We used oocysts of the species Cryptosporidium parvum (Iowa isolate), aged one to two months when measured (Waterborne Inc, New Orleans). The supplied oocysts were harvested from infected calves, extracted from feces with diethyl ether and purified using percoll density gradient centrifugation. Viable oocysts were stored in PBS, with penicillin, streptomycin, gentamicin, amphotericin B and 0.01 % polysorbate 20. Neutralized oocysts were stored in PBS with 5 % Formalin and 0.01 % polysorbate 20. Stocks were stored at 4 • C. To purify and remove storage solution, oocysts were washed twice by centrifuging at 3000 rcf for 2 min, with sterile water, with the supernatant discarded. We used Vibrio cholerae (V. cholerae) str. 'El Tor' clinical isolates N16961 . These bacteria were provided by Felipe Cava (Umeå university). We grew bacteria using standard laboratory conditions. Cultures were streaked onto LB plates with 200 µg mL -1 streptomycin, and single colonies are selected and grown overnight in TG Broth (5 g L -1 Tryptone, 10 g L -1 NaCl, 5 % glycerol) at 30 • C and sub-cultured in fresh TG Broth before measurement.