Changes in white blood cell count and formation of lesions in mice experimentally infected with Encephalitozoon cuniculi

White blood cell count (WBC) and formation of histological lesions were eva luated in mice experimentally infected with E. cuniculi during 120 days of observation. WBC showed a significant decrease of some leukocytes including lymphocytes at 10, 30, 60, and 90 days after infection. On the other hand the number of monocytes was increased in the second half of the experiment. Lesion devel oped earliest in the liver. Later on other organs studied (brain, lung, kid ney and heart) were showen to be infected in the acute stage of infection. Some relationship between changes in WBC and movement of these cells into i nfected tissues was inferred.