[The evaluation of the effect of formol and sodium hypochlorite on the demonstration of Cryptosporidium oocysts in feces by Heine's method].

Cryptosporidium oocysts were searched by Heine's method in stools of nine calves with cryptosporidiosis after stool treatment with two disinfectants, 10% paraformaldehyde solution and 14.5% sodium hypochlorite solution. After 30 minutes exposition to sodium hypochlorite solution oocysts became non refractile and acquired a reddish tinge, making their identification difficult. No morphological alterations occurred in oocysts after paraformaldehyde treatment. We recommend paraformaldehyde at 10% concentration as means of human immunodeficiency virus (HIV) inactivation for routine use in stool examinations and therefore making safer those type of procedures for laboratory personnel, when using Heine's method.