Malaria rapid diagnostic devices: performance characteristics of the ParaSight F device determined in a multisite field study.

Microscopic detection of parasites has been the reference standard for malaria diagnosis for decades. However, difficulty in maintaining required technical skills and infrastructure has spurred the development of several nonmicroscopic malaria rapid diagnostic devices based on the detection of malaria parasite antigen in whole blood. The ParaSight F test is one such device. It detects the presence of Plasmodium falciparum-specific histidine-rich protein 2 by using an antigen-capture immunochromatographic strip format. The present study was conducted at outpatient malaria clinics in Iquitos, Peru, and Maesod, Thailand. Duplicate, blinded, expert microscopy was employed as the reference standard for evaluating device performance. Of 2,988 eligible patients, microscopy showed that 547 (18%) had P. falciparum, 658 (22%) had P. vivax, 2 (0.07%) had P. malariae, and 1,750 (59%) were negative for Plasmodium. Mixed infections (P. falciparum and P. vivax) were identified in 31 patients (1%). The overall sensitivity of ParaSight F for P. falciparum was 95%. When stratified by magnitude of parasitemia (no. of asexual parasites per microliter of whole blood), sensitivities were 83% (>0 to 500 parasites/microl), 87% (501 to 1,000/microl), 98% (1,001 to 5,000/microl), and 98% (>5,000/microl). Device specificity was 86%.

Mycobacterium thermoresistible recovered from a cutaneous lesion in an otherwise healthy individual.

This is the first report of coinfection by Mycobacterium thermoresistible and Mycobacterium fortuitum and only the fifth case of human infection by M. thermoresistible reported in the world literature.

Reproducible rat model for comparing late rectal toxicity from different brachytherapy techniques.

PURPOSE: Newer brachytherapy techniques, such as pulse-simulated low dose rate (PDR) and high dose rate (HDR) offer clinical and technical advantages over the conventional continuous low dose rate (CLDR) irradiation. The impact of these techniques on late normal tissue toxicity has remained largely undefined, with mathematical modeling and limited clinical experience providing some guidelines. We sought to develop a reproducible rat model for quantifying and comparing late rectal toxicity from different brachytherapy techniques. METHODS AND MATERIALS: An intrarectal applicator has been designed and techniques have been developed to deliver clinically relevant doses of CLDR to allow comparison to PDR and HDR. Female Wistar rats are utilized. The endpoints assessed are rectal obstruction and a histological grading of late rectal injury. RESULTS: Analysis of 65 rats given either sham or single acute pulse irradiation has demonstrated the model to be reproducible and reliable in evaluating late rectal toxicity. CONCLUSIONS: The use of this rat model to compare late rectal injury from various doses, dose rates, and fractionation parameters utilized by CLDR, PDR, and HDR will provide another tool for safely implementing these techniques into the clinical setting.

Effects of continuous low-dose-rate brachytherapy on the rectum of the rat.

The dose-limiting factor in essentially all curative radiotherapy is damage to normal tissue. In spite of this, our understanding of radiation-induced damage to normal tissue leaves much to be desired. Damage to the rectum is often observed after clinical brachytherapy of pelvic malignancies. A model in which the rectum of the rat is irradiated with a uniform and reproducible dose of brachytherapy irradiation was developed. This system consists of an intracavitary applicator, which is used in conjunction with methods that reduce fecal flow, a jacket that restrains rat movement and a lead-shielded chamber to contain rats during low-dose-rate brachytherapy. Irradiation was applied in 48-h intervals separated by 48-h breaks during which the applicator was removed. Methods to analyze the sequelae of brachytherapy irradiation of the rectum were also developed. The total dose of 0.75 Gy/h continuous low-dose-rate brachytherapy required to produce obstruction in the rat rectum has been measured. The ED50 was 70.6 +/- 4.2 Gy. The length of time between irradiation and obstruction was also correlated with total dose. Other effects on the rectum that were related to dose were diarrhea and rectovaginal fistula. This irradiation system can produce uniform and reliable brachytherapy doses to the rat rectum. The late effects in normal tissues observed in this model are similar to those observed in humans after irradiation of the rectum. The model should be appropriate for analyzing relative changes in the rectum resulting from different dose rates and fractionation schemes relevant to brachytherapy.