Intragenomic sequence variation of the ITS-1 region within a single flow-cytometry-counted Cyclospora cayetanensis oocysts.

Cyclospora cayetanensis, a protozoan of emerging concern, causes self-limiting gastroenteritis in immune-competent hosts. It has been established that sequence variability exists in the first internal transcribed spacer region (ITS-1) of the ribosomal DNA operon from collections of oocysts obtained from individual or pooled fecal samples. To determine if single oocysts also exhibited ITS-1 sequence variability, DNA was extracted from individually flow-cytometry-counted oocysts. We determined that ITS-1 sequence variability exists at an individual-genome level for C. cayetanensis and approached or exceeded the variability exhibited among oocyst collections. ITS-1 variability, at the genome level, reduces this region's utility for inferring relationships between strains.

Enhanced concentration and isolation of Cyclospora cayetanensis oocysts from human fecal samples.

Cyclospora cayetanensis is the causative agent of cyclosporiasis, an emerging infectious disease. We present a new method for the purification of C. cayetanensis oocysts from feces using a modified detachment solution and Renocal-sucrose gradient sedimentation. This method yields oocysts free from adherent fecal debris and amenable to processing using flow cytometry.

Latent schistosomiasis in Portuguese soldiers.

Schistosomiasis was diagnosed in two Portuguese soldiers who had been deployed to Portuguese colonies in Africa. The first veteran was diagnosed as having schistosomiasis 34 years after returning from Angola, and the second veteran was found with Schistosoma haematobium infection 40 years after returning from Mozambique. The patient with Schistosoma mansoni had an active infection, because eggs were recovered with living miracidia. The second patient had developed urothelial cancer, but eggs recovered were calcified.

History of U.S. military contributions to the study of parasitic diseases.

U.S. military researchers have made major contributions to the discovery, diagnosis, treatment, and prevention of a number of parasitic diseases. We review the paramount U.S. military contributions to the understanding of leishmaniasis, filariasis, schistosomiasis, trypanosomiasis, gastrointestinal parasites, intestinal capillariasis, and angiostrongyliasis.

Detection of Cyclospora cayetanensis in animal fecal isolates from Nepal using an FTA filter-base polymerase chain reaction method.

Cyclospora cayetanensis is an emerging protozoan parasite capable of causing a protracted diarrheal illness in both immunocompromised and immunocompetent individuals. Ingestion of fresh produce and water sources contaminated with mature sporulated oocysts results in acquisition of cyclosporiasis. Currently, no animal model exists for the study of this pathogenic parasite and the only confirmed reservoir host for C. cayetanensis in nature is humans. Previously, Cyclospora-like oocysts had been detected by microscopy in several animals including non-human primates. However, their phylogenetic relationship to C. cayetanensis remained uncertain due to the limited availability of molecular techniques to differentiate and speciate these isolates. In the present study, we examined a series of fecal isolates obtained from dogs, chickens, and monkeys collected between May and September 2002 from several geographic regions of Nepal. All samples were examined by microscopy and a polymerase chain reaction (PCR) for the presence of C. cayetanensis. Both microscopic and conventional PCR/restriction fragment length polymorphism (RFLP) analysis demonstrated the presence of Cyclospora sp. in the fecal samples of two dogs, one chicken, and one monkey. Application of a species-specific multiplex PCR assay confirmed the presence of both Eimeria sp. and C. cayetanensis in the positive chicken sample and only C. cayetanensis in the dog and monkey samples. However, in the absence of tissue analysis, the assignment of these animals as a natural reservoir host for C. cayetanensis remains to be determined.

Reevaluation of the employment of Fick's law for diffusion dosimeters.

This paper reconsiders the means of applying Fick's first law to passive diffusion dosimeters. The performance of the organic vapor monitor (OVM), a commercially available dosimeter, is modeled in terms of gradients, which are generated by evaporating a compound from the dosimeter. The fluxes induced by the gradients are determined gravimetrically. The ratio of a flux and a gradient is reported as a Fick's law proportionality constant, the sampling rate. The sampling rate for the gradient across the OVM is calculated from a harmonic average of the sampling rates of two other gradients. The OVM sampling rates for nine compounds determined by the new methodology agree well with published values. Further analysis of the other two gradients provides a value for an apparent reduction in sampling rate in the absence of airflow across the dosimeter (a boundary-layer effect). Procedures are also described to validate measured air concentrations by determining the sampling rates before and after exposure and by correcting for the boundary-layer effect. Sampling rates were found to be stable during 2-4-day exposures in a variety of conditions. In contrast, the boundary-layer effect caused the measured air concentrations to be substantially lower than the estimated true air concentrations.