Wastewater Surveillance of US Coast Guard Installations and Seagoing Military Vessels to Mitigate the Risk of COVID-19 Outbreaks, March 2021-August 2022

OBJECTIVES

Military training centers and seagoing vessels are often environments at high risk for the spread of COVID-19 and other contagious diseases, because military trainees and personnel arrive after traveling from many parts of the country and live in congregate settings. We examined whether levels of SARS-CoV-2 genetic material in wastewater correlated with SARS-CoV-2 infections among military personnel living in communal barracks and vessels at US Coast Guard training centers in the United States.

METHODS

The Coast Guard developed and established 3 laboratories with wastewater testing capability at Coast Guard training centers from March 2021 through August 2022. We analyzed wastewater from barracks housing trainees and from 4 Coast Guard vessels for the presence of SARS-CoV-2 genes N and E and quantified the results relative to levels of a fecal indicator virus, pepper mild mottle virus. We compared quantified data with the timing of medically diagnosed COVID-19 infection among (1) military personnel who had presented with symptoms or had been discovered through contact tracing and had medical tests and (2) military personnel who had been discovered through routine surveillance by positive SARS-CoV-2 antigen or polymerase chain reaction test results.

RESULTS

Levels of viral genes in wastewater at Coast Guard locations were best correlated with diagnosed COVID-19 cases when wastewater testing was performed twice weekly with passive samplers deployed for the entire week; such testing detected ≥1 COVID-19 case 69.8% of the time and ≥3 cases 88.3% of the time. Wastewater assessment in vessels did not continue because of logistical constraints.

CONCLUSION

Wastewater testing is an effective tool for measuring the presence and patterns of SARS-CoV-2 infections among military populations. Success with wastewater testing for SARS-CoV-2 infections suggests that other diseases may be assessed with similar approaches.

Direct labeling of monoclonal antibodies with 99mTc and radioimmunodetection of a murine mammary carcinoma with 99mTc-B2C114

Two anti-CEA antibodies, B2C114 and IORCEA1, were radiolabeled with 99mTc by two direct methods (mercaptoethanol and ascorbic acid reduction), and the radio-immunoimaging properties of B2C114 were assessed in mice bearing an M3-reactive tumor. The labeling efficiency was greater than 90% as measured by ITLC in saline, methylethylketone and with serum albumin impregnated sheets using ethanol: water: NH4OH (2:5:1). The label was stable to challenge with excess DTPA, and in the case of ascorbic acid reduction, serum analysis showed that 10-15% of the radioactivity was lost during incubation. In vitro studies demonstrated that the radiolabeled antibodies retained their immunoreactivity. Biodistribution studies in normal Balb/c mice showed that the pattern of uptake was quite similar for both antibodies. Biodistribution of the 99mTc-B2C114 and image studies in the animal model showed that the tumor was clearly visualized and that B2C114 labeled with 99mTc is a possible candidate for human radioimmunodetection of CEA-expressing tumors.

Microbiological Quality of Cream-Type Pies During Processing

In-line samples of crust, filling and topping were collected from pies being prepared by all U.S. firms making frozen cream-type pies for interstate distribution. All firms adhered to Good Manufacturing Practices, as determined by visual inspection. Geometric mean aerobic plate count values were generally low for crust, filling and topping, ranging from 49 CFU/g for topping containing dairy ingredients as it was deposited onto the pie filling to 2400 CFU/g for filling containing dairy ingredients as it was deposited into the crust of the pie. Geometric mean coliform, Escherichia coli and Staphylococcus aureus values were generally lower than the limits of detection, which were 3/g for coliforms and E. coli and 10/g for S. aureus .

Microbiological Quality of Crabmeat During Processing

Duplicate samples of crab and crabmeat (body meat and claw meat) were collected four times a day for two consecutive days at seven in-line locations (plus finished product claw and body meat) along the processing lines of 47 crabmeat plants located along the Atlantic Ocean and Gulf of Mexico coasts of the United States. All the plants adhered to Good Manufacturing Practice, as determined by visual inspection. Two sanitation inspections and sample collections were conducted at 5-month intervals to reflect seasonal variation. In all, 8,477 in-line samples and 2,459 finished product units of blue crab and crabmeat and 522 in-line samples and 128 finished product units of red crab and Maine crab and crabmeat were analyzed microbiologically. Geometric mean aerobic plate count at 35°C (APC 35) values increased from 1,200 CFU/g before pick to 20,000 CFU/g in the finished product (body meat). For claw meat, APC 35 values increased from 15,000 CFU/g before pick to 24,000 CFU/g in the finished product. Aerobic plate count at 30°C (APC 30) values were consistently higher (2-fold or less) than APC 35 values. Coliform counts in both finished products were ≥19/g in approximately 60% of the units. Coliforms exceeded 500/g in 3.8 and 3.2% of the finished product units for body meat and claw meat, respectively. Geometric mean Escherichia coli counts were <3 for all sample sites and finished products, with only 3.3 and 2.7% of the units showing detectable E. coli for body meat and claw meat, respectively. Geometric mean values for Staphylococcus aureus were 16.8/g for finished body meat and 16.0/g for finished claw meat; approximately 20% of the units of both finished products had S. aureus values >100/g. S. aureus counts increased significantly after picking.

Microbiological Quality of Biscuit Dough, Snack Cakes and Soy Protein Meat Extender

The microbiological quality of refrigerated biscuit dough, nonrefrigerated chocolate-flavored cream- or custard-filled snack cakes, and seasoned or unseasoned textured soy or vegetable protein meat extender was determined by a statistically based national survey at the retail level. For refrigerated biscuit dough, geometric means of aerobic plate counts (APC) and counts of yeasts and molds, coliforms, Escherichia coli and Staphylococcus aureus were 34,000, 46, 11, <3 and <3 microorganisms/g, respectively, and for seasoned and unseasoned meat extender 1,500 and 210 (APC seasoned and unseasoned), <25, <3, <3 and <10 microorganisms/g, respectively. Because of the limited availability of unseasoned meat extender in retail markets, the APC of 210 bacteria/g is not necessarily representative of the country.

Microbiological Quality of Frozen Breaded Onion Rings and Tuna Pot Pies

The microbiological quality of precooked or partially cooked frozen breaded onion rings and tuna pot pies was determined by a national sampling at the retail level. The number of units examined and the geometric means for aerobic plate counts at 30 and 35°C, respectively, were 1,590 units of onion rings, 340 and 250/g; tuna pot pies, 1,290 units, 2,400 and 1,600/g. Geometric means for coliform organisms, Escherichia coli and Staphylococcus aureus in onion rings were <3, <3 and <10/g, respectively; those for tuna pies were 5, <3 and <10/g.

Microbiological Quality of Breaded Shrimp During Processing

Duplicate samples of shrimp or breading materials were collected four times a day for two consecutive days at 12 locations along the processing lines of 33 shrimp-breading firms in the United States during 63 inspections. All firms were using good manufacturing practices. For stock shrimp, the geometric mean aerobic plate count at 35°C incubation (APC 35) was reduced from 2.1 × 10⁶ to 3.3 × 10⁵ colony-forming units (CFU)/g for the frozen finished product. At 35°C, an APC 35 of ≤10⁶ CFU/g was found for 78% of the finished samples. At 30°C incubation, the mean APC was reduced from 7.8 × 10⁶ CFU/g for the stock shrimp to 7.6 × 10⁵ CPU/g for the finished product. Coliform mean counts were virtually static (64 to 83/g) up to the batter-breading steps; however, these counts reached 148 to 160/g at the first batter-breading step and remained constant until the breaded shrimp were frozen. Mean Escherichia coli and Staphylococcus aureus counts were ≤3 and ≤10/g, respectively, for all 12 in-line sampling locations. Salmonella organisms were found in one of 118 finished product samples tested for this pathogen.

Microbiological Quality of Fresh Blue Crabmeat, Clams and Oysters

The microbiological quality of fresh blue crabmeat, soft- and hardshell clams and shucked Eastern oysters was determined at the retail (crabmeat, oysters) and wholesale (clams) levels. Geometric means of aerobic plate counts incubated at 35°C were: blue crabmeat 140,000 colony-forming units (CFU)/g, hardshell clams, 950 CFU/g, softshell clams 680 CFU/g and shucked Eastern oysters 390,000 CFU/g. Coliform geometric means ranged from 3,6/100 g for hardshell clams to 21/g for blue crabmeat. Means for fecal coliforms or Escherichia coli ranged from <3/100 g for clams to 27/100 g for oysters, The mean Staphylococcus aureus count in blue crabmeat was 10/g.

Microbiological Quality of Cocoa Powder, Dry Instant Chocolate Drink Mix, Dry Nondairy Coffee Creamer and Frozen Nondairy Topping Obtained at Retail Markets

A national survey was conducted of the microbiological quality of three dry ingredients used in beverages and one frozen non-dairy topping obtained at retail markets. Geometric mean aerobic plate counts (APCs) of units examined at 35°C were as follows: 1,313 units of cocoa powder, 6,600 CFU/g; 1,552 units of dry instant chocolate drink mix, 290 CFU/g; 1,559 units of dry non-dairy coffee creamer, 37 CFU/g; and 1,532 units of frozen non-dairy topping, 34 CFU/g. At 30°C, the geometric mean APC was 34 CFU/g for frozen nondairy topping. Geometric means for most probable number determinations of coliform bacteria and Escherichia coli were <3/g for the four products. Geometric mean values for Staphylococcus aureus in three of the products were <10/g; no S. aureus was found in cocoa powder. Geometric mean values for yeasts and molds in dry instant chocolate drink mix and dry nondairy coffee creamer were 8 and 6 CFU/g, respectively.

Microbiological quality of five potato products obtained at retail markets

The microbiological quality of frozen hash brown potatoes, dried hash brown potatoes with onions, frozen french fried potatoes, dried instant mashed potatoes, and potato salad was determined by a national sampling at the retail level. A wide range of results was obtained, with most sampling units of each products having excellent microbiological quality. Geometric mean aerobic plate counts were as follows: dried hash brown potatoes, 270/g; frozen hash brown potatoes with onions, 580/g; frozen french fried potatoes 78/g; dried instant mashed potatoes, 1.1 x 10(3)/g; and potato salad, 3.6 x 10(3)/g. Mean values of coliforms, Escherichia coli, and Staphylococcus aureus were less than 10/g.

Microbiological quality of some spices and herbs in retail markets

The microbiological quality of 10 spices or herbs was determined by a national survey at the retail level. Aerobic plate count values for the 10 products ranged from less than 100 to 3.1 X 10(8) per g; mean values of the individual spices or herbs ranged from 1,400 to 820,000 per g. Coliform counts ranged from less than 3 to 1.1 X 10(6) per g; however, mean values were less than 20 per g for all products. Escherichia coli counts ranged from less than 3 to 2,300 per g. Except for celery seed, which had a mean value of 7 per g, all mean values were less than 3 per g. Yeast and mold counts were made for 5 of the 10 products. Mean values were generally low; the highest mean (290 per g) was obtained for cinnamon.

Microbiological quality of frozen cauliflower, corn, and peas obtained at retail markets

The microbiological quality of blanched frozen cauliflower, cut corn, and peas at the retail level was determined. At 35 degrees C, mean aerobic plate count (APC) values for cauliflower, corn, and peas, respectively, were 30,000, 6,100, and 4,700 per g; at 30 degrees C, the mean APC values were 45,000, 8,500, and 6,800 per g, respectively. Geometric means for coliform, Escherichia coli, and Staphylococcus aureus counts for all three vegetables were less than 10 per g.

Characterization of Vibrio cholerae isolated from oysters

Of 790 samples of oyster shellstock freshly harvested during a 12-month survey, 111 (most of which were harvested from June through August) contained Vibrio cholerae non-O1 (611 strains), and seven contained O1 Inaba (11 strains) organisms. None of the V. cholerae strains isolated were enterotoxigenic by immunological and biological tests.

Microbiological quality of frozen shrimp and lobster tail in the retail market

The microbiological quality of three frozen shrimp products and frozen lobster tail at the retail level was determined. The number of retail units of the four products examined and the geometric means for aerobic plate counts at 30 and 35 degrees C, respectively, were: 1,464 units of cooked, peeled shrimp--13,000 and 7,200 per g; 1,468 units of raw, peeled shrimp--860,000 and 300,000 per g; 1,300 units of raw, in-shell shrimp--800,000 and 300,000 per g; 1,315 units of lobster tail--140,000 and 42,000 per g. Geometric means for coliform, Escherichia coli, and Staphylococcus aureus counts for all products were < 10 per g.

Usefulness of the stomacher in a microbiological regulatory laboratory

The relative efficiency of the Waring blender, the Stomacher 400, and the Stomacher 3500 for preparing food samples for microbiological analysis was studied. Comparative aerobic plate count (APC) values were determined on 671 samples, representing 30 categories of foods. Of the 26 categories of nonfatty foods, the blender gave significantly higher geometric mean APC values than those given by the Stomacher 400 and the Stomacher 3500 in 65 and 69 percent of the categories, respectively. In a comparison of the two Stomacher models, the Stomacher 400 gave significantly higher geometric mean APC values than these given by the Stomacher 3500 in 73 percent of the food categories. Addition of Tween 80 to four categories of fatty foods at concentrations of 0.5, 1.0, and 2.0 percent did not raise the APC values given by either model of stomacher to the levels given by the Waring blender. Overall, the efficiency of both models of Stomacher, relative to the blender and to each other, was specific and depended upon the particular food being analyzed.

Microbiological quality of frozen breaded fish and shellfish products

A survey was made of the microbiological quality of seven frozen, breaded, precooked fish and shellfish products and of frozen, breaded, uncooked shrimp at the retail level. Geometric mean aerobic plate counts per gram (and number of units examined) were as follows: fish sticks, 8,300 (1,539); fish cakes, 5,600 (1,378); crab cakes, 4,900 (1,226); scallops, 1,700 (1,392); clams, 450 (1,384); haddock, 15,000 (1,306); fish in fish and chips dinner, 7,200 (1,485); and uncooked shrimp, 220,000 (1,462). Geometric mean coliform, Escherichia coli, and Staphylococcus aureus counts for all eight products ranged from 1 to 10/g.