Associations between Giardia infection and faecal microbiota in calves

Giardia duodenalis (synonyms G. lamblia and G. intestinalis) is a gastrointestinal protozoan parasite prevalent worldwide. Giardiasis causes diarrheal disease in calves, other animals and humans. Young animals and humans tend to be more prone for clinical Giardia infection. Giardia spp. assemblages A and B have wider host range and are potentially zoonotic, while rest six out of eight assemblages (C-H) are more species specific. Association with Giardia infection and changes in gastrointestinal microbiota has been established in mice, dogs, and children. Giardia has been reported in bovine animals worldwide, but its effect on gastrointestinal microbiota and vice versa has not been widely studied. This thesis studied the prevalence of Giardia infection and the possible association with faecal microbial changes in three-week-old dairy calves in South-East Estonian farm. Faecal swabs and faecal samples of 62 calves were collected 21 days after birth. Bacterial DNA was sequenced from the fecal swab samples and immunofluorescein staining method was used for faecal samples for Giardia oocyte detection. Positive Giardia infection was considered when at least one oocyte was present in the faecal sample. Out of 62 calves, 20 (32%) were positive for Giardia infection. Five bacterial phyla were identified, and the faecal microbiota composition was found to be different during Giardia infection when compared to Giardia free calves, establishing an association between Giardia infection and faecal microbiota in three-weekold dairy calves.

Giardia duodenalis (sünonüümid G. lamblia ja G. intestinalis) on kogu maailmas levinud seedetrakti parasiit, algloom. Giardiaas põhjustab vasikate, teiste loomade ja inimeste kõhulahtisust. Noortel loomadel ja inimestel on kalduvus kliinilisele Giardia infektsioonile. Giardia spp. genotüüpidel A ja B on laiem peremeeste ring ja need võivad olla zoonootilised, samas kui ülejäänud kuus genotüüpi (C-H) on liigispetsiifilisemad. Hiirtel, koertel ja lastel on leitud seos Giardia infektsiooni ja seedetrakti mikrobiota muutuste vahel. Giardia-t on raporteeritud veistel ülemaailmselt, kuid selle mõju seedetrakti mikrobiotale (ja vastupidi) pole laialdaselt uuritud. Käesolevas lõputöös uuriti Giardia nakkuse levimust ja võimalikku seost rooja mikrobioota muutustega kolmenädalastel piimavasikatel ühes farmis KaguEestis. Kokku 62 vasika pärasoolest koguti tampooni- ja roojaproovid 21 päeva pärast sündi. Rooja tampooniproovidest sekveneeriti bakteriaalne DNA, ja roojaproovidest Giardia ootsüstide tuvastamiseks kasutati immunofluorestseiini värvimismeetodit. Giardia positiivseks loeti proovi siis, kui leidus vähemalt üks ootsüst. Ühtekokku leiti 20 (32%) vasikat, kes olid Giardia infektsiooni suhtes positiivsed. Tuvastati viis bakteriaalset sugukonda, ja leiti, et rooja mikrobioota koostis erines kui võrreldi Giardia positiivseid vasikaid Giardia vabade vasikatega; seega tuvastati seos Giardia nakkuse ja rooja mikrobioota vahel kolmenädalastel piimavasikatel.