Mass Screening Test Research Articles

Adaptation of the meconium drug test for mass screening

For purposes of mass drug screening, the procedure for analysis of meconium for drugs was modified into a one-step extraction and analysis by enzyme immunoassay. The accuracy of this modified method was tested by comparing the results of simultaneous analysis of 61 meconium samples for cocaine opiate and cannabinoid metabolites by both the original and the modified methods. In 61 samples analyzed, opiate was detected in 8 (13%) samples by the original method and in 9 (15%) by the modified method; cocaine was detected in 39 (64%) samples by the original method and in 39 (64%) by the modified method. The concordance between the negative and positive results of the modified versus the original methods was 98% and 100%, respectively, for opiate and 95% and 98%, respectively, for cocaine. Only one sample was positive for cannabinoid. Thus a comparison of positive results for cannabinoid was not done; however, all the negative results obtained by the modified method were confirmed by the original method. The clinical experience of mass meconium drug testing using the modified method in 1991 is also reported. In four centers tested (total tests = 4409), the prevalence of presence of drug was consistent with the high- or low-risk status of the population. This simplified, rapid procedure can be performed in most clinical laboratories. This adaptation has made the meconium drug test feasible for large-scale clinical and research use.

Conjunctival impression cytology with transfer as a field-applicable indicator of vitamin A status for mass screening.

The increasing importance of vitamin A deficiency in even its mild subclinical form underlines the need for a mass screening test. Clinical, biochemical and cytological methods of assessing vitamin A deficiency in a public health setting have been described and widely used. The cytological method shows promise because it enables early detection of vitamin A deficiency. However interpretation is problematic since histopathological changes are gradual with the progressive disappearance of goblet cells and appearance of enlarged epithelial cells. The reliability and validity of the impression cytology with transfer (ICT) test were assessed in order to produce a meaningful standard for this cytological method. The ICT test was performed in Senegal on 1451 children, in the course of two surveys conducted in 1989 and 1990 in rural areas. Reliability, estimated by Cohen's kappa test for evaluating intra-reader variability, and sensitivity were highest for the abnormal-normal classification (kappa = 0.91; 95% confidence interval (CI): 0.89-0.93; and sensitivity = 74%; 95% CI 66-82%). The ICT method is a cheap, noninvasive and easy test to perform in the field. This method is also reproducible and fairly sensitive according to the abnormal-normal classification. As illustrated by our proposed 50% cutoff of abnormal cytology calculated in relation to 5% of serum retinol values below 0.35 mumol/L criterion, ICT only requires a small sample for the assessment of the overall health of a community in contrast to xerophthalmia and blood vitamin A deficiency tests.

Detection and Mechanisms of Russian Wheat Aphid (Homoptera: Aphididae) Resistance in Barley

A collection of 524 barley lines from areas of the world where the Russian wheat aphid, Diuraphts noxia (Mordvilko), and barley, Hordeum vulgare L., have coexisted was evaluated for sympatric resistance to this pest. Mass screening tests were conducted in a growth chamber and greenhouse with seedlingsplanted in flats. Additional teststo determine the mechanisms of resistance were performed with nine of these lines. The lines and their sources are PI 366444, PI 366447, PI 366449, PI 366450, PI 366453 (Afghanistan); CI 1412, PI 430140, PI 430142 (Iran); and PI 447219 (Spain). Various levels of antibiosis and tolerance were exhibited in most of the lines tested in comparison with ‘Wintermalt’ (CI 15767), the susceptible control. For example, in the antibiosis test, an average of 27.3 nymphs per adult were produced on PI 366449 compared with 50.0 on ‘Wintermalt’. In the tolerance test, plant growth and leaf area of some of the resistant entries were not affected by the Russian wheat aphid, whereas growth and leaf area of infested ‘Wintermalt’ plants was only 61% of noninfested ‘Wintermalt’ plants. Plant survivors of these tests have been saved for developing Russian wheat aphid plant-resistant germplasm for the North American barley industry.

Mass screening for rectal neoplasm in Jiashan county, China

Jiashan county is a rural area in China with very high incidence and mortality rates of colorectal cancer. From 1980 to 1984, we conducted a mass screening for rectal neoplasm in the 11 people's communes in this county. Of the 72,879 individuals who were eligible for screening, 60,496 participated, presenting an overall participation rate of 83.0%. Both the fecal occult blood (OB) test and rectoscopy were performed on 47,560 of the participants, and rectoscopy only was performed on the remaining 12,936 individuals. From the mass screening, 15 rectal cancers, 3 carcinoids, 899 polyps, 98 ulcers, and 7 inflammatory tumors were detected, a total of 1022 cases. Eight of the 15 detected cases of rectal cancer were in Dukes' stage A. We did not find any evidence for an association between schistosomiasis and colorectal cancer. Results from the OB test were found to have a negative correlation with results from rectoscopy (odds ratio = 0.8, 95% CI = 0.6, 1.1). The OB test had a high false positive rate of 32.7%, and a poor positive predictive value of 3.5 %. Both its positive and negative predictive powers were below 1.0, in other words, its positive likelihood ratio was below 1.0 and negative likelihood ratio was above 1.0, indicating that the OB test is not informative and has a poor predictive accuracy for rectal neoplasm. In addition, there were a number of practical problems concerning the use of the OB test for mass screening in the rural community. We therefore recommend rectoscopy, but not the OB test, as a simple, feasible and effective procedure in a screening and control program for rectal cancer in the rural areas, at least in China.

A pilot study on the usefulness of a new test for mass screening of colorectal cancer in Japan

A new screening test (Shamsuddin and Elsayed, 1988) based on the enzymatic detection of the disaccharide beta-D-Gal(1----3)-D-GalNAc in the rectal mucus of patients with colorectal (CR) cancer and precancerous conditions such as inflammatory bowel disease (IBD) and polyp (precancerous lesions) was evaluated in 85 Japanese patients. Following a 15-minute reaction, a sensitivity of 80.0% (8/10) for CR cancer and 72.2% (8/11) for precancerous lesions was obtained. The overall specificity for combined CR cancers and precancerous lesions was 62.2% (28/45). Correlation with abnormal mucin production in the tissues of CR cancer and precancerous lesions was studied by high-iron diamine-Alcian blue and/or periodic acid-Schiff-Alcian blue (pH = 1.0). The agreement of the results with this test was 77.8% (7/9) for CR cancers and 75.0% (6/8) for precancerous conditions. Because of the simplicity of this test, low cost, stability of the sample and reagents and accuracy for CR cancer and precancerous lesions, the test may have potential use for mass screening of cancer and high risk individuals, particularly CR cancer in Japan.

Resistance in Triticale to the Russian Wheat Aphid (Homoptera: Aphididae)

The Russian wheat aphid, Diuraphis noxia (Mordvilko), has become a serious threat to wheat, Triticum spp., production in the western United States. The use of resistant wheat cultivars as a management strategy for this pest is highly desirable. Thus, several collections of wheat and related species have been tested to locate sources of resistance. The USDA-ARS National Triticale Collection, consisting of 731 lines, was one of the collections tested. Initial mass screening tests were done in greenhouse flats in environmental chambers. Seven triticale, xTriticosecale Wittmack, lines with varying degrees of resistance were identified. Four lines from Russia (PI 386148, PI 386149, PI 386150, and PI 386156) and one line from California (CI 82) were the most resistant in the screening tests. Additional tests were done with all seven lines to determine the mechanisms of resistance. Antibiosis appeared to be the most discernible mechanism of resistance, with significantly lower reproduction occurring on the triticales than on ‘TAM W-101’ wheat, Triticum aestivum L., or ‘Snoopy’ rye, Secale cereale L. Greater levels of resistance in the triticales over ‘TAM W-101’ were observed also in antixenosis and tolerance tests. The Russian triticales have been incorporated into the wheat breeding program for development of germplasm resistant to D. noxia .

Estimation of validity of mass screening program for gastric cancer in Osaka, Japan

To assess the validity of mass screening tests for gastric cancer conducted with three types of radiographic techniques, i.e., photofluorography by a mirror camera, photofluorography by an image intensifier, and direct radiography, 105,122 persons who underwent a total of 272,667 screening tests during 1970 through 1982 were followed through December 31, 1983 by means of a record linkage to the Osaka Cancer Registry, Osaka, Japan. The results of 1 year's follow-up from screening were defined as the gold standard and test performance values were calculated. Sensitivity of screening with photofluorography by a mirror camera, photofluorography by an image intensifier, and direct radiography was 90%, 89%, and 91%, and specificity was 86%, 92%, and 91%, respectively. The receiver operating characteristics curve for screening with photofluorography by an image intensifier resembled that for direct radiography and these two curves were located somewhat to the left of the curve for screening with photofluorography by a mirror camera. The authors conclude that the validity of screening with photofluorography by an image intensifier is almost equivalent to that of screening with direct radiography and both are superior to that of screening with photofluorography by a mirror camera.

Blood transfusion in Asia

Transfusion transmitted infections continued to be one of the most serious concern of blood transfusion services in Asia. World wide population surveys show that there are higher incidences of Hepatitis B anti-genaemia in Asian countries (3 to 20%) than in Australia, Europe or the Americas (0.5 to 3%). Mass screening test for HBsAg by EIA method on all donated blood has been carried out since 1984. Positive results are checked and confirmed by neutralization method. Asymptomatic carrier rate has been found to be high. Approximately 9.7% of first time donors are positive for HBsAg whereas the incidence of positivity for anti-HBs and/or anti-HBc is around 35%. To ensure a safe blood supply, protective measures are directed at two main areas of work. At the Blood Donor Centres, this is approached by identifying and excluding potential voluntary non-renurerated donors at risk. In the laboratories, the focus is on improved methods of detecting weak positive HBsAg. Since 1987, 109 samples which gave ultra weak positive results were encountered. Follow up studies involving other markers of HBV are still being continued at three monthly intervals. 77% of these samples remain weakly reactive, while 15% are non-reactive and 8% produce inconsistent results. Results will be updated periodically. Weakly positive samples which lie beyond the lower limits of detection by routine conventional methods might well be a contributory cause of PTH, and could often be mistakenly labelled as that caused by NANBV.

Perspective From the American Academy of Pediatrics

Ten years ago, the initial report of the Committee on Genetics of the American Academy of Pediatrics was published, drawing heavily on the landmark report published 2 years earlier by the National Academy of Sciences. That report stated that new mass screening tests should not be implemented without pilot studies or facilities for follow-up. I would like to deal with the efficacy of screening as determined by pilot studies, the effectiveness of routine screening, and the importance of follow-up. The Cooperative Study of Sickle Cell Disease was essentially the first phase of a large pilot program that systematically demonstrated that sepsis, meningitis, and acute splenic sequestration occurred in young infants with sickle cell disease. Previous reports suggested, and the cooperative study corroborated, that without prior diagnosis many of these infants would die. The randomized trial of oral penicillin prophylaxis was the second phase of the pilot program, demonstrating that early treatment significantly reduced mortality. Thus, the results of this pilot program, conducted with support of the National Institutes of Health, documented that newborn screening for sickle cell disease satisfied a major criterion for screening: An intervention capable of reducing mortality would be efficacious if applied before the usual age of clinical diagnosis. The pilot program was conducted under ideal conditions. The findings are not enough to conclude that screening for sickle cell disease and other hemoglobinopathies will always be effective when performed routinely.

Opportunities for cancer prevention and early detection among children.

The tumors of infants, children, and adolescents are generally deep seated rather than superficially located cancers of epithelial structures. Appropriate mass screening techniques (i.e., pap smear, mammogram, hemoccult test, or chest radiograph) have not been available for the early detection of childhood tumors. It is widely believed that the tumors of children are not suitable for mass screening tests. Therefore, they are diagnosed most often at an advanced stage. An inexpensive urine test has been found to be effective in detecting neuroblastoma at an early, preclinical stage in infants as young as 6 months. The tumors detected in this manner have a high rate of curability. This test appears to be suitable for wide application and has been shown to be both cost-effective and medically effective. Much less is known about the possible causes of the cancers of children than about the cancers of adults, so preventive measures are less well defined. Children in whom cancer develops are more likely to have a genetic predisposition due to one of the rare but numerous heritable genetic defects associated with more than 100 such known syndromes or an acquired genetic defect. Such children are predisposed to cancer because they already have an inherited or acquired somatic genetic lesion and are more susceptible to another genetic insult that results in neoplasia. Such children should be screened regularly for the early detection of cancer. They also constitute a special population to which maximal preventive efforts should be applied, both because they are at high risk and because they constitute a unique population for testing the effectiveness of proposed preventive measures. Cancer is a multifactorial, multistep process that results in the highest incidence of cancer among older adults after a lifetime of exposure to known and presumed cancer risks. Current efforts at cancer prevention are aimed primarily at adults. A greater challenge, which should be even more effective, is to motivate children, their parents, and teachers to prevent the cancers of adults during childhood.

Determination of pyrimidine 5'-nucleotidase (P5N) activity in whole blood as an index of lead exposure.

A simple method for determining pyrimidine 5'-nucleotidase (P5N) activity in whole blood has been developed, inhibiting the plasma activity for UMP-hydrolysis by concanavalin (Con A). Con A specifically inhibits the activity of plasma 5'-nucleotidase (5N) but does not affect erythrocyte P5N activity. The anticoagulant EDTA partially inhibits 5N activity but slightly activates P5N. P5N activity determined by the present method with heparinised blood and Con A was comparable with that by the method reported previously and correlated well with blood lead concentrations. The mean value and SD for P5N activity in normal subjects (n = 72) not exposed to lead are 16.2 and 2.5 mumole/h/g Hb, respectively. The present method can eliminate not only the isolation step of RBC but also Hb determination, the activity being expressed as mumole/h/l blood or RBC. Thus the procedures are so simplified that the assay may be used as a routine test for mass screening of lead exposure.

Determination of urinary vanillylmandelic acid and homovanillic acid by high performance liquid chromatography for mass screening of neuroblastoma.

In order to develop a mass screening method for the early detection of neuroblastoma, we measured urinary vanillylmandelic acid (VMA) and homovanillic acid (HVA) by a high performance liquid chromatography (HPLC) equipped with an electrochemical detector. Urinary samples were collected on a piece of filter paper and then pre-treated by a simple method. Measurement of VMA and HVA was performed within a short period of time, and by about 80 samples per a day could be analyzed by automatic system. The method described herein proved to be reliable, and we thus recommend it as a useful method for measurement of both VMA and HVA, leading to more accurate detection of neuroblastoma in mass screening test.

Reproducibility and diagnostic value of Hemoccult-II test. A colonoscopic evaluation in asymptomatic patients.

Inter-observer agreement rate in double readings of 246 Hemoccult-II tests was 0.88 (Kappa analysis). The slides were not rehydrated. The Hemoccult-II test was performed immediately before 748 total colonoscopies in asymptomatic patients after previous polypectomy or radical surgery for cancer to estimate the diagnostic value of the test in mass screening, accepting a higher prevalence of neoplasia in the study group but realizing that colonoscopy can only be performed in high-risk groups. Another purpose was to investigate the possibility of replacing colonoscopy with Hemoccult-II in surveillance after previous adenoma or cancer. The 79 colonoscopies after a positive test showed cancer in 3, adenomas in 13, and other intestinal pathology in 34 cases. The 669 colonoscopies after negative tests showed cancer in 1, adenomas in 67, and other pathology in 141 cases. In conclusion, the test cannot be used as a guideline for colonoscopy in follow-up programs for patients who have had adenomas, since it missed 84% of the new cases in the present series. The test does not exclude the presence of colorectal carcinoma, but the risk of cancer is probably several times less in patients with negative tests (1 of 669) than in patients with positive tests (3 of 79), which may justify the use of the Hemoccult-II test for mass screening in asymptomatic populations.

Semiautomated enzyme immunoassay of thyrotropin as a mass screening test for neonatal hypothyroidism.

A sensitive, simple, and rapid semiautomated sandwich enzyme immunoassay (EIA) was developed for measuring thyrotropin in dried blood samples on filter paper for use in screening for neonatal hypothyroidism. Good correlation was found between values for thyrotropin determined by this method and those determined by radioimmunoassay (RIA) (r=0.94). In pilot tests on 17,160 newborn infants in the general population, five cases of primary hypothyroidism were detected by both EIA and RIA. The recall rate was slightly highter in EIA than in RIA.

Comparative study on varietal resistance to rice green leafhoppersNephoteitix virescens (Distant) andN. nigropictus (St⇘l)

Employing three different methods, 108 rice varieties were screened for resistance againstN. virescens andN. nigropictus. In mass screening test, 76 varieties suffered significantly less damage byN. virescens, whileN. nigropictus caused less damage to 72 varieties. Ten varietiesviz. Ptb 2, Ptb 18, Ptb 7, Khama 49/8, Ptb 21, DS 1, ARC 6049, Khama 49/2, ARC 10243 and Jhingasail were greatly detrimental to insect bionomics in the studies using first instar nymphs and newly emerged adults. Adult longevity test could be a good criterion to identify the high degree of resistance in the varieties. From an overall assessment, Ptb 18, Ptb 2 and Ptb 7 were identified as highly resistant to both the species.

Application of visual signal detection concepts to clinical decision analysis.

The performance of both clinical diagnostic and mass screening tests is commonly measured in terms of the two basic parameters, sensitivity and specificity. Selection of cut-off points, balancing the sensitivity-specificity trade-off, and comparison with alternative tests are often a matter of arbitrary decisions and are frequently made without consideration of outcome. Some of the concepts used in the analysis of visual signal detection systems can be helpful in this aspect of screening test selection and evaluation. A simplified version of these concepts is developed and its application to clinical and public health optometry is illustrated.

Comparative values of school physical examinations and mass screening tests

In this study mass screenings identified more problems than did physical examinations, but more problems per 100 contacts were identified by physical examinations (51.6) than by screenings (4.7). When time necessary to accomplish the evaluation is considered, screenings are a more efficient way of identifying problems in the general diagnostic categories for which screenings can be provided, but most (85.8%) of the problems identified by physical examination were in categories for which screenings are not provided. Overall, 99.1% of the problems were identified without overlap between physical examinations and screenings. Eighty-three percent of the problems identified by physical examinations were previously unknown. By the end of the school year, 86.3% of the problems identified by physical examinations and 94.5% of those identified by screenings had been or were in the process of being resolved. The integration of physical examinations and screenings in a school setting, staffed by nurse practitioners supported by physicians, can maximize the identification and resolution of health problems.

Comparison of agar-gel diffusion tests, counterimmunoelectrophoresis and enzyme-linked immunosorbent assay in the sera of skin test positives for paragonimiasis

Agar-gel diffusion test (AGD), counterimmunoelectrophoresis (CIEP) and enzyme-linked immunosorbent assay(ELISA) were examined with the sera of skin test positives for paragonimiasis. The crude antigen(Paragonimus whole worm extracts: protein concentration, 7.56mg/ml) and human sera were used in AGD and CIEP. And in ELISA test, diluted antigen with 1:40,000 of crude antigen and diluted sera with 1:100, 1:200 were used in the test. The positive identical ratio between AGD and CIEP reactions is 98 % and negative identical ratio is 100 %. One or three precipitin bands are observed in AGD. One to seven precipitin bands are also revealed in CIEP. Especially, deeply stained bands are observed in CIEP than those of AGD. The positive identical ratios between AGD and ELISA tests are 96 % in 1:100 diluted sera, and 94 % in 1:200 diluted sera. But the negative identical ratios between AGD and ELISA tests are 97 % and 99 % respectively in 1:100 and 1:200 diluted sera. The positive identical ratios between CIEP and ELISA tests are 98 % and 96 % respectively in 1:100 and 1:200 diluted sera, but also 97 % and 99 % in 1:100 and 1:200. Control sera, such as clonorchiasis, amoebiasis and toxoplasmosis, revealed all negatives with Paragonimus antigen in AGD, CIEP and ELISA tests. By above results, ELISA was most sensitive, next CIEP and AGD. But AGD test appears to be more useful when used to crude antigen without cross reaction with other parasitic infections. CIEP test is basically equal in terms of precipitin reaction, but CIEP is able to be detected more sensitively and rapidly though less simple in handiwork than AGD. Consequently, three methods for immunological tests of paragonimiasis have good correlations with one another. Also, each of these has both merits and demerits in immunological test for paragonimiasis. But the ELISA test was proved to be the most sensitive and convenient tool for mass screening test, especially in case of using purified antigen.

A Neonatal Screening Test for Argininosuccinic Acid Lyase Deficiency and Other Urea Cycle Disorders

A simple enzyme-multiple auxotroph assay has been developed for the identification of newborn infants with several of the inherited metabolic defects in the Krebs cycle for the detoxification of ammonia and in the ornithine metabolic pathway. This mass screening test is used with dried filter paper blood specimens and can easily be added to existing multiple testing programs presently used in screening for phenylketonuria or congenital hypothyroidism. This assay can be used to detect patients with citrullinemia, argininosuccinic acid lyase deficiency, and argininemia. In addition to these urea cycle disorders, the several types of ornithinemia, which can result in gyrate atrophy of the retina or mental retardation, should be detectable with this assay. The strengths and weaknesses of this assay are discussed and a large-scale pilot screening trial is proposed.

A new type of hypermethioninemia in neonates.

Eleven hypermethioninemic patients were found by mass screening tests of neonates. Three of these had persistent hypermethioninemia while in the others it was transient. Serum concentrations of methionine were constantly higher than those of controls, especially in the persistent group. The enzyme activities of methionine adenosyltransferase in the liver tissues of both groups of patients were within normal limits. Serum concentrations of total folate in the persistent group were strikingly elevated and fatty degeneration of the liver tissues was a constant feature. It improved after several months under a low-methionine diet. The hypermethioninemia reported here is not associated with any clinical or biochemical finding reported previously.