New clonal protozoal cultures (I) contain cells of a single protozoal species selected from Histomonas meleagridis (HM), Tetratrichomonas gallinarum (TG) and Blastocystis sp. (BS). Independent claims are included for: (1) vaccine formulations (A) containing inactivated or living clonal protozoal cells as in (I), or antibodies (II) directed against these cells； (2) the production of (I), by: (a) providing a starting sample containing cells of HA, TG and/or BS, (b) optionally culturing the cells in a medium containing a carbohydrate source and optionally bacteria of at least one strain living symbiotically in situ with the protozoal cells (or a corresponding lysate), (c) isolating the protozoal cells by micro-manipulation, (d) culturing the isolated cells in a medium as for (b), and optionally (e) determining the purity of the obtained protozoal culture (I)； (3) determining the effect of test agent(s) on cells of HM, TG or BS, involving: (i) contacting a culture (I) (optionally after adjusting the cell count) with medium as defined in (b) above and culturing, (ii) adding the test agent(s), (iii) determining the protozoal cell count, and (iv) comparing the protozoal cell count before and after adding the test agent(s)； (4) detecting of HM, TG or BS in a sample, involving: (i) contacting the sample with at least one oligonucleotide (III) specific for HA, TG or BS or an antibody (II), (ii) optionally subjecting a sample-(III) mixture to nucleic acid amplification, and (iii) detecting any nucleic acid amplification products, (III)-protozoal cell bonding or (II)-protozoal cell bonding； (5) a kit for detecting HA, TG or BS or the corresponding antibodies (II) in a sample, containing: (a) clonal cells of HA, TG or BS or corresponding antibodies (II) (both optionally immobilized on a solid carrier), and (b) components for detecting protozoal cell-(II) bonding, specifically conjugated antibodies (preferably with radioactive, enzymatic or fluorescent labeling). ACTIVITY : Proto
