The intestinal microbiota consist mainly of bacteria, but viruses, fungi and parasites can also be found here. A wide range of single cell parasites, or protozoans, are common parasites of the intestinal tract. Few species do any real damage, but some may occasionally damage the intestinal lining, leading to inflammation and common symptoms of diarrhea1. Especially in immune incompetent individuals, the clinical impact of such an infection can be extremely damaging.

The intestinal bacteria and their metabolites can strongly interfere with the physiology and survival of protozoa and, consequently, with the outcome of many protozoa infections1 . Modulating the intestinal microbiota composition through the administration of probiotics is therefore considered as a potential therapeutic application against protozoan infections. Several in vitro and mice studies have already shown the beneficial effect of probiotics in preventing and controlling protozoa infections2. A number of human studies have also studied the effect of probiotic administration in the treatment of protozoa infection and have shown that probiotics can reduce the number of parasites and the severity of symptoms3. Although the exact mechanisms are not yet known, proposed mechanisms by which probiotics may sustain these effects include adhesion site competition, nutriment composition, secretion of active molecules that inhibit protozoa development, and/or modulation of immunity1 2.

The administration of probiotics may thus reduce the risk of protozoa infection and, in addition, reduce symptoms of infection and assist with recovery.

Written by Tessa Hemrika, medical writer Winclove Probiotics 


  • 1. a. b. c. Berrilli, F., et al., Interactions between parasites and microbial communities in the human gut. Front Cell Infect Microbiol, 2012. 2: p. 141.
  • 2. a. b. Travers, M.A., et al., Probiotics for the control of parasites: an overview. J Parasitol Res, 2011. 2011: p. 610769.
  • 3. Vitetta, L., et al., Modulating the Gut Micro-Environment in the Treatment of Intestinal Parasites. J Clin Med, 2016. 5(11).