Utilizando a técnica de imunofluorescência indireta, foram demonstradas imunoglobulinas G e M, no soro humano, contra o Cryptosporidium, coccídeo implicado recentemente como agente de doença intestinal humana, principalmente em pacientes imunocomprometidos. Foi obtida positividade de 62% para imunoglobulinas G e M nos soros das crianças immunocompetentes com oocistos nas fezes e, respectivamente, 20% e 40%, nos soros das crianças sem oocistos. Nos pacientes adultos , com o vírus da imunodeficiência humana e excreção fecal do parasita, foram encontrados índices de positividade de 57% da IgG mas apenas 2% para IgM e aqueles com excreção não determinada apresentaram 23% da IgG. Crianças com o vírus da imunodeficiência humana, apresentaram apenas 14% da IgG e foram negativas quanto à IgM. Os resultados apontaram para a utilidade do teste, associado a outras técnicas parasitológicas, em estudos populacionais retrospectivos ou diagnósticos na infecção aguda e, ainda, que a resposta imune humoral a este protozoário necessita de maiores investigações, nos pacientes imunocomprometidos, principalmente crianças.
Cryptosporidium sp., a coccidian parasite usually found in the faeces of cattle, has been recently implicated as an agent of human intestinal disease, mainly in immunocompromised patients. In the study realized, by an indirect immunofluorescence technique, specific immunoglobulins (IgG and IgM) have been demonstrated in human serum against Cryptosporidium oocysts. Purified oocysts were used as antigens in the indirect immunofluorecence assay. After analyzing this test in sera from selected groups of patients, the frequency of both specific IgG and IgM of immunocompetent children who were excreting oocysts in their faeces was 62% and in children with negative excretion of oocysts was 20% and 40%, respectively. In adults infected with the human immunodeficiency virus (HIV) and who were excreting Cryptosporidium in their stools, the frequency was 57% for IgG but only 2% for IgM. Twenty three percent of immunocompromised adults with not determined excretion of oocysts in their stools had anti-Cryptosporidium IgG in their sera. Children infected with human immunodeficiency virus had no IgM and only 14% had IgG detectable in their sera. The indirect immunoflorescence assay, when used with other parasitological techniques appears to be useful for retrospective population studies and for diagnosis of acute infection. The humoral immune response of HIV positive patients to this protozoan agent needs clarification.
