PCR technology offers alternatives to conventional diagnosis ofCryptosporidium for both clinical and environmental samples. We compared microscopic examination by a conventional acid-fast staining procedure with a recently developed PCR test that can not only detect Cryptosporidium but is also able to differentiate between what appear to be host-adapted genotypes of the parasite. Examinations were performed on 511 stool specimens referred for screening on the basis of diarrhea. PCR detected a total of 36 positives out of the 511 samples, while routine microscopy detected 29 positives. Additional positives detected by PCR were eventually confirmed to be positive by microscopy. A total of five samples that were positive by routine microscopy at Western Diagnostic Pathology but negative by PCR and by microscopy in our laboratory were treated as false positives. Microscopy therefore exhibited 83.7% sensitivity and 98.9% specificity compared to PCR. PCR was more sensitive and easier to interpret but required more hands-on time to perform and was more expensive than microscopy. PCR, however, was very adaptable to batch analysis, reducing the costs considerably. Bulk buying of reagents and modifications to the procedure would decrease the cost of the PCR test even more. An important advantage of the PCR test, its ability to directly differentiate between different Cryptosporidiumgenotypes, will assist in determining the source of cryptosporidial outbreaks. Sensitivity, specificity, ability to genotype, ease of use, and adaptability to batch testing make PCR a useful tool for future diagnosis and studies on the molecular epidemiology ofCryptosporidium infections.
. Cost effectiveness of two methods of screening for asymptomatic bacteriuria. A comparison of two methods of screening schoolgirls for asymptomatic bacteriuria has shown that a supervised method of collection successfully obtained specimens of urine from 96 3%, but that the home self-administered use of dipslides was successful in only 702%. The failure to obtain the return of satisfactory dipslides was most frequent in children under seven and over 11 years of age, and in children from the lower social classes; satisfactory dipslides were returned by 84% of children from social classes I, II, and III non-manual workers, but by only 58% of children from social class V and the unemployed. The cost per child screened was £0-77 with the supervised method and £0 26 with the dipslide method. An alternative supervised method which would have successfully screened 85% would have cost £0' 55 per child screened. Using the home dipslide method, the cost per case of asymptomatic bacteriuria detected would vary from £10 40 to £20-00, depending on the age group screened.
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