared with nitazoxanide (NTZ). Forty male Swiss albino mice were allocated into four groups: negative control, infected untreated, NTZ-treated ( $$\:100\text{\:mg/kg/day}$$ ), and crude Origanum oil-treated ( $$\:0.5\text{\:mL/kg/day}$$ ). The essential oil was evaluated in its crude form without chemical characterization (e.g., GC-MS). Mice were orally infected with $$\:1\times\:{10}^{5}\text{\:Blastocystis}$$ cysts and treated for seven days. Treatment efficacy was assessed by fecal cyst counts, intestinal nitric oxide (NO) and malondialdehyde (MDA) levels, and histopathological examination of intestinal tissues. Data was analyzed using one-way ANOVA. Infected untreated mice exhibited reduced activity and soft stools. Clinical improvement was observed in both treatment groups within 5–7 days, and no mortality occurred during the study. The infected untreated group showed the highest cyst burden ( $$\:6.2\times\:{10}^{5}\pm\:0.4\times\:{10}^{5}\text{\:cysts/g\:stool}$$ ), whereas NTZ and crude Origanum oil treatment significantly reduced cyst shedding by $$\:85.6\%$$ and $$\:91.3\%$$ , respectively, compared with infected controls ( $$\:p<0.001$$ ). No cysts were detected in the non-infected control group. Infection was associated with significant increases in intestinal NO and MDA levels, indicating oxidative stress and inflammation. Both treatments significantly reduced these markers ( $$\:p<0.001$$ ), with values in the Origanum-treated group approaching those of the negative control group. Histopathological examination revealed villous atrophy, epithelial desquamation, and inflammatory cell infiltration in infected untreated mice. NTZ treatment resulted in partial improvement of these lesions, whereas crude Origanum oil treatment was associated with marked restoration of villous architecture and minimal inflammatory changes. Under this experimental model, crude Origanum vulgare essential oil improved parasitological, biochemical, and histopathological parameters in Blastocystis-infected mice. Because chemical profiling was not performed, these effects reflect the biological activity of the crude extract as a whole. Further studies incorporating GC-MS characterization are needed to identify active constituents, optimize dosing, and confirm these findings in other models and clinical settings.