Contribution to the laboratory diagnosis of human cryptosporidiosis

Human cryptosporidiosis is an infection caused by Cryptosporidium spp, a coccidial protozoan of emergencial pathogenicity and responsible for severe and prostrating watery diarrhea, mainly in immunocompromised patients. Smears of stools submitted to concentration and staining by carbol fuchsin technique has been used in our laboratory as a diagnostic procedure for cryptosporidiosis. The long time observing the smears in the microscope due to the small size of the forms and the low contrast of the staining led us to introduce some modifications in the original protocol for the acid-fast staining. The smears were treated with the carbol fuchsin solution for 3 minutes as recommended by LENNETTE et al., 1985 and the solution of the ethyl alcohol 70%-chloride acid 0.5% was used instead of the ethyl alcohol-sulfuric acid 5% recommended by HENRIKSEN & POHLENZ, 1981. Smears were treated with the discoloration solution for 2 minutes. These modifications promoted a better washing out of the excess of carbol fuchsin therefore increasing the dye efficiency. In such conditions, the visualization of protozoan oocysts on the slides examined became easier. They were observed by the contrast of their intense pink-reddish pigmentation against the blue background. It's worthwhile to emphasize that these modifications offer advantages when time and accuracy are concerned.

dogs may be a reservoir host for Angiostrongylus costaricensis

Angiostrongylus costaricensis is a parasitic nematode of wild rodents. Several other vertebrate species including man may become infected by ingestion of the third stage larvae produced by the intermediate hosts, usually slugs from the family Veronicellidae. There is a report of the diagnosis of abdominal angiostrongyliasis in Canis familiaris with lesions resembling those found in human disease. As a preliminar evaluation of the adequacy of a canine model for pathogenetic studies, a dog was inoculated with 75 L3 of A. costaricensis. Infection was established and fist stage larvae were found in feces up to 88 days post infection, sometimes in very large numbers (9.5 x 10(4) L1/g). No clinical manifestations or significant lesions were detected. These are indications that dog may play a role as a reservoir host for A. costaricensis.

Diagnosis of cytomegalovirus infections by qualitative and quantitative PCR in HIV infected patients

A high incidence of cytomegalovirus (CMV) infections is observed in Brazil. These viruses are causatives of significant morbidity and mortality among patients with advanced human immunodeficiency virus (HIV) infection. This work, shows the application of a PCR on determination of CMV load in the buffy coat and plasma. We analyzed the samples of 247 HIV infected patients in order to diagnose CMV infection and disease. We developed a semi-quantitative PCR that amplifies part of the glycoprotein B (gB) gene of CMV. The semi-quantitative PCR was carried out only in positive clinical samples in a qualitative PCR confirmed by a nested-PCR. CD4 lymphocyte count, HIV viral load and CMV disease symptom were correlated with CMV load. CMV genome was detected in the buffy coat of 82 of 237 (34.6%) patients, in 10 of these the CMV load was determined varying between 928 and 332 880 viral copies/mug DNA. None of these 237 patients developed any suggestive manifestation of CMV disease. For the other 10 HIV infected patients selected based on the suspicion of CMV disease, CMV genome was detected in only one case. This patient presented a high CMV load, 8 000 000 copies/mug DNA, and developed a disseminated form of CMV disease including hepatitis and retinitis. Our results were greatly influenced by the impact of the highly active antiretroviral therapy that reduced incidence of CMV viremia and occurrence of CMV disease in the HIV infected patients.