PFA-100 System: A New Method for Assessment of Platelet Dysfunction.

This is a celebratory reprint of a historical paper published in STH in 1998. The original Abstract follows.The PFA-100 system is a platelet function analyzer designed to measure platelet-related primary hemostasis. The instrument uses two disposable cartridges: a collagen/epinephrine (CEPI) and a collagen/ADP (CADP) cartridge. Previous experience has shown that CEPI cartridges detect qualitative platelet defects, including acetylsalicylic acid (ASA)-induced abnormalities, while CADP cartridges detect only thrombocytopathies and not ASA use. In this seven-center trial, 206 healthy subjects and 176 persons with various platelet-related defects, including 127 ASA users, were studied. The platelet function status was determined by a platelet function test panel. Comparisons were made as to how well the defects were identified by the PFA-100 system and by platelet aggregometry. The reference intervals for both cartridges, testing the 206 healthy subjects, were similar to values described in smaller studies in the literature (mean closure time [CT] of 132 seconds for CEPI and 93 seconds for CADP). The use of different lot numbers of cartridges or duplicate versus singleton testing revealed no differences. Compared with the platelet function status, the PFA-100 system had a clinical sensitivity of 94.9% and a specificity of 88.8%. For aggregometry, a sensitivity of 94.3% and a specificity of 88.3% were obtained. These values are based on all 382 specimens. A separate analysis of sensitivity by type of platelet defect, ASA use versus congenital thrombocytopathies, revealed for the PFA-100 system a 94.5% sensitivity in identifying ASA users and a 95.9% sensitivity in identifying the other defects. For aggregometry, the values were 100% for ASA users and 79.6% for congenital defects. Analysis of concordance between the PFA-100 system and aggregometry revealed no difference in clinical sensitivity and specificity between the systems (p > 0.9999). The overall agreement was 87.5%, with a Kappa index of 0.751. The two tests are thus equivalent in their ability to identify normal and abnormal platelet defects. Testing 126 subjects who took 325 mg ASA revealed that the PFA-100 system (CEPI) was able to detect 71.7% of ASA-induced defects with a positive predictive value of 97.8%. The overall clinical accuracy of the system, calculated from the area under the receiver operating characteristic curve, was 0.977. The data suggest that the PFA-100 system is highly accurate in discriminating normal from abnormal platelet function. The ease of operation of the instrument makes it a useful tool to use in screening patients for platelet-related hemostasis defects.

The Discovery of the Venetian Blind Effect: A Translation of Münster (1941).

Münster, the first to discover the effects of a luminance disparity on perceived depth, described two: (1) The apparent displacement in depth of one of a pair of objects relative to the other when viewed with a luminance disparity, and (2) The apparent overall displacement of objects viewed with a luminance disparity away from the observer. The first, which is the Venetian blind effect, was ascribed to irradiation. Current evidence suggests that irradiation fails to account for the effect, implying that neural mechanisms are involved. The second was thought to be related to the perceived distance of a monocularly viewed stimulus embedded in a dichoptically viewed stimulus. However, the measured effect was probably due to aniseikonia. Münster offered a compelling and seemingly complete account of the Venetian blind effect using irradiation theory. Münster's irradiation theory effectively inhibited further research by relegating the perceived depth displacement to largely non-neural mechanisms. It is now becoming clear that Münster's measurement of the Venetian blind effect represents the discovery of one of several mechanisms supporting stereopsis, though he and many others failed to recognize that discovery at the time.

Laboratory comparison of the VisuLize IX antigen assay with the Asserachrome IX antigen assay.

Factor IX antigen levels are used primarily to assess factor IX levels in patients with liver insufficiency or who are receiving oral vitamin K antagonist therapy. We evaluated the test performance of a new factor IX antigen enzyme-linked immunoassay kit and compared it to our currently used enzyme-linked immunoassay method. Samples from normal donors and patients with known hemophilia B of varying severity were tested by using a predicate factor IX antigen method (Asserachachrome IX:Ag) and a new factor IX antigen method (VisuLize IX Antigen). The 2 methods were evaluated for performance, correlation, differences, and bias. Test samples included 46 normal donors, 14 commercial products, and 16, 18, and 15 severe, moderate, and mildly deficient factor IX deficient plasmas, respectively. The 2 methods correlated well using regression analysis. However, there were significant differences using the paired t test with bias plots indicating higher absolute values for the VisuLize IX antigen method in the severe and moderate deficiency range, but not the normal range. Testing commercially prepared survey material, the Asserachrome method demonstrated a consistently lower result than expected. The VisuLize factor IX is a new method for determining antigenic levels in human plasma. This method has a much shorter incubation time and demonstrates good correlation with current factor IX antigenic methods.

Comparison of samples obtained from 3.2% sodium citrate glass and two 3.2% sodium citrate plastic blood collection tubes used in coagulation testing.

We sought to compare coagulation test results obtained from patients using 2 plastic blood collection tubes and the traditional glass blood collection tube. Blood specimens were obtained from 241 patients in 3.2% buffered sodium citrate using standard glass tubes, in 3.2% buffered sodium citrate in plastic tubes, and in 3.2% sodium citrate "sandwich" tubes (plastic within plastic). All samples were obtained and processed contemporaneously and tested for prothrombin time (PT) and activated partial thromboplastin time (aPTT). Residual plasma was frozen at -70 degrees C for future testing, including fibrinogen, antithrombin, plasminogen, protein C and protein S (functional and antigenic), dilute Russell viper venom time (DRVVT), ristocetin cofactor, factor XIII, D dimer, anti-Xa activity, and prothrombin fragment. Although paired t test analysis revealed statistically significant differences (P < .05) between glass and plastic for PT, aPTT, fibrinogen, protein C (functional and antigenic), functional protein S, DRVVT and confirmation method, antithrombin, and factor XIII, these differences were not considered clinically significant.

Effects of pentasaccharide (fondaparinux) and direct thrombin inhibitors on coagulation testing.

CONTEXT: Direct thrombin inhibitors (DTIs) and fondaparinux represent a new class of anticoagulants. The effects of DTIs on activated partial thromboplastin time and prothrombin time measurements have been reported previously, but there are limited data on the impact of these anticoagulants on other coagulation tests. OBJECTIVE: To determine the effects of fondaparinux and 3 DTIs (argatroban, bivalirudin, and lepirudin) on miscellaneous coagulation tests. DESIGN: Bivalirudin, lepirudin, argatroban, and fondaparinux were added to pooled normal plasma and tested for fibrinogen, antithrombin (thrombin and Xa substrate methods), plasminogen, protein C (clot and chromogenic methods), protein S, von Willebrand factor, D-dimer, lupus anticoagulant testing (dilute Russell viper venom test [DRVVT] with ratio), and factors II, IX, and X activities. RESULTS: We found no drug interference on antithrombin, plasminogen, chromogenic protein C, von Willebrand factor, or D-dimer results. All DTIs falsely decreased fibrinogen values, while falsely increasing protein C and protein S levels. All DTIs prolonged the DRVVT, and only argatroban yielded DRVVT ratios less than 1.2. Lepirudin demonstrated no effect on factor II activity, and only argatroban demonstrated decreased factor X activity. All DTI samples demonstrated a linear, dose-dependent, false decrease of factor IX activity. CONCLUSIONS: Using in vitro methods, we demonstrated DTI effects on numerous clot-based assays, but we found no interference with latex agglutination, chromogenic, or platelet aggregation methods. Fondaparinux only affected measurement of protein S activity. Caution must be used when interpreting coagulation test results on patients receiving these drugs.

Comparing direct thrombin inhibitors using aPTT, ecarin clotting times, and thrombin inhibitor management testing.

BACKGROUND: Patients with heparin-induced thrombocytopenia and thrombosis may be acutely anticoagulated with direct thrombin inhibitors (DTIs). The anticoagulation is typically monitored using the activated partial thromboplastin time (aPTT) or ecarin clotting time (ECT). OBJECTIVE: To compare 14 methods for measuring aPTT, as well as ECT and thrombin inhibitor management test (TIM), in samples containing DTIs. METHODS: DTIs were added to pooled normal plasma to achieve low (0.1-1.2 microg/mL) and high (1.5-8.0 microg/mL) drug concentrations. Each low-concentration DTI sample was tested using all aPTT reagents, while each low- and high-concentration DTI was tested using the ECT and TIM. RESULTS: All aPTT reagents had a significant dose-dependent correlation with drug concentration. Only Actin FSL and APTT-S demonstrated equivalent aPTT ratios obtained from any DTI. The TAS-aPTT was the most sensitive aPTT reagent to argatroban, with the aPTT ranging from 52.7 to 121.2 seconds corresponding to 0.1 to 1.2 microg/mL of drug concentration. The TAS-aPTT and Pathromtin were the most sensitive aPTT reagents to bivalirudin, with aPTTs of 87.4 seconds and 101.5 seconds, respectively, at 1.2 microg/mL of drug. Pathromtin was the most sensitive aPTT reagent to lepirudin, with a maximum aPTT of 108.9 seconds at 1.2 microg/mL of drug. There was no statistically significant difference between the TIM and ECT clotting times for each DTI. Lepirudin and bivalirudin ECT and TIM clotting times were equivalent. CONCLUSIONS: There are unique differences between reagent manufacturers in the monitoring of DTIs. Acceptable alternatives to aPTT monitoring of DTI anticoagulation include the ECT and TIM.

Effect of direct thrombin inhibitors, bivalirudin, lepirudin, and argatroban, on prothrombin time and INR values.

Direct thrombin inhibitors (DTIs) represent a new class of promising anticoagulation agents. The DTIs frequently are used to provide initial anticoagulation, with long-term therapy requiring eventual transition to coumarins. Unfortunately, DTIs not only prolong the activated partial thromboplastin time but also can affect international normalized ratio (INR) values. We approximated the DTI effect on INRs by each drug to pooled plasma at concentrations between 0.1 and 1.2 microg/mL. We then concurrently tested these samples using 14 prothrombin time (PT) reagents. By using repeated measures analysis of variance, we found significant differences (P < .05) between the median INRs for lepirudin and argatroban for all PT reagents, between lepirudin and bivalirudin for all reagents except PT-Fibrinogen HS Plus (P = .07), and between bivalirudin and argatroban for all reagents except Thromborel S (P = .05). The DTI effect on INRs was dependent on drug, drug concentration, and reagent. Argatroban had the most effect on INRs, while lepirudin had the least effect. Reagents with a lower international sensitivity index were less affected by DTI; ThromboMax HS was the least sensitive PT reagent to any DTI.

Blastic mantle cell lymphoma developing concurrently in a patient with chronic myelogenous leukemia and a review of the literature.

Non-Hodgkin's lymphoma (NHL) occurring as a synchronous malignancy with chronic myelogenous leukemia (CML) is rare. To our knowledge, this is the first case reported of a patient who developed mantle cell lymphoma (MCL) after therapy with imatinib mesylate for CML. After a 3-year history of CML, the patient developed a lymphocytosis associated with diarrhea, anorexia, and weight loss. Imaging studies revealed abdominal adenopathy and extensive lymphomatous infiltration of the liver, stomach, pancreas, and kidneys. Flow cytometric and cytogenetic studies were consistent with MCL. Fluorescence in situ hybridization (FISH) of the bone marrow revealed a genetically distinct lymphoid neoplasm rather than an extramedullary blast crisis of CML. The development of lung cancer, prostate cancer, CML and MCL in this patient suggests a genetic predisposition, although other factors, including environmental exposures and therapy with imatinib mesylate could have had a contributory or synergistic role in the development of MCL.

Variability of plasma anti-Xa activities with different lots of enoxaparin.

BACKGROUND: Previous studies have indicated the variability of anti-Xa activity in different sources of heparin and the variability of different methods used for measuring anti-Xa activity. Manufacturers of low-molecular-weight heparins (LMWHs) determine each lot's anti-Xa activity against the World Health Organization standard, but little information is known about anti-Xa activity variation between lots of LMWH and the impact on reported anti-Xa activity in patient samples. OBJECTIVE: To determine the variation of plasma anti-Xa activity in patients receiving enoxaparin when different lots of enoxaparin are used for test calibration. METHODS: We obtained 7 lots of enoxaparin containing approximately 10,000 IU/mL and one lot containing approximately 15,000 IU/mL of anti-Xa activity. For each lot, a 2.0 anti-Xa IU/mL dilution was prepared and a calibration curve performed using a chromogenic method. To test the variation in reported results between the different calibration lots, 20 patient samples were tested. Nineteen patients receiving enoxaparin and one patient not receiving enoxaparin (negative control) were tested in a blinded fashion, and the changes in light absorbance recorded. Anti-Xa activity results from tested plasmas were then extrapolated from each enoxaparin lot calibration curve. RESULTS: Using Student's paired t-test, there were statistically significant differences between the plasma anti-Xa activities generated from the various enoxaparin lots. In the range of 0.5-1.0 IU/mL of anti-Xa activity, 3 (4.2%) samples had a >0.2 IU/mL difference (maximum difference 0.33 IU/mL) in anti-Xa activity between 2 lots of enoxaparin. For samples that had supratherapeutic anti-Xa activities (1.0-1.5 IU/mL anti-Xa activity), there was a wider variation (>0.2 IU/mL) in anti-Xa activity, which may have resulted in a dosing change. CONCLUSIONS: The statistical differences in plasma anti-Xa activities noted between enoxaparin lots are not clinically significant. However, anti-Xa activities in the upper therapeutic and supratherapeutic ranges (>1.0 IU/mL of anti-Xa activity) resulted in a deviation of >0.3 IU/mL in reported anti-Xa activity, which may result in dosing changes.

Anti-Xa stability of diluted enoxaparin for use in pediatrics.

BACKGROUND: The use of enoxaparin in low-weight pediatric patients is becoming common practice. Anti-Xa stability of unit-dose syringes prepared after dilution beyond one day is presently unknown. OBJECTIVE: To evaluate the anti-Xa stability of diluted enoxaparin stored in glass vials and tuberculin syringes. METHODS: Four separate batches of enoxaparin were diluted with sterile water to a final concentration of 20 mg/mL (2000 IU/mL) and aliquoted into plastic 1-mL syringes containing 6 mg (0.3 mL) or maintained in the glass vial. Syringes were stored at room temperature or under refrigeration. The glass vial used for diluting was stored at room temperature. The anti-Xa activity was measured on the date of preparation to 4 weeks. Statistical comparisons determined whether differences in anti-Xa activity in diluted enoxaparin are affected by the storage medium or temperature. A paired t-test was used to determine any significant differences between the anti-Xa activity on date of preparation (baseline) and subsequent time periods, with p < 0.05 considered statistically significant. RESULTS: The mean baseline anti-Xa activity was 2607 IU/mL (95% CI 2300 to 2914). No measurable decrease occurred in diluted enoxaparin anti-Xa activity in the glass vial maintained over the 4-week period. Compared with the glass vial, room temperature and refrigerated syringe samples had trending decreases of anti-Xa activity at weeks 3 and 4, but did not reach statistical significance. CONCLUSIONS: A nonsignificant decrease in anti-Xa activity occurred starting at day 22 for the diluted enoxaparin in tuberculin syringes, regardless of storage temperature. Storage up to 4 weeks of diluted enoxaparin in glass or prefilled syringes does not result in a statistically significant loss of anticoagulant potential, as measured by anti-Xa activity.

Comparison of six D-dimer methods in patients suspected of deep vein thrombosis.

We evaluated six D-dimer methods to determine their sensitivity, specificity, and negative predictive values (NPV) in symptomatic patients suspected of deep vein thrombosis (DVT). In patients suspected of DVT a whole blood D-dimer test (SimpliRED, Agen) was performed, and then tested using enzyme-linked immunosorbent assay (VIDAS D-Dimer, BioMerieux; Asserachrome D-Di, Stago International; Dimertest Gold, Agen) and automated immunoturbidometric methods (Advanced D-Dimer, Dade Behring; MiniQuant, Biopool). Each D-dimer method was independently compared with radiographic results to determine sensitivity and NPV. There were 151 patients enrolled in the study. Thirty-five (23.2%) patients had a positive Doppler ultrasound, with 26 proximal, eight distal, and one patient with both proximal and distal thrombus. Two patients (1.3%) had inconclusive studies and were excluded from the analyses. For all patients, the sensitivities for the rapid D-dimer methods were: SimpliRED, 82.3% [95% confidence interval (CI), 80.3-84.3%]; VIDAS D-Dimer, 91.4% (95% CI, 89.9-92.9%); MiniQuant D-Dimer, 96.3% (95% CI, 95.1-97.5%); and Advanced D-Dimer, 97.1% (95% CI, 96.3-97.9%). The sensitivity improved for SimpliRED (86.4%; 95% CI, 83.3-89.4%), VIDAS D-Dimer (95.5%; 95% CI, 85.0-100%), MiniQuant D-Dimer (100%; 95% CI, 96.9-100%) and Advanced D-Dimer (100%; 95% CI, 98.9-100%) in the inpatient population. The automated immunoturbidometric methods, the MiniQuant D-Dimer and Advanced D-Dimer, demonstrated comparable sensitivities and NPV with the VIDAS D-Dimer method in symptomatic patients suspected of DVT, which would suggest that these newer D-dimer methods could be used as part of the diagnostic algorithm for patients suspected of DVT.

Effects of hemoglobin glutamer-250 (bovine) (HBOC-201, Hemopure) on coagulation testing.

Polymerized bovine hemoglobin is currently under investigation as an alternative to blood-banked human red blood cells. Because of the dark red hemolyzed appearance of hemoglobin-based oxygen carrier (HBOC)-201, we sought to describe the effects of HBOC-201 on coagulation analyzers that perform prothrombin times, activated partial thromboplastin times, fibrinogen, and antithrombin. Pooled normal plasma was combined with HBOC-201 to achieve plasma hemoglobin levels of 1.4, 2.6, 3.8, 4.8, and 6.2 g/dL. Results for each test using HBOC-201-prepared plasma were compared with results using saline-matched controls. Two consecutive absolute result differences of >10% between saline controls and HBOC-201 samples were used for determining interference in test accuracy by the concentration of HBOC-201. Mechanical detection methods (fibrometer, STA, CS-190) and the MDA-180 method were less affected by increasing levels of HBOC-201 than optical detection devices for all test parameters.

Microvascular abnormalities in sickle cell disease: a computer-assisted intravital microscopy study.

The conjunctival microcirculation of 18 homozygous sickle cell disease (SCD) patients during steady-state, painful crisis, and postcrisis conditions was recorded on high-resolution videotapes using intravital microscopy. Selected videotape sequences were subsequently coded, frame-captured, studied, and blindly analyzed using computer-assisted image analysis protocols. At steady-state (baseline), all SCD patients exhibited some of the following morphometric abnormalities: abnormal vessel diameter, comma signs, blood sludging, boxcar blood flow phenomenon, distended vessels, damaged vessels, hemosiderin deposits, vessel tortuosity, and microaneurysms. There was a decrease in vascularity (diminished presence of conjunctival vessels) in SCD patients compared with non-SCD controls, giving the bulbar conjunctiva a "blanched" avascular appearance in most but not all SCD patients during steady-state. Averaged steady-state red cell velocity in SCD patients was slower than in non-SCD controls. During painful crisis, a further decrease in vascularity (caused by flow stoppage in small vessels) and a 36.7% +/- 5.2% decrease in large vessel (mostly venular) diameter resulted. In addition, the conjunctival red cell velocities either slowed significantly (6.6% +/- 13.1%; P <.01) or were reduced to a trickle (unmeasurable) during crisis. The microvascular changes observed during crisis were transient and reverted to steady-state baseline after resolution of crisis. When combined, intravital microscopy and computer-assisted image analysis (computer-assisted intravital microscopy) represent the availability of a noninvasive tool to quantify microvascular abnormalities in vascular diseases, including sickle cell disease. The ability to identify and relocate the same conjunctival vessels for longitudinal studies uniquely underscores the applicability of this quantitative real-time technology.

Microvascular abnormalities in pediatric diabetic patients.

Microvascular abnormalities are associated with and causative of the development of end-stage organ complications in adult diabetic patients. Whether the same microvascular abnormalities are present in pediatric patients is not known and has not been studied because of a lack of real-time technology, methodology to study young patients, and availability of an appropriate noninvasive site for in vivo studies. We hypothesized that microvascular abnormalities should be present in pediatric patients despite their young age and the relatively short durations of the disease. In this study, computer-assisted intravital microscopy (CAIM) was adapted to blindly quantify microvascular abnormalities in 12 pediatric type 1 diabetic mellitus (T1DM) patients (ages = 6-16 years; mean +/- SD = 11.42 +/- 3.42; duration since diagnosis = 2-14 years; mean +/- SD = 6.75 +/- 3.79) in vivo, using the microcirculation of the bulbar conjunctiva as a noninvasive site. Microvascular abnormalities, commonly found in adult patients, existed in the conjunctival microcirculation of all pediatric T1DM patients in varying degrees despite their relatively young age. A severity index (SI) was developed to reflect the cumulative severity of the microvascular abnormalities and was computed as the summation of all microvascular abnormalities found in each patient. SI for the 12 T1DM patients (mean +/- SD = 7.42 +/- 1.88; median = 8; mode = 9) differed significantly from that for the nondiabetic controls (mean +/- SD = 0.67 +/- 0.78; median = 0.5; mode = 0; P < 0.0001). In addition, SI correlated with hemoglobin A1c levels (mean +/- SD = 9.18 +/- 1.57) of T1DM patients but did not correlate with the duration of disease since diagnosis of the same patients. This observation raises the possibility that diabetic pathogenesis may precede the onset of overt disease or clinical diagnosis. This study confirms that CAIM may represent the availability of a useful real-time technology to study conjunctival microvascular abnormalities in vascular diseases in juvenile as well as adult patients.

Comparative Thermal Resistance of Human and Simian Rotaviruses Assayed on Cells Grown in a Serum-Free Medium.

Thermal resistance of the Wa strain of human rotavirus was compared with that of SA-11 simian rotavirus in a plaque assay with MA-104 cells grown in conventional cell culture medium supplemented with filtrate from reconstituted and acid-precipitated nonfat dry milk. Both viruses produced two-component survival curves at 56 and 60°C. Average D-values (min) for the Wa human virus were 306.3 at 56°C, 47.8 at 60°C, 12.3 at 62.8°C and 2.4 at 65°C, with a z-value of 4.33°C. For the SA-11 simian virus, the average D-values were 890.5 at 56°C, with a z-value of 4.35°C. These values indicate that low levels of rotavirus should be inactivated by pasteurization processes.

A Method for Recovery of Poliovirus 1 from a Variety of Foods.

A method was developed for the recovery of low numbers of plaque-forming units (PFU) of inoculated poliovirus type 1 from seven different foods. Viruses were eluted at pH 9.0 from 25-g food test portions, concentrated at pH 4.5, and eluted at pH 7.5. The final eluates were assayed for PFU in African green monkey kidney (BGM) cell monolayers. The average virus input ranged from 55 to 79 PFU per unit portion. The average percent recoveries were as follows: potato salad, 61; radishes, 54; celery, 45; mushrooms, 44; carrots, 42; clams, 38; and oysters, 35. Three control products were negative for each food.

Thermal Resistance of Three Parvoviruses: A Possible Human Isolate, the Minute Virus of Mice, and the Latent Rat Virus.

Thermal inactivation of three parvoviruses - a possible human isolate (H-1), the minute virus of mice (MVM), and the latent rat virus (RV) - was investigated over a wide range of time and temperature contacts. The H-1 virus was inactivated at a lower FN50 value than were the RV and HVM. Ten minute inactivating temperatures were 74.5°C for H-1 virus, 86.5°C for MVM and 88.5°C for RV when inocula concentrations were ca. 1 × 103. All three viruses were shown to survive when processed at the milk pasteurization times and temperatures advocated in the U.S. Public Health Service milk ordinance and code.

Foodborne Viruses: Their Importance and Need for Research 1.

All viruses known to be normally transmissible through foods and of concern to human health emanate from the human intestine. The outbreaks of hepatitis A and recently of gastroenteritis attributed to Norwalk-like viruses most likely developed from feces-contaminated fingers of infected food handlers or water polluted with feces. With few exceptions no recorded outbreak has depended on the ability of virus to withstand even limited heating in food. New and better methods of detection are needed for hepatitis A and Norwalk viruses in foods. It has been well documented that international trade in food products of animal origin can result in the introduction of animal disease into areas in which the disease does not exist. This fact has given rise to programs of research and development for industrially applicable technology to rid animal products from the agents of animal diseases. The survival of viruses inclusive of etiological agents of foot-and-mouth disease, African swine fever, swine vesicular disease and hog cholera virus is reviewed in this paper and new research approaches are suggested. The general need for additional research of foodborne viruses is discussed.

Persistence of Polioviruses in Shellstock and Shucked Oysters Stored at Refrigeration Temperature.

Poliovirus persistence was monitored in shellstock and shucked oysters stored at 5°C. The oysters either bioaccumulated viruses from seawater contaminated with feces-associated or cell-culture-grown viruses or they were innoculated with a needle and syringe. The viruses were detected in the oysters for > 28 d, the longest estimated time period between harvest and consumption of fresh oysters. These results indicate that if oysters are contaminated when harvested, they will probably be contaminated when purchased for processing in the home or food establishment.

Food Contaminants - Viruses.

Viruses have been detected in a limited number of foods. Although methods used to examine these foods were usually restricted to detection of human enteroviruses, animal viruses were found in some meats, milk, and eggs; limitations in methodology may have caused other viruses present to go undetected. As the sensitivity of methods increases, studies are being undertaken to detect a greater variety of human intestinal viruses. Data from these investigations should provide the information needed to determine the incidence and public health significance of food contamination by viruses. In areas where virus-contaminated foods may be expected, washing and heating foods to 70 C should provide reasonable protection against the inadvertent consumption of viruses.