## 4 Discussion
(Group B) showed the lowest microbial community diversity lacking 6 phyla: _Deferribacteres, Synergistetes, Chlamydia, SR1, OP1_, and _WPS-2_, while animals harboring _Cryptosporidium_ spp. and _E. bieneusi_ (Group D) lack four phyla _Chlanyduae, SR1, OP1_, and _WPS-2_, which suggested that the four phyla, _Chlanyduae, SR1, OP1_, and _WPS-2_ responded to _Cryptosporidium_ spp. sensitively and _Cryptosporidium_ spp. might decrease host intestinal microbial community diversity. These results are consistent with the observations made in mice and Coquerel's sifakas by others [48; 49]. From the study, most Bactrian camels tended to share a similar intestinal microbiota regardless of the weighted or unweighted UniFrac distance metric (PCoA plot). Compared with the unweighted UniFrac metric, weighted UniFrac metric can distinguish the difference of OTU abundance. Meanwhile, after considering OTU abundance, the maximum explanation of principal coordinate component increased. The dispersal of two camels of Group A (A1 and A2) fed with wheat straw and concentrates mixture to others of Group A indicated that the diet might influence bacterial communities [50]. Although the animal in Group E (1 sample) shared the same dietary and environment with others, it was scattered significantly. Therefore, the combined effect of _E. bieneusi_ and _G. duodenalis_ may have a considerable influence on microbiota composition of hosts. Analysis of microbiota at the genus level revealed a notable difference in bacterial genera between Groups A, C, D, and the Control group. The significant bacterial genera in Groups A, C, and D compared to Control were different from each group except for _Akkermansia_ and Fibrobacter. The bacterial genera that exhibited the greatest statistical significance in Groups A, C, and D were _Akkermansia, Oscillospira, Allobaculum_, respectively, with all having a higher predicted relative abundance. Compared with the control group, a bacterial genus underrepresented both in Group A and C was _Akkermansia_. Bacteria in this genus were known play an important role in provision of nutrition to intestinal mucosa and control of function of intestinal barrier [51; 52]. _E. bieneusi_ and _G. duodenalis_ were known as the intestinal epithelial barrier breaker [53; 54], but the pathogenesis of the two parasites was not clear. It was possible that _E. bieneusi_ or _G. duodenalis_ break intestinal mucosa of the host by reducing the relative abundance of _Akkermansia_. _Fibrobacter_ bacteria were known for solubilizing cellulose [55; 56]. The abundance of _Fibrobacter_ was significantly reduced in Group C and D compare to the Control animals. It was speculated that _Cryptosporidium_ spp., _G. duodenalis_, and _E. bieneusi_ may impair the host nutrition efficiency by reducing _Fibrobacter_ bacteria abundance. A study on patients with inflammatory bowel diseases showed _Oscillospira_ was negatively associated with colonic disease of patients [57]. We observed that _Oscillospira_ genus in individuals with _G. duodenalis_ infection was more abundant than Control. It might be possible, when _G. duodenalis_ existed, that the increased _Oscillospira_ could exhaust the nutrient of hosts. In agreement with the current finding, a study identified that _Oscillospira_ had been detected in the intestines of vegetarians and can be able to utilize host glycans by producing a diverse glycoside hydrolase repertoire [58]. A recent study showed that feeding mice with Bactrian camel milk resulted in establishment of predominant _Allobaculum_ and as _Akkermansia_ genus in mouse intestinal [59]. _Allobaculum_ bacteria were beneficial to the host by supplying short-chain fatty acids and providing control of inflammation [60; 61; 62]. We observed that _Allobaculum_ was significantly decreased by co-infection with _Cryptosporidium_ spp. and _E. bieneusi_ in Group D. The decreased abundance of bacteria of this genus by co-infection with _Cryptosporidium_ spp. and _E.