Immunoperoxidase for the detection for the detection of antibodies in cerebrospinal fluid in neurocysticercosis: use of Cysticercus cellulosae and Cysticercus longicollis particles fixed on microscopy slides

The ORF strain of Cysticercus longicollis represents an important model for the study of heterologous antigens in the immunodiagnosis of neurocysticercosis (NC). The immunoperoxidase (IP) technique was standardized using a particulate antigen suspension of Cysticercus longicollis (Cl) and Cysticercus cellulosae (Cc). Cerebrospinal fluid (CSF) samples were incubated on the antigen fixed to microscopy slides; the conjugate employed was anti-IgG-peroxidase and the enzymatic reaction was started by covering the slides with chromogen solution (diaminobenzidine/H2O2). After washing with distilled water, the slide was stained with 2% malachite green in water. Of the CSF samples from 21 patients with NC, 19 (90.5%) were positive, whereas the 8 CSF samples from the control group (100%) were negative. The results of the IP-Cl test applied to 127 CSF samples from patients with suspected NC showed 28.3% reactivity as opposed to 29.1 % for the IP-Cc test. The agreement index for the IP test (Cl x Cc) was 94.2%, with no significant difference between the two antigens.

Description of the egg of Anopheles (Anopheles) intermedius (Peryassu, 1908) (Diptera: Culicidae) by scanning electron microscopy

The egg of Anopheles (Anopheles) intermedius (Peryassu, 1908) is described and illustrated with scanning electron micrographs. Literature data on An. (Ano.) maculipes (Theobald, 1903) is provided

Cyclospora cayetanensis in sputum and stool samples

We report the observation of acid-fast Cyclospora cayetanensis oocysts in a sputum sample. The patient, a 60 year-old, HIV negative man, was successfully treated for pulmonary tuberculosis during 1997. On February 1998, he was admitted to our center due to loss of weight, cough with purulent expectoration, dysphonia and a radiological picture of pulmonary fibrosis. Bacilloscopic study of sputum (negative for acid-fast bacilli) stained with Ziehl-Neelsen technique showed large (8-10 µm) spherical, acid-fast Cyclospora cayetanensis oocysts. No other pathogens were isolated on cultures from this sample or from laryngeal biopsy. Serial parasitologic studies showed C. cayetanensis and also eggs of Trichuris trichiura, Ascaris lumbricoides and Hymenolepis nana and of Entamoeba coli cysts. The patient lives in the outskirts of Buenos Aires in a brick-made house with potable water and works as builder of sewers. He travelled in several occasions to the rural area of province of Tucumán which has poor sanitary conditions. C. cayetanensis is an emergent agent of diarrhea and as far as we know this is the first time the parasite is observed in respiratory samples.

Diagnosis of pulmonary pneumocystosis by microscopy on wet mount preparations

We have compared the searching of the presence of "honeycomb" structures by direct microscopy on wet mount preparations with the direct immunofluorescence (DIF) for the diagnosis of Pneumocystis carinii pneumonia (PCP) in 115 bronchoalveolar (BAL) fluids. The samples belonged to 115 AIDS patients; 87 with presumptive diagnosis of PCP and 28 with presumptive diagnosis other than PCP. The obtained results were coincident in 114 out of 115 studied samples (27 were positive and 87 negative) with both techniques. A higher percentage of positive results (32.18%) among patients with presumptive diagnosis of PCP with respect to those with presumptive diagnosis other than PCP (3.57%) was observed. One BAL fluid was positive only with DIF, showed scarce and isolated P. carinii elements and absence of typical "honeycomb" structures. The searching for "honeycomb" structures by direct microscopy on wet mount preparations could be considered as a cheap and rapid alternative for diagnosis of PCP when other techniques are not available or as screening test for DIF. This method showed a sensitivity close to DIF when it was applied to BAL fluids of AIDS patients with poor clinical condition and it was performed by an experienced microscopist.

Evaluation of a rapid dipstick test, Malar-CheckTM, for the diagnosis of Plasmodium falciparum malaria in Brazil

The present study was carried out to evaluate the Malar-CheckTM Pf test, an immunochromatographic assay that detects Plasmodium falciparum Histidine Rich Protein II, does not require equipment, and is easy and rapid to perform. In dilution assays performed to test sensitivity against known parasite density, Malar-CheckTMwere compared with thick blood smear (TBS), the gold standard for diagnosis. Palo Alto isolate or P. falciparum blood from patients with different parasitemias was used. The average cut-off points for each technique in three independent experiments were 12 and 71 parasites/mm³ (TBS and Malar-CheckTM, respectively). In the field assays, samples were collected from patients with fever who visited endemic regions. Compared to TBS, Malar-CheckTMyielded true-positive results in 38 patients, false-positive results in 3, true-negative results in 23, and false-negative result in 1. Malar-CheckTMperformed with samples from falciparum-infected patients after treatment showed persistence of antigen up to 30 days. Malar-CheckTM should aid the diagnosis of P. falciparum in remote areas and improve routine diagnosis even when microscopy is available. Previous P. falciparum infection, which can determine a false-positive test in cured individuals, should be considered. The prompt results obtained with the Malar-CheckTM for early diagnosis could avoid disease evolution to severe cases.

Scanning electron microscopy of third-instar sarcophagid (Diptera: Sarcophagidae) recovered from a mummified human corpse in Thailand

The third-instar of an unidentified sarcophagid, recovered from a mummified body of a 32-yr-old Thai male was examined using scanning electron microscopy (SEM). Although the morphological features of this larva are similar to the other sarcophagid larvae, some features could be helpful for species identification, which is a basic requirement for estimation of postmortem interval in forensic investigation. These features included number and arrangement of papillae on the anterior spiracle, structure of spines, size of circumspiracular tubercles at caudal segment and branching peculiarity of the posterior spiracular hairs. This information could benefit future identification of the sarcophagid larvae that exist in Thailand.

Pulmonary tuberculosis: relationship between sputum bacilloscopy and radiological lesions

OBJECTIVES: To determine the frequency of radiological manifestations of chest tuberculosis among the tuberculosis outpatients at the Santa Casa de Misericórdia de São Paulo Hospital, and to correlate these radiological findings with the sputum bacilloscopy. SAMPLE AND METHODS: A review was made of the medical record cards and chest X-rays of all patients attended between January 1996 and December 1998. Patients with a diagnosis of tuberculosis who presented intrathoracic manifestations of the disease and negative anti-HIV serology were selected. RESULTS: The selection included 153 patients, with an average age of 37.5 years, who were predominantly male (60.8%) and white (56.9%). Pulmonary lesions were present in 121 (79.9%) and extrapulmonary lesions in 32 (20.1%). Parenchymal-infiltrate lesions appeared in 56 patients (36.6%), cavity lesions in 55 (36.0%), pleural effusion in 28 (18.3%), isolated nodules in 6 (3.9%), mediastinal enlargement in 4 (2.6%) and miliary pattern in 4 (2.6%). Cavities were present in 45.5% of the patients with pulmonary lesions, generally in association with the parenchymal-infiltrate lesions. Parenchymal infiltrate was present in 86.8% of the patients with pulmonary lesions. There was significant presence of alcohol-acid resistant bacillus in the sputum of patients with cavities (76.4%), in comparison with those without cavities (50%) (p = 0.003). CONCLUSIONS: Parenchymal-infiltrate lesions are the most frequent radiological manifestation of pulmonary tuberculosis, and they are generally associated with cavities. There is a relationship between the presence of acid fast bacilli in sputum and pulmonary cavity lesions.

PCR - based diagnosis to evaluate the performance of malaria reference centers

Although the Giemsa-stained thick blood smear (GTS) remains the gold standard for the diagnosis of malaria, molecular methods are more sensitive and specific to detect parasites and can be used at reference centers to evaluate the performance of microscopy. The description of the Plasmodium falciparum, P. vivax, P. malariae and P. ovale ssrRNA gene sequences allowed the development of a polymerase chain reaction (PCR) that had been used to differentiate the four species. The objective of this study was to determine Plasmodium species through PCR in 190 positive smears from patients in order to verify the quality of diagnosis at SUCEN's Malaria Laboratory. Considering only the 131 positive results in both techniques, GTS detected 4.6% of mixed and 3.1% of P. malariae infections whereas PCR identified 19.1% and 13.8%, respectively.

Refractive index matching applied to fecal smear clearing

Thick smears of human feces can be made adequate for identification of helminth eggs by means of refractive index matching. Although this effect can be obtained by simply spreading a fleck of feces on a microscope slide, a glycerol solution has been routinely used to this end. Aiming at practicability, a new quantitative technique has been developed. To enhance both sharpness and contrast of the images, a sucrose solution (refractive index = 1.49) is used, which reduces the effect of light-scattering particulates. To each slide a template-measured (38.5 mm³) fecal sample is transferred. Thus, egg counts and sensitivity evaluations are easily made.

PREHISTORICAL Pediculus humanus capitis INFESTATION: QUANTITATIVE DATA AND LOW VACUUM SCANNING MICROSCOPY

A pre-Columbian Peruvian scalp was examined decades ago by a researcher from the Oswaldo Cruz Foundation. Professor Olympio da Fonseca Filho described nits and adult lice attached to hair shafts and commented about the origin of head lice infestations on mankind. This same scalp was sent to our laboratory and is the subject of the present paper. Analysis showed a massive infestation with nine eggs/cm2 and an impressive number of very well preserved adult lice. The infestation age was roughly estimated as nine months before death based on the distance of nits from the hair root and the medium rate of hair growth. A small traditional textile was associated with the scalp, possibly part of the funerary belongings. Other morphological aspects visualized by low-vacuum scanning electron microscopy are also presented here for adults and nits.

Scanning electron microscopy and X-ray spectroscopy applied to mycelial phase of sporothrix schenckii

Scanning electron microscopy applied to the mycelial phase of Sporothrix schenckii shows a matted mycelium with conidia of a regular pattern. X-Ray microanalysis applied in energy dispersive spectroscopy and also in wavelength dispersive spectroscopy reveals the presence of several elements of Mendeleef's classification.

Study of chelicerae in the tick Amblyomma cajennense (Fabricius 1787) by scanning electron microscopy

Chelicerae de Amblyomma cajennense foram examinados em microscopia de varredura. Esta técnica mostrou detalhes não evidenciáveis ao poder de resolução do microscópio ótico.

Confocal fluorescence microscopy: a powerful tool in the study of Chagas' disease

Confocal scanning fluorescence microscopy has become widely used in cell biology and pathology. In conjunction with monoclonal antibodies it may turn out to be a powerful diagnostic tool that also enables detailed studies of tissue forms of Trypanosoma cruzi.