Nonspecific immunomodulation influences the course and location of Cryptosporidium parvum infection in neonatal BALB/c mice.

The influence of nonspecific immunomodulation with Thymomodulin (a calf thymic extract with immunomodulatory activity) and hydrocortisone on the course and location of Cryptosporidium parvum infection in neonatal BALB/c mice (infected with 10(6) or 10(5) oocysts on day 7 of life) was studied using scanning electron microscopy of the inner surface of different parts of intestine. Daily peroral treatment of suckling mice with 20 mg/kg/day of Thymomodulin for 5 days before inoculation resulted in an earlier peak and earlier termination of cryptosporidial infection when compared with control infected mice. On the other hand, peroral administration of 25 mg/kg of hydrocortisone every second day led to the persistence of cryptosporidial infection in the ileum of immunosuppressed mice until the end of observation (day 15 post infection), whereas only transient infection was observed in the intestine of control infected mice. The location of infection was also altered in hydrocortisone--treated mice--the severe infection was observed in more proximal parts of the intestine (anterior and middle jejunum), whereas no cryptosporidia were found in these parts of the intestine in nontreated infected mice.